using System.Security.Claims;
using Foxel.Models;
using Foxel.Models.DataBase;
using Foxel.Models.Response.Album;
using Microsoft.EntityFrameworkCore;
using Foxel.Services.Mapping; // 添加 using

namespace Foxel.Services.Media;

public class AlbumService(
    IDbContextFactory<MyDbContext> contextFactory,
    IHttpContextAccessor httpContextAccessor,
    IMappingService mappingService) // 注入新的映射服务
    : IAlbumService
{
    public async Task<PaginatedResult<AlbumResponse>> GetAlbumsAsync(int page = 1, int pageSize = 10, int? userId = null)
    {
        if (page < 1) page = 1;
        if (pageSize < 1) pageSize = 10;

        await using var dbContext = await contextFactory.CreateDbContextAsync();

        // 构建查询
        IQueryable<Album> query = dbContext.Albums
            .Include(a => a.User)
            .Include(a => a.CoverPicture) // 确保包含封面图片
            .Include(a => a.Pictures) // 确保包含图片集合以计算 PictureCount
            .OrderByDescending(a => a.CreatedAt);

        // 如果指定了用户ID，则只获取该用户的相册
        if (userId.HasValue)
        {
            query = query.Where(a => a.UserId == userId.Value);
        }

        // 获取总数和分页数据
        var totalCount = await query.CountAsync();
        var albums = await query
            // .Include(a => a.CoverPicture) // 已在上面包含
            .Skip((page - 1) * pageSize)
            .Take(pageSize)
            .ToListAsync();

        // 获取每个相册中的图片数量 - 不再需要，MapAlbumToResponse 会处理
        // var albumIds = albums.Select(a => a.Id).ToList();
        // var albumPictureCounts = await dbContext.Pictures
        //     .Where(p => p.AlbumId != null && albumIds.Contains(p.AlbumId.Value))
        //     .GroupBy(p => p.AlbumId)
        //     .Select(g => new { AlbumId = g.Key, Count = g.Count() })
        //     .ToDictionaryAsync(x => x.AlbumId!.Value, x => x.Count);

        // 转换为响应模型
        var albumResponses = albums.Select(mappingService.MapAlbumToResponse).ToList();
        // var albumResponses = albums.Select(a => new AlbumResponse
        // {
        //     Id = a.Id,
        //     Name = a.Name,
        //     Description = a.Description,
        //     PictureCount = albumPictureCounts.GetValueOrDefault(a.Id, 0), // 使用 MapAlbumToResponse 后不再需要
        //     UserId = a.UserId,
        //     Username = a.User.UserName,
        //     CreatedAt = a.CreatedAt,
        //     UpdatedAt = a.UpdatedAt
        // }).ToList();

        return new PaginatedResult<AlbumResponse>
        {
            Data = albumResponses,
            Page = page,
            PageSize = pageSize,
            TotalCount = totalCount
        };
    }

    public async Task<AlbumResponse> GetAlbumByIdAsync(int id)
    {
        await using var dbContext = await contextFactory.CreateDbContextAsync();

        var album = await dbContext.Albums
            .Include(a => a.User)
            .Include(a => a.CoverPicture) // 确保包含封面图片
            .Include(a => a.Pictures) // 确保包含图片集合以计算 PictureCount
            .FirstOrDefaultAsync(a => a.Id == id);

        if (album == null)
            throw new KeyNotFoundException($"找不到ID为{id}的相册");

        // 获取相册中图片的数量 - 不再需要
        // var pictureCount = await dbContext.Pictures
        //     .Where(p => p.AlbumId == id)
        //     .CountAsync();

        // 转换为响应模型
        return mappingService.MapAlbumToResponse(album);
        // var response = new AlbumResponse
        // {
        //     Id = album.Id,
        //     Name = album.Name,
        //     Description = album.Description,
        //     PictureCount = pictureCount, // 使用 MapAlbumToResponse 后不再需要
        //     UserId = album.UserId,
        //     Username = album.User.UserName,
        //     CreatedAt = album.CreatedAt,
        //     UpdatedAt = album.UpdatedAt
        // };
        //
        // return response;
    }

    public async Task<AlbumResponse> CreateAlbumAsync(string name, string? description, int userId, int? coverPictureId)
    {
        if (string.IsNullOrWhiteSpace(name))
            throw new ArgumentException("相册名称不能为空", nameof(name));

        await using var dbContext = await contextFactory.CreateDbContextAsync();

        // 检查用户是否存在
        var user = await dbContext.Users.FindAsync(userId);
        if (user == null)
            throw new KeyNotFoundException($"找不到ID为{userId}的用户");

        // 创建新相册
        var album = new Album
        {
            Name = name.Trim(),
            Description = description?.Trim() ?? string.Empty,
            UserId = userId,
            // User = user, // EF Core 会自动关联
            CreatedAt = DateTime.UtcNow,
            UpdatedAt = DateTime.UtcNow,
            CoverPictureId = coverPictureId
        };

        dbContext.Albums.Add(album);
        await dbContext.SaveChangesAsync();

        // 重新加载创建的相册以包含导航属性，用于 MapAlbumToResponse
        var createdAlbum = await dbContext.Albums
            .Include(a => a.User)
            .Include(a => a.CoverPicture)
            .Include(a => a.Pictures)
            .FirstAsync(a => a.Id == album.Id);

        // 转换为响应模型
        return mappingService.MapAlbumToResponse(createdAlbum);
        // return new AlbumResponse
        // {
        //     Id = album.Id,
        //     Name = album.Name,
        //     Description = album.Description,
        //     PictureCount = 0, // MapAlbumToResponse 会处理
        //     UserId = album.UserId,
        //     Username = user.UserName, // MapAlbumToResponse 会处理
        //     CreatedAt = album.CreatedAt,
        //     UpdatedAt = album.UpdatedAt
        // };
    }

    public async Task<AlbumResponse> UpdateAlbumAsync(int id, string name, string? description, int? userId = null, int? coverPictureId = null)
    {
        if (string.IsNullOrWhiteSpace(name))
            throw new ArgumentException("相册名称不能为空", nameof(name));

        await using var dbContext = await contextFactory.CreateDbContextAsync();

        // 获取相册
        var album = await dbContext.Albums
            // .Include(a => a.User) // 将在更新后重新加载
            // .Include(a => a.Pictures) // 将在更新后重新加载
            .FirstOrDefaultAsync(a => a.Id == id);

        if (album == null)
            throw new KeyNotFoundException($"找不到ID为{id}的相册");
        if (!userId.HasValue) // userId 仍然需要用于权限检查
            throw new ArgumentException("无效的用户ID", nameof(userId));
        if (album.UserId != userId.Value)
        {
            throw new UnauthorizedAccessException("您没有权限更新此相册");
        }

        // 更新相册信息
        album.Name = name.Trim();
        album.Description = description?.Trim() ?? album.Description;
        album.UpdatedAt = DateTime.UtcNow;
        album.CoverPictureId = coverPictureId;

        await dbContext.SaveChangesAsync();

        // 重新加载更新后的相册以包含导航属性
        var updatedAlbum = await dbContext.Albums
            .Include(a => a.User)
            .Include(a => a.CoverPicture)
            .Include(a => a.Pictures)
            .FirstAsync(a => a.Id == album.Id);
            
        // 转换为响应模型
        return mappingService.MapAlbumToResponse(updatedAlbum);
        // return new AlbumResponse
        // {
        //     Id = album.Id,
        //     Name = album.Name,
        //     Description = album.Description,
        //     PictureCount = album.Pictures?.Count ?? 0, // MapAlbumToResponse 会处理
        //     UserId = album.UserId,
        //     Username = album.User.UserName, // MapAlbumToResponse 会处理
        //     CreatedAt = album.CreatedAt,
        //     UpdatedAt = album.UpdatedAt
        // };
    }

    public async Task<bool> DeleteAlbumAsync(int id)
    {
        await using var dbContext = await contextFactory.CreateDbContextAsync();

        var album = await dbContext.Albums.FindAsync(id);
        if (album == null)
            return false;

        // 先找出所有属于这个相册的图片
        var pictures = await dbContext.Pictures
            .Where(p => p.AlbumId == id)
            .ToListAsync();

        // 将这些图片的AlbumId设置为null
        foreach (var picture in pictures)
        {
            picture.AlbumId = null;
            picture.Album = null;
        }

        // 保存图片更改
        await dbContext.SaveChangesAsync();

        // 然后删除相册
        dbContext.Albums.Remove(album);
        await dbContext.SaveChangesAsync();

        return true;
    }

    public async Task<bool> AddPictureToAlbumAsync(int albumId, int pictureId)
    {
        await using var dbContext = await contextFactory.CreateDbContextAsync();

        // 获取相册和图片
        var album = await dbContext.Albums.FindAsync(albumId);
        if (album == null)
            throw new KeyNotFoundException($"找不到ID为{albumId}的相册");

        var picture = await dbContext.Pictures.FindAsync(pictureId);
        if (picture == null)
            throw new KeyNotFoundException($"找不到ID为{pictureId}的图片");

        // 将图片添加到相册
        picture.AlbumId = albumId;
        picture.Album = album;

        await dbContext.SaveChangesAsync();

        return true;
    }

    public async Task<bool> RemovePictureFromAlbumAsync(int albumId, int pictureId)
    {
        await using var dbContext = await contextFactory.CreateDbContextAsync();

        // 获取图片
        var picture = await dbContext.Pictures
            .FirstOrDefaultAsync(p => p.Id == pictureId && p.AlbumId == albumId);

        if (picture == null)
            throw new KeyNotFoundException($"在相册中找不到ID为{pictureId}的图片");

        // 从相册中移除图片
        picture.AlbumId = null;
        picture.Album = null;

        await dbContext.SaveChangesAsync();

        return true;
    }

    public async Task<bool> AddPicturesToAlbumAsync(int albumId, List<int> pictureIds)
    {
        await using var dbContext = await contextFactory.CreateDbContextAsync();

        var album = await dbContext.Albums.FindAsync(albumId)
            ?? throw new KeyNotFoundException("相册不存在");

        // 检查是否有权限修改此相册
        var currentUser = httpContextAccessor.HttpContext?.User;
        if (currentUser != null)
        {
            var userId = int.Parse(currentUser.FindFirst(ClaimTypes.NameIdentifier)?.Value ?? "0");
            if (album.UserId != userId)
            {
                throw new UnauthorizedAccessException("您没有权限修改此相册");
            }
        }

        var successCount = 0;

        foreach (var pictureId in pictureIds)
        {
            var picture = await dbContext.Pictures.FindAsync(pictureId);
            if (picture == null) continue; // 跳过不存在的图片

            // 直接更新 Picture 的 AlbumId
            if (picture.AlbumId != albumId)
            {
                picture.AlbumId = albumId;
                successCount++;
            }
        }

        if (successCount > 0)
        {
            await dbContext.SaveChangesAsync();
            return true;
        }

        return false;
    }

    public async Task<bool> SetAlbumCoverAsync(int albumId, int pictureId, int userId)
    {
        await using var dbContext = await contextFactory.CreateDbContextAsync();

        var album = await dbContext.Albums.FirstOrDefaultAsync(a => a.Id == albumId);
        if (album == null)
            throw new KeyNotFoundException($"找不到ID为 {albumId} 的相册");

        // 权限检查：只有相册所有者可以设置封面
        if (album.UserId != userId)
            throw new UnauthorizedAccessException("您没有权限修改此相册的封面");

        var picture = await dbContext.Pictures.FirstOrDefaultAsync(p => p.Id == pictureId);
        if (picture == null)
            throw new KeyNotFoundException($"找不到ID为 {pictureId} 的图片");

        // 确保图片属于该相册
        if (picture.AlbumId != albumId)
            throw new InvalidOperationException($"图片 {pictureId} 不属于相册 {albumId}");

        album.CoverPictureId = pictureId;
        album.UpdatedAt = DateTime.UtcNow;

        await dbContext.SaveChangesAsync();
        return true;
    }
}