using System.Diagnostics;
using System.Security.Claims;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.EntityFrameworkCore;
using Yavsc.Blogspot;
using Yavsc.Models;
using Yavsc.Models.Access;
using Yavsc.Models.Blog;
using Yavsc.Server.Exceptions;
using Yavsc.Server.Helpers;
using Yavsc.Services;
using Yavsc.ViewModels.Auth;

public class BlogSpotService
{
    private readonly ApplicationDbContext _context;
    private readonly IAuthorizationService _authorizationService;
    private readonly IFileSystemAuthManager fileSystemAuthManager;

    public BlogSpotService(
        ApplicationDbContext context,
        IAuthorizationService authorizationService,
        IFileSystemAuthManager fileSystemAuthManager)
    {
        _authorizationService = authorizationService;
        _context = context;
        this.fileSystemAuthManager = fileSystemAuthManager;
    }

    public BlogPost Create(string userId, BlogPost post, IFormFileCollection files)
    {
        // Sauvegarder le post d'abord pour obtenir son ID
        // Le createur vient de l'authentification, donc on ne le prend pas du post
        post.AuthorId = userId;
        _context.BlogSpot.Add(post);
        _context.SaveChanges(userId);

        // Traiter les fichiers attaches s'il y en a
        if (files != null && files.Count > 0)
        {
            var user = _context.Users.FirstOrDefault(u => u.Id == userId);
            if (user != null)
            {
                try
                {
                    string blogFilesSubdir = $"blogs/{post.Id}";
                    string destDir = Path.Combine(
                        AbstractFileSystemHelpers.UserFilesDirName,
                        user.UserName,
                        blogFilesSubdir);
                    var di = new DirectoryInfo(destDir);
                    if (!di.Exists) di.Create();

                    foreach (var formFile in files)
                    {
                        var fileInfo = user.ReceiveUserFile(destDir, formFile);
                        if (fileInfo != null && !fileInfo.QuotaOffense)
                        {
                            var uploadedFile = new UploadedFile
                            {
                                Path = fileInfo.FileName,
                                ContentType = formFile.ContentType,
                                Length = formFile.Length
                            };
                            _context.UploadedFiles.Add(uploadedFile);
                            _context.SaveChanges(userId);

                            var attachment = new BlogAttachedFile
                            {
                                PostId = post.Id,
                                FileId = uploadedFile.Id
                            };
                            _context.BlogAttachedFiles.Add(attachment);
                        }
                    }
                    _context.SaveChanges(userId);
                }
                catch (Exception ex)
                {
                    Debug.WriteLine($"Erreur lors du traitement des fichiers : {ex.Message}");
                }
            }
        }

        return post;
    }

    public async Task<BlogPostEditViewModel> GetPostForEdition(ClaimsPrincipal user, long blogPostId)
    {
        var blog = await _context.BlogSpot
            .Include(x => x.Author)
            .Include(x => x.ACL)
            .SingleAsync(m => m.Id == blogPostId);

        var auth = await _authorizationService.AuthorizeAsync(user, blog, new EditPermission());
        if (!auth.Succeeded)
            throw new AuthorizationFailureException(auth);

        var pub = await _context.blogSpotPublications.AnyAsync(x => x.BlogpostId == blog.Id);
        ScrubAclForViewer(blog, user);

        return new BlogPostEditViewModel(blog, pub);
    }

    public async Task<BlogPost> Details(ClaimsPrincipal user, long blogPostId)
    {
        BlogPost blog = await _context.BlogSpot
            .Include(p => p.Author)
            .Include(p => p.Tags)
            .Include(p => p.Comments)
            .Include(p => p.ACL)
            .SingleAsync(m => m.Id == blogPostId);

        if (blog == null)
            return null;

        // Hydrate le flag [NotMapped] depuis la table de publication.
        blog.IsPublished = await _context.blogSpotPublications
            .AnyAsync(pub => pub.BlogpostId == blogPostId);

        var auth = await _authorizationService.AuthorizeAsync(user, blog, new ReadPermission());
        if (!auth.Succeeded)
            throw new AuthorizationFailureException(auth);

        ScrubAclForViewer(blog, user);

        foreach (var c in blog.Comments)
            c.Author = _context.Users.First(u => u.Id == c.AuthorId);

        return blog;
    }

    public async Task Modify(ClaimsPrincipal user, BlogPostEditViewModel blogEdit)
    {
        var blog = _context.BlogSpot.SingleOrDefault(b => b.Id == blogEdit.Id);
        Debug.Assert(blog != null);

        var auth = await _authorizationService.AuthorizeAsync(user, blog, new EditPermission());
        if (!auth.Succeeded)
            throw new AuthorizationFailureException(auth);

        blog.Article = blogEdit.Article;
        blog.Title = blogEdit.Title;
        blog.Photo = blogEdit.Photo;
        blog.ACL = blogEdit.ACL;
        _context.Update(blog);

        var publication = await _context.blogSpotPublications
            .SingleOrDefaultAsync(p => p.BlogpostId == blogEdit.Id);

        if (publication != null)
        {
            if (!blogEdit.Publish)
                _context.blogSpotPublications.Remove(publication);
        }
        else if (blogEdit.Publish)
        {
            _context.blogSpotPublications.Add(new BlogSpotPublication { BlogpostId = blogEdit.Id });
        }

        _context.SaveChanges(user.GetUserId());
    }

    public async Task Modify(ClaimsPrincipal user, BlogPost blog)
    {
        var existing = await _context.BlogSpot
            .Include(b => b.ACL)
            .SingleOrDefaultAsync(b => b.Id == blog.Id);

        if (existing == null)
            throw new InvalidOperationException($"Blog post {blog.Id} not found.");

        var auth = await _authorizationService.AuthorizeAsync(user, existing, new EditPermission());
        if (!auth.Succeeded)
            throw new AuthorizationFailureException(auth);

        existing.Title = blog.Title;
        existing.Article = blog.Article;
        existing.Photo = blog.Photo;
        existing.ACL = blog.ACL;

        _context.Update(existing);
        _context.SaveChanges(user.GetUserId());
    }

    public async Task<IEnumerable<IBlogPost>> Index(ClaimsPrincipal user, string id, int skip = 0, int take = 25)
    {
        IEnumerable<IBlogPost> posts;

        if (user.Identity.IsAuthenticated)
        {
            string viewerId = user.GetUserId();
            long[] userCircles = await _context.Circle.Include(c => c.Members)
                .Where(c => c.Members.Any(m => m.MemberId == viewerId))
                .Select(c => c.Id)
                .ToArrayAsync();

            posts = _context.BlogSpot
                .Include(b => b.Author)
                .Include(p => p.ACL)
                .Include(p => p.Tags)
                .Include(p => p.Comments)
                .Where(p => p.ACL == null
                    || p.ACL.Count == 0
                    || p.AuthorId == viewerId
                    || (userCircles != null && p.ACL.Any(a => userCircles.Contains(a.CircleId))));
        }
        else
        {
            posts = _context.blogSpotPublications
                .Include(p => p.BlogPost)
                .Include(b => b.BlogPost.Author)
                .Include(p => p.BlogPost.ACL)
                .Include(p => p.BlogPost.Tags)
                .Include(p => p.BlogPost.Comments)
                .Where(p => p.BlogPost.ACL == null || p.BlogPost.ACL.Count == 0)
                .Select(p => p.BlogPost)
                .ToArray();
        }

        var materialised = posts.ToList();

        var postIds = materialised.Select(p => p.Id).ToList();
        if (postIds.Count > 0)
        {
            var publishedIds = await _context.blogSpotPublications
                .Where(pub => postIds.Contains(pub.BlogpostId))
                .Select(pub => pub.BlogpostId)
                .ToListAsync();

            var publishedSet = publishedIds.ToHashSet();
            foreach (var post in materialised.OfType<BlogPost>())
                post.IsPublished = publishedSet.Contains(post.Id);
        }

        foreach (var post in materialised.OfType<BlogPost>())
            ScrubAclForViewer(post, user);

        return materialised
            .OrderByDescending(p => p.DateModified)
            .Skip(skip)
            .Take(take);
    }

    public async Task Delete(ClaimsPrincipal user, long id)
    {
        BlogPost blog = _context.BlogSpot.Single(m => m.Id == id);
        _context.BlogSpot.Remove(blog);
        _context.SaveChanges(user.GetUserId());
    }

    public async Task<IEnumerable<BlogPost>> UserPosts(string posterName, string? readerId, int pageLen = 10, int pageNum = 0)
    {
        string? posterId = (await _context.Users.SingleOrDefaultAsync(u => u.UserName == posterName))?.Id;
        if (posterId == null) return Array.Empty<BlogPost>();

        var posts = _context.UserPosts(posterId, readerId).ToList();
        var isOwnerReader = string.Equals(readerId, posterId, StringComparison.Ordinal);

        foreach (var post in posts)
        {
            if (!isOwnerReader)
                post.ACL = new List<CircleAuthorizationToBlogPost>();
        }

        return posts;
    }

    public object? GetTitle(string title)
    {
        return _context.BlogSpot
            .Include(b => b.Author)
            .Where(x => x.Title == title)
            .OrderByDescending(x => x.DateCreated)
            .ToList();
    }

    public async Task<BlogPost?> GetBlogPostAsync(long value)
    {
        return await _context.BlogSpot
            .Include(b => b.Author)
            .Include(b => b.ACL)
            .SingleOrDefaultAsync(x => x.Id == value);
    }

    public async Task<bool> SetPublishAsync(ClaimsPrincipal user, long postId, bool publish)
    {
        var blog = await _context.BlogSpot.SingleOrDefaultAsync(b => b.Id == postId);
        if (blog == null) return false;

        var auth = await _authorizationService.AuthorizeAsync(user, blog, new EditPermission());
        if (!auth.Succeeded)
            throw new AuthorizationFailureException(auth);

        var existing = await _context.blogSpotPublications.SingleOrDefaultAsync(p => p.BlogpostId == postId);
        if (publish)
        {
            if (existing == null)
                _context.blogSpotPublications.Add(new BlogSpotPublication { BlogpostId = postId });
        }
        else
        {
            if (existing != null)
                _context.blogSpotPublications.Remove(existing);
        }

        await _context.SaveChangesAsync(user.GetUserId());
        return true;
    }

    private static void ScrubAclForViewer(BlogPost post, ClaimsPrincipal? user)
    {
        if (!IsOwner(post, user))
            post.ACL = new List<CircleAuthorizationToBlogPost>();
    }

    private static bool IsOwner(BlogPost post, ClaimsPrincipal? user)
    {
        if (user?.Identity?.IsAuthenticated != true) return false;
        return string.Equals(user.GetUserId(), post.AuthorId, StringComparison.Ordinal);
    }
}