using GermanApp.Domain.Entities;
using Microsoft.EntityFrameworkCore;

namespace GermanApp.Infrastructure.Data.DbContext;

/// <summary>
/// Entity Framework Core database context.
/// This is part of the Infrastructure layer.
/// </summary>
public class AppDbContext : Microsoft.EntityFrameworkCore.DbContext
{
    public AppDbContext(DbContextOptions<AppDbContext> options) : base(options)
    {
    }

    // DbSets for domain entities
    public DbSet<Level> Levels { get; set; } = null!;
    public DbSet<Lesson> Lessons { get; set; } = null!;
    public DbSet<User> Users { get; set; } = null!;
    public DbSet<UserProgress> UserProgress { get; set; } = null!;
    public DbSet<RefreshToken> RefreshTokens { get; set; } = null!;
    public DbSet<Quiz> Quizzes { get; set; } = null!;
    public DbSet<QuizQuestion> QuizQuestions { get; set; } = null!;
    public DbSet<QuizOption> QuizOptions { get; set; } = null!;
    public DbSet<StorySegment> StorySegments { get; set; } = null!;
    public DbSet<StoryProgress> StoryProgress { get; set; } = null!;

    // Note: Value objects are not stored directly as entities.
    // They are owned by entities and stored as part of the entity's data.

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        // Configure Level entity
        modelBuilder.Entity<Level>(builder =>
        {
            builder.HasKey(l => l.Id);
            builder.Property(l => l.Name).IsRequired().HasMaxLength(100);
            builder.Property(l => l.Code).IsRequired().HasMaxLength(10);
            builder.Property(l => l.Order).IsRequired();

            // Ensure unique constraints
            builder.HasIndex(l => l.Code).IsUnique();
            builder.HasIndex(l => l.Order).IsUnique();
        });

        // Configure Lesson entity
        modelBuilder.Entity<Lesson>(builder =>
        {
            builder.HasKey(l => l.Id);
            builder.Property(l => l.Title).IsRequired().HasMaxLength(200);
            builder.Property(l => l.Description).HasMaxLength(2000);
            builder.Property(l => l.Topic).IsRequired().HasMaxLength(100);
            builder.Property(l => l.LevelId).IsRequired();
            builder.Property(l => l.Order).IsRequired();
            builder.Property(l => l.IsActive).HasDefaultValue(true);
            builder.Property(l => l.CreatedAt).IsRequired();
            builder.Property(l => l.UpdatedAt).IsRequired(false);

            // Foreign key to Level with unique constraint per level
            builder.HasOne(l => l.Level)
                   .WithMany()
                   .HasForeignKey(l => l.LevelId)
                   .OnDelete(DeleteBehavior.Cascade);

            // Unique constraint: one lesson per level per order
            builder.HasIndex(l => new { l.LevelId, l.Order }).IsUnique();

            // Value object: GermanWord would be configured as an owned entity
            // builder.OwnsMany(l => l.Words, wordBuilder =>
            // {
            //     wordBuilder.Property(w => w.Value).HasColumnName("WordValue");
            //     wordBuilder.Property(w => w.Translation).HasColumnName("Translation");
            //     wordBuilder.Property(w => w.Article).HasColumnName("Article");
            //     wordBuilder.Property(w => w.PartOfSpeech).HasColumnName("PartOfSpeech");
            // });
        });

        // Configure UserProgress entity
        modelBuilder.Entity<UserProgress>(builder =>
        {
            builder.HasKey(up => up.Id);
            builder.Property(up => up.UserId).IsRequired();
            builder.Property(up => up.LessonId).IsRequired();
            builder.Property(up => up.IsCompleted).HasDefaultValue(false);
            builder.Property(up => up.QuizScore).HasDefaultValue(0);
            builder.Property(up => up.LastAttemptDate).IsRequired();

            // Foreign keys
            builder.HasOne(up => up.User)
                   .WithMany()
                   .HasForeignKey(up => up.UserId)
                   .OnDelete(DeleteBehavior.Cascade);

            builder.HasOne(up => up.Lesson)
                   .WithMany()
                   .HasForeignKey(up => up.LessonId)
                   .OnDelete(DeleteBehavior.Cascade);

            // Unique constraint: one progress record per user per lesson
            builder.HasIndex(up => new { up.UserId, up.LessonId }).IsUnique();
        });

        // Configure User entity
        modelBuilder.Entity<User>(builder =>
        {
            builder.HasKey(u => u.Id);
            builder.Property(u => u.Username).IsRequired().HasMaxLength(50);
            builder.Property(u => u.Email).IsRequired().HasMaxLength(100);
            builder.Property(u => u.PasswordHash).IsRequired().HasMaxLength(255);
            builder.Property(u => u.CurrentLevel).HasMaxLength(10).HasDefaultValue("A1");
            builder.Property(u => u.Streak).HasDefaultValue(0);
            builder.Property(u => u.TotalPoints).HasDefaultValue(0);
            builder.Property(u => u.CreatedAt).IsRequired();

            // Ensure unique constraints
            builder.HasIndex(u => u.Username).IsUnique();
            builder.HasIndex(u => u.Email).IsUnique();
        });

        // Configure RefreshToken entity
        modelBuilder.Entity<RefreshToken>(builder =>
        {
            builder.HasKey(r => r.Id);
            builder.Property(r => r.UserId).IsRequired();
            builder.Property(r => r.Token).IsRequired().HasMaxLength(255);
            builder.Property(r => r.ExpiresAt).IsRequired();
            builder.Property(r => r.IsActive).HasDefaultValue(true);
            builder.Property(r => r.CreatedAt).IsRequired();
            builder.Property(r => r.RevokedAt).IsRequired(false);

            // Foreign key to User
            builder.HasOne<User>()
                   .WithMany()
                   .HasForeignKey(r => r.UserId)
                   .OnDelete(DeleteBehavior.Cascade);
        });

        // Configure Quiz entity
        modelBuilder.Entity<Quiz>(builder =>
        {
            builder.HasKey(q => q.Id);
            builder.Property(q => q.LessonId).IsRequired();
            builder.Property(q => q.Title).IsRequired().HasMaxLength(200);
            builder.Property(q => q.Description).HasMaxLength(2000);
            builder.Property(q => q.PassingScore).IsRequired().HasDefaultValue(80);
            builder.Property(q => q.TimeLimitMinutes).HasDefaultValue(0);
            builder.Property(q => q.IsActive).HasDefaultValue(true);
            builder.Property(q => q.ShuffleQuestions).HasDefaultValue(true);
            builder.Property(q => q.CreatedAt).IsRequired();
            builder.Property(q => q.UpdatedAt).IsRequired(false);

            // Foreign key to Lesson
            builder.HasOne(q => q.Lesson)
                   .WithMany()
                   .HasForeignKey(q => q.LessonId)
                   .OnDelete(DeleteBehavior.Cascade);

            // Navigation to questions
            builder.HasMany(q => q.Questions)
                   .WithOne(qq => qq.Quiz)
                   .HasForeignKey(qq => qq.QuizId)
                   .OnDelete(DeleteBehavior.Cascade);
        });

        // Configure QuizQuestion entity
        modelBuilder.Entity<QuizQuestion>(builder =>
        {
            builder.HasKey(q => q.Id);
            builder.Property(q => q.QuizId).IsRequired();
            builder.Property(q => q.QuestionText).IsRequired().HasMaxLength(2000);
            builder.Property(q => q.Type).IsRequired();
            builder.Property(q => q.CorrectAnswer).HasMaxLength(1000);
            builder.Property(q => q.Points).IsRequired().HasDefaultValue(1);
            builder.Property(q => q.Difficulty).IsRequired().HasDefaultValue(3);
            builder.Property(q => q.Order).IsRequired().HasDefaultValue(1);
            builder.Property(q => q.IsActive).HasDefaultValue(true);
            builder.Property(q => q.CreatedAt).IsRequired();
            builder.Property(q => q.UpdatedAt).IsRequired(false);

            // Foreign key to Quiz
            builder.HasOne(q => q.Quiz)
                   .WithMany(qq => qq.Questions)
                   .HasForeignKey(q => q.QuizId)
                   .OnDelete(DeleteBehavior.Cascade);

            // Unique constraint: one question per quiz per order
            builder.HasIndex(q => new { q.QuizId, q.Order }).IsUnique();

            // Navigation to options
            builder.HasMany(q => q.Options)
                   .WithOne(o => o.QuizQuestion)
                   .HasForeignKey(o => o.QuizQuestionId)
                   .OnDelete(DeleteBehavior.Cascade);
        });

        // Configure QuizOption entity
        modelBuilder.Entity<QuizOption>(builder =>
        {
            builder.HasKey(o => o.Id);
            builder.Property(o => o.QuizQuestionId).IsRequired();
            builder.Property(o => o.Text).IsRequired().HasMaxLength(1000);
            builder.Property(o => o.IsCorrect).IsRequired().HasDefaultValue(false);
            builder.Property(o => o.Order).IsRequired().HasDefaultValue(1);

            // Foreign key to QuizQuestion
            builder.HasOne(o => o.QuizQuestion)
                   .WithMany(q => q.Options)
                   .HasForeignKey(o => o.QuizQuestionId)
                   .OnDelete(DeleteBehavior.Cascade);

            // Unique constraint: one option per question per order
            builder.HasIndex(o => new { o.QuizQuestionId, o.Order }).IsUnique();
        });

        // Configure StorySegment entity
        modelBuilder.Entity<StorySegment>(builder =>
        {
            builder.HasKey(s => s.Id);
            builder.Property(s => s.LevelId).IsRequired();
            builder.Property(s => s.LessonId).IsRequired(false);
            builder.Property(s => s.Content).IsRequired();
            builder.Property(s => s.AudioUrl).HasMaxLength(255).IsRequired(false);
            builder.Property(s => s.Order).IsRequired();
            builder.Property(s => s.Title).IsRequired().HasMaxLength(200);
            builder.Property(s => s.Theme).IsRequired().HasMaxLength(100);
            builder.Property(s => s.EstimatedReadingMinutes).IsRequired().HasDefaultValue(2);
            builder.Property(s => s.IsActive).HasDefaultValue(true);
            builder.Property(s => s.CreatedAt).IsRequired();
            builder.Property(s => s.UpdatedAt).IsRequired(false);

            // Foreign key to Level
            builder.HasOne(s => s.Level)
                   .WithMany()
                   .HasForeignKey(s => s.LevelId)
                   .OnDelete(DeleteBehavior.Cascade);

            // Foreign key to Lesson (optional)
            builder.HasOne(s => s.Lesson)
                   .WithMany()
                   .HasForeignKey(s => s.LessonId)
                   .OnDelete(DeleteBehavior.SetNull);

            // Unique constraint: one segment per level per order
            builder.HasIndex(s => new { s.LevelId, s.Order }).IsUnique();
        });

        // Configure StoryProgress entity
        modelBuilder.Entity<StoryProgress>(builder =>
        {
            builder.HasKey(sp => sp.Id);
            builder.Property(sp => sp.UserId).IsRequired();
            builder.Property(sp => sp.LevelId).IsRequired();
            builder.Property(sp => sp.StorySegmentId).IsRequired();
            builder.Property(sp => sp.IsCompleted).HasDefaultValue(false);
            builder.Property(sp => sp.UnlockedAt).IsRequired();
            builder.Property(sp => sp.CompletedAt).IsRequired(false);
            builder.Property(sp => sp.CreatedAt).IsRequired();
            builder.Property(sp => sp.UpdatedAt).IsRequired(false);

            // Foreign key to User
            builder.HasOne(sp => sp.User)
                   .WithMany()
                   .HasForeignKey(sp => sp.UserId)
                   .OnDelete(DeleteBehavior.Cascade);

            // Foreign key to Level
            builder.HasOne(sp => sp.Level)
                   .WithMany()
                   .HasForeignKey(sp => sp.LevelId)
                   .OnDelete(DeleteBehavior.Cascade);

            // Foreign key to StorySegment
            builder.HasOne(sp => sp.StorySegment)
                   .WithMany()
                   .HasForeignKey(sp => sp.StorySegmentId)
                   .OnDelete(DeleteBehavior.Cascade);

            // Unique constraint: one progress record per user per segment
            builder.HasIndex(sp => new { sp.UserId, sp.StorySegmentId }).IsUnique();
        });

        // Seed data (optional) - Note: For EF Core, we need to set properties directly
        // In a real application, use migrations or a separate seeding mechanism
        // modelBuilder.Entity<Lesson>().HasData(
        //     new { Id = 1, Title = "Greetings", Description = "Basic German greetings", Level = 1, CreatedAt = DateTime.UtcNow },
        //     new { Id = 2, Title = "Numbers", Description = "German numbers 1-100", Level = 1, CreatedAt = DateTime.UtcNow },
        //     new { Id = 3, Title = "Grammar Basics", Description = "Basic German grammar", Level = 2, CreatedAt = DateTime.UtcNow }
        // );
    }
}