using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Reflection;
using Avalonia.PropertyGrid.Models;

namespace Avalonia.PropertyGrid.Services;

/// <summary>
/// Service for creating PropertyItem collections from objects
/// </summary>
public class PropertyItemFactory
{
    private static readonly HashSet<Type> SimpleTypes = new()
    {
        typeof(string), typeof(int), typeof(long), typeof(short), typeof(byte),
        typeof(uint), typeof(ulong), typeof(ushort), typeof(sbyte),
        typeof(float), typeof(double), typeof(decimal),
        typeof(bool), typeof(char), typeof(DateTime), typeof(DateTimeOffset),
        typeof(TimeSpan), typeof(Guid)
    };

    /// <summary>
    /// Creates a collection of PropertyItems from an object
    /// </summary>
    public static List<PropertyItem> CreatePropertyItems(object? obj, int indentLevel = 0)
    {
        if (obj == null)
            return new List<PropertyItem>();

        var properties = new List<PropertyItem>();
        var type = obj.GetType();

        // Check if this is a collection (but not a string or dictionary)
        if (IsCollection(obj))
        {
            return CreateCollectionItems(obj, indentLevel);
        }

        foreach (var prop in type.GetProperties(BindingFlags.Public | BindingFlags.Instance))
        {
            // Skip indexed properties
            if (prop.GetIndexParameters().Length > 0)
                continue;

            var item = CreatePropertyItem(obj, prop, indentLevel);

            if (item != null && item.IsBrowsable)
            {
                properties.Add(item);
            }
        }

        // Sort by order, then by category, then by name
        return properties.OrderBy(p => p.Order)
                        .ThenBy(p => p.Category)
                        .ThenBy(p => p.DisplayName)
                        .ToList();
    }

    /// <summary>
    /// Creates PropertyItems for collection elements
    /// </summary>
    private static List<PropertyItem> CreateCollectionItems(object collection, int indentLevel)
    {
        var items = new List<PropertyItem>();

        if (collection is System.Collections.IEnumerable enumerable)
        {
            int index = 0;
            foreach (var element in enumerable)
            {
                if (element == null)
                {
                    index++;
                    continue;
                }

                var elementType = element.GetType();
                var isSimple = IsSimpleType(elementType);

                // For simple types, show the value in the display name
                string displayName = $"[{index}]";
                if (isSimple || elementType == typeof(string))
                {
                    var valueStr = element.ToString();
                    if (!string.IsNullOrEmpty(valueStr) && valueStr.Length <= 50)
                    {
                        displayName = $"[{index}] = {valueStr}";
                    }
                }

                var item = new PropertyItem
                {
                    Name = $"[{index}]",
                    DisplayName = displayName,
                    Description = $"Item at index {index}",
                    Category = "Items",
                    PropertyType = elementType,
                    IsReadOnly = true, // Collection items are read-only for now
                    Instance = collection,
                    IndentLevel = indentLevel,
                    Value = element,
                    Converter = TypeDescriptor.GetConverter(elementType),
                    Order = index,
                    IsBrowsable = true,
                    IsExpandable = !isSimple && elementType.IsClass && elementType != typeof(string)
                };

                items.Add(item);
                index++;
            }
        }

        return items;
    }

    /// <summary>
    /// Checks if an object is a collection (excluding strings and dictionaries)
    /// </summary>
    private static bool IsCollection(object obj)
    {
        if (obj == null)
            return false;

        var type = obj.GetType();

        // Exclude strings and dictionaries
        if (type == typeof(string))
            return false;

        if (typeof(System.Collections.IDictionary).IsAssignableFrom(type))
            return false;

        // Check if it implements IEnumerable
        return typeof(System.Collections.IEnumerable).IsAssignableFrom(type);
    }

    /// <summary>
    /// Creates a single PropertyItem from a PropertyInfo
    /// </summary>
    public static PropertyItem? CreatePropertyItem(object instance, PropertyInfo propertyInfo, int indentLevel = 0)
    {
        // Check if browsable
        var browsableAttr = propertyInfo.GetCustomAttribute<BrowsableAttribute>();
        if (browsableAttr != null && !browsableAttr.Browsable)
            return null;

        var item = new PropertyItem
        {
            Name = propertyInfo.Name,
            DisplayName = GetDisplayName(propertyInfo),
            Description = GetDescription(propertyInfo),
            Category = GetCategory(propertyInfo),
            PropertyType = propertyInfo.PropertyType,
            IsReadOnly = !propertyInfo.CanWrite || propertyInfo.GetCustomAttribute<ReadOnlyAttribute>()?.IsReadOnly == true,
            PropertyInfo = propertyInfo,
            Instance = instance,
            IndentLevel = indentLevel,
            Converter = TypeDescriptor.GetConverter(propertyInfo.PropertyType),
            Order = GetOrder(propertyInfo),
            IsBrowsable = true
        };

        // Get the current value
        try
        {
            item.Value = propertyInfo.GetValue(instance);
        }
        catch
        {
            item.Value = null;
        }

        // Check if expandable (complex type)
        var propType = propertyInfo.PropertyType;
        item.IsExpandable = !IsSimpleType(propType) && propType.IsClass && propType != typeof(string);

        return item;
    }

    private static string GetDisplayName(PropertyInfo prop)
    {
        var displayAttr = prop.GetCustomAttribute<DisplayAttribute>();
        if (displayAttr?.Name != null)
            return displayAttr.Name;

        var displayNameAttr = prop.GetCustomAttribute<DisplayNameAttribute>();
        if (displayNameAttr?.DisplayName != null)
            return displayNameAttr.DisplayName;

        // Add spaces before capital letters
        return AddSpacesToCamelCase(prop.Name);
    }

    private static string? GetDescription(PropertyInfo prop)
    {
        var displayAttr = prop.GetCustomAttribute<DisplayAttribute>();
        if (displayAttr?.Description != null)
            return displayAttr.Description;

        var descriptionAttr = prop.GetCustomAttribute<DescriptionAttribute>();
        return descriptionAttr?.Description;
    }

    private static string GetCategory(PropertyInfo prop)
    {
        var categoryAttr = prop.GetCustomAttribute<CategoryAttribute>();
        if (categoryAttr?.Category != null && categoryAttr.Category != CategoryAttribute.Default.Category)
            return categoryAttr.Category;

        var displayAttr = prop.GetCustomAttribute<DisplayAttribute>();
        if (displayAttr?.GroupName != null)
            return displayAttr.GroupName;

        return "Misc";
    }

    private static int GetOrder(PropertyInfo prop)
    {
        var displayAttr = prop.GetCustomAttribute<DisplayAttribute>();
        return displayAttr?.GetOrder() ?? int.MaxValue;
    }

    private static bool IsSimpleType(Type type)
    {
        type = Nullable.GetUnderlyingType(type) ?? type;
        return SimpleTypes.Contains(type) || type.IsEnum;
    }

    private static string AddSpacesToCamelCase(string text)
    {
        if (string.IsNullOrWhiteSpace(text))
            return string.Empty;

        var result = new System.Text.StringBuilder();
        result.Append(text[0]);

        for (int i = 1; i < text.Length; i++)
        {
            if (char.IsUpper(text[i]) && !char.IsUpper(text[i - 1]))
            {
                result.Append(' ');
            }
            result.Append(text[i]);
        }

        return result.ToString();
    }
}