using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;

using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using Service.AppSettingModel;

namespace Application;

/// <summary>
/// 认证应用服务接口
/// </summary>
public interface IAuthApplication
{
    /// <summary>
    /// 用户登录
    /// </summary>
    LoginResponse Login(LoginRequest request);
}

/// <summary>
/// 认证应用服务实现
/// </summary>
public class AuthApplication(
    IOptions<AuthSettings> authSettings,
    IOptions<JwtSettings> jwtSettings,
    ILogger<AuthApplication> logger) : IAuthApplication
{
    private readonly AuthSettings _authSettings = authSettings.Value;
    private readonly JwtSettings _jwtSettings = jwtSettings.Value;
    private readonly ILogger<AuthApplication> _logger = logger;

    public LoginResponse Login(LoginRequest request)
    {
        // 验证密码
        if (string.IsNullOrEmpty(request.Password))
        {
            throw new ValidationException("密码不能为空");
        }

        if (request.Password != _authSettings.Password)
        {
            _logger.LogWarning("登录失败: 密码错误");
            throw new ValidationException("密码错误");
        }

        // 生成JWT Token
        var token = GenerateJwtToken();
        var expiresAt = DateTime.UtcNow.AddHours(_jwtSettings.ExpirationHours);

        _logger.LogInformation("用户登录成功");

        return new LoginResponse
        {
            Token = token,
            ExpiresAt = expiresAt
        };
    }

    /// <summary>
    /// 生成JWT Token
    /// </summary>
    private string GenerateJwtToken()
    {
        var securityKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_jwtSettings.SecretKey));
        var credentials = new SigningCredentials(securityKey, SecurityAlgorithms.HmacSha256);

        var claims = new[]
        {
            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
            new Claim(JwtRegisteredClaimNames.Iat, DateTimeOffset.UtcNow.ToUnixTimeSeconds().ToString()),
            new Claim("auth", "password-auth")
        };

        var token = new JwtSecurityToken(
            issuer: _jwtSettings.Issuer,
            audience: _jwtSettings.Audience,
            claims: claims,
            expires: DateTime.UtcNow.AddHours(_jwtSettings.ExpirationHours),
            signingCredentials: credentials
        );

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