/* ESPNOW Example

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/

/*
   This example shows how to use ESPNOW.
   Prepare two device, one for sending ESPNOW data and another for receiving
   ESPNOW data.
*/
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <assert.h>
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include "freertos/timers.h"
#include "nvs_flash.h"
#include "esp_event_loop.h"
#include "tcpip_adapter.h"
#include "esp_wifi.h"
#include "esp_log.h"
#include "esp_system.h"
#include "esp_now.h"
#include "rom/ets_sys.h"
#include "crc.h"
#include "espnow_example.h"

static const char *TAG = "espnow_example";

static xQueueHandle example_espnow_queue;

static uint8_t example_broadcast_mac[ESP_NOW_ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
static uint16_t s_example_espnow_seq[EXAMPLE_ESPNOW_DATA_MAX] = { 0, 0 };

static void example_espnow_deinit(example_espnow_send_param_t *send_param);

static esp_err_t example_event_handler(void *ctx, system_event_t *event)
{
    switch(event->event_id) {
    case SYSTEM_EVENT_STA_START:
        ESP_LOGI(TAG, "WiFi started");
        break;
    default:
        break;
    }
    return ESP_OK;
}

/* WiFi should start before using ESPNOW */
static void example_wifi_init(void)
{
    tcpip_adapter_init();
    ESP_ERROR_CHECK( esp_event_loop_init(example_event_handler, NULL) );
    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK( esp_wifi_init(&cfg) );
    ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM) );
    ESP_ERROR_CHECK( esp_wifi_set_mode(ESPNOW_WIFI_MODE) );
    ESP_ERROR_CHECK( esp_wifi_start());

    /* In order to simplify example, channel is set after WiFi started.
     * This is not necessary in real application if the two devices have
     * been already on the same channel.
     */
    ESP_ERROR_CHECK( esp_wifi_set_channel(CONFIG_ESPNOW_CHANNEL, 0) );
}

/* ESPNOW sending or receiving callback function is called in WiFi task.
 * Users should not do lengthy operations from this task. Instead, post
 * necessary data to a queue and handle it from a lower priority task. */
static void example_espnow_send_cb(const uint8_t *mac_addr, esp_now_send_status_t status)
{
    example_espnow_event_t evt;
    example_espnow_event_send_cb_t *send_cb = &evt.info.send_cb;

    if (mac_addr == NULL) {
        ESP_LOGE(TAG, "Send cb arg error");
        return;
    }

    evt.id = EXAMPLE_ESPNOW_SEND_CB;
    memcpy(send_cb->mac_addr, mac_addr, ESP_NOW_ETH_ALEN);
    send_cb->status = status;
    if (xQueueSend(example_espnow_queue, &evt, portMAX_DELAY) != pdTRUE) {
        ESP_LOGW(TAG, "Send send queue fail");
    }
}

static void example_espnow_recv_cb(const uint8_t *mac_addr, const uint8_t *data, int len)
{
    example_espnow_event_t evt;
    example_espnow_event_recv_cb_t *recv_cb = &evt.info.recv_cb;

    if (mac_addr == NULL || data == NULL || len <= 0) {
        ESP_LOGE(TAG, "Receive cb arg error");
        return;
    }

    evt.id = EXAMPLE_ESPNOW_RECV_CB;
    memcpy(recv_cb->mac_addr, mac_addr, ESP_NOW_ETH_ALEN);
    recv_cb->data = malloc(len);
    if (recv_cb->data == NULL) {
        ESP_LOGE(TAG, "Malloc receive data fail");
        return;
    }
    memcpy(recv_cb->data, data, len);
    recv_cb->data_len = len;
    if (xQueueSend(example_espnow_queue, &evt, portMAX_DELAY) != pdTRUE) {
        ESP_LOGW(TAG, "Send receive queue fail");
        free(recv_cb->data);
    }
}

/* Parse received ESPNOW data. */
int example_espnow_data_parse(uint8_t *data, uint16_t data_len, uint8_t *state, uint16_t *seq, int *magic)
{
    example_espnow_data_t *buf = (example_espnow_data_t *)data;
    uint16_t crc, crc_cal = 0;

    if (data_len < sizeof(example_espnow_data_t)) {
        ESP_LOGE(TAG, "Receive ESPNOW data too short, len:%d", data_len);
        return -1;
    }

    *state = buf->state;
    *seq = buf->seq_num;
    *magic = buf->magic;
    crc = buf->crc;
    buf->crc = 0;
    crc_cal = crc16_le(UINT16_MAX, (uint8_t const *)buf, data_len);

    if (crc_cal == crc) {
        return buf->type;
    }

    return -1;
}

/* Prepare ESPNOW data to be sent. */
void example_espnow_data_prepare(example_espnow_send_param_t *send_param)
{
    example_espnow_data_t *buf = (example_espnow_data_t *)send_param->buffer;
    int i = 0;

    assert(send_param->len >= sizeof(example_espnow_data_t));

    buf->type = IS_BROADCAST_ADDR(send_param->dest_mac) ? EXAMPLE_ESPNOW_DATA_BROADCAST : EXAMPLE_ESPNOW_DATA_UNICAST;
    buf->state = send_param->state;
    buf->seq_num = s_example_espnow_seq[buf->type]++;
    buf->crc = 0;
    buf->magic = send_param->magic;
    for (i = 0; i < send_param->len - sizeof(example_espnow_data_t); i++) {
        buf->payload[i] = (uint8_t)esp_random();
    }
    buf->crc = crc16_le(UINT16_MAX, (uint8_t const *)buf, send_param->len);
}

static void example_espnow_task(void *pvParameter)
{
    example_espnow_event_t evt;
    uint8_t recv_state = 0;
    uint16_t recv_seq = 0;
    int recv_magic = 0;
    bool is_broadcast = false;
    int ret;

    vTaskDelay(5000 / portTICK_RATE_MS);
    ESP_LOGI(TAG, "Start sending broadcast data");

    /* Start sending broadcast ESPNOW data. */
    example_espnow_send_param_t *send_param = (example_espnow_send_param_t *)pvParameter;
    if (esp_now_send(send_param->dest_mac, send_param->buffer, send_param->len) != ESP_OK) {
        ESP_LOGE(TAG, "Send error");
        example_espnow_deinit(send_param);
        vTaskDelete(NULL);
    }

    while (xQueueReceive(example_espnow_queue, &evt, portMAX_DELAY) == pdTRUE) {
        switch (evt.id) {
            case EXAMPLE_ESPNOW_SEND_CB:
            {
                example_espnow_event_send_cb_t *send_cb = &evt.info.send_cb;
                is_broadcast = IS_BROADCAST_ADDR(send_cb->mac_addr);

                ESP_LOGD(TAG, "Send data to "MACSTR", status1: %d", MAC2STR(send_cb->mac_addr), send_cb->status);

                if (is_broadcast && (send_param->broadcast == false)) {
                    break;
                }

                if (!is_broadcast) {
                    send_param->count--;
                    if (send_param->count == 0) {
                        ESP_LOGI(TAG, "Send done");
                        example_espnow_deinit(send_param);
                        vTaskDelete(NULL);
                    }
                }

                /* Delay a while before sending the next data. */
                if (send_param->delay > 0) {
                    vTaskDelay(send_param->delay/portTICK_RATE_MS);
                }

                ESP_LOGI(TAG, "send data to "MACSTR"", MAC2STR(send_cb->mac_addr));

                memcpy(send_param->dest_mac, send_cb->mac_addr, ESP_NOW_ETH_ALEN);
                example_espnow_data_prepare(send_param);

                /* Send the next data after the previous data is sent. */
                if (esp_now_send(send_param->dest_mac, send_param->buffer, send_param->len) != ESP_OK) {
                    ESP_LOGE(TAG, "Send error");
                    example_espnow_deinit(send_param);
                    vTaskDelete(NULL);
                }
                break;
            }
            case EXAMPLE_ESPNOW_RECV_CB:
            {
                example_espnow_event_recv_cb_t *recv_cb = &evt.info.recv_cb;

                ret = example_espnow_data_parse(recv_cb->data, recv_cb->data_len, &recv_state, &recv_seq, &recv_magic);
                free(recv_cb->data);
                if (ret == EXAMPLE_ESPNOW_DATA_BROADCAST) {
                    ESP_LOGI(TAG, "Receive %dth broadcast data from: "MACSTR", len: %d", recv_seq, MAC2STR(recv_cb->mac_addr), recv_cb->data_len);

                    /* If MAC address does not exist in peer list, add it to peer list. */
                    if (esp_now_is_peer_exist(recv_cb->mac_addr) == false) {
                        esp_now_peer_info_t *peer = malloc(sizeof(esp_now_peer_info_t));
                        if (peer == NULL) {
                            ESP_LOGE(TAG, "Malloc peer information fail");
                            example_espnow_deinit(send_param);
                            vTaskDelete(NULL);
                        }
                        memset(peer, 0, sizeof(esp_now_peer_info_t));
                        peer->channel = CONFIG_ESPNOW_CHANNEL;
                        peer->ifidx = ESPNOW_WIFI_IF;
                        peer->encrypt = true;
                        memcpy(peer->lmk, CONFIG_ESPNOW_LMK, ESP_NOW_KEY_LEN);
                        memcpy(peer->peer_addr, recv_cb->mac_addr, ESP_NOW_ETH_ALEN);
                        ESP_ERROR_CHECK( esp_now_add_peer(peer) );
                        free(peer);
                    }

                    /* Indicates that the device has received broadcast ESPNOW data. */
                    if (send_param->state == 0) {
                        send_param->state = 1;
                    }

                    /* If receive broadcast ESPNOW data which indicates that the other device has received
                     * broadcast ESPNOW data and the local magic number is bigger than that in the received
                     * broadcast ESPNOW data, stop sending broadcast ESPNOW data and start sending unicast
                     * ESPNOW data.
                     */
                    if (recv_state == 1) {
                        /* The device which has the bigger magic number sends ESPNOW data, the other one
                         * receives ESPNOW data.
                         */
                        if (send_param->unicast == false && send_param->magic >= recv_magic) {
                    	    ESP_LOGI(TAG, "Start sending unicast data");
                    	    ESP_LOGI(TAG, "send data to "MACSTR"", MAC2STR(recv_cb->mac_addr));

                    	    /* Start sending unicast ESPNOW data. */
                            memcpy(send_param->dest_mac, recv_cb->mac_addr, ESP_NOW_ETH_ALEN);
                            example_espnow_data_prepare(send_param);
                            if (esp_now_send(send_param->dest_mac, send_param->buffer, send_param->len) != ESP_OK) {
                                ESP_LOGE(TAG, "Send error");
                                example_espnow_deinit(send_param);
                                vTaskDelete(NULL);
                            }
                            else {
                                send_param->broadcast = false;
                                send_param->unicast = true;
                            }
                        }
                    }
                }
                else if (ret == EXAMPLE_ESPNOW_DATA_UNICAST) {
                    ESP_LOGI(TAG, "Receive %dth unicast data from: "MACSTR", len: %d", recv_seq, MAC2STR(recv_cb->mac_addr), recv_cb->data_len);

                    /* If receive unicast ESPNOW data, also stop sending broadcast ESPNOW data. */
                    send_param->broadcast = false;
                }
                else {
                    ESP_LOGI(TAG, "Receive error data from: "MACSTR"", MAC2STR(recv_cb->mac_addr));
                }
                break;
            }
            default:
                ESP_LOGE(TAG, "Callback type error: %d", evt.id);
                break;
        }
    }
}

static esp_err_t example_espnow_init(void)
{
    example_espnow_send_param_t *send_param;

    example_espnow_queue = xQueueCreate(ESPNOW_QUEUE_SIZE, sizeof(example_espnow_event_t));
    if (example_espnow_queue == NULL) {
        ESP_LOGE(TAG, "Create mutex fail");
        return ESP_FAIL;
    }

    /* Initialize ESPNOW and register sending and receiving callback function. */
    ESP_ERROR_CHECK( esp_now_init() );
    ESP_ERROR_CHECK( esp_now_register_send_cb(example_espnow_send_cb) );
    ESP_ERROR_CHECK( esp_now_register_recv_cb(example_espnow_recv_cb) );

    /* Set primary master key. */
    ESP_ERROR_CHECK( esp_now_set_pmk((uint8_t *)CONFIG_ESPNOW_PMK) );

    /* Add broadcast peer information to peer list. */
    esp_now_peer_info_t *peer = malloc(sizeof(esp_now_peer_info_t));
    if (peer == NULL) {
        ESP_LOGE(TAG, "Malloc peer information fail");
        vSemaphoreDelete(example_espnow_queue);
        esp_now_deinit();
        return ESP_FAIL;
    }
    memset(peer, 0, sizeof(esp_now_peer_info_t));
    peer->channel = CONFIG_ESPNOW_CHANNEL;
    peer->ifidx = ESPNOW_WIFI_IF;
    peer->encrypt = false;
    memcpy(peer->peer_addr, example_broadcast_mac, ESP_NOW_ETH_ALEN);
    ESP_ERROR_CHECK( esp_now_add_peer(peer) );
    free(peer);

    /* Initialize sending parameters. */
    send_param = malloc(sizeof(example_espnow_send_param_t));
    memset(send_param, 0, sizeof(example_espnow_send_param_t));
    if (send_param == NULL) {
        ESP_LOGE(TAG, "Malloc send parameter fail");
        vSemaphoreDelete(example_espnow_queue);
        esp_now_deinit();
        return ESP_FAIL;
    }
    send_param->unicast = false;
    send_param->broadcast = true;
    send_param->state = 0;
    send_param->magic = esp_random();
    send_param->count = CONFIG_ESPNOW_SEND_COUNT;
    send_param->delay = CONFIG_ESPNOW_SEND_DELAY;
    send_param->len = CONFIG_ESPNOW_SEND_LEN;
    send_param->buffer = malloc(CONFIG_ESPNOW_SEND_LEN);
    if (send_param->buffer == NULL) {
        ESP_LOGE(TAG, "Malloc send buffer fail");
        free(send_param);
        vSemaphoreDelete(example_espnow_queue);
        esp_now_deinit();
        return ESP_FAIL;
    }
    memcpy(send_param->dest_mac, example_broadcast_mac, ESP_NOW_ETH_ALEN);
    example_espnow_data_prepare(send_param);

    xTaskCreate(example_espnow_task, "example_espnow_task", 2048, send_param, 4, NULL);

    return ESP_OK;
}

static void example_espnow_deinit(example_espnow_send_param_t *send_param)
{
    free(send_param->buffer);
    free(send_param);
    vSemaphoreDelete(example_espnow_queue);
    esp_now_deinit();
}

void app_main()
{
    // Initialize NVS
    ESP_ERROR_CHECK( nvs_flash_init() );

    example_wifi_init();
    example_espnow_init();
}
