using Microsoft.EntityFrameworkCore;
using MilliSim.Common.Dtos;
using MilliSim.Common.Entities;
using MilliSim.Common.Models;
using MilliSim.Data;
using MilliSim.Services.Infrastructure;

namespace MilliSim.Services;

public class DashboardService : IDashboardService
{
    private readonly MilliSimDbContext _db;
    private readonly ICurrentUserService _currentUser;
    private readonly IFileStorageService _fileStorage;

    public DashboardService(MilliSimDbContext db, ICurrentUserService currentUser, IFileStorageService fileStorage)
    {
        _db = db;
        _currentUser = currentUser;
        _fileStorage = fileStorage;
    }

    public async Task<ApiResponse<DashboardData>> GetDashboardDataAsync()
    {
        var userId = _currentUser.UserId;

        // ===== Stats =====
        var projectCount = await _db.Projects.CountAsync();
        var customerCount = await _db.Users.CountAsync(u => u.Role == UserRole.Customer);

        var todayStart = DateTime.Now.Date;
        var todayEnd = todayStart.AddDays(1);
        var todayVisits = await _db.OperationLogs
            .CountAsync(l => l.CreatedAt >= todayStart && l.CreatedAt < todayEnd);

        var activeAuthorizations = await _db.Authorizations
            .CountAsync(a => a.Status == AuthorizationStatus.Active);

        var unreadMessages = await _db.Notifications
            .Where(n => n.UserId == null || n.UserId == userId)
            .Where(n => !_db.NotificationReads.Any(r => r.NotificationId == n.Id && r.UserId == userId))
            .CountAsync();

        // ===== Trends: 近 7 天 =====
        var startDate = DateTime.Now.Date.AddDays(-6);
        var endDate = DateTime.Now.Date.AddDays(1);

        var visits = await _db.OperationLogs
            .Where(l => l.CreatedAt >= startDate && l.CreatedAt < endDate)
            .GroupBy(l => l.CreatedAt.Date)
            .Select(g => new { Date = g.Key, Count = g.Count() })
            .ToListAsync();

        var experiences = await _db.ExperienceLogs
            .Where(l => l.CreatedAt >= startDate && l.CreatedAt < endDate)
            .GroupBy(l => l.CreatedAt.Date)
            .Select(g => new { Date = g.Key, Count = g.Count() })
            .ToListAsync();

        var trends = new List<TrendData>();
        for (var i = 0; i < 7; i++)
        {
            var date = startDate.AddDays(i);
            trends.Add(new TrendData
            {
                Date = date.ToString("MM-dd"),
                Visits = visits.FirstOrDefault(v => v.Date == date)?.Count ?? 0,
                Experiences = experiences.FirstOrDefault(e => e.Date == date)?.Count ?? 0
            });
        }

        // 如果没有真实数据则返回模拟数据
        if (trends.Sum(t => t.Visits + t.Experiences) == 0)
        {
            var random = new Random();
            foreach (var t in trends)
            {
                t.Visits = random.Next(50, 200);
                t.Experiences = random.Next(10, 80);
            }
        }

        // ===== CategoryDistribution: 按分类统计项目数 =====
        var categoryDistribution = await _db.Projects
            .Join(_db.ProjectCategories,
                p => p.CategoryId,
                c => c.Id,
                (p, c) => new { c.Name })
            .GroupBy(x => x.Name)
            .Select(g => new CategoryDistribution
            {
                Name = g.Key,
                Count = g.Count()
            })
            .ToListAsync();

        // ===== RecentActivities: 当前用户最近 10 条操作日志 =====
        var recentLogEntities = await _db.OperationLogs
            .Where(l => l.UserId == userId)
            .OrderByDescending(l => l.CreatedAt)
            .Take(10)
            .ToListAsync();

        var recentUserIds = recentLogEntities.Select(l => l.UserId).Distinct().ToList();
        var recentNicknames = await _db.Users
            .Where(u => recentUserIds.Contains(u.Id))
            .ToDictionaryAsync(u => u.Id, u => u.Nickname);

        var recentActivities = recentLogEntities.Select(l => new OperationLogDto
        {
            Id = l.Id,
            UserId = l.UserId,
            Username = l.Username,
            Nickname = recentNicknames.GetValueOrDefault(l.UserId) ?? string.Empty,
            Module = l.Module,
            Operation = l.Operation,
            Detail = l.Detail,
            Ip = l.Ip,
            CreatedAt = l.CreatedAt
        }).ToList();

        // ===== HotProjects: 按 ExperienceCount 倒序取 6 个（封面需 COS 签名） =====
        var hotProjectEntities = await _db.Projects
            .Include(p => p.Category)
            .OrderByDescending(p => p.ExperienceCount)
            .Take(6)
            .ToListAsync();

        var hotProjects = hotProjectEntities.Select(p => new ProjectDto
        {
            Id = p.Id,
            Name = p.Name,
            CategoryId = p.CategoryId,
            CategoryName = p.Category != null ? p.Category.Name : string.Empty,
            CoverImage = _fileStorage.GetSignedUrl(p.CoverImage),
            Description = p.Description,
            Status = p.Status,
            IsFeatured = p.IsFeatured,
            ViewCount = p.ViewCount,
            ExperienceCount = p.ExperienceCount,
            FavoriteCount = p.FavoriteCount,
            CreatedAt = p.CreatedAt
        }).ToList();

        var data = new DashboardData
        {
            Stats = new DashboardStats
            {
                ProjectCount = projectCount,
                CustomerCount = customerCount,
                TodayVisits = todayVisits,
                ActiveAuthorizations = activeAuthorizations,
                UnreadMessages = unreadMessages
            },
            Trends = trends,
            CategoryDistribution = categoryDistribution,
            RecentActivities = recentActivities,
            HotProjects = hotProjects
        };

        return ApiResponse<DashboardData>.Success(data);
    }
}