namespace GermanApp.Domain.Entities;

/// <summary>
/// Represents a user in the DeutschLernen system.
/// </summary>
public class User
{
    public int Id { get; private set; }
    public string Username { get; private set; } = string.Empty;
    public string Email { get; private set; } = string.Empty;
    public string PasswordHash { get; private set; } = string.Empty;
    public string CurrentLevel { get; private set; } = "A1";
    public string Role { get; private set; } = "User";  // Default role is "User", "Admin" for administrators
    public int Streak { get; private set; }
    public int TotalPoints { get; private set; }
    public DateTime CreatedAt { get; private set; }

    /// <summary>
    /// Constructor for EF Core deserialization.
    /// </summary>
    private User() { }

    /// <summary>
    /// Factory method to create a new user.
    /// </summary>
    public static User Create(string username, string email, string passwordHash)
    {
        return new User
        {
            Username = username,
            Email = email.ToLowerInvariant(),
            PasswordHash = passwordHash,
            CurrentLevel = "A1",
            Role = "User",  // Explicitly set default role
            Streak = 0,
            TotalPoints = 0,
            CreatedAt = DateTime.UtcNow
        };
    }

    /// <summary>
    /// Updates user's gamification stats.
    /// </summary>
    public void AddPoints(int points)
    {
        TotalPoints += points;
    }

    /// <summary>
    /// Updates user's streak.
    /// </summary>
    public void UpdateStreak(int streak)
    {
        Streak = streak;
    }

    /// <summary>
    /// Updates user's current level.
    /// </summary>
    public void UpdateLevel(string level)
    {
        CurrentLevel = level;
    }

    /// <summary>
    /// Changes user's email.
    /// </summary>
    public void ChangeEmail(string newEmail)
    {
        Email = newEmail?.ToLowerInvariant() ?? string.Empty;
    }

    /// <summary>
    /// Changes user's password hash.
    /// </summary>
    public void ChangePassword(string newPasswordHash)
    {
        PasswordHash = newPasswordHash;
    }

    /// <summary>
    /// Assigns admin role to user (bootstrap only).
    /// </summary>
    public void AssignAdminRole()
    {
        Role = "Admin";
    }

    /// <summary>
    /// Sets the user's role.
    /// </summary>
    /// <param name="role">The role to assign (User or Admin)</param>
    public void SetRole(string role)
    {
        if (role != "Admin" && role != "User")
            throw new ArgumentException("Role must be 'Admin' or 'User'.", nameof(role));
        Role = role;
    }

    /// <summary>
    /// Checks if user has admin role.
    /// </summary>
    public bool IsAdmin() => Role == "Admin";

    // Navigation properties
    public virtual ICollection<StoryProgress> StoryProgress { get; private set; } = new List<StoryProgress>();
}