using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Security.Cryptography;
using System.Text;
using Microsoft.IdentityModel.Tokens;
using ROLAC.API.Entities;

namespace ROLAC.API.Services;

public class TokenService : ITokenService
{
    private readonly IConfiguration _config;

    public TokenService(IConfiguration config)
    {
        _config = config;
    }

    public string GenerateAccessToken(AppUser user, IList<string> roles)
    {
        var secretKey = _config["Jwt:SecretKey"]!;
        var issuer    = _config["Jwt:Issuer"]!;
        var audience  = _config["Jwt:Audience"]!;
        var expiryMin = int.Parse(_config["Jwt:AccessTokenExpiryMinutes"]!);

        var claims = new List<Claim>
        {
            new(JwtRegisteredClaimNames.Sub,   user.Id),
            new(JwtRegisteredClaimNames.Email, user.Email!),
            new(JwtRegisteredClaimNames.Jti,   Guid.NewGuid().ToString()),
        };

        // Use the short JWT claim name "role" so the payload is clean and
        // JsonWebTokenHandler (the v7.x default validator) can read it without
        // needing an inbound claim-type map applied.
        foreach (var role in roles)
            claims.Add(new Claim("role", role));

        var key   = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(secretKey));
        var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);

        var token = new JwtSecurityToken(
            issuer:             issuer,
            audience:           audience,
            claims:             claims,
            expires:            DateTime.UtcNow.AddMinutes(expiryMin),
            signingCredentials: creds);

        return new JwtSecurityTokenHandler().WriteToken(token);
    }

    public string GenerateRefreshToken()
    {
        var bytes = new byte[64];
        using var rng = RandomNumberGenerator.Create();
        rng.GetBytes(bytes);
        return Convert.ToBase64String(bytes);
    }

    public string HashToken(string rawToken)
    {
        var bytes = SHA256.HashData(Encoding.UTF8.GetBytes(rawToken));
        return Convert.ToHexString(bytes).ToLower();
    }
}