import os
import time
import math
import copy
from functools import partial
from typing import Optional, Callable, Any
from collections import OrderedDict

import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.utils.checkpoint as checkpoint
from timm.models.layers import DropPath, trunc_normal_
from fvcore.nn import FlopCountAnalysis, flop_count_str, flop_count, parameter_count

DropPath.__repr__ = lambda self: f"timm.DropPath({self.drop_prob})"
# train speed is slower after enabling this opts.
# torch.backends.cudnn.enabled = True
# torch.backends.cudnn.benchmark = True
# torch.backends.cudnn.deterministic = True

try:
    from .csm_triton import cross_scan_fn, cross_merge_fn
except:
    from csm_triton import cross_scan_fn, cross_merge_fn

try:
    from .csms6s import selective_scan_fn, selective_scan_flop_jit
except:
    from csms6s import selective_scan_fn, selective_scan_flop_jit

# FLOPs counter not prepared fro mamba2
try:
    from .mamba2.ssd_minimal import selective_scan_chunk_fn
except:
    from mamba2.ssd_minimal import selective_scan_chunk_fn


# =====================================================
# we have this class as linear and conv init differ from each other
# this function enable loading from both conv2d or linear
class Linear2d(nn.Linear):
    def forward(self, x: torch.Tensor):
        # B, C, H, W = x.shape
        return F.conv2d(x, self.weight[:, :, None, None], self.bias)

    def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs):
        state_dict[prefix + "weight"] = state_dict[prefix + "weight"].view(self.weight.shape)
        return super()._load_from_state_dict(state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs)


class LayerNorm2d(nn.LayerNorm):
    def forward(self, x: torch.Tensor):
        x = x.permute(0, 2, 3, 1)
        x = nn.functional.layer_norm(x, self.normalized_shape, self.weight, self.bias, self.eps)
        x = x.permute(0, 3, 1, 2)
        return x


class PatchMerging2D(nn.Module):
    def __init__(self, dim, out_dim=-1, norm_layer=nn.LayerNorm, channel_first=False):
        super().__init__()
        self.dim = dim
        Linear = Linear2d if channel_first else nn.Linear
        self._patch_merging_pad = self._patch_merging_pad_channel_first if channel_first else self._patch_merging_pad_channel_last
        self.reduction = Linear(4 * dim, (2 * dim) if out_dim < 0 else out_dim, bias=False)
        self.norm = norm_layer(4 * dim)

    @staticmethod
    def _patch_merging_pad_channel_last(x: torch.Tensor):
        H, W, _ = x.shape[-3:]
        if (W % 2 != 0) or (H % 2 != 0):
            x = F.pad(x, (0, 0, 0, W % 2, 0, H % 2))
        x0 = x[..., 0::2, 0::2, :]  # ... H/2 W/2 C
        x1 = x[..., 1::2, 0::2, :]  # ... H/2 W/2 C
        x2 = x[..., 0::2, 1::2, :]  # ... H/2 W/2 C
        x3 = x[..., 1::2, 1::2, :]  # ... H/2 W/2 C
        x = torch.cat([x0, x1, x2, x3], -1)  # ... H/2 W/2 4*C
        return x

    @staticmethod
    def _patch_merging_pad_channel_first(x: torch.Tensor):
        H, W = x.shape[-2:]
        if (W % 2 != 0) or (H % 2 != 0):
            x = F.pad(x, (0, 0, 0, W % 2, 0, H % 2))
        x0 = x[..., 0::2, 0::2]  # ... H/2 W/2
        x1 = x[..., 1::2, 0::2]  # ... H/2 W/2
        x2 = x[..., 0::2, 1::2]  # ... H/2 W/2
        x3 = x[..., 1::2, 1::2]  # ... H/2 W/2
        x = torch.cat([x0, x1, x2, x3], 1)  # ... H/2 W/2 4*C
        return x

    def forward(self, x):
        x = self._patch_merging_pad(x)
        x = self.norm(x)
        x = self.reduction(x)

        return x


class Permute(nn.Module):
    def __init__(self, *args):
        super().__init__()
        self.args = args

    def forward(self, x: torch.Tensor):
        return x.permute(*self.args)


class Mlp(nn.Module):
    def __init__(self, in_features, hidden_features=None, out_features=None, act_layer=nn.GELU, drop=0.,channels_first=False):
        super().__init__()
        out_features = out_features or in_features
        hidden_features = hidden_features or in_features

        Linear = Linear2d if channels_first else nn.Linear
        self.fc1 = Linear(in_features, hidden_features)
        self.act = act_layer()
        self.fc2 = Linear(hidden_features, out_features)
        self.drop = nn.Dropout(drop)

    def forward(self, x):
        x = self.fc1(x)
        x = self.act(x)
        x = self.drop(x)
        x = self.fc2(x)
        x = self.drop(x)
        return x


class gMlp(nn.Module):
    def __init__(self, in_features, hidden_features=None, out_features=None, act_layer=nn.GELU, drop=0.,channels_first=False):
        super().__init__()
        self.channel_first = channels_first
        out_features = out_features or in_features
        hidden_features = hidden_features or in_features

        Linear = Linear2d if channels_first else nn.Linear
        self.fc1 = Linear(in_features, 2 * hidden_features)
        self.act = act_layer()
        self.fc2 = Linear(hidden_features, out_features)
        self.drop = nn.Dropout(drop)

    def forward(self, x: torch.Tensor):
        x = self.fc1(x)
        x, z = x.chunk(2, dim=(1 if self.channel_first else -1))
        x = self.fc2(x * self.act(z))
        x = self.drop(x)
        return x


class SoftmaxSpatial(nn.Softmax):
    def forward(self, x: torch.Tensor):
        if self.dim == -1:
            B, C, H, W = x.shape
            return super().forward(x.view(B, C, -1)).view(B, C, H, W)
        elif self.dim == 1:
            B, H, W, C = x.shape
            return super().forward(x.view(B, -1, C)).view(B, H, W, C)
        else:
            raise NotImplementedError


# =====================================================
class mamba_init:
    @staticmethod
    def dt_init(dt_rank, d_inner, dt_scale=1.0, dt_init="random", dt_min=0.001, dt_max=0.1, dt_init_floor=1e-4):
        dt_proj = nn.Linear(dt_rank, d_inner, bias=True)

        # Initialize special dt projection to preserve variance at initialization
        dt_init_std = dt_rank**-0.5 * dt_scale
        if dt_init == "constant":
            nn.init.constant_(dt_proj.weight, dt_init_std)
        elif dt_init == "random":
            nn.init.uniform_(dt_proj.weight, -dt_init_std, dt_init_std)
        else:
            raise NotImplementedError

        # Initialize dt bias so that F.softplus(dt_bias) is between dt_min and dt_max
        dt = torch.exp(
            torch.rand(d_inner) * (math.log(dt_max) - math.log(dt_min))
            + math.log(dt_min)
        ).clamp(min=dt_init_floor)
        # Inverse of softplus: https://github.com/pytorch/pytorch/issues/72759
        inv_dt = dt + torch.log(-torch.expm1(-dt))
        with torch.no_grad():
            dt_proj.bias.copy_(inv_dt)
        # Our initialization would set all Linear.bias to zero, need to mark this one as _no_reinit
        # dt_proj.bias._no_reinit = True
        
        return dt_proj

    @staticmethod
    def A_log_init(d_state, d_inner, copies=-1, device=None, merge=True):
        # S4D real initialization
        A = torch.arange(1, d_state + 1, dtype=torch.float32, device=device).view(1, -1).repeat(d_inner, 1).contiguous()
        A_log = torch.log(A)  # Keep A_log in fp32
        if copies > 0:
            A_log = A_log[None].repeat(copies, 1, 1).contiguous()
            if merge:
                A_log = A_log.flatten(0, 1)
        A_log = nn.Parameter(A_log)
        A_log._no_weight_decay = True
        return A_log

    @staticmethod
    def D_init(d_inner, copies=-1, device=None, merge=True):
        # D "skip" parameter
        D = torch.ones(d_inner, device=device)
        if copies > 0:
            D = D[None].repeat(copies, 1).contiguous()
            if merge:
                D = D.flatten(0, 1)
        D = nn.Parameter(D)  # Keep in fp32
        D._no_weight_decay = True
        return D

    @classmethod
    def init_dt_A_D(cls, d_state, dt_rank, d_inner, dt_scale, dt_init, dt_min, dt_max, dt_init_floor, k_group=4):
        # dt proj ============================
        dt_projs = [
            cls.dt_init(dt_rank, d_inner, dt_scale, dt_init, dt_min, dt_max, dt_init_floor)
            for _ in range(k_group)
        ]
        dt_projs_weight = nn.Parameter(torch.stack([t.weight for t in dt_projs], dim=0)) # (K, inner, rank)
        dt_projs_bias = nn.Parameter(torch.stack([t.bias for t in dt_projs], dim=0)) # (K, inner)
        del dt_projs
            
        # A, D =======================================
        A_logs = cls.A_log_init(d_state, d_inner, copies=k_group, merge=True) # (K * D, N)
        Ds = cls.D_init(d_inner, copies=k_group, merge=True) # (K * D)  
        return A_logs, Ds, dt_projs_weight, dt_projs_bias


# support: v0, v0seq
class SS2Dv0:
    def __initv0__(
        self,
        # basic dims ===========
        d_model=96,
        d_state=16,
        ssm_ratio=2.0,
        dt_rank="auto",
        # ======================
        dropout=0.0,
        # ======================
        seq=False,
        force_fp32=True,
        **kwargs,
    ):
        if "channel_first" in kwargs:
            assert not kwargs["channel_first"]
        act_layer = nn.SiLU
        dt_min = 0.001
        dt_max = 0.1
        dt_init = "random"
        dt_scale = 1.0
        dt_init_floor = 1e-4
        bias = False
        conv_bias = True
        d_conv = 3
        k_group = 4
        factory_kwargs = {"device": None, "dtype": None}
        super().__init__()
        d_inner = int(ssm_ratio * d_model)
        dt_rank = math.ceil(d_model / 16) if dt_rank == "auto" else dt_rank

        self.forward = self.forwardv0 
        if seq:
            self.forward = partial(self.forwardv0, seq=True)
        if not force_fp32:
            self.forward = partial(self.forwardv0, force_fp32=False)

        # in proj ============================
        self.in_proj = nn.Linear(d_model, d_inner * 2, bias=bias)
        self.act: nn.Module = act_layer()
        self.conv2d = nn.Conv2d(
            in_channels=d_inner,
            out_channels=d_inner,
            groups=d_inner,
            bias=conv_bias,
            kernel_size=d_conv,
            padding=(d_conv - 1) // 2,
            **factory_kwargs,
        )

        # x proj ============================
        self.x_proj = [
            nn.Linear(d_inner, (dt_rank + d_state * 2), bias=False)
            for _ in range(k_group)
        ]
        self.x_proj_weight = nn.Parameter(torch.stack([t.weight for t in self.x_proj], dim=0)) # (K, N, inner)
        del self.x_proj

        # dt proj, A, D ============================
        self.A_logs, self.Ds, self.dt_projs_weight, self.dt_projs_bias = mamba_init.init_dt_A_D(
            d_state, dt_rank, d_inner, dt_scale, dt_init, dt_min, dt_max, dt_init_floor, k_group=4,
        )

        # out proj =======================================
        self.out_norm = nn.LayerNorm(d_inner)
        self.out_proj = nn.Linear(d_inner, d_model, bias=bias)
        self.dropout = nn.Dropout(dropout) if dropout > 0. else nn.Identity()

    def forwardv0(self, x: torch.Tensor, seq=False, force_fp32=True, **kwargs):
        x = self.in_proj(x)
        x, z = x.chunk(2, dim=-1) # (b, h, w, d)
        z = self.act(z)
        x = x.permute(0, 3, 1, 2).contiguous()
        x = self.conv2d(x) # (b, d, h, w)
        x = self.act(x)
        selective_scan = partial(selective_scan_fn, backend="mamba")
        
        B, D, H, W = x.shape
        D, N = self.A_logs.shape
        K, D, R = self.dt_projs_weight.shape
        L = H * W

        x_hwwh = torch.stack([x.view(B, -1, L), torch.transpose(x, dim0=2, dim1=3).contiguous().view(B, -1, L)], dim=1).view(B, 2, -1, L)
        xs = torch.cat([x_hwwh, torch.flip(x_hwwh, dims=[-1])], dim=1) # (b, k, d, l)

        x_dbl = torch.einsum("b k d l, k c d -> b k c l", xs, self.x_proj_weight)
        if hasattr(self, "x_proj_bias"):
            x_dbl = x_dbl + self.x_proj_bias.view(1, K, -1, 1)
        dts, Bs, Cs = torch.split(x_dbl, [R, N, N], dim=2)
        dts = torch.einsum("b k r l, k d r -> b k d l", dts, self.dt_projs_weight)

        xs = xs.view(B, -1, L) # (b, k * d, l)
        dts = dts.contiguous().view(B, -1, L) # (b, k * d, l)
        Bs = Bs.contiguous() # (b, k, d_state, l)
        Cs = Cs.contiguous() # (b, k, d_state, l)
        
        As = -self.A_logs.float().exp() # (k * d, d_state)
        Ds = self.Ds.float() # (k * d)
        dt_projs_bias = self.dt_projs_bias.float().view(-1) # (k * d)

        # assert len(xs.shape) == 3 and len(dts.shape) == 3 and len(Bs.shape) == 4 and len(Cs.shape) == 4
        # assert len(As.shape) == 2 and len(Ds.shape) == 1 and len(dt_projs_bias.shape) == 1
        to_fp32 = lambda *args: (_a.to(torch.float32) for _a in args)
        
        if force_fp32:
            xs, dts, Bs, Cs = to_fp32(xs, dts, Bs, Cs)

        if seq:
            out_y = []
            for i in range(4):
                yi = selective_scan(
                    xs.view(B, K, -1, L)[:, i], dts.view(B, K, -1, L)[:, i], 
                    As.view(K, -1, N)[i], Bs[:, i].unsqueeze(1), Cs[:, i].unsqueeze(1), Ds.view(K, -1)[i],
                    delta_bias=dt_projs_bias.view(K, -1)[i],
                    delta_softplus=True,
                ).view(B, -1, L)
                out_y.append(yi)
            out_y = torch.stack(out_y, dim=1)
        else:
            out_y = selective_scan(
                xs, dts, 
                As, Bs, Cs, Ds,
                delta_bias=dt_projs_bias,
                delta_softplus=True,
            ).view(B, K, -1, L)
        assert out_y.dtype == torch.float

        inv_y = torch.flip(out_y[:, 2:4], dims=[-1]).view(B, 2, -1, L)
        wh_y = torch.transpose(out_y[:, 1].view(B, -1, W, H), dim0=2, dim1=3).contiguous().view(B, -1, L)
        invwh_y = torch.transpose(inv_y[:, 1].view(B, -1, W, H), dim0=2, dim1=3).contiguous().view(B, -1, L)
        y = out_y[:, 0] + inv_y[:, 0] + wh_y + invwh_y
        
        y = y.transpose(dim0=1, dim1=2).contiguous() # (B, L, C)
        y = self.out_norm(y).view(B, H, W, -1)

        y = y * z
        out = self.dropout(self.out_proj(y))
        return out


# support: v01-v05; v051d,v052d,v052dc; 
# postfix: _onsigmoid,_onsoftmax,_ondwconv3,_onnone;_nozact,_noz;_oact;_no32;
# history support: v2,v3;v31d,v32d,v32dc;
class SS2Dv2:
    def __initv2__(
        self,
        # basic dims ===========
        d_model=96,
        d_state=16,
        ssm_ratio=2.0,
        dt_rank="auto",
        act_layer=nn.SiLU,
        # dwconv ===============
        d_conv=3, # < 2 means no conv 
        conv_bias=True,
        # ======================
        dropout=0.0,
        bias=False,
        # dt init ==============
        dt_min=0.001,
        dt_max=0.1,
        dt_init="random",
        dt_scale=1.0,
        dt_init_floor=1e-4,
        initialize="v0",
        # ======================
        forward_type="v2",
        channel_first=False,
        # ======================
        **kwargs,    
    ):
        factory_kwargs = {"device": None, "dtype": None}
        super().__init__()
        self.k_group = 4
        self.d_model = int(d_model)
        self.d_state = int(d_state)
        self.d_inner = int(ssm_ratio * d_model)
        self.dt_rank = int(math.ceil(self.d_model / 16) if dt_rank == "auto" else dt_rank)
        self.channel_first = channel_first
        self.with_dconv = d_conv > 1
        Linear = Linear2d if channel_first else nn.Linear
        self.forward = self.forwardv2

        # tags for forward_type ==============================
        checkpostfix = self.checkpostfix
        self.disable_force32, forward_type = checkpostfix("_no32", forward_type)
        self.oact, forward_type = checkpostfix("_oact", forward_type)
        self.disable_z, forward_type = checkpostfix("_noz", forward_type)
        self.disable_z_act, forward_type = checkpostfix("_nozact", forward_type)
        self.out_norm, forward_type = self.get_outnorm(forward_type, self.d_inner, channel_first)

        # forward_type debug =======================================
        FORWARD_TYPES = dict(
            v01=partial(self.forward_corev2, force_fp32=(not self.disable_force32), selective_scan_backend="mamba", scan_force_torch=True),
            v02=partial(self.forward_corev2, force_fp32=(not self.disable_force32), selective_scan_backend="mamba"),
            v03=partial(self.forward_corev2, force_fp32=(not self.disable_force32), selective_scan_backend="oflex"),
            v04=partial(self.forward_corev2, force_fp32=False), # selective_scan_backend="oflex", scan_mode="cross2d"
            v05=partial(self.forward_corev2, force_fp32=False, no_einsum=True),  # selective_scan_backend="oflex", scan_mode="cross2d"
            # ===============================
            v051d=partial(self.forward_corev2, force_fp32=False, no_einsum=True, scan_mode="unidi"),
            v052d=partial(self.forward_corev2, force_fp32=False, no_einsum=True, scan_mode="bidi"),
            v052dc=partial(self.forward_corev2, force_fp32=False, no_einsum=True, scan_mode="cascade2d"),
            v052d3=partial(self.forward_corev2, force_fp32=False, no_einsum=True, scan_mode=3), # debug
            # ===============================
            v2=partial(self.forward_corev2, force_fp32=(not self.disable_force32), selective_scan_backend="core"),
            v3=partial(self.forward_corev2, force_fp32=False, selective_scan_backend="oflex"),
        )
        self.forward_core = FORWARD_TYPES.get(forward_type, None)

        # in proj =======================================
        d_proj = self.d_inner if self.disable_z else (self.d_inner * 2)
        self.in_proj = Linear(self.d_model, d_proj, bias=bias)
        self.act: nn.Module = act_layer()
        
        # conv =======================================
        if self.with_dconv:
            self.conv2d = nn.Conv2d(
                in_channels=self.d_inner,
                out_channels=self.d_inner,
                groups=self.d_inner,
                bias=conv_bias,
                kernel_size=d_conv,
                padding=(d_conv - 1) // 2,
                **factory_kwargs,
            )

        # x proj ============================
        self.x_proj = [
            nn.Linear(self.d_inner, (self.dt_rank + self.d_state * 2), bias=False)
            for _ in range(self.k_group)
        ]
        self.x_proj_weight = nn.Parameter(torch.stack([t.weight for t in self.x_proj], dim=0)) # (K, N, inner)
        del self.x_proj
        
        # out proj =======================================
        self.out_act = nn.GELU() if self.oact else nn.Identity()
        self.out_proj = Linear(self.d_inner, self.d_model, bias=bias)
        self.dropout = nn.Dropout(dropout) if dropout > 0. else nn.Identity()

        if initialize in ["v0"]:
            self.A_logs, self.Ds, self.dt_projs_weight, self.dt_projs_bias = mamba_init.init_dt_A_D(
                self.d_state, self.dt_rank, self.d_inner, dt_scale, dt_init, dt_min, dt_max, dt_init_floor, k_group=self.k_group,
            )
        elif initialize in ["v1"]:
            # simple init dt_projs, A_logs, Ds
            self.Ds = nn.Parameter(torch.ones((self.k_group * self.d_inner)))
            self.A_logs = nn.Parameter(torch.randn((self.k_group * self.d_inner, self.d_state))) # A == -A_logs.exp() < 0; # 0 < exp(A * dt) < 1
            self.dt_projs_weight = nn.Parameter(0.1 * torch.randn((self.k_group, self.d_inner, self.dt_rank))) # 0.1 is added in 0430
            self.dt_projs_bias = nn.Parameter(0.1 * torch.randn((self.k_group, self.d_inner))) # 0.1 is added in 0430
        elif initialize in ["v2"]:
            # simple init dt_projs, A_logs, Ds
            self.Ds = nn.Parameter(torch.ones((self.k_group * self.d_inner)))
            self.A_logs = nn.Parameter(torch.zeros((self.k_group * self.d_inner, self.d_state))) # A == -A_logs.exp() < 0; # 0 < exp(A * dt) < 1
            self.dt_projs_weight = nn.Parameter(0.1 * torch.rand((self.k_group, self.d_inner, self.dt_rank)))
            self.dt_projs_bias = nn.Parameter(0.1 * torch.rand((self.k_group, self.d_inner)))

    def forward_corev2(
        self,
        x: torch.Tensor=None, 
        # ==============================
        force_fp32=False, # True: input fp32
        # ==============================
        ssoflex=True, # True: input 16 or 32 output 32 False: output dtype as input
        no_einsum=False, # replace einsum with linear or conv1d to raise throughput
        # ==============================
        selective_scan_backend = None,
        # ==============================
        scan_mode = "cross2d",
        scan_force_torch = False,
        # ==============================
        **kwargs,
    ):
        assert selective_scan_backend in [None, "oflex", "mamba", "torch"]
        _scan_mode = dict(cross2d=0, unidi=1, bidi=2, cascade2d=-1).get(scan_mode, None) if isinstance(scan_mode, str) else scan_mode # for debug
        assert isinstance(_scan_mode, int)
        delta_softplus = True
        out_norm = self.out_norm
        channel_first = self.channel_first
        to_fp32 = lambda *args: (_a.to(torch.float32) for _a in args)

        B, D, H, W = x.shape
        N = self.d_state
        K, D, R = self.k_group, self.d_inner, self.dt_rank
        L = H * W

        def selective_scan(u, delta, A, B, C, D=None, delta_bias=None, delta_softplus=True):
            return selective_scan_fn(u, delta, A, B, C, D, delta_bias, delta_softplus, ssoflex, backend=selective_scan_backend)
        
        if _scan_mode == -1:
            x_proj_bias = getattr(self, "x_proj_bias", None)
            def scan_rowcol(
                x: torch.Tensor, 
                proj_weight: torch.Tensor, 
                proj_bias: torch.Tensor, 
                dt_weight: torch.Tensor, 
                dt_bias: torch.Tensor, # (2*c)
                _As: torch.Tensor, # As = -torch.exp(A_logs.to(torch.float))[:2,] # (2*c, d_state)
                _Ds: torch.Tensor,
                width = True,
            ):
                # x: (B, D, H, W)
                # proj_weight: (2 * D, (R+N+N))
                XB, XD, XH, XW = x.shape
                if width:
                    _B, _D, _L = XB * XH, XD, XW
                    xs = x.permute(0, 2, 1, 3).contiguous()
                else:
                    _B, _D, _L = XB * XW, XD, XH
                    xs = x.permute(0, 3, 1, 2).contiguous()
                xs = torch.stack([xs, xs.flip(dims=[-1])], dim=2) # (B, H, 2, D, W)
                if no_einsum:
                    x_dbl = F.conv1d(xs.view(_B, -1, _L), proj_weight.view(-1, _D, 1), bias=(proj_bias.view(-1) if proj_bias is not None else None), groups=2)
                    dts, Bs, Cs = torch.split(x_dbl.view(_B, 2, -1, _L), [R, N, N], dim=2)
                    dts = F.conv1d(dts.contiguous().view(_B, -1, _L), dt_weight.view(2 * _D, -1, 1), groups=2)
                else:
                    x_dbl = torch.einsum("b k d l, k c d -> b k c l", xs, proj_weight)
                    if x_proj_bias is not None:
                        x_dbl = x_dbl + x_proj_bias.view(1, 2, -1, 1)
                    dts, Bs, Cs = torch.split(x_dbl, [R, N, N], dim=2)
                    dts = torch.einsum("b k r l, k d r -> b k d l", dts, dt_weight)

                xs = xs.view(_B, -1, _L)
                dts = dts.contiguous().view(_B, -1, _L)
                As = _As.view(-1, N).to(torch.float)
                Bs = Bs.contiguous().view(_B, 2, N, _L)
                Cs = Cs.contiguous().view(_B, 2, N, _L)
                Ds = _Ds.view(-1)
                delta_bias = dt_bias.view(-1).to(torch.float)

                if force_fp32:
                    xs = xs.to(torch.float)
                dts = dts.to(xs.dtype)
                Bs = Bs.to(xs.dtype)
                Cs = Cs.to(xs.dtype)

                ys: torch.Tensor = selective_scan(
                    xs, dts, As, Bs, Cs, Ds, delta_bias, delta_softplus
                ).view(_B, 2, -1, _L)
                return ys
            
            As = -self.A_logs.to(torch.float).exp().view(4, -1, N)
            x = F.layer_norm(x.permute(0, 2, 3, 1), normalized_shape=(int(x.shape[1]),)).permute(0, 3, 1, 2).contiguous() # added0510 to avoid nan
            y_row = scan_rowcol(
                x,
                proj_weight = self.x_proj_weight.view(4, -1, D)[:2].contiguous(), 
                proj_bias = (x_proj_bias.view(4, -1)[:2].contiguous() if x_proj_bias is not None else None),
                dt_weight = self.dt_projs_weight.view(4, D, -1)[:2].contiguous(),
                dt_bias = (self.dt_projs_bias.view(4, -1)[:2].contiguous() if self.dt_projs_bias is not None else None),
                _As = As[:2].contiguous().view(-1, N),
                _Ds = self.Ds.view(4, -1)[:2].contiguous().view(-1),
                width=True,
            ).view(B, H, 2, -1, W).sum(dim=2).permute(0, 2, 1, 3) # (B,C,H,W)
            y_row = F.layer_norm(y_row.permute(0, 2, 3, 1), normalized_shape=(int(y_row.shape[1]),)).permute(0, 3, 1, 2).contiguous() # added0510 to avoid nan
            y_col = scan_rowcol(
                y_row,
                proj_weight = self.x_proj_weight.view(4, -1, D)[2:].contiguous().to(y_row.dtype), 
                proj_bias = (x_proj_bias.view(4, -1)[2:].contiguous().to(y_row.dtype) if x_proj_bias is not None else None),
                dt_weight = self.dt_projs_weight.view(4, D, -1)[2:].contiguous().to(y_row.dtype),
                dt_bias = (self.dt_projs_bias.view(4, -1)[2:].contiguous().to(y_row.dtype) if self.dt_projs_bias is not None else None),
                _As = As[2:].contiguous().view(-1, N),
                _Ds = self.Ds.view(4, -1)[2:].contiguous().view(-1),
                width=False,
            ).view(B, W, 2, -1, H).sum(dim=2).permute(0, 2, 3, 1)
            y = y_col
        else:
            x_proj_bias = getattr(self, "x_proj_bias", None)
            xs = cross_scan_fn(x, in_channel_first=True, out_channel_first=True, scans=_scan_mode, force_torch=scan_force_torch)
            if no_einsum:
                x_dbl = F.conv1d(xs.view(B, -1, L), self.x_proj_weight.view(-1, D, 1), bias=(x_proj_bias.view(-1) if x_proj_bias is not None else None), groups=K)
                dts, Bs, Cs = torch.split(x_dbl.view(B, K, -1, L), [R, N, N], dim=2)
                if hasattr(self, "dt_projs_weight"):
                    dts = F.conv1d(dts.contiguous().view(B, -1, L), self.dt_projs_weight.view(K * D, -1, 1), groups=K)
            else:
                x_dbl = torch.einsum("b k d l, k c d -> b k c l", xs, self.x_proj_weight)
                if x_proj_bias is not None:
                    x_dbl = x_dbl + x_proj_bias.view(1, K, -1, 1)
                dts, Bs, Cs = torch.split(x_dbl, [R, N, N], dim=2)
                if hasattr(self, "dt_projs_weight"):
                    dts = torch.einsum("b k r l, k d r -> b k d l", dts, self.dt_projs_weight)

            xs = xs.view(B, -1, L)
            dts = dts.contiguous().view(B, -1, L)
            As = -self.A_logs.to(torch.float).exp() # (k * c, d_state)
            Ds = self.Ds.to(torch.float) # (K * c)
            Bs = Bs.contiguous().view(B, K, N, L)
            Cs = Cs.contiguous().view(B, K, N, L)
            delta_bias = self.dt_projs_bias.view(-1).to(torch.float)

            if force_fp32:
                xs, dts, Bs, Cs = to_fp32(xs, dts, Bs, Cs)

            ys: torch.Tensor = selective_scan(
                xs, dts, As, Bs, Cs, Ds, delta_bias, delta_softplus
            ).view(B, K, -1, H, W)
            
            y: torch.Tensor = cross_merge_fn(ys, in_channel_first=True, out_channel_first=True, scans=_scan_mode, force_torch=scan_force_torch)

            if getattr(self, "__DEBUG__", False):
                setattr(self, "__data__", dict(
                    A_logs=self.A_logs, Bs=Bs, Cs=Cs, Ds=Ds,
                    us=xs, dts=dts, delta_bias=delta_bias,
                    ys=ys, y=y, H=H, W=W,
                ))

        y = y.view(B, -1, H, W)
        if not channel_first:
            y = y.view(B, -1, H * W).transpose(dim0=1, dim1=2).contiguous().view(B, H, W, -1) # (B, L, C)
        y = out_norm(y)

        return y.to(x.dtype)

    def forwardv2(self, x: torch.Tensor, **kwargs):
        x = self.in_proj(x)
        if not self.disable_z:
            x, z = x.chunk(2, dim=(1 if self.channel_first else -1)) # (b, h, w, d)
            if not self.disable_z_act:
                z = self.act(z)
        if not self.channel_first:
            x = x.permute(0, 3, 1, 2).contiguous()
        if self.with_dconv:
            x = self.conv2d(x) # (b, d, h, w)
        x = self.act(x)
        y = self.forward_core(x)
        y = self.out_act(y)
        if not self.disable_z:
            y = y * z
        out = self.dropout(self.out_proj(y))
        return out

    @staticmethod
    def get_outnorm(forward_type="", d_inner=192, channel_first=True):
        def checkpostfix(tag, value):
            ret = value[-len(tag):] == tag
            if ret:
                value = value[:-len(tag)]
            return ret, value

        LayerNorm = LayerNorm2d if channel_first else nn.LayerNorm

        out_norm_none, forward_type = checkpostfix("_onnone", forward_type)
        out_norm_dwconv3, forward_type = checkpostfix("_ondwconv3", forward_type)
        out_norm_cnorm, forward_type = checkpostfix("_oncnorm", forward_type)
        out_norm_softmax, forward_type = checkpostfix("_onsoftmax", forward_type)
        out_norm_sigmoid, forward_type = checkpostfix("_onsigmoid", forward_type)

        out_norm = nn.Identity()
        if out_norm_none:
            out_norm = nn.Identity()
        elif out_norm_cnorm:
            out_norm = nn.Sequential(
                LayerNorm(d_inner),
                (nn.Identity() if channel_first else Permute(0, 3, 1, 2)),
                nn.Conv2d(d_inner, d_inner, kernel_size=3, padding=1, groups=d_inner, bias=False),
                (nn.Identity() if channel_first else Permute(0, 2, 3, 1)),
            )
        elif out_norm_dwconv3:
            out_norm = nn.Sequential(
                (nn.Identity() if channel_first else Permute(0, 3, 1, 2)),
                nn.Conv2d(d_inner, d_inner, kernel_size=3, padding=1, groups=d_inner, bias=False),
                (nn.Identity() if channel_first else Permute(0, 2, 3, 1)),
            )
        elif out_norm_softmax:
            out_norm = SoftmaxSpatial(dim=(-1 if channel_first else 1))
        elif out_norm_sigmoid:
            out_norm = nn.Sigmoid()
        else:
            out_norm = LayerNorm(d_inner)

        return out_norm, forward_type

    @staticmethod
    def checkpostfix(tag, value):
        ret = value[-len(tag):] == tag
        if ret:
            value = value[:-len(tag)]
        return ret, value


# support: xv1a,xv2a,xv3a; 
# postfix: _cpos;_ocov;_ocov2;_ca,_ca1;_act;_mul;_onsigmoid,_onsoftmax,_ondwconv3,_onnone;
class SS2Dv3:
    def __initxv__(
        self,
        # basic dims ===========
        d_model=96,
        d_state=16,
        ssm_ratio=2.0,
        dt_rank="auto",
        # dwconv ===============
        d_conv=3, # < 2 means no conv 
        conv_bias=True,
        # ======================
        dropout=0.0,
        bias=False,
        # dt init ==============
        dt_min=0.001,
        dt_max=0.1,
        dt_init="random",
        dt_scale=1.0,
        dt_init_floor=1e-4,
        initialize="v0",
        # ======================
        forward_type="v2",
        channel_first=False,
        # ======================
        **kwargs,
    ):
        super().__init__()
        d_inner = int(ssm_ratio * d_model)
        dt_rank = math.ceil(d_model / 16) if dt_rank == "auto" else dt_rank
        self.channel_first = channel_first
        self.d_state = d_state
        self.dt_rank = dt_rank
        self.d_inner = d_inner
        k_group = 4
        self.with_dconv = d_conv > 1
        Linear = Linear2d if channel_first else nn.Linear
        self.forward = self.forwardxv

        # tags for forward_type ==============================
        checkpostfix = SS2Dv2.checkpostfix
        self.out_norm, forward_type = SS2Dv2.get_outnorm(forward_type, d_inner, channel_first)
        self.omul, forward_type = checkpostfix("_mul", forward_type)
        self.oact, forward_type = checkpostfix("_act", forward_type)
        self.f_omul = nn.Identity() if self.omul else None
        self.out_act = nn.GELU() if self.oact else nn.Identity()

        mode = forward_type[:4]
        assert mode in ["xv1a", "xv2a", "xv3a"]

        self.forward = partial(self.forwardxv, mode=mode)
        self.dts_dim = dict(xv1a=self.dt_rank, xv2a=self.d_inner, xv3a=4 * self.dt_rank)[mode]
        d_inner_all = d_inner + self.dts_dim + 8 * d_state
        self.in_proj = Linear(d_model, d_inner_all, bias=bias)
        
        # conv =======================================
        self.cpos = False
        self.iconv = False
        self.oconv = False
        self.oconv2 = False
        if self.with_dconv:
            cact, forward_type = checkpostfix("_ca", forward_type)
            cact1, forward_type = checkpostfix("_ca1", forward_type)
            self.cact = nn.SiLU() if cact else nn.Identity()
            self.cact = nn.GELU() if cact1 else self.cact
                
            self.oconv2, forward_type = checkpostfix("_ocov2", forward_type)
            self.oconv, forward_type = checkpostfix("_ocov", forward_type)
            self.cpos, forward_type = checkpostfix("_cpos", forward_type)
            self.iconv = (not self.oconv) and (not self.oconv2)

            if self.iconv:
                self.conv2d = nn.Conv2d(
                    in_channels=d_model,
                    out_channels=d_model,
                    groups=d_model,
                    bias=conv_bias,
                    kernel_size=d_conv,
                    padding=(d_conv - 1) // 2,
                )
            if self.oconv:
                self.oconv2d = nn.Conv2d(
                    in_channels=d_inner,
                    out_channels=d_inner,
                    groups=d_inner,
                    bias=conv_bias,
                    kernel_size=d_conv,
                    padding=(d_conv - 1) // 2,
                )
            if self.oconv2:
                self.conv2d = nn.Conv2d(
                    in_channels=d_inner_all,
                    out_channels=d_inner_all,
                    groups=d_inner_all,
                    bias=conv_bias,
                    kernel_size=d_conv,
                    padding=(d_conv - 1) // 2,
                )

        # out proj =======================================
        self.out_proj = Linear(d_inner, d_model, bias=bias)
        self.dropout = nn.Dropout(dropout) if dropout > 0.0 else nn.Identity()

        if initialize in ["v0"]:
            self.A_logs, self.Ds, self.dt_projs_weight, self.dt_projs_bias = mamba_init.init_dt_A_D(
                d_state, dt_rank, d_inner, dt_scale, dt_init, dt_min, dt_max, dt_init_floor, k_group=4,
            )
        elif initialize in ["v1"]:
            # simple init dt_projs, A_logs, Ds
            self.Ds = nn.Parameter(torch.ones((k_group * d_inner)))
            self.A_logs = nn.Parameter(torch.randn((k_group * d_inner, d_state))) # A == -A_logs.exp() < 0; # 0 < exp(A * dt) < 1
            self.dt_projs_weight = nn.Parameter(torch.randn((k_group, d_inner, dt_rank)))
            self.dt_projs_bias = nn.Parameter(torch.randn((k_group, d_inner))) 
        elif initialize in ["v2"]:
            # simple init dt_projs, A_logs, Ds
            self.Ds = nn.Parameter(torch.ones((k_group * d_inner)))
            self.A_logs = nn.Parameter(torch.zeros((k_group * d_inner, d_state))) # A == -A_logs.exp() < 0; # 0 < exp(A * dt) < 1
            self.dt_projs_weight = nn.Parameter(0.1 * torch.rand((k_group, d_inner, dt_rank)))
            self.dt_projs_bias = nn.Parameter(0.1 * torch.rand((k_group, d_inner)))


        if forward_type.startswith("xv2"):
            del self.dt_projs_weight
            self.dt_projs_weight = None

    def forwardxv(self, x: torch.Tensor, **kwargs):
        B, (H, W) = x.shape[0], (x.shape[2:4] if self.channel_first else x.shape[1:3])
        L = H * W
        force_fp32 = False
        delta_softplus = True
        out_norm = self.out_norm
        to_dtype = True

        to_fp32 = lambda *args: (_a.to(torch.float32) for _a in args)

        def selective_scan(u, delta, A, B, C, D, delta_bias, delta_softplus):
            return selective_scan_fn(u, delta, A, B, C, D, delta_bias, delta_softplus, oflex=True, backend=None)

        if self.iconv:
            x = self.cact(self.conv2d(x)) # (b, d, h, w)
        elif self.cpos:
            x = x + self.conv2d(x) # (b, d, h, w)

        x = self.in_proj(x)
        
        if self.oconv2:
            x = self.conv2d(x) # (b, d, h, w)

        us, dts, Bs, Cs = x.split([self.d_inner, self.dts_dim, 4 * self.d_state, 4 * self.d_state], dim=(1 if self.channel_first else -1))

        _us = us
        # Bs, Cs = Bs.view(B, H, W, 4, -1), Cs.view(B, H, W, 4, -1)
        # Bs, Cs = Bs.view(B, 4, -1, H, W), Cs.view(B, 4, -1, H, W)
        us = cross_scan_fn(us.contiguous(), in_channel_first=self.channel_first, out_channel_first=True).view(B, -1, L)
        Bs = cross_scan_fn(Bs.contiguous(), in_channel_first=self.channel_first, out_channel_first=True, one_by_one=True).view(B, 4, -1, L)
        Cs = cross_scan_fn(Cs.contiguous(), in_channel_first=self.channel_first, out_channel_first=True, one_by_one=True).view(B, 4, -1, L)
        dts = cross_scan_fn(dts.contiguous(), in_channel_first=self.channel_first, out_channel_first=True, one_by_one=(self.dts_dim == 4 * self.dt_rank)).view(B, L, -1)
        if self.dts_dim == self.dt_rank:
            dts = F.conv1d(dts, self.dt_projs_weight.view(4 * self.d_inner, self.dt_rank, 1), None, groups=4)
        elif self.dts_dim == 4 * self.dt_rank:
            dts = F.conv1d(dts, self.dt_projs_weight.view(4 * self.d_inner, self.dt_rank, 1), None, groups=4)

        As = -self.A_logs.to(torch.float).exp() # (k * c, d_state)
        Ds = self.Ds.to(torch.float) # (K * c)
        delta_bias = self.dt_projs_bias.view(-1).to(torch.float) # (K * c)

        if force_fp32:
            us, dts, Bs, Cs = to_fp32(us, dts, Bs, Cs)

        ys: torch.Tensor = selective_scan(
            us, dts, As, Bs, Cs, Ds, delta_bias, delta_softplus
        ).view(B, 4, -1, H, W)
        y: torch.Tensor = cross_merge_fn(ys.contiguous(), in_channel_first=self.channel_first, out_channel_first=True)
        y = y.view(B, -1, H, W) if self.channel_first else y.view(B, H, W, -1)
        y = out_norm(y)
        
        if getattr(self, "__DEBUG__", False):
            setattr(self, "__data__", dict(
                A_logs=self.A_logs, Bs=Bs, Cs=Cs, Ds=Ds,
                us=us, dts=dts, delta_bias=delta_bias,
                ys=ys, y=y,
            ))

        y = (y.to(x.dtype) if to_dtype else y)
        
        y = self.out_act(y)
        
        if self.omul:
            y = y * _us

        if self.oconv:
            y = y + self.cact(self.oconv2d(_us))

        out = self.dropout(self.out_proj(y))
        return out


# mamba2 support ================================
class SS2Dm0:
    def __initm0__(
        self,
        # basic dims ===========
        d_model=96,
        d_state=16, # now with mamba2, dstate should be bigger...
        ssm_ratio=2.0,
        dt_rank="auto",
        act_layer=nn.GELU,
        # dwconv ===============
        d_conv=3, # < 2 means no conv 
        conv_bias=True,
        # ======================
        dropout=0.0,
        bias=False,
        # dt init ==============
        dt_min=0.001,
        dt_max=0.1,
        dt_init="random",
        dt_scale=1.0,
        dt_init_floor=1e-4,
        initialize="v2",
        # ======================
        forward_type="m0",
        # ======================
        with_initial_state=False,
        # ======================
        **kwargs,    
    ):
        factory_kwargs = {"device": None, "dtype": None}
        super().__init__()
        d_inner = int(ssm_ratio * d_model)
        dt_rank = math.ceil(d_model / 16) if dt_rank == "auto" else dt_rank
        assert d_inner % dt_rank == 0
        self.with_dconv = d_conv > 1
        Linear = nn.Linear
        self.forward = self.forwardm0

        # tags for forward_type ==============================
        checkpostfix = SS2Dv2.checkpostfix
        self.disable_force32, forward_type = checkpostfix("_no32", forward_type)
        self.oact, forward_type = checkpostfix("_oact", forward_type)
        self.disable_z, forward_type = checkpostfix("_noz", forward_type)
        self.disable_z_act, forward_type = checkpostfix("_nozact", forward_type)
        self.out_norm, forward_type = SS2Dv2.get_outnorm(forward_type, d_inner, False)

        # forward_type debug =======================================
        FORWARD_TYPES = dict(
            m0=partial(self.forward_corem0, force_fp32=False, dstate=d_state),
        )
        self.forward_core = FORWARD_TYPES.get(forward_type, None)
        k_group = 4

        # in proj =======================================
        d_proj = d_inner if self.disable_z else (d_inner * 2)
        self.in_proj = Linear(d_model, d_proj, bias=bias)
        self.act: nn.Module = act_layer()
        
        # conv =======================================
        if self.with_dconv:
            self.conv2d = nn.Sequential(
                Permute(0, 3, 1, 2),
                nn.Conv2d(
                    in_channels=d_inner,
                    out_channels=d_inner,
                    groups=d_inner,
                    bias=conv_bias,
                    kernel_size=d_conv,
                    padding=(d_conv - 1) // 2,
                    **factory_kwargs,
                ),
                Permute(0, 2, 3, 1),
            ) 
        
        # x proj ============================
        self.x_proj = [
            nn.Linear(d_inner, (dt_rank + d_state * 2), bias=False)
            for _ in range(k_group)
        ]
        self.x_proj_weight = nn.Parameter(torch.stack([t.weight for t in self.x_proj], dim=0)) # (K, N, inner)
        del self.x_proj
        
        # out proj =======================================
        self.out_act = nn.GELU() if self.oact else nn.Identity()
        self.out_proj = Linear(d_inner, d_model, bias=bias)
        self.dropout = nn.Dropout(dropout) if dropout > 0. else nn.Identity()

        if initialize in ["v1"]:
            # simple init dt_projs, A_logs, Ds
            self.Ds = nn.Parameter(torch.ones((k_group, dt_rank, int(d_inner // dt_rank))))
            self.A_logs = nn.Parameter(torch.randn((k_group, dt_rank))) # A == -A_logs.exp() < 0; # 0 < exp(A * dt) < 1
            self.dt_projs_bias = nn.Parameter(0.1 * torch.randn((k_group, dt_rank))) # 0.1 is added in 0430
        elif initialize in ["v2"]:
            # simple init dt_projs, A_logs, Ds
            self.Ds = nn.Parameter(torch.ones((k_group, dt_rank, int(d_inner // dt_rank))))
            self.A_logs = nn.Parameter(torch.zeros((k_group, dt_rank))) # A == -A_logs.exp() < 0; # 0 < exp(A * dt) < 1
            self.dt_projs_bias = nn.Parameter(0.1 * torch.rand((k_group, dt_rank)))

        # init state ============================
        self.initial_state = None
        if with_initial_state:
            self.initial_state = nn.Parameter(torch.zeros((1, k_group * dt_rank, int(d_inner // dt_rank), d_state)), requires_grad=False)

    def forward_corem0(
        self,
        x: torch.Tensor=None, 
        # ==============================
        force_fp32=False, # True: input fp32
        chunk_size = 64,
        dstate = 64,        
        # ==============================
        selective_scan_backend = None,
        scan_mode = "cross2d",
        scan_force_torch = False,
        # ==============================
        **kwargs,
    ):
        assert scan_mode in ["unidi", "bidi", "cross2d"]
        assert selective_scan_backend in [None, "triton", "torch"]
        x_proj_bias = getattr(self, "x_proj_bias", None)
        to_fp32 = lambda *args: (_a.to(torch.float32) for _a in args)

        N = dstate
        B, H, W, RD = x.shape
        K, R = self.A_logs.shape
        K, R, D = self.Ds.shape
        assert RD == R * D
        L = H * W
        KR = K * R
        _scan_mode = dict(cross2d=0, unidi=1, bidi=2, cascade2d=3)[scan_mode]

        initial_state = None
        if self.initial_state is not None:
            assert self.initial_state.shape[-1] == dstate
            initial_state = self.initial_state.detach().repeat(B, 1, 1, 1)
        xs = cross_scan_fn(x.view(B, H, W, RD), in_channel_first=False, out_channel_first=False, scans=_scan_mode, force_torch=scan_force_torch) # (B, H, W, 4, D)
        x_dbl = torch.einsum("b l k d, k c d -> b l k c", xs, self.x_proj_weight)
        if x_proj_bias is not None:
            x_dbl = x_dbl + x_proj_bias.view(1, -1, K, 1)
        dts, Bs, Cs = torch.split(x_dbl, [R, N, N], dim=3)
        xs = xs.contiguous().view(B, L, KR, D)
        dts = dts.contiguous().view(B, L, KR)
        Bs = Bs.contiguous().view(B, L, K, N)
        Cs = Cs.contiguous().view(B, L, K, N)
        if force_fp32:
            xs, dts, Bs, Cs = to_fp32(xs, dts, Bs, Cs)

        As = -self.A_logs.to(torch.float).exp().view(KR)
        Ds = self.Ds.to(torch.float).view(KR, D)
        dt_bias = self.dt_projs_bias.view(KR)

        if force_fp32:
            xs, dts, Bs, Cs = to_fp32(xs, dts, Bs, Cs)

        ys, final_state = selective_scan_chunk_fn(
            xs, dts, As, Bs, Cs, chunk_size=chunk_size, D=Ds, dt_bias=dt_bias, 
            initial_states=initial_state, dt_softplus=True, return_final_states=True,
            backend=selective_scan_backend,
        )
        y: torch.Tensor = cross_merge_fn(ys.view(B, H, W, K, RD), in_channel_first=False, out_channel_first=False, scans=_scan_mode, force_torch=scan_force_torch)

        if getattr(self, "__DEBUG__", False):
            setattr(self, "__data__", dict(
                A_logs=self.A_logs, Bs=Bs, Cs=Cs, Ds=self.Ds,
                us=xs, dts=dts, delta_bias=self.dt_projs_bias, 
                initial_state=self.initial_state, final_satte=final_state,
                ys=ys, y=y, H=H, W=W,
            ))
        if self.initial_state is not None:
            self.initial_state = nn.Parameter(final_state.detach().sum(0, keepdim=True), requires_grad=False)

        y = self.out_norm(y.view(B, H, W, -1))

        return y.to(x.dtype)

    def forwardm0(self, x: torch.Tensor, **kwargs):
        x = self.in_proj(x)
        if not self.disable_z:
            x, z = x.chunk(2, dim=(1 if self.channel_first else -1)) # (b, h, w, d)
            if not self.disable_z_act:
                z = self.act(z)
        if self.with_dconv:
            x = self.conv2d(x) # (b, d, h, w)
        x = self.act(x)
        y = self.forward_core(x)
        y = self.out_act(y)
        if not self.disable_z:
            y = y * z
        out = self.dropout(self.out_proj(y))
        return out


class SS2D(nn.Module, SS2Dv0, SS2Dv2, SS2Dv3, SS2Dm0):
    def __init__(
        self,
        # basic dims ===========
        d_model=96,
        d_state=16,
        ssm_ratio=2.0,
        dt_rank="auto",
        act_layer=nn.SiLU,
        # dwconv ===============
        d_conv=3, # < 2 means no conv 
        conv_bias=True,
        # ======================
        dropout=0.0,
        bias=False,
        # dt init ==============
        dt_min=0.001,
        dt_max=0.1,
        dt_init="random",
        dt_scale=1.0,
        dt_init_floor=1e-4,
        initialize="v0",
        # ======================
        forward_type="v2",
        channel_first=False,
        # ======================
        **kwargs,
    ):
        nn.Module.__init__(self)
        kwargs.update(
            d_model=d_model, d_state=d_state, ssm_ratio=ssm_ratio, dt_rank=dt_rank,
            act_layer=act_layer, d_conv=d_conv, conv_bias=conv_bias, dropout=dropout, bias=bias,
            dt_min=dt_min, dt_max=dt_max, dt_init=dt_init, dt_scale=dt_scale, dt_init_floor=dt_init_floor,
            initialize=initialize, forward_type=forward_type, channel_first=channel_first,
        )
        if forward_type in ["v0", "v0seq"]:
            self.__initv0__(seq=("seq" in forward_type), **kwargs)
        elif forward_type.startswith("xv"):
            self.__initxv__(**kwargs)
        elif forward_type.startswith("m"):
            self.__initm0__(**kwargs)
        else:
            self.__initv2__(**kwargs)


# =====================================================
class VSSBlock(nn.Module):
    def __init__(
        self,
        hidden_dim: int = 0,
        drop_path: float = 0,
        norm_layer: nn.Module = nn.LayerNorm,
        channel_first=False,
        # =============================
        ssm_d_state: int = 16,
        ssm_ratio=2.0,
        ssm_dt_rank: Any = "auto",
        ssm_act_layer=nn.SiLU,
        ssm_conv: int = 3,
        ssm_conv_bias=True,
        ssm_drop_rate: float = 0,
        ssm_init="v0",
        forward_type="v2",
        # =============================
        mlp_ratio=4.0,
        mlp_act_layer=nn.GELU,
        mlp_drop_rate: float = 0.0,
        gmlp=False,
        # =============================
        use_checkpoint: bool = False,
        post_norm: bool = False,
        # =============================
        _SS2D: type = SS2D,
        **kwargs,
    ):
        super().__init__()
        self.ssm_branch = ssm_ratio > 0
        self.mlp_branch = mlp_ratio > 0
        self.use_checkpoint = use_checkpoint
        self.post_norm = post_norm

        if self.ssm_branch:
            self.norm = norm_layer(hidden_dim)
            self.op = _SS2D(
                d_model=hidden_dim, 
                d_state=ssm_d_state, 
                ssm_ratio=ssm_ratio,
                dt_rank=ssm_dt_rank,
                act_layer=ssm_act_layer,
                # ==========================
                d_conv=ssm_conv,
                conv_bias=ssm_conv_bias,
                # ==========================
                dropout=ssm_drop_rate,
                # bias=False,
                # ==========================
                # dt_min=0.001,
                # dt_max=0.1,
                # dt_init="random",
                # dt_scale="random",
                # dt_init_floor=1e-4,
                initialize=ssm_init,
                # ==========================
                forward_type=forward_type,
                channel_first=channel_first,
            )
        
        self.drop_path = DropPath(drop_path)
        
        if self.mlp_branch:
            _MLP = Mlp if not gmlp else gMlp
            self.norm2 = norm_layer(hidden_dim)
            mlp_hidden_dim = int(hidden_dim * mlp_ratio)
            self.mlp = _MLP(in_features=hidden_dim, hidden_features=mlp_hidden_dim, act_layer=mlp_act_layer, drop=mlp_drop_rate, channels_first=channel_first)

    def _forward(self, input: torch.Tensor):
        x = input
        if self.ssm_branch:
            if self.post_norm:
                x = x + self.drop_path(self.norm(self.op(x)))
            else:
                x = x + self.drop_path(self.op(self.norm(x)))
        if self.mlp_branch:
            if self.post_norm:
                x = x + self.drop_path(self.norm2(self.mlp(x))) # FFN
            else:
                x = x + self.drop_path(self.mlp(self.norm2(x))) # FFN
        return x

    def forward(self, input: torch.Tensor):
        if self.use_checkpoint:
            return checkpoint.checkpoint(self._forward, input)
        else:
            return self._forward(input)


class VSSM(nn.Module):
    def __init__(
        self, 
        patch_size=4, 
        in_chans=3, 
        num_classes=1000, 
        depths=[2, 2, 9, 2], 
        dims=[96, 192, 384, 768], 
        # =========================
        ssm_d_state=16,
        ssm_ratio=2.0,
        ssm_dt_rank="auto",
        ssm_act_layer="silu",        
        ssm_conv=3,
        ssm_conv_bias=True,
        ssm_drop_rate=0.0, 
        ssm_init="v0",
        forward_type="v2",
        # =========================
        mlp_ratio=4.0,
        mlp_act_layer="gelu",
        mlp_drop_rate=0.0,
        gmlp=False,
        # =========================
        drop_path_rate=0.1, 
        patch_norm=True, 
        norm_layer="LN", # "BN", "LN2D"
        downsample_version: str = "v2", # "v1", "v2", "v3"
        patchembed_version: str = "v1", # "v1", "v2"
        use_checkpoint=False,  
        # =========================
        posembed=False,
        imgsize=224,
        _SS2D=SS2D,
        # =========================
        **kwargs,
    ):
        super().__init__()
        self.channel_first = (norm_layer.lower() in ["bn", "ln2d"])
        self.num_classes = num_classes
        self.num_layers = len(depths)
        if isinstance(dims, int):
            dims = [int(dims * 2 ** i_layer) for i_layer in range(self.num_layers)]
        self.num_features = dims[-1]
        self.dims = dims
        dpr = [x.item() for x in torch.linspace(0, drop_path_rate, sum(depths))]  # stochastic depth decay rule
        
        _NORMLAYERS = dict(
            ln=nn.LayerNorm,
            ln2d=LayerNorm2d,
            bn=nn.BatchNorm2d,
        )

        _ACTLAYERS = dict(
            silu=nn.SiLU, 
            gelu=nn.GELU, 
            relu=nn.ReLU, 
            sigmoid=nn.Sigmoid,
        )

        norm_layer: nn.Module = _NORMLAYERS.get(norm_layer.lower(), None)
        ssm_act_layer: nn.Module = _ACTLAYERS.get(ssm_act_layer.lower(), None)
        mlp_act_layer: nn.Module = _ACTLAYERS.get(mlp_act_layer.lower(), None)

        self.pos_embed = self._pos_embed(dims[0], patch_size, imgsize) if posembed else None

        _make_patch_embed = dict(
            v1=self._make_patch_embed, 
            v2=self._make_patch_embed_v2,
        ).get(patchembed_version, None)
        self.patch_embed = _make_patch_embed(in_chans, dims[0], patch_size, patch_norm, norm_layer, channel_first=self.channel_first)

        _make_downsample = dict(
            v1=PatchMerging2D, 
            v2=self._make_downsample, 
            v3=self._make_downsample_v3, 
            none=(lambda *_, **_k: None),
        ).get(downsample_version, None)

        self.layers = nn.ModuleList()
        for i_layer in range(self.num_layers):
            downsample = _make_downsample(
                self.dims[i_layer], 
                self.dims[i_layer + 1], 
                norm_layer=norm_layer,
                channel_first=self.channel_first,
            ) if (i_layer < self.num_layers - 1) else nn.Identity()

            self.layers.append(self._make_layer(
                dim = self.dims[i_layer],
                drop_path = dpr[sum(depths[:i_layer]):sum(depths[:i_layer + 1])],
                use_checkpoint=use_checkpoint,
                norm_layer=norm_layer,
                downsample=downsample,
                channel_first=self.channel_first,
                # =================
                ssm_d_state=ssm_d_state,
                ssm_ratio=ssm_ratio,
                ssm_dt_rank=ssm_dt_rank,
                ssm_act_layer=ssm_act_layer,
                ssm_conv=ssm_conv,
                ssm_conv_bias=ssm_conv_bias,
                ssm_drop_rate=ssm_drop_rate,
                ssm_init=ssm_init,
                forward_type=forward_type,
                # =================
                mlp_ratio=mlp_ratio,
                mlp_act_layer=mlp_act_layer,
                mlp_drop_rate=mlp_drop_rate,
                gmlp=gmlp,
                # =================
                _SS2D=_SS2D,
            ))

        self.classifier = nn.Sequential(OrderedDict(
            norm=norm_layer(self.num_features), # B,H,W,C
            permute=(Permute(0, 3, 1, 2) if not self.channel_first else nn.Identity()),
            avgpool=nn.AdaptiveAvgPool2d(1),
            flatten=nn.Flatten(1),
            head=nn.Linear(self.num_features, num_classes),
        ))

        self.apply(self._init_weights)

    @staticmethod
    def _pos_embed(embed_dims, patch_size, img_size):
        patch_height, patch_width = (img_size // patch_size, img_size // patch_size)
        pos_embed = nn.Parameter(torch.zeros(1, embed_dims, patch_height, patch_width))
        trunc_normal_(pos_embed, std=0.02)
        return pos_embed

    def _init_weights(self, m: nn.Module):
        if isinstance(m, nn.Linear):
            trunc_normal_(m.weight, std=.02)
            if isinstance(m, nn.Linear) and m.bias is not None:
                nn.init.constant_(m.bias, 0)
        elif isinstance(m, nn.LayerNorm):
            nn.init.constant_(m.bias, 0)
            nn.init.constant_(m.weight, 1.0)

    # used in building optimizer
    @torch.jit.ignore
    def no_weight_decay(self):
        return {"pos_embed"}

    # used in building optimizer
    @torch.jit.ignore
    def no_weight_decay_keywords(self):
        return {}

    @staticmethod
    def _make_patch_embed(in_chans=3, embed_dim=96, patch_size=4, patch_norm=True, norm_layer=nn.LayerNorm, channel_first=False):
        # if channel first, then Norm and Output are both channel_first
        return nn.Sequential(
            nn.Conv2d(in_chans, embed_dim, kernel_size=patch_size, stride=patch_size, bias=True),
            (nn.Identity() if channel_first else Permute(0, 2, 3, 1)),
            (norm_layer(embed_dim) if patch_norm else nn.Identity()),
        )

    @staticmethod
    def _make_patch_embed_v2(in_chans=3, embed_dim=96, patch_size=4, patch_norm=True, norm_layer=nn.LayerNorm, channel_first=False):
        # if channel first, then Norm and Output are both channel_first
        stride = patch_size // 2
        kernel_size = stride + 1
        padding = 1
        return nn.Sequential(
            nn.Conv2d(in_chans, embed_dim // 2, kernel_size=kernel_size, stride=stride, padding=padding),
            (nn.Identity() if (channel_first or (not patch_norm)) else Permute(0, 2, 3, 1)),
            (norm_layer(embed_dim // 2) if patch_norm else nn.Identity()),
            (nn.Identity() if (channel_first or (not patch_norm)) else Permute(0, 3, 1, 2)),
            nn.GELU(),
            nn.Conv2d(embed_dim // 2, embed_dim, kernel_size=kernel_size, stride=stride, padding=padding),
            (nn.Identity() if channel_first else Permute(0, 2, 3, 1)),
            (norm_layer(embed_dim) if patch_norm else nn.Identity()),
        )
    
    @staticmethod
    def _make_downsample(dim=96, out_dim=192, norm_layer=nn.LayerNorm, channel_first=False):
        # if channel first, then Norm and Output are both channel_first
        return nn.Sequential(
            (nn.Identity() if channel_first else Permute(0, 3, 1, 2)),
            nn.Conv2d(dim, out_dim, kernel_size=2, stride=2),
            (nn.Identity() if channel_first else Permute(0, 2, 3, 1)),
            norm_layer(out_dim),
        )

    @staticmethod
    def _make_downsample_v3(dim=96, out_dim=192, norm_layer=nn.LayerNorm, channel_first=False):
        # if channel first, then Norm and Output are both channel_first
        return nn.Sequential(
            (nn.Identity() if channel_first else Permute(0, 3, 1, 2)),
            nn.Conv2d(dim, out_dim, kernel_size=3, stride=2, padding=1),
            (nn.Identity() if channel_first else Permute(0, 2, 3, 1)),
            norm_layer(out_dim),
        )

    @staticmethod
    def _make_layer(
        dim=96, 
        drop_path=[0.1, 0.1], 
        use_checkpoint=False, 
        norm_layer=nn.LayerNorm,
        downsample=nn.Identity(),
        channel_first=False,
        # ===========================
        ssm_d_state=16,
        ssm_ratio=2.0,
        ssm_dt_rank="auto",       
        ssm_act_layer=nn.SiLU,
        ssm_conv=3,
        ssm_conv_bias=True,
        ssm_drop_rate=0.0, 
        ssm_init="v0",
        forward_type="v2",
        # ===========================
        mlp_ratio=4.0,
        mlp_act_layer=nn.GELU,
        mlp_drop_rate=0.0,
        gmlp=False,
        # ===========================
        _SS2D=SS2D,
        **kwargs,
    ):
        # if channel first, then Norm and Output are both channel_first
        depth = len(drop_path)
        blocks = []
        for d in range(depth):
            blocks.append(VSSBlock(
                hidden_dim=dim, 
                drop_path=drop_path[d],
                norm_layer=norm_layer,
                channel_first=channel_first,
                ssm_d_state=ssm_d_state,
                ssm_ratio=ssm_ratio,
                ssm_dt_rank=ssm_dt_rank,
                ssm_act_layer=ssm_act_layer,
                ssm_conv=ssm_conv,
                ssm_conv_bias=ssm_conv_bias,
                ssm_drop_rate=ssm_drop_rate,
                ssm_init=ssm_init,
                forward_type=forward_type,
                mlp_ratio=mlp_ratio,
                mlp_act_layer=mlp_act_layer,
                mlp_drop_rate=mlp_drop_rate,
                gmlp=gmlp,
                use_checkpoint=use_checkpoint,
                _SS2D=_SS2D,
            ))
        
        return nn.Sequential(OrderedDict(
            blocks=nn.Sequential(*blocks,),
            downsample=downsample,
        ))

    def forward(self, x: torch.Tensor):
        x = self.patch_embed(x)
        if self.pos_embed is not None:
            pos_embed = self.pos_embed.permute(0, 2, 3, 1) if not self.channel_first else self.pos_embed
            x = x + pos_embed
        for layer in self.layers:
            x = layer(x)
        x = self.classifier(x)
        return x

    def flops(self, shape=(3, 224, 224), verbose=True):
        # shape = self.__input_shape__[1:]
        supported_ops={
            "aten::silu": None, # as relu is in _IGNORED_OPS
            "aten::neg": None, # as relu is in _IGNORED_OPS
            "aten::exp": None, # as relu is in _IGNORED_OPS
            "aten::flip": None, # as permute is in _IGNORED_OPS
            # "prim::PythonOp.CrossScan": None,
            # "prim::PythonOp.CrossMerge": None,
            "prim::PythonOp.SelectiveScanCuda": partial(selective_scan_flop_jit, backend="prefixsum", verbose=verbose),
        }

        model = copy.deepcopy(self)
        model.cuda().eval()

        input = torch.randn((1, *shape), device=next(model.parameters()).device)
        params = parameter_count(model)[""]
        Gflops, unsupported = flop_count(model=model, inputs=(input,), supported_ops=supported_ops)

        del model, input
        return sum(Gflops.values()) * 1e9
        return f"params {params} GFLOPs {sum(Gflops.values())}"

    # used to load ckpt from previous training code
    def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs):

        def check_name(src, state_dict: dict = state_dict, strict=False):
            if strict:
                if prefix + src in list(state_dict.keys()):
                    return True
            else:
                key = prefix + src
                for k in list(state_dict.keys()):
                    if k.startswith(key):
                        return True
            return False

        def change_name(src, dst, state_dict: dict = state_dict, strict=False):
            if strict:
                if prefix + src in list(state_dict.keys()):
                    state_dict[prefix + dst] = state_dict[prefix + src]
                    state_dict.pop(prefix + src)
            else:
                key = prefix + src
                for k in list(state_dict.keys()):
                    if k.startswith(key):
                        new_k = prefix + dst + k[len(key):]
                        state_dict[new_k] = state_dict[k]
                        state_dict.pop(k)

        if check_name("pos_embed", strict=True):
            srcEmb: torch.Tensor = state_dict[prefix + "pos_embed"]
            state_dict[prefix + "pos_embed"] = F.interpolate(srcEmb.float(), size=self.pos_embed.shape[2:4], align_corners=False, mode="bicubic").to(srcEmb.device)

        change_name("patch_embed.proj", "patch_embed.0")
        change_name("patch_embed.norm", "patch_embed.2")
        for i in range(100):
            for j in range(100):
                change_name(f"layers.{i}.blocks.{j}.ln_1", f"layers.{i}.blocks.{j}.norm")
                change_name(f"layers.{i}.blocks.{j}.self_attention", f"layers.{i}.blocks.{j}.op")
        change_name("norm", "classifier.norm")
        change_name("head", "classifier.head")

        return super()._load_from_state_dict(state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs)


# compatible with openmmlab
class Backbone_VSSM(VSSM):
    def __init__(self, out_indices=(0, 1, 2, 3), pretrained=None, norm_layer="ln", **kwargs):
        kwargs.update(norm_layer=norm_layer)
        super().__init__(**kwargs)
        self.channel_first = (norm_layer.lower() in ["bn", "ln2d"])
        _NORMLAYERS = dict(
            ln=nn.LayerNorm,
            ln2d=LayerNorm2d,
            bn=nn.BatchNorm2d,
        )
        norm_layer: nn.Module = _NORMLAYERS.get(norm_layer.lower(), None)        
        
        self.out_indices = out_indices
        for i in out_indices:
            layer = norm_layer(self.dims[i])
            layer_name = f'outnorm{i}'
            self.add_module(layer_name, layer)

        del self.classifier
        self.load_pretrained(pretrained)

    def load_pretrained(self, ckpt=None, key="model"):
        if ckpt is None:
            return
        
        try:
            _ckpt = torch.load(open(ckpt, "rb"), map_location=torch.device("cpu"))
            print(f"Successfully load ckpt {ckpt}")
            incompatibleKeys = self.load_state_dict(_ckpt[key], strict=False)
            print(incompatibleKeys)        
        except Exception as e:
            print(f"Failed loading checkpoint form {ckpt}: {e}")

    def forward(self, x):
        def layer_forward(l, x):
            x = l.blocks(x)
            y = l.downsample(x)
            return x, y

        x = self.patch_embed(x)
        outs = []
        for i, layer in enumerate(self.layers):
            o, x = layer_forward(layer, x) # (B, H, W, C)
            if i in self.out_indices:
                norm_layer = getattr(self, f'outnorm{i}')
                out = norm_layer(o)
                if not self.channel_first:
                    out = out.permute(0, 3, 1, 2)
                outs.append(out.contiguous())

        if len(self.out_indices) == 0:
            return x
        
        return outs


# =====================================================
def vanilla_vmamba_tiny():
    return VSSM(
        depths=[2, 2, 9, 2], dims=96, drop_path_rate=0.2, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=16, ssm_ratio=2.0, ssm_dt_rank="auto", ssm_act_layer="silu",
        ssm_conv=3, ssm_conv_bias=True, ssm_drop_rate=0.0, 
        ssm_init="v0", forward_type="v0", 
        mlp_ratio=0.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer="ln", 
        downsample_version="v1", patchembed_version="v1", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


def vanilla_vmamba_small():
    return VSSM(
        depths=[2, 2, 27, 2], dims=96, drop_path_rate=0.3, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=16, ssm_ratio=2.0, ssm_dt_rank="auto", ssm_act_layer="silu",
        ssm_conv=3, ssm_conv_bias=True, ssm_drop_rate=0.0, 
        ssm_init="v0", forward_type="v0", 
        mlp_ratio=0.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer="ln", 
        downsample_version="v1", patchembed_version="v1", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


def vanilla_vmamba_base():
    return VSSM(
        depths=[2, 2, 27, 2], dims=128, drop_path_rate=0.6, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=16, ssm_ratio=2.0, ssm_dt_rank="auto", ssm_act_layer="silu",
        ssm_conv=3, ssm_conv_bias=True, ssm_drop_rate=0.0, 
        ssm_init="v0", forward_type="v0", 
        mlp_ratio=0.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer="ln", 
        downsample_version="v1", patchembed_version="v1", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


# =====================================================
def vmamba_tiny_s2l5(channel_first=True):
    return VSSM(
        depths=[2, 2, 5, 2], dims=96, drop_path_rate=0.2, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=1, ssm_ratio=2.0, ssm_dt_rank="auto", ssm_act_layer="silu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v0", forward_type="v05_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer=("ln2d" if channel_first else "ln"), 
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


def vmamba_small_s2l15(channel_first=True):
    return VSSM(
        depths=[2, 2, 15, 2], dims=96, drop_path_rate=0.3, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=1, ssm_ratio=2.0, ssm_dt_rank="auto", ssm_act_layer="silu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v0", forward_type="v05_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer=("ln2d" if channel_first else "ln"), 
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


def vmamba_base_s2l15(channel_first=True):
    return VSSM(
        depths=[2, 2, 15, 2], dims=128, drop_path_rate=0.6, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=1, ssm_ratio=2.0, ssm_dt_rank="auto", ssm_act_layer="silu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v0", forward_type="v05_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer=("ln2d" if channel_first else "ln"), 
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


# =====================================================
def vmamba_tiny_s1l8(channel_first=True):
    return VSSM(
        depths=[2, 2, 8, 2], dims=96, drop_path_rate=0.2, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=1, ssm_ratio=1.0, ssm_dt_rank="auto", ssm_act_layer="silu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v0", forward_type="v05_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer=("ln2d" if channel_first else "ln"), 
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


def vmamba_small_s1l20(channel_first=True):
    return VSSM(
        depths=[2, 2, 20, 2], dims=96, drop_path_rate=0.3, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=1, ssm_ratio=1.0, ssm_dt_rank="auto", ssm_act_layer="silu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v0", forward_type="v05_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer=("ln2d" if channel_first else "ln"), 
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


def vmamba_base_s1l20(channel_first=True):
    return VSSM(
        depths=[2, 2, 20, 2], dims=128, drop_path_rate=0.5, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=1, ssm_ratio=1.0, ssm_dt_rank="auto", ssm_act_layer="silu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v0", forward_type="v05_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer=("ln2d" if channel_first else "ln"), 
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


# mamba2 support =====================================================
# FLOPS count do not work now for mamba2!
def vmamba_tiny_m2():
    return VSSM(
        depths=[2, 2, 4, 2], dims=96, drop_path_rate=0.2, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=64, ssm_ratio=1.0, ssm_dt_rank="auto", ssm_act_layer="gelu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v2", forward_type="m0_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer="ln",
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


def vmamba_small_m2():
    return VSSM(
        depths=[2, 2, 12, 2], dims=96, drop_path_rate=0.3, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=64, ssm_ratio=1.0, ssm_dt_rank="auto", ssm_act_layer="gelu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v2", forward_type="m0_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer="ln",
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


def vmamba_base_m2():
    return VSSM(
        depths=[2, 2, 12, 2], dims=128, drop_path_rate=0.3, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=64, ssm_ratio=1.0, ssm_dt_rank="auto", ssm_act_layer="gelu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v2", forward_type="m0_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer="ln",
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )


if __name__ == "__main__":
    model_ref = vmamba_tiny_s1l8()

    model = VSSM(
        depths=[2, 2, 4, 2], dims=96, drop_path_rate=0.2, 
        patch_size=4, in_chans=3, num_classes=1000, 
        ssm_d_state=64, ssm_ratio=1.0, ssm_dt_rank="auto", ssm_act_layer="gelu",
        ssm_conv=3, ssm_conv_bias=False, ssm_drop_rate=0.0, 
        ssm_init="v2", forward_type="m0_noz", 
        mlp_ratio=4.0, mlp_act_layer="gelu", mlp_drop_rate=0.0, gmlp=False,
        patch_norm=True, norm_layer="ln",
        downsample_version="v3", patchembed_version="v2", 
        use_checkpoint=False, posembed=False, imgsize=224, 
    )
    print(parameter_count(model)[""])
    print(model.flops()) # wrong
    model.cuda().train()
    model_ref.cuda().train()

    def bench(model):
        import time
        inp = torch.randn((128, 3, 224, 224)).cuda()
        for _ in range(30):
            model(inp)
        torch.cuda.synchronize()
        tim = time.time()
        for _ in range(30):
            model(inp)
        torch.cuda.synchronize()
        tim1 = time.time() - tim

        for _ in range(30):
            model(inp).sum().backward()
        torch.cuda.synchronize()
        tim = time.time()
        for _ in range(30):
            model(inp).sum().backward()
        torch.cuda.synchronize()
        tim2 = time.time() - tim

        return tim1 / 30, tim2 / 30
    
    print(bench(model_ref))
    print(bench(model))

    breakpoint()


