using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Nuuru.Server.Data;
using Nuuru.Server.DTOs;
using Nuuru.Server.Extensions;
using Nuuru.Server.Services;

namespace Nuuru.Server.Controllers
{
    [ApiController]
    [Route("api/stats")]
    public class StatsController : ControllerBase
    {
        private readonly ApplicationDbContext _context;
        private readonly IUserBadgeService _userBadgeService;
        private readonly ILogger<StatsController> _logger;

        public StatsController(
            ApplicationDbContext context,
            IUserBadgeService userBadgeService,
            ILogger<StatsController> logger)
        {
            _context = context;
            _userBadgeService = userBadgeService;
            _logger = logger;
        }

        /// <summary>
        /// Get global site statistics
        /// </summary>
        [HttpGet]
        [AllowAnonymous]
        public async Task<IActionResult> GetGlobalStats()
        {
            try
            {
                // Run count queries in parallel
                var galleryPostCountTask = _context.BooruPosts.CountAsync();
                var tagCountTask = _context.BooruTags.CountAsync();
                var threadCountTask = _context.ForumThreads.CountAsync();
                var forumPostCountTask = _context.ForumPosts.CountAsync();

                // Get 3 most recent threads with author and category info
                var recentThreadsTask = _context.ForumThreads
                    .Include(t => t.Author)
                    .Include(t => t.Category)
                    .OrderByDescending(t => t.CreatedAt)
                    .Take(3)
                    .AsSplitQuery()
                    .ToListAsync();

                await Task.WhenAll(
                    galleryPostCountTask,
                    tagCountTask,
                    threadCountTask,
                    forumPostCountTask,
                    recentThreadsTask
                );

                var recentThreads = await recentThreadsTask;

                // Batch-fetch display info for thread authors
                var authorIds = recentThreads
                    .Where(t => t.Author != null)
                    .Select(t => t.Author!.Id)
                    .Distinct();
                var displayInfoMap = await _userBadgeService.GetUsersDisplayInfoAsync(authorIds);

                var recentThreadDtos = recentThreads.ToDto(includeFirstPost: false, requestingUserId: null, displayInfoMap: displayInfoMap);

                return Ok(new GlobalStatsDto
                {
                    GalleryPostCount = await galleryPostCountTask,
                    TagCount = await tagCountTask,
                    ThreadCount = await threadCountTask,
                    ForumPostCount = await forumPostCountTask,
                    RecentThreads = recentThreadDtos
                });
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error retrieving global stats");
                return StatusCode(500, new { error = "Failed to retrieve global stats" });
            }
        }
    }
}