using System;
using System.Security.Cryptography;
using System.Text;
using Dapper;
using Microsoft.Data.Sqlite;

namespace Gott.Services;

public class AuthService
{
    private readonly string _connectionString;

    public AuthService(string dbPath)
    {
        _connectionString = $"Data Source={dbPath}";
        InitializeTable();
    }

    private SqliteConnection CreateConnection()
    {
        var conn = new SqliteConnection(_connectionString);
        conn.Open();
        return conn;
    }

    private void InitializeTable()
    {
        using var conn = CreateConnection();
        conn.Execute(@"
            CREATE TABLE IF NOT EXISTS tokens (
                token      TEXT NOT NULL PRIMARY KEY,
                user_id    TEXT NOT NULL,
                created_at TEXT NOT NULL
            );
            CREATE INDEX IF NOT EXISTS idx_tokens_user ON tokens(user_id);
        ");
    }

    public string HashPassword(string password)
    {
        var bytes = SHA256.HashData(Encoding.UTF8.GetBytes(password));
        return Convert.ToHexStringLower(bytes);
    }

    public bool VerifyPassword(string password, string hash)
    {
        return HashPassword(password) == hash;
    }

    public string CreateToken(string userId)
    {
        var token = Convert.ToHexStringLower(RandomNumberGenerator.GetBytes(32));
        using var conn = CreateConnection();
        conn.Execute(
            "INSERT INTO tokens (token, user_id, created_at) VALUES (@token, @userId, @now)",
            new { token, userId, now = DateTime.UtcNow.ToString("o") });
        return token;
    }

    public string ValidateToken(string token)
    {
        if (string.IsNullOrEmpty(token)) return null;
        using var conn = CreateConnection();
        return conn.QuerySingleOrDefault<string>(
            "SELECT user_id FROM tokens WHERE token = @token", new { token });
    }

    public void RevokeToken(string token)
    {
        if (string.IsNullOrEmpty(token)) return;
        using var conn = CreateConnection();
        conn.Execute("DELETE FROM tokens WHERE token = @token", new { token });
    }
}