using System.Diagnostics.CodeAnalysis;
using System.Web;
using Authinator.Backend.Utils;
using Isopoh.Cryptography.Argon2;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;

namespace Authinator.Backend.Database.Tables;

public class User {
	public int     Id        { get; set; }
	public int     Iteration { get; set; }
	public string  Reference { get; set; } = null!;
	public string? Username  { get; set; }
	public string? Password  { get; set; }
	public string? Email     { get; set; }

	public List<Group> Groups { get; set; } = new();

	public bool IsSignupComplete => !string.IsNullOrEmpty(Username) && !string.IsNullOrEmpty(Password) && !string.IsNullOrEmpty(Email);

	public string GetAuthToken() => $"auth:{Id}:{Iteration}:{GetAuthTokenExpiry()}:".HmacWithMessage(ConfigCache.HmacSecret);

	private static long GetAuthTokenExpiry() => DateTimeOffset.UtcNow.Add(ConfigCache.AuthTokenLifetime).ToUnixTimeSeconds();

	public string GetSignupToken() => $"register:{Id}:".HmacWithMessage(ConfigCache.HmacSecret);

	public string GetPwResetToken() => $"reset:{Id}:{Iteration}:{GetPwResetTokenExpiry()}:".HmacWithMessage(ConfigCache.HmacSecret);

	private static long GetPwResetTokenExpiry() => DateTimeOffset.UtcNow.Add(ConfigCache.PwResetTokenLifetime).ToUnixTimeSeconds();

	[SuppressMessage("ReSharper.DPA", "DPA0001: Memory allocation issues")]
	public bool ValidatePassword(string password) => Argon2.Verify(Password ?? string.Empty, password);

	[SuppressMessage("ReSharper.DPA", "DPA0001: Memory allocation issues")]
	public void SetPassword(string password) => Password = Argon2.Hash(password);

	public class Configuration : IEntityTypeConfiguration<User> {
		public void Configure(EntityTypeBuilder<User> user) {
			user.ToTable("Users");
			user.HasKey(p => p.Id);

			user.Property(b => b.Iteration).HasColumnName("Iteration").HasDefaultValue(0);
			user.Property(b => b.Reference).HasColumnName("Reference").IsRequired();
			user.Property(b => b.Username).HasColumnName("Username");
			user.Property(b => b.Password).HasColumnName("Password");
			user.Property(b => b.Email).HasColumnName("Email");

			user.HasMany(p => p.Groups).WithMany();
		}
	}

	private bool Equals(User other) => Id == other.Id;

	public override bool Equals(object? obj) {
		if (ReferenceEquals(null, obj))
			return false;
		if (ReferenceEquals(this, obj))
			return true;

		return obj.GetType() == GetType() && Equals((User)obj);
	}

	public override int GetHashCode() => Id;

	public static bool operator ==(User? left, User? right) => Equals(left, right);

	public static bool operator !=(User? left, User? right) => !Equals(left, right);
}

public static class UserUtils {
	public static User? ValidateAuthToken(this DbSet<User> users, string token) {
		if (string.IsNullOrWhiteSpace(token) || !token.StartsWith("auth:") || token.Split(":").Length != 5)
			return null;

		var index   = token.LastIndexOf(":", StringComparison.Ordinal) + 1;
		var hmac    = token[index..].FixUrlEncodedBase64();
		var message = token[..index];

		if (message.Hmac(ConfigCache.HmacSecret) != hmac)
			return null;

		var expiry = long.Parse(message.Split(":")[3]);
		if (DateTimeOffset.FromUnixTimeSeconds(expiry) < DateTimeOffset.UtcNow)
			return null;

		var userId        = int.Parse(message.Split(":")[1]);
		var userIteration = int.Parse(message.Split(":")[2]);

		return users.Include(p => p.Groups).FirstOrDefault(p => p.Id == userId && p.Iteration == userIteration);
	}

	public static bool ValidateResetToken(this User user, string token) {
		if (string.IsNullOrWhiteSpace(token) || !token.StartsWith("reset:") || token.Split(":").Length != 5)
			return false;

		var index   = token.LastIndexOf(":", StringComparison.Ordinal) + 1;
		var hmac    = token[index..].FixUrlEncodedBase64();
		var message = token[..index];

		if (message.Hmac(ConfigCache.HmacSecret) != hmac)
			return false;

		var expiry = long.Parse(message.Split(":")[3]);
		if (DateTimeOffset.FromUnixTimeSeconds(expiry) < DateTimeOffset.UtcNow)
			return false;

		var userId        = int.Parse(message.Split(":")[1]);
		var userIteration = int.Parse(message.Split(":")[2]);

		return user.Id == userId && user.Iteration == userIteration;
	}
}