using Application.Abstractions.Messaging;
using Application.Abstractions.Data;
using SharedKernel.Storage;
using Microsoft.EntityFrameworkCore;

namespace Application.Features.Forum.Post.Delete;

public sealed class Handler(IAppDbContext db, IFileStorage fileStorage) : ICommandHandler<Command>
{
    public async Task Handle(Command request, CancellationToken ct)
    {
        if (request.IDs is null || request.IDs.Length == 0)
        {
            return;
        }

        var posts = await db.Post.Where(c => request.IDs.Contains(c.ID)).ToListAsync(ct);

        // 썸네일 파일 삭제
        foreach (var post in posts)
        {
            if (!string.IsNullOrEmpty(post.Thumbnail))
            {
                fileStorage.DeleteByUrl(post.Thumbnail);
            }
        }

        // Board/BoardGroup 카운트 감소
        var boardIDs = posts.Select(c => c.BoardID).Distinct().ToList();
        var boards = await db.Board.Where(c => boardIDs.Contains(c.ID)).ToListAsync(ct);
        var groupIDs = boards.Select(c => c.BoardGroupID).Distinct().ToList();
        var groups = await db.BoardGroup.Where(c => groupIDs.Contains(c.ID)).ToListAsync(ct);

        foreach (var board in boards)
        {
            var count = posts.Count(c => c.BoardID == board.ID);
            board.Posts -= count;
            board.UpdatedAt = DateTime.UtcNow;
        }

        foreach (var group in groups)
        {
            var relatedBoards = boards.Where(b => b.BoardGroupID == group.ID).Select(b => b.ID).ToList();
            var count = posts.Count(c => relatedBoards.Contains(c.BoardID));
            group.Posts -= count;
            group.UpdatedAt = DateTime.UtcNow;
        }

        db.Post.RemoveRange(posts);
        await db.SaveChangesAsync(ct);
    }
}