using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authorization;
using Volo.Abp.Application.Dtos;
using Volo.Abp.Authorization;
using Volo.Abp.Domain.Entities;
using Volo.Abp.Domain.Repositories;
using Volo.Abp.Identity;

namespace Erp.Platform.Forum;

[Authorize]
public class ForumAppService : PlatformAppService, IForumAppService
{
    private readonly IRepository<ForumCategory, Guid> _categoryRepository;
    private readonly IRepository<ForumTopic, Guid> _topicRepository;
    private readonly IRepository<ForumPost, Guid> _postRepository;
    private readonly IIdentityUserRepository _identityUserRepository;


    public ForumAppService(
        IRepository<ForumCategory, Guid> categoryRepository,
        IRepository<ForumTopic, Guid> topicRepository,
        IRepository<ForumPost, Guid> postRepository,
        IIdentityUserRepository identityUserRepository)
    {
        _categoryRepository = categoryRepository;
        _topicRepository = topicRepository;
        _postRepository = postRepository;
        _identityUserRepository = identityUserRepository;

    }

    // Search functionality
    public async Task<ForumSearchResultDto> SearchAsync(SearchForumInput input)
    {
        var result = new ForumSearchResultDto
        {
            Categories = [],
            Topics = [],
            Posts = [],
            TotalCount = 0
        };

        if (string.IsNullOrWhiteSpace(input.Query))
            return result;

        var query = input.Query.ToLower();

        // Search in categories
        if (input.SearchInCategories)
        {
            var categoryQuery = await _categoryRepository.GetQueryableAsync();
            var categories = await AsyncExecuter.ToListAsync(
                categoryQuery.Where(c => c.IsActive &&
                    (c.Name.ToLower().Contains(query) ||
                     c.Description.ToLower().Contains(query)))
                .Take(10)
            );

            result.Categories = ObjectMapper.Map<List<ForumCategory>, List<ForumCategoryDto>>(categories);
        }

        // Search in topics
        if (input.SearchInTopics)
        {
            var topicQuery = await _topicRepository.GetQueryableAsync();
            var topics = await AsyncExecuter.ToListAsync(
                topicQuery.Where(t =>
                    t.Title.ToLower().Contains(query) ||
                    t.Content.ToLower().Contains(query) ||
                    t.AuthorName.ToLower().Contains(query))
                .OrderByDescending(t => t.CreationTime)
                .Take(20)
            );

            result.Topics = ObjectMapper.Map<List<ForumTopic>, List<ForumTopicDto>>(topics);
        }

        // Search in posts
        if (input.SearchInPosts)
        {
            var postQuery = await _postRepository.GetQueryableAsync();
            var posts = await AsyncExecuter.ToListAsync(
                postQuery.Where(p =>
                    p.Content.ToLower().Contains(query) ||
                    p.AuthorName.ToLower().Contains(query))
                .OrderByDescending(p => p.CreationTime)
                .Take(30)
            );

            result.Posts = ObjectMapper.Map<List<ForumPost>, List<ForumPostDto>>(posts);
        }

        result.TotalCount = result.Categories.Count + result.Topics.Count + result.Posts.Count;
        return result;
    }

    // Category management
    public async Task<PagedResultDto<ForumCategoryDto>> GetCategoriesAsync(GetCategoriesInput input)
    {
        var queryable = await _categoryRepository.GetQueryableAsync();

        if (input.IsActive.HasValue)
        {
            queryable = queryable.Where(c => c.IsActive == input.IsActive.Value);
        }

        if (!string.IsNullOrWhiteSpace(input.Search))
        {
            var search = input.Search.ToLower();
            queryable = queryable.Where(c =>
                c.Name.ToLower().Contains(search) ||
                c.Description.ToLower().Contains(search));
        }

        queryable = queryable.OrderBy(c => c.DisplayOrder);

        var totalCount = await AsyncExecuter.CountAsync(queryable);

        var skipCount = input.SkipCount >= 0 ? input.SkipCount : 0;
        var maxResultCount = input.MaxResultCount > 0 ? input.MaxResultCount : 10;

        var categories = await AsyncExecuter.ToListAsync(
            queryable.Skip(input.SkipCount).Take(input.MaxResultCount)
        );

        return new PagedResultDto<ForumCategoryDto>(
            totalCount,
            ObjectMapper.Map<List<ForumCategory>, List<ForumCategoryDto>>(categories)
        );
    }

    public async Task<ForumCategoryDto> GetCategoryAsync(Guid id)
    {
        var category = await _categoryRepository.GetAsync(id);

        return ObjectMapper.Map<ForumCategory, ForumCategoryDto>(category);
    }

    public async Task<ForumCategoryDto> GetCategoryBySlugAsync(string slug)
    {
        var category = await _categoryRepository.FirstOrDefaultAsync(c => c.Slug == slug);
        if (category == null)
            throw new EntityNotFoundException(typeof(ForumCategory), slug);

        return ObjectMapper.Map<ForumCategory, ForumCategoryDto>(category);
    }

    [Authorize("App.ForumManagement.Create")]
    public async Task<ForumCategoryDto> CreateCategoryAsync(CreateForumCategoryDto input)
    {
        var category = new ForumCategory
        {
            Name = input.Name,
            Slug = input.Slug,
            Description = input.Description,
            Icon = input.Icon,
            DisplayOrder = input.DisplayOrder,
            IsActive = input.IsActive,
            IsLocked = input.IsLocked

        };

        await _categoryRepository.InsertAsync(category);
        return ObjectMapper.Map<ForumCategory, ForumCategoryDto>(category);
    }

    [Authorize("App.ForumManagement.Update")]
    public async Task<ForumCategoryDto> UpdateCategoryAsync(Guid id, UpdateForumCategoryDto input)
    {
        var category = await _categoryRepository.GetAsync(id);

        category.Name = input.Name;
        category.Slug = input.Slug;
        category.Description = input.Description;
        category.Icon = input.Icon;
        category.DisplayOrder = input.DisplayOrder;
        category.IsActive = input.IsActive;
        category.IsLocked = input.IsLocked;

        await _categoryRepository.UpdateAsync(category);
        return ObjectMapper.Map<ForumCategory, ForumCategoryDto>(category);
    }

    [Authorize("App.ForumManagement.Update")]
    public async Task<ForumCategoryDto> UpdateCategoryLockAsync(Guid id)
    {
        var category = await _categoryRepository.GetAsync(id);
        category.IsLocked = !category.IsLocked;

        await _categoryRepository.UpdateAsync(category);
        return ObjectMapper.Map<ForumCategory, ForumCategoryDto>(category);
    }

    [Authorize("App.ForumManagement.Update")]
    public async Task<ForumCategoryDto> UpdateCategoryActiveAsync(Guid id)
    {
        var category = await _categoryRepository.GetAsync(id);
        category.IsActive = !category.IsActive;

        await _categoryRepository.UpdateAsync(category);
        return ObjectMapper.Map<ForumCategory, ForumCategoryDto>(category);
    }

    [Authorize("App.ForumManagement.Delete")]
    public async Task DeleteCategoryAsync(Guid id)
    {
        // Delete all topics and posts in this category
        var topics = await _topicRepository.GetListAsync(t => t.CategoryId == id);
        var topicIds = topics.Select(t => t.Id).ToList();

        if (topicIds.Any())
        {
            await _postRepository.DeleteAsync(p => topicIds.Contains(p.TopicId));
            await _topicRepository.DeleteAsync(t => t.CategoryId == id);
        }

        await _categoryRepository.DeleteAsync(id);
    }

    // Topic management
    public async Task<PagedResultDto<ForumTopicDto>> GetTopicsAsync(GetTopicsInput input)
    {
        var queryable = await _topicRepository.GetQueryableAsync();

        if (input.CategoryId.HasValue)
        {
            queryable = queryable.Where(t => t.CategoryId == input.CategoryId.Value);
        }

        if (input.IsPinned.HasValue)
        {
            queryable = queryable.Where(t => t.IsPinned == input.IsPinned.Value);
        }

        if (input.IsSolved.HasValue)
        {
            queryable = queryable.Where(t => t.IsSolved == input.IsSolved.Value);
        }

        if (!string.IsNullOrWhiteSpace(input.Search))
        {
            var search = input.Search.ToLower();
            queryable = queryable.Where(t =>
                t.Title.ToLower().Contains(search) ||
                t.Content.ToLower().Contains(search));
        }

        queryable = queryable.OrderByDescending(t => t.IsPinned)
                           .ThenByDescending(t => t.CreationTime);

        var totalCount = await AsyncExecuter.CountAsync(queryable);
        var topics = await AsyncExecuter.ToListAsync(
            queryable.Skip(input.SkipCount).Take(input.MaxResultCount)
        );

        return new PagedResultDto<ForumTopicDto>(
            totalCount,
            ObjectMapper.Map<List<ForumTopic>, List<ForumTopicDto>>(topics)
        );
    }

    public async Task<ForumTopicDto> GetTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);

        topic.ViewCount++;
        await _topicRepository.UpdateAsync(topic);

        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task<ForumTopicDto> CreateTopicAsync(CreateForumTopicDto input)
    {
        var topic = new ForumTopic(
            GuidGenerator.Create(),
            input.Title,
            input.Content,
            input.CategoryId,
            CurrentUser.Id.Value,
            CurrentUser.Name,
            input.TenantId
        )
        {
            IsPinned = input.IsPinned,
            IsLocked = input.IsLocked
        };

        await _topicRepository.InsertAsync(topic);

        // Update category topic count
        var category = await _categoryRepository.GetAsync(input.CategoryId);
        category.TopicCount++;
        await _categoryRepository.UpdateAsync(category);

        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task<ForumTopicDto> UpdateTopicAsync(Guid id, UpdateForumTopicDto input)
    {
        var topic = await _topicRepository.GetAsync(id);

        topic.Title = input.Title;
        topic.Content = input.Content;
        topic.IsPinned = input.IsPinned;
        topic.IsLocked = input.IsLocked;
        topic.IsSolved = input.IsSolved;

        await _topicRepository.UpdateAsync(topic);
        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task DeleteTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);

        // Delete all posts in this topic
        await _postRepository.DeleteAsync(p => p.TopicId == id);

        // Update category counts
        var category = await _categoryRepository.GetAsync(topic.CategoryId);
        category.TopicCount = Math.Max(0, category.TopicCount ?? 0 - 1);
        var postCount = await _postRepository.CountAsync(p => p.TopicId == id);
        category.PostCount = Math.Max(0, category.PostCount ?? 0 - postCount);
        await _categoryRepository.UpdateAsync(category);

        await _topicRepository.DeleteAsync(id);
    }

    // Post management
    public async Task<PagedResultDto<ForumPostDto>> GetPostsAsync(GetPostsInput input)
    {
        var queryable = await _postRepository.GetQueryableAsync();

        if (input.TopicId.HasValue)
        {
            queryable = queryable.Where(p => p.TopicId == input.TopicId.Value);

            // Increment view count
            var topic = await _topicRepository.GetAsync(input.TopicId.Value);
        }

        if (input.IsAcceptedAnswer.HasValue)
        {
            queryable = queryable.Where(p => p.IsAcceptedAnswer == input.IsAcceptedAnswer.Value);
        }

        if (!string.IsNullOrWhiteSpace(input.Search))
        {
            var search = input.Search.ToLower();
            queryable = queryable.Where(p => p.Content.ToLower().Contains(search));
        }

        queryable = queryable.OrderBy(p => p.CreationTime);

        var totalCount = await AsyncExecuter.CountAsync(queryable);
        var posts = await AsyncExecuter.ToListAsync(
            queryable.Skip(input.SkipCount).Take(input.MaxResultCount)
        );

        return new PagedResultDto<ForumPostDto>(
            totalCount,
            ObjectMapper.Map<List<ForumPost>, List<ForumPostDto>>(posts)
        );
    }

    public async Task<ForumPostDto> GetPostAsync(Guid id)
    {
        var post = await _postRepository.GetAsync(id);
        return ObjectMapper.Map<ForumPost, ForumPostDto>(post);
    }

    public async Task<ForumPostDto> CreatePostAsync(CreateForumPostDto input)
    {
        var post = new ForumPost(
            GuidGenerator.Create(),
            input.TopicId,
            input.Content,
            CurrentUser.Id.Value,
            CurrentUser.Name,
            input.ParentPostId,
            input.TenantId
        );

        await _postRepository.InsertAsync(post, autoSave: true);

        // 🔽 Update topic
        var topic = await _topicRepository.GetAsync(input.TopicId);
        topic.ReplyCount++;
        topic.LastPostId = post.Id;
        topic.LastPostDate = post.CreationTime;
        topic.LastPostUserId = post.AuthorId;
        topic.LastPostUserName = post.AuthorName;
        await _topicRepository.UpdateAsync(topic);

        // 🔽 Update category
        var category = await _categoryRepository.GetAsync(topic.CategoryId);
        category.PostCount++;
        category.LastPostId = post.Id;
        category.LastPostDate = post.CreationTime;
        category.LastPostUserId = post.AuthorId;
        category.LastPostUserName = post.AuthorName;
        await _categoryRepository.UpdateAsync(category);

        return ObjectMapper.Map<ForumPost, ForumPostDto>(post);
    }

    public async Task<ForumPostDto> UpdatePostAsync(Guid id, UpdateForumPostDto input)
    {
        var post = await _postRepository.GetAsync(id);

        // Check if user can edit this post
        if (post.AuthorId != CurrentUser.Id && !await AuthorizationService.IsGrantedAsync("Forum.Posts.Edit"))
        {
            throw new AbpAuthorizationException();
        }

        post.Content = input.Content;
        post.IsAcceptedAnswer = input.IsAcceptedAnswer;

        await _postRepository.UpdateAsync(post);
        return ObjectMapper.Map<ForumPost, ForumPostDto>(post);
    }

    public async Task DeletePostAsync(Guid id)
    {
        var post = await _postRepository.GetAsync(id);
        var topic = await _topicRepository.GetAsync(post.TopicId);
        var category = await _categoryRepository.GetAsync(topic.CategoryId);

        await _postRepository.DeleteAsync(id);

        topic.ReplyCount = Math.Max(0, topic.ReplyCount - 1);
        category.PostCount = Math.Max(0, category.PostCount ?? 0 - 1);

        // 🔁 Last post değişti mi kontrol et
        var latestPost = await _postRepository
            .GetQueryableAsync()
            .ContinueWith(q => q.Result
                .Where(p => p.TopicId == topic.Id)
                .OrderByDescending(p => p.CreationTime)
                .FirstOrDefault()
            );

        if (latestPost != null)
        {
            topic.LastPostId = latestPost.Id;
            topic.LastPostDate = latestPost.CreationTime;
            topic.LastPostUserId = latestPost.AuthorId;
            topic.LastPostUserName = latestPost.AuthorName;

            category.LastPostId = latestPost.Id;
            category.LastPostDate = latestPost.CreationTime;
            category.LastPostUserId = latestPost.AuthorId;
            category.LastPostUserName = latestPost.AuthorName;
        }
        else
        {
            // Tüm postlar silindiyse
            topic.LastPostId = null;
            topic.LastPostDate = null;
            topic.LastPostUserId = null;
            topic.LastPostUserName = null;

            category.LastPostId = null;
            category.LastPostDate = null;
            category.LastPostUserId = null;
            category.LastPostUserName = null;
        }

        await _topicRepository.UpdateAsync(topic);
        await _categoryRepository.UpdateAsync(category);
    }

    public async Task<ForumPostDto> LikePostAsync(Guid id)
    {
        var post = await _postRepository.GetAsync(id);
        post.LikeCount++;
        await _postRepository.UpdateAsync(post);

        var topic = await _topicRepository.GetAsync(post.TopicId);
        var postsInTopic = await _postRepository.GetListAsync(p => p.TopicId == topic.Id);

        topic.LikeCount = postsInTopic.Sum(p => p.LikeCount ?? 0);
        await _topicRepository.UpdateAsync(topic);

        return ObjectMapper.Map<ForumPost, ForumPostDto>(post);
    }

    public async Task<ForumPostDto> UnlikePostAsync(Guid id)
    {
        var post = await _postRepository.GetAsync(id);
        post.LikeCount = Math.Max(0, post.LikeCount ?? 0 - 1);
        await _postRepository.UpdateAsync(post);

        // 🔽 Topic'in toplam beğeni sayısını güncelle
        var topic = await _topicRepository.GetAsync(post.TopicId);

        var postsInTopic = await _postRepository.GetListAsync(p => p.TopicId == topic.Id);
        topic.LikeCount = postsInTopic.Sum(p => p.LikeCount ?? 0);

        await _topicRepository.UpdateAsync(topic);

        return ObjectMapper.Map<ForumPost, ForumPostDto>(post);
    }

    public async Task<ForumPostDto> MarkPostAsync(Guid id)
    {
        var post = await _postRepository.GetAsync(id);
        post.IsAcceptedAnswer = true;

        await _postRepository.UpdateAsync(post);

        return ObjectMapper.Map<ForumPost, ForumPostDto>(post);
    }

    public async Task<ForumPostDto> UnmarkPostAsync(Guid id)
    {
        var post = await _postRepository.GetAsync(id);
        post.IsAcceptedAnswer = false;
        await _postRepository.UpdateAsync(post);

        return ObjectMapper.Map<ForumPost, ForumPostDto>(post);
    }

    // Like/Unlike topic
    public async Task<ForumTopicDto> LikeTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);
        topic.LikeCount++;

        await _topicRepository.UpdateAsync(topic);
        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task<ForumTopicDto> UnlikeTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);
        topic.LikeCount = Math.Max(0, topic.LikeCount - 1);

        await _topicRepository.UpdateAsync(topic);
        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task<ForumTopicDto> PinTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);
        topic.IsPinned = true;

        await _topicRepository.UpdateAsync(topic);
        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task<ForumTopicDto> UnpinTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);
        topic.IsPinned = false;
        await _topicRepository.UpdateAsync(topic);
        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task<ForumTopicDto> LockTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);
        topic.IsLocked = true;

        await _topicRepository.UpdateAsync(topic);
        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task<ForumTopicDto> UnlockTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);
        topic.IsLocked = false;
        await _topicRepository.UpdateAsync(topic);
        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task<ForumTopicDto> SolvedTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);
        topic.IsSolved = true;

        await _topicRepository.UpdateAsync(topic);
        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    public async Task<ForumTopicDto> UnsolvedTopicAsync(Guid id)
    {
        var topic = await _topicRepository.GetAsync(id);
        topic.IsSolved = false;

        await _topicRepository.UpdateAsync(topic);
        return ObjectMapper.Map<ForumTopic, ForumTopicDto>(topic);
    }

    // Statistics
    public async Task<ForumStatsDto> GetForumStatsAsync()
    {
        var totalCategories = await _categoryRepository.CountAsync();
        var totalTopics = await _topicRepository.CountAsync();
        var totalPosts = await _postRepository.CountAsync();
        var totalUsers = await _identityUserRepository.GetCountAsync();

        return new ForumStatsDto
        {
            TotalCategories = totalCategories,
            TotalTopics = totalTopics,
            TotalPosts = totalPosts,
            TotalUsers = totalUsers,
            ActiveUsers = totalUsers
        };
    }
}