// (c) Copyright Microsoft Corporation.
// This source is subject to the Microsoft Public License (Ms-PL).
// Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
// All other rights reserved.

using System.Collections;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Diagnostics;
using System.Globalization;
using System.Reflection;

namespace AtomUI.Utils;

internal static class TypeHelper
{
    internal const char LeftIndexerToken = '[';
    internal const char PropertyNameSeparator = '.';
    internal const char RightIndexerToken = ']';
    internal const char LeftParenthesisToken = '(';
    internal const char RightParenthesisToken = ')';

    private static Type? FindGenericType(Type definition, Type? type)
    {
        while ((type != null) && (type != typeof(object)))
        {
            if (type.IsGenericType && (type.GetGenericTypeDefinition() == definition))
            {
                return type;
            }

            if (definition.IsInterface)
            {
                foreach (Type type2 in type.GetInterfaces())
                {
                    Type? type3 = FindGenericType(definition, type2);
                    if (type3 != null)
                    {
                        return type3;
                    }
                }
            }

            type = type.BaseType;
        }

        return null;
    }

    /// <summary>
    /// Finds an int or string indexer in the specified collection of members, where int indexers take priority
    /// over string indexers.  If found, this method will return the associated PropertyInfo and set the out index
    /// argument to its appropriate value.  If not found, the return value will be null, as will the index.
    /// </summary>
    /// <param name="members">Collection of members to search through for an indexer.</param>
    /// <param name="stringIndex">String value of indexer argument.</param>
    /// <param name="index">Resultant index value.</param>
    /// <returns>Indexer PropertyInfo if found, null otherwise.</returns>
    private static PropertyInfo? FindIndexerInMembers(MemberInfo?[] members, string stringIndex, out object[]? index)
    {
        index = null;
        ParameterInfo[] parameters;
        PropertyInfo?   stringIndexer = null;

        foreach (var member in members)
        {
            if (member is not PropertyInfo pi)
            {
                continue;
            }

            // Only a single parameter is supported and it must be a string or Int32 value.
            parameters = pi.GetIndexParameters();
            if (parameters.Length > 1)
            {
                continue;
            }

            if (parameters[0].ParameterType == typeof(int))
            {
                int intIndex = -1;
                if (Int32.TryParse(stringIndex.Trim(), NumberStyles.None, CultureInfo.InvariantCulture, out intIndex))
                {
                    index = [intIndex];
                    return pi;
                }
            }

            // If string indexer is found save it, in case there is an int indexer.
            if (parameters[0].ParameterType == typeof(string))
            {
                index         = [stringIndex];
                stringIndexer = pi;
            }
        }

        return stringIndexer;
    }

    /// <summary>
    /// Gets the default member name that is used for an indexer (e.g. "Item").
    /// </summary>
    /// <param name="type">Type to check.</param>
    /// <returns>Default member name.</returns>
    private static string? GetDefaultMemberName(this Type type)
    {
        var attributes = type.GetCustomAttributes(typeof(DefaultMemberAttribute), true);
        if (attributes.Length == 1)
        {
            var defaultMemberAttribute = (DefaultMemberAttribute)attributes[0];
            return defaultMemberAttribute.MemberName;
        }

        return null;
    }

    /// <summary>
    /// Finds the PropertyInfo for the specified property path within this Type, and returns
    /// the value of GetShortName on its DisplayAttribute, if one exists. GetShortName will return
    /// the value of Name if there is no ShortName specified.
    /// </summary>
    /// <param name="type">Type to search</param>
    /// <param name="propertyPath">property path</param>
    /// <returns>DisplayAttribute.ShortName if it exists, null otherwise</returns>
    internal static string? GetDisplayName(this Type type, string propertyPath)
    {
        PropertyInfo? propertyInfo = type.GetNestedProperty(propertyPath);
        if (propertyInfo != null)
        {
            object[] attributes = propertyInfo.GetCustomAttributes(typeof(DisplayAttribute), true);
            if (attributes.Length > 0)
            {
                Debug.Assert(attributes.Length == 1);
                if (attributes[0] is DisplayAttribute displayAttribute)
                {
                    return displayAttribute.GetShortName();
                }
            }
        }

        return null;
    }

    internal static Type GetEnumerableItemType(this Type enumerableType)
    {
        Type? type = FindGenericType(typeof(IEnumerable<>), enumerableType);
        if (type != null)
        {
            return type.GetGenericArguments()[0];
        }

        return enumerableType;
    }

    /// <summary>
    /// Retrieves the value and type of a property. That property can be nested and its path
    /// can include indexers. Each element of the path needs to be a public instance property.
    /// </summary>
    /// <param name="parentType">The parent Type</param>
    /// <param name="propertyPath">Property path</param>
    /// <param name="exception">Potential exception</param>
    /// <param name="item">Parent item which will be set to the property value if non-null.</param>
    /// <returns></returns>
    private static PropertyInfo? GetNestedProperty(this Type? parentType, string? propertyPath,
                                                   out Exception? exception, ref object? item)
    {
        exception = null;
        if (parentType == null || string.IsNullOrEmpty(propertyPath))
        {
            item = null;
            return null;
        }

        Type          type          = parentType;
        PropertyInfo? propertyInfo  = null;
        List<string>  propertyNames = SplitPropertyPath(propertyPath);
        for (int i = 0; i < propertyNames.Count; i++)
        {
            // if we can't find the property or it is not of the correct type,
            // treat it as a null value
            propertyInfo = type.GetPropertyOrIndexer(propertyNames[i], out object[]? index);
            if (propertyInfo == null)
            {
                item = null;
                return null;
            }

            if (!propertyInfo.CanRead)
            {
                exception =
                    new InvalidOperationException(
                        $"The property named '{propertyNames[i]}' on type '{type.GetTypeName()}' cannot be read.");
                item = null;
                return null;
            }

            if (item != null)
            {
                item = propertyInfo.GetValue(item, index);
            }

            type = propertyInfo.PropertyType.GetNonNullableType();
        }

        return propertyInfo;
    }

    /// <summary>
    /// Finds the leaf PropertyInfo for the specified property path, and returns its value
    /// if the item is non-null.
    /// </summary>
    /// <param name="parentType">Type to search.</param>
    /// <param name="propertyPath">Property path.</param>
    /// <param name="item">Parent item which will be set to the property value if non-null.</param>
    /// <returns>The PropertyInfo.</returns>
    internal static PropertyInfo? GetNestedProperty(this Type parentType, string? propertyPath, ref object? item)
    {
        return parentType.GetNestedProperty(propertyPath, out Exception? ex, ref item);
    }

    internal static PropertyInfo? GetNestedProperty(this Type? parentType, string? propertyPath)
    {
        if (parentType != null)
        {
            object? item = null;
            return parentType.GetNestedProperty(propertyPath, ref item);
        }

        return null;
    }

    /// <summary>
    /// Returns the friendly name for a type
    /// </summary>
    /// <param name="type">The type to get the name from</param>
    /// <returns>Textual representation of the input type</returns>
    internal static string GetTypeName(this Type type)
    {
        Type   baseType = type.GetNonNullableType();
        string s        = baseType.Name;
        if (type != baseType)
        {
            s += '?';
        }

        return s;
    }

    internal static Type? GetNestedPropertyType(this Type? parentType, string? propertyPath)
    {
        if (parentType == null || string.IsNullOrEmpty(propertyPath))
        {
            return parentType;
        }

        PropertyInfo? propertyInfo = parentType.GetNestedProperty(propertyPath);
        if (propertyInfo != null)
        {
            return propertyInfo.PropertyType;
        }

        return null;
    }

    /// <summary>
    /// Retrieves the value of a property. That property can be nested and its path can
    /// include indexers. Each element of the path needs to be a public instance property.
    /// The return value will either be of type propertyType or it will be null.
    /// </summary>
    /// <param name="item">Object that exposes the property</param>
    /// <param name="propertyPath">Property path</param>
    /// <param name="propertyType">Property type</param>
    /// <param name="exception">Potential exception</param>
    /// <returns>Property value</returns>
    internal static object? GetNestedPropertyValue(object? item, string? propertyPath, Type propertyType,
                                                   out Exception? exception)
    {
        exception = null;

        // if the item is null, treat the property value as null
        if (item == null)
        {
            return null;
        }

        // if the propertyPath is null or empty, return the item
        if (string.IsNullOrEmpty(propertyPath))
        {
            return item;
        }

        object?       propertyValue = item;
        Type          itemType      = item.GetType();
        PropertyInfo? propertyInfo  = itemType.GetNestedProperty(propertyPath, out exception, ref propertyValue);
        if (propertyInfo != null && propertyInfo.PropertyType != propertyType)
        {
            return null;
        }

        return propertyValue;
    }

    /// <summary>
    /// Gets the value of a given property path on a particular data item.
    /// </summary>
    /// <param name="item">Parent data item.</param>
    /// <param name="propertyPath">Property path.</param>
    /// <returns>Value.</returns>
    internal static object? GetNestedPropertyValue(object? item, string? propertyPath)
    {
        if (item != null)
        {
            Type parentType = item.GetType();
            if (string.IsNullOrEmpty(propertyPath))
            {
                return item;
            }
            else
            {
                object? nestedValue = item;
                parentType.GetNestedProperty(propertyPath, ref nestedValue);
                return nestedValue;
            }
        }

        return null;
    }

    internal static Type GetNonNullableType(this Type type)
    {
        if (IsNullableType(type))
        {
            return type.GetGenericArguments()[0];
        }

        return type;
    }

    /// <summary>
    /// Returns the PropertyInfo for the specified property path.  If the property path
    /// refers to an indexer (e.g. "[abc]"), then the index out parameter will be set to the value
    /// specified in the property path.  This method only supports indexers with a single parameter
    /// that is either an int or a string.  Int parameters take priority over string parameters.
    /// </summary>
    /// <param name="type">Type to search.</param>
    /// <param name="propertyPath">Property path.</param>
    /// <param name="index">Set to the index if return value is an indexer, otherwise null.</param>
    /// <returns>PropertyInfo for either a property or an indexer.</returns>
    internal static PropertyInfo? GetPropertyOrIndexer(this Type type, string? propertyPath, out object[]? index)
    {
        index = null;

        if (string.IsNullOrEmpty(propertyPath))
        {
            return null;
        }

        // Return the default value of GetProperty if the first character is not an indexer token.
        if (propertyPath[0] != LeftIndexerToken)
        {
            var property = type.GetProperty(propertyPath);
            if (property != null)
            {
                return property;
            }

            // GetProperty does not return inherited interface properties,
            // so we need to enumerate them manually.
            if (type.IsInterface)
            {
                foreach (var typeInterface in type.GetInterfaces())
                {
                    property = type.GetProperty(propertyPath);
                    if (property != null)
                    {
                        return property;
                    }
                }
            }

            return null;
        }

        if (propertyPath.Length < 2 || propertyPath[propertyPath.Length - 1] != RightIndexerToken)
        {
            // Return null if the indexer does not meet the standard format (i.e. "[x]").
            return null;
        }

        string stringIndex = propertyPath.Substring(1, propertyPath.Length - 2);
        var    indexer     = FindIndexerInMembers(type.GetDefaultMembers(), stringIndex, out index);
        if (indexer != null)
        {
            // We found the indexer, so return it.
            return indexer;
        }

        var elementType = type.GetElementType();
        if (elementType == null)
        {
            var genericArguments = type.GetGenericArguments();
            if (genericArguments.Length == 1)
            {
                elementType = genericArguments[0];
            }
        }

        if (elementType != null)
        {
            // If the object is of type IList, try to use its default indexer.
            if (typeof(IList<>).MakeGenericType(elementType) is Type genericList
                && genericList.IsAssignableFrom(type))
            {
                indexer = FindIndexerInMembers(genericList.GetDefaultMembers(), stringIndex, out index);
            }

            if (typeof(IReadOnlyList<>).MakeGenericType(elementType) is Type genericReadOnlyList
                && genericReadOnlyList.IsAssignableFrom(type))
            {
                indexer = FindIndexerInMembers(genericReadOnlyList.GetDefaultMembers(), stringIndex, out index);
            }
        }

        return indexer;
    }

    internal static bool IsEnumerableType(this Type enumerableType)
    {
        return (FindGenericType(typeof(IEnumerable<>), enumerableType) != null);
    }

    internal static bool IsNullableType(this Type? type)
    {
        if (type == null)
        {
            return false;
        }
        return type.IsGenericType && (type.GetGenericTypeDefinition() == typeof(Nullable<>));
    }

    internal static bool IsNullableEnum(this Type type)
    {
        return type.IsNullableType() &&
               type.GetGenericArguments().Length == 1 &&
               type.GetGenericArguments()[0].IsEnum;
    }

    /// <summary>
    /// If the specified property is an indexer, this method will prepend the object's
    /// default member name to it (e.g. "[foo]" returns "Item[foo]").
    /// </summary>
    /// <param name="item">Declaring data item.</param>
    /// <param name="property">Property name.</param>
    /// <returns>Property with default member name prepended, or property if unchanged.</returns>
    internal static string? PrependDefaultMemberName(object? item, string? property)
    {
        if (item != null && !string.IsNullOrEmpty(property) && property[0] == LeftIndexerToken)
        {
            // The leaf property name is an indexer, so add the default member name.
            Type    declaringType     = item.GetType();
            string? defaultMemberName = declaringType.GetNonNullableType().GetDefaultMemberName();
            if (!string.IsNullOrEmpty(defaultMemberName))
            {
                return defaultMemberName + property;
            }
        }

        return property;
    }

    /// <summary>
    /// If the specified property is an indexer, this method will remove the object's
    /// default member name from it (e.g. "Item[foo]" returns "[foo]").
    /// </summary>
    /// <param name="property">Property name.</param>
    /// <returns>Property with default member name removed, or property if unchanged.</returns>
    internal static string RemoveDefaultMemberName(string property)
    {
        if (!string.IsNullOrEmpty(property) && property[property.Length - 1] == RightIndexerToken)
        {
            // The property is an indexer, so remove the default member name.
            int leftIndexerToken = property.IndexOf(TypeHelper.LeftIndexerToken);
            if (leftIndexerToken >= 0)
            {
                return property.Substring(leftIndexerToken);
            }
        }

        return property;
    }

    /// <summary>
    /// Returns a list of substrings where each one represents a single property within a nested
    /// property path which may include indexers.  For example, the string "abc.d[efg][h].ijk"
    /// would return the substrings: "abc", "d", "[efg]", "[h]", and "ijk".
    /// </summary>
    /// <param name="propertyPath">Path to split.</param>
    /// <returns>List of property substrings.</returns>
    internal static List<string> SplitPropertyPath(string? propertyPath)
    {
        List<string> propertyPaths = new List<string>();
        if (!string.IsNullOrEmpty(propertyPath))
        {
            bool parenthesisOn = false;
            int  startIndex    = 0;
            for (int index = 0; index < propertyPath!.Length; index++)
            {
                if (parenthesisOn)
                {
                    if (propertyPath[index] == RightParenthesisToken)
                    {
                        parenthesisOn = false;
                        startIndex    = index + 1;
                    }

                    continue;
                }

                if (propertyPath[index] == LeftParenthesisToken)
                {
                    parenthesisOn = true;
                    if (startIndex != index)
                    {
                        propertyPaths.Add(propertyPath.Substring(startIndex, index - startIndex));
                        startIndex = index + 1;
                    }
                }
                else if (propertyPath[index] == PropertyNameSeparator)
                {
                    if (startIndex != index)
                    {
                        propertyPaths.Add(propertyPath.Substring(startIndex, index - startIndex));
                    }

                    startIndex = index + 1;
                }
                else if (startIndex != index && propertyPath[index] == LeftIndexerToken)
                {
                    propertyPaths.Add(propertyPath.Substring(startIndex, index - startIndex));
                    startIndex = index;
                }
                else if (index == propertyPath.Length - 1)
                {
                    propertyPaths.Add(propertyPath.Substring(startIndex));
                }
            }
        }

        return propertyPaths;
    }

    /// <summary>
    /// Checks a MemberInfo object (e.g. a Type or PropertyInfo) for the ReadOnly attribute
    /// and returns the value of IsReadOnly if it exists.
    /// </summary>
    /// <param name="memberInfo">MemberInfo to check</param>
    /// <returns>true if MemberInfo is read-only, false otherwise</returns>
    internal static bool GetIsReadOnly(this MemberInfo? memberInfo)
    {
        if (memberInfo != null)
        {
            // Check if ReadOnlyAttribute is defined on the member
            object[] attributes = memberInfo.GetCustomAttributes(typeof(ReadOnlyAttribute), true);
            if (attributes.Length > 0)
            {
                ReadOnlyAttribute readOnlyAttribute = (ReadOnlyAttribute)attributes[0];
                return readOnlyAttribute.IsReadOnly;
            }
        }

        return false;
    }

    internal static Type? GetItemType(this IEnumerable list)
    {
        Type  listType = list.GetType();
        Type? itemType = null;

        // if it's a generic enumerable, we get the generic type

        // Unfortunately, if data source is fed from a bare IEnumerable, TypeHelper will report an element type of object,
        // which is not particularly interesting.  We deal with it further on.
        if (listType.IsEnumerableType())
        {
            itemType = listType.GetEnumerableItemType();
        }

        // Bare IEnumerables mean that result type will be object.  In that case, we try to get something more interesting
        if (itemType == null || itemType == typeof(object))
        {
            // We haven't located a type yet.. try a different approach.
            // Does the list have anything in it?

            IEnumerator en = list.GetEnumerator();
            if (en.MoveNext() && en.Current != null)
            {
                return en.Current.GetType();
            }
        }

        // if we're null at this point, give up
        return itemType;
    }
}