using MediatR;
using FluentResults;
using Microsoft.EntityFrameworkCore;
using NexusReader.Application.DTOs.User;
using NexusReader.Data.Persistence;

namespace NexusReader.Application.Queries.User;

public class GetUserProfileQueryHandler : IRequestHandler<GetUserProfileQuery, Result<UserProfileDto>>
{
    private readonly IDbContextFactory<AppDbContext> _dbContextFactory;

    public GetUserProfileQueryHandler(IDbContextFactory<AppDbContext> dbContextFactory)
    {
        _dbContextFactory = dbContextFactory;
    }

    public async Task<Result<UserProfileDto>> Handle(GetUserProfileQuery request, CancellationToken cancellationToken)
    {
        using var dbContext = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
        var profile = await dbContext.Users
            .Where(u => u.Id == request.UserId)
            .Select(u => new UserProfileDto
            {
                Email = u.Email ?? string.Empty,
                UserId = u.Id,
                AITokensUsed = u.AITokensUsed,
                TenantId = u.TenantId != null && u.TenantId.Length == 36 ? new Guid(u.TenantId) : Guid.Empty,
                Plan = u.SubscriptionPlan != null ? new SubscriptionPlanDto
                {
                    Id = u.SubscriptionPlan.Id,
                    Name = u.SubscriptionPlan.PlanName,
                    AITokenLimit = u.SubscriptionPlan.AITokenLimit,
                    MonthlyPrice = u.SubscriptionPlan.MonthlyPrice
                } : new SubscriptionPlanDto(),
                AverageQuizScore = u.QuizResults.Any(q => q.TotalQuestions > 0) 
                    ? (int)u.QuizResults.Where(q => q.TotalQuestions > 0).Average(q => (double)q.Score / q.TotalQuestions * 100) 
                    : 0,
                DisplayName = u.DisplayName,
                BooksReadCount = u.Ebooks.Count(),
                ConceptsMappedCount = dbContext.KnowledgeUnits.Count(k => k.TenantId == u.TenantId || k.TenantId == "global" || string.IsNullOrEmpty(k.TenantId)),
                LastReadBook = u.Ebooks.OrderByDescending(e => e.LastReadDate).Select(e => new LastReadBookDto
                {
                    Id = e.Id,
                    Title = e.Title,
                    Author = new AuthorDto 
                    { 
                        Id = e.Author.Id, 
                        Name = e.Author.Name 
                    },
                    CoverUrl = e.CoverUrl,
                    Progress = e.Progress,
                    LastChapter = e.LastChapter ?? "Rozpoczynanie...",
                    LastChapterIndex = e.LastChapterIndex,
                    Description = e.Description,
                    IsReadyForReading = e.IsReadyForReading
                }).FirstOrDefault(),
                RecentQuizzes = u.QuizResults.OrderByDescending(q => q.CompletedDate).Take(5).Select(q => new QuizResultDto
                {
                    Id = q.Id,
                    Topic = q.Topic,
                    Score = q.Score,
                    TotalQuestions = q.TotalQuestions,
                    Percentage = q.Percentage,
                    CompletedDate = q.CompletedDate
                }).ToList(),
                MappedConcepts = dbContext.KnowledgeUnits
                    .Where(k => k.TenantId == u.TenantId || k.TenantId == "global" || string.IsNullOrEmpty(k.TenantId))
                    .OrderByDescending(k => k.CreatedAt)
                    .Take(6)
                    .Select(k => new MappedConceptDto
                    {
                        Id = k.Id,
                        Type = k.Type.ToString(),
                        Content = k.Content
                    })
                    .ToList(),
                Roles = dbContext.UserRoles
                    .Where(ur => ur.UserId == u.Id)
                    .Join(dbContext.Roles, ur => ur.RoleId, r => r.Id, (ur, r) => r.Name!)
                    .ToArray()
            })
            .FirstOrDefaultAsync(cancellationToken);

        if (profile == null)
        {
            return Result.Fail("Profile not found.");
        }

        return Result.Ok(profile);
    }
}