using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Nuuru.Server.Auth;
using Nuuru.Server.DTOs.Admin;
using Nuuru.Server.Extensions;
using Nuuru.Server.Models.Forum;
using Nuuru.Server.Services;

namespace Nuuru.Server.Controllers
{
    [ApiController]
    [Route("api/forum/categories")]
    public class ForumCategoryController : ControllerBase
    {
        private readonly IForumCategoryService _categoryService;
        private readonly IUserBadgeService _userBadgeService;
        private readonly ILogger<ForumCategoryController> _logger;

        public ForumCategoryController(
            IForumCategoryService categoryService,
            IUserBadgeService userBadgeService,
            ILogger<ForumCategoryController> logger)
        {
            _categoryService = categoryService;
            _userBadgeService = userBadgeService;
            _logger = logger;
        }

        /// <summary>
        /// Get all forum categories with stats
        /// </summary>
        [HttpGet]
        [AllowAnonymous]
        public async Task<IActionResult> GetCategories()
        {
            try
            {
                var userId = User.GetUserId();
                var categories = await _categoryService.GetVisibleCategoriesAsync(userId);
                var categoryDtos = new List<DTOs.Forum.ForumCategoryDto>();

                var latestThreads = new List<Models.Forum.ForumThread>();
                var categoryStats = new List<(int threadCount, int postCount)>();

                foreach (var category in categories)
                {
                    var stats = await _categoryService.GetCategoryStatsAsync(category.Id);
                    var latestThread = await _categoryService.GetLatestThreadAsync(category.Id);
                    
                    categoryStats.Add(stats);
                    if (latestThread != null) latestThreads.Add(latestThread);
                }

                // Batch-fetch display info for all latest thread authors and last post authors
                var authorIds = latestThreads
                    .Where(t => t.Author != null)
                    .Select(t => t.Author!.Id)
                    .Concat(latestThreads.Where(t => t.LastPost?.Author != null).Select(t => t.LastPost!.Author!.Id))
                    .Distinct()
                    .ToList();
                var displayInfoMap = await _userBadgeService.GetUsersDisplayInfoAsync(authorIds);

                for (int i = 0; i < categories.Count(); i++)
                {
                    var category = categories.ElementAt(i);
                    var (threadCount, postCount) = categoryStats[i];
                    var latestThread = latestThreads.FirstOrDefault(t => t.CategoryId == category.Id);
                    
                    categoryDtos.Add(category.ToDto(threadCount, postCount, latestThread, displayInfoMap));
                }

                return Ok(categoryDtos);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error retrieving forum categories");
                return StatusCode(500, new { error = "Failed to retrieve categories" });
            }
        }

        /// <summary>
        /// Get a single category by slug
        /// </summary>
        [HttpGet("{slug}")]
        [AllowAnonymous]
        public async Task<IActionResult> GetCategory(string slug)
        {
            try
            {
                ForumCategory? category;
                if (slug.Equals("clan", StringComparison.OrdinalIgnoreCase))
                {
                    var userId = User.GetUserId();
                    if (!userId.HasValue)
                        return StatusCode(403, new { error = "Log in to access your clan forum." });
                    category = await _categoryService.GetClanCategoryForUserAsync(userId.Value);
                    if (category == null)
                        return NotFound(new { error = "Your clan does not have a forum." });
                }
                else
                {
                    category = await _categoryService.GetCategoryBySlugAsync(slug);
                }
                if (category == null)
                {
                    return NotFound(new { error = "Category not found" });
                }

                var (threadCount, postCount) = await _categoryService.GetCategoryStatsAsync(category.Id);
                var latestThread = await _categoryService.GetLatestThreadAsync(category.Id);

                // Fetch display info for authors
                var authorIds = new List<Guid>();
                if (latestThread?.Author != null) authorIds.Add(latestThread.Author.Id);
                if (latestThread?.LastPost?.Author != null) authorIds.Add(latestThread.LastPost.Author.Id);
                var displayInfoMap = await _userBadgeService.GetUsersDisplayInfoAsync(authorIds.Distinct());

                var categoryDto = category.ToDto(threadCount, postCount, latestThread, displayInfoMap);

                return Ok(categoryDto);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error retrieving category {Slug}", slug);
                return StatusCode(500, new { error = "Failed to retrieve category" });
            }
        }

        /// <summary>
        /// Create a new forum category
        /// </summary>
        [HttpPost]
        [Authorize(Policy = Permissions.Admin.ManageCategories)]
        public async Task<IActionResult> CreateCategory([FromBody] CreateForumCategoryRequest request)
        {
            try
            {
                var category = await _categoryService.CreateCategoryAsync(request);
                var (threadCount, postCount) = await _categoryService.GetCategoryStatsAsync(category.Id);
                var categoryDto = category.ToDto(threadCount, postCount, null, null);

                return CreatedAtAction(nameof(GetCategory), new { slug = category.Slug }, categoryDto);
            }
            catch (InvalidOperationException ex)
            {
                return BadRequest(new { error = ex.Message });
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error creating forum category");
                return StatusCode(500, new { error = "Failed to create forum category" });
            }
        }

        /// <summary>
        /// Update an existing forum category
        /// </summary>
        [HttpPut("{id:guid}")]
        [Authorize(Policy = Permissions.Admin.ManageCategories)]
        public async Task<IActionResult> UpdateCategory(Guid id, [FromBody] UpdateForumCategoryRequest request)
        {
            try
            {
                var category = await _categoryService.UpdateCategoryAsync(id, request);
                if (category == null)
                {
                    return NotFound(new { error = "Forum category not found" });
                }

                var (threadCount, postCount) = await _categoryService.GetCategoryStatsAsync(category.Id);
                var latestThread = await _categoryService.GetLatestThreadAsync(category.Id);

                // Fetch display info for authors
                var authorIds = new List<Guid>();
                if (latestThread?.Author != null) authorIds.Add(latestThread.Author.Id);
                if (latestThread?.LastPost?.Author != null) authorIds.Add(latestThread.LastPost.Author.Id);
                var displayInfoMap = await _userBadgeService.GetUsersDisplayInfoAsync(authorIds.Distinct());

                var categoryDto = category.ToDto(threadCount, postCount, latestThread, displayInfoMap);

                return Ok(categoryDto);
            }
            catch (InvalidOperationException ex)
            {
                return BadRequest(new { error = ex.Message });
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error updating forum category {Id}", id);
                return StatusCode(500, new { error = "Failed to update forum category" });
            }
        }

        /// <summary>
        /// Delete a forum category (only if it has no threads)
        /// </summary>
        [HttpDelete("{id:guid}")]
        [Authorize(Policy = Permissions.Admin.ManageCategories)]
        public async Task<IActionResult> DeleteCategory(Guid id)
        {
            try
            {
                var result = await _categoryService.DeleteCategoryAsync(id);
                if (!result)
                {
                    return NotFound(new { error = "Forum category not found" });
                }

                return Ok(new { message = "Forum category deleted successfully" });
            }
            catch (InvalidOperationException ex)
            {
                return BadRequest(new { error = ex.Message });
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error deleting forum category {Id}", id);
                return StatusCode(500, new { error = "Failed to delete forum category" });
            }
        }
    }
}