using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Security.Cryptography;
using System.Text;
using Microsoft.Extensions.Configuration;
using Microsoft.IdentityModel.Tokens;
using MilliSim.Common.Entities;
using MilliSim.Common.Models;

namespace MilliSim.Services.Infrastructure;

public interface IJwtService
{
    string GenerateToken(User user);
    ClaimsPrincipal? ValidateToken(string token);
}

public class JwtService : IJwtService
{
    private readonly IConfiguration _config;

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

    public string GenerateToken(User user)
    {
        var secretKey = _config["Jwt:SecretKey"]!;
        var issuer = _config["Jwt:Issuer"];
        var audience = _config["Jwt:Audience"];
        var expireDays = int.Parse(_config["Jwt:ExpireDays"] ?? "7");

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

        var claims = new List<Claim>
        {
            new(ClaimTypes.NameIdentifier, user.Id.ToString()),
            new(ClaimTypes.Name, user.Username),
            new(ClaimTypes.Role, user.Role.ToString()),
            new("nickname", user.Nickname),
            new("role", ((int)user.Role).ToString())
        };

        var token = new JwtSecurityToken(
            issuer: issuer,
            audience: audience,
            claims: claims,
            expires: DateTime.Now.AddDays(expireDays),
            signingCredentials: credentials
        );

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

    public ClaimsPrincipal? ValidateToken(string token)
    {
        try
        {
            var secretKey = _config["Jwt:SecretKey"]!;
            var issuer = _config["Jwt:Issuer"];
            var audience = _config["Jwt:Audience"];

            var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(secretKey));
            var handler = new JwtSecurityTokenHandler();

            var parameters = new TokenValidationParameters
            {
                ValidateIssuer = true,
                ValidateAudience = true,
                ValidateLifetime = true,
                ValidateIssuerSigningKey = true,
                ValidIssuer = issuer,
                ValidAudience = audience,
                IssuerSigningKey = key,
                ClockSkew = TimeSpan.Zero
            };

            return handler.ValidateToken(token, parameters, out _);
        }
        catch
        {
            return null;
        }
    }
}