using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging.Abstractions;
using NSubstitute;
using UniVerse.Application.DTOs.Notifications;
using UniVerse.Application.Interfaces;
using UniVerse.Domain.Entities;
using UniVerse.Infrastructure.Data;
using UniVerse.Infrastructure.Services;
using Xunit;

namespace UniVerse.Api.Tests.Users;

public class UserServiceTests
{
    [Fact]
    public async Task GetStatsAsync_ReturnsLevelProgressThresholds()
    {
        await using var db = CreateDbContext();
        SeedLevelThresholds(db);
        db.Users.Add(new User { Id = 1, Email = "student@test.local", Xp = 120 });
        await db.SaveChangesAsync();
        var service = CreateService(db);

        var stats = await service.GetStatsAsync(1);

        Assert.Equal(2, stats.Level);
        Assert.Equal(100, stats.CurrentLevelXp);
        Assert.Equal(300, stats.NextLevelXp);
    }

    [Fact]
    public async Task GetStatsAsync_ReturnsNullNextLevelAtMaxConfiguredLevel()
    {
        await using var db = CreateDbContext();
        SeedLevelThresholds(db);
        db.Users.Add(new User { Id = 1, Email = "student@test.local", Xp = 350 });
        await db.SaveChangesAsync();
        var service = CreateService(db);

        var stats = await service.GetStatsAsync(1);

        Assert.Equal(3, stats.Level);
        Assert.Equal(300, stats.CurrentLevelXp);
        Assert.Null(stats.NextLevelXp);
    }

    [Fact]
    public async Task GetStatsAsync_ReturnsEnrollmentSlotStateAndRules()
    {
        await using var db = CreateDbContext();
        SeedLevelThresholds(db);
        var now = DateTime.UtcNow;
        db.Users.Add(new User { Id = 1, Email = "student@test.local", Xp = 350 });
        db.Courses.Add(new Course { Id = 1, Name = "Course" });
        db.Lectures.AddRange(
            Lecture(1, now.AddDays(1)),
            Lecture(2, now.AddDays(2)),
            Lecture(3, now.AddDays(-1)));
        db.LectureEnrollments.AddRange(
            new LectureEnrollment { LectureId = 1, UserId = 1 },
            new LectureEnrollment { LectureId = 2, UserId = 1 },
            new LectureEnrollment { LectureId = 3, UserId = 1 });
        await db.SaveChangesAsync();
        var service = CreateService(db);

        var stats = await service.GetStatsAsync(1);

        Assert.Equal(3, stats.ActiveEnrollments);
        Assert.Equal(5, stats.EnrollmentSlotLimit);
        Assert.Equal(new[] { 1, 3, 4 }, stats.EnrollmentSlotRules.Select(rule => rule.Level));
        Assert.Equal(new[] { 3, 5, 7 }, stats.EnrollmentSlotRules.Select(rule => rule.Slots));
    }

    private static AppDbContext CreateDbContext()
    {
        var options = new DbContextOptionsBuilder<AppDbContext>()
            .UseInMemoryDatabase($"UserServiceTests_{Guid.NewGuid()}")
            .Options;
        return new AppDbContext(options);
    }

    private static UserService CreateService(AppDbContext db)
    {
        var notifications = Substitute.For<INotificationService>();
        notifications.CreateUserNotificationAsync(
                Arg.Any<int>(),
                Arg.Any<string>(),
                Arg.Any<string>(),
                Arg.Any<string>(),
                Arg.Any<CancellationToken>())
            .Returns(callInfo => new UserNotificationDto(1, callInfo.ArgAt<string>(1), callInfo.ArgAt<string>(2), callInfo.ArgAt<string>(3), false, DateTime.UtcNow));
        notifications.SendAsync(Arg.Any<NotificationMessage>(), Arg.Any<CancellationToken>())
            .Returns(Task.CompletedTask);

        var gamification = new GamificationService(db, notifications, NullLogger<GamificationService>.Instance);
        return new UserService(db, gamification);
    }

    private static void SeedLevelThresholds(AppDbContext db)
    {
        db.LevelThresholds.AddRange(
            new LevelThreshold { Level = 1, RequiredXp = 0 },
            new LevelThreshold { Level = 2, RequiredXp = 100 },
            new LevelThreshold { Level = 3, RequiredXp = 300 });
        db.SaveChanges();
    }

    private static Lecture Lecture(int id, DateTime startsAt) => new()
    {
        Id = id,
        CourseId = 1,
        Title = $"Lecture {id}",
        StartsAt = startsAt,
        EndsAt = startsAt.AddHours(2),
        IsOpen = true,
        MaxEnrollments = 30
    };
}