using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Text;
using Kurisu.RemoteCall.Abstractions;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.IdentityModel.Tokens;

namespace Dlhis.Jip.Api.ClientHandlers;

public class JipTokenHandler : IAsyncAuthTokenHandler
{
    /// <inheritdoc />
    public async Task<string> GetTokenAsync(IServiceProvider serviceProvider)
    {
        var configuration = serviceProvider.GetService<IConfiguration>()!;

        var jwtKey = configuration.GetSection("JinkoOptions:Jip:Key").Value;
        var jwtSecret = configuration.GetSection("JinkoOptions:Jip:Secret").Value;
        const int min = 5;

        var now = DateTime.Now.AddMinutes(-min);
        var expires = DateTime.Now.AddMinutes(min);

        var claims = new List<Claim>
        {
            new(JwtRegisteredClaimNames.Nbf, $"{new DateTimeOffset(now).ToUnixTimeSeconds()}"),
            new(JwtRegisteredClaimNames.Exp, $"{new DateTimeOffset(expires).ToUnixTimeSeconds()}"),
            new(JwtRegisteredClaimNames.Iss, jwtKey),
        };

        var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(jwtSecret));
        var descriptor = new SecurityTokenDescriptor
        {
            Subject = new ClaimsIdentity(claims),
            Issuer = jwtKey,
            IssuedAt = now,
            NotBefore = now,
            Expires = expires,
            SigningCredentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256)
        };

        var jwtHandler = new JwtSecurityTokenHandler();
        var securityToken = jwtHandler.CreateToken(descriptor);
        return await Task.FromResult(jwtHandler.WriteToken(securityToken));
    }
}