using AutoMapper;
using FastEndpoints;
using MetaCourse.Api.Data;
using MetaCourse.Api.DTOs.UserCourses;
using MetaCourse.Api.Entities;
using Microsoft.EntityFrameworkCore;

namespace MetaCourse.Api.Endpoints.UserCourses;

public class EnrollEndpoint(AppDbContext db, AutoMapper.IMapper mapper) : Endpoint<EnrollDto, GetEnrollmentDto>
{
    public override void Configure()
    {
        Post("api/courses/{courseId}/enroll");
        AllowAnonymous();
        Summary(s => s.Summary = "Inscrit un utilisateur à un cours publié");
    }

    public override async Task HandleAsync(EnrollDto req, CancellationToken ct)
    {
        var course = await db.Courses.FirstOrDefaultAsync(c => c.Id == req.CourseId, ct);
        if (course is null)
        {
            AddError("Le cours n'existe pas.");
            await SendErrorsAsync(404, ct);
            return;
        }

        if (course.Status != CourseStatus.Published)
        {
            AddError("Impossible de s'inscrire à un cours non publié.");
            await SendErrorsAsync(422, ct);
            return;
        }

        var userExists = await db.Users.AnyAsync(u => u.Id == req.UserId, ct);
        if (!userExists)
        {
            AddError("L'utilisateur n'existe pas.");
            await SendErrorsAsync(404, ct);
            return;
        }

        var alreadyEnrolled = await db.UserCourses
            .AnyAsync(uc => uc.UserId == req.UserId && uc.CourseId == req.CourseId, ct);

        if (alreadyEnrolled)
        {
            AddError("L'utilisateur est déjà inscrit à ce cours.");
            await SendErrorsAsync(409, ct);
            return;
        }

        var enrollment = new UserCourse
        {
            UserId = req.UserId,
            CourseId = req.CourseId
        };
        db.UserCourses.Add(enrollment);
        await db.SaveChangesAsync(ct);

        var result = await db.UserCourses
            .Include(uc => uc.Course)
            .FirstAsync(uc => uc.UserId == req.UserId && uc.CourseId == req.CourseId, ct);

        await SendAsync(mapper.Map<GetEnrollmentDto>(result), 201, ct);
    }
}