using Microsoft.Extensions.Configuration;
using Microsoft.IdentityModel.Tokens;
using OnlyPrompt.Backend.Database.Models;
using OnlyPrompt.Backend.Utils;
using System;
using System.Collections.Generic;
using System.IdentityModel.Tokens.Jwt;
using System.Linq;
using System.Security.Claims;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

namespace OnlyPrompt.Backend.Services.Jwt
{
	public class JwtTokenService : ITokenService
	{
		private string _key;
		private string _issuer;
		private string _audience;
		private TimeSpan _valid;

		public JwtTokenService(IConfiguration config)
		{
			config = config.GetSection("Jwt");
			_key = config["Key"];
			_issuer = config["Issuer"];
			_audience = config["Audience"];
			_valid = config.GetValue<TimeSpan>("Valid");
		}

		public string BuildToken(UserModel user, out DateTime validUntil)
		{
			var claims = user.GetClaims().ToList();
			validUntil = DateTime.UtcNow.Add(_valid);
			claims.Add(new Claim("exp", new DateTimeOffset(validUntil).ToUnixTimeSeconds().ToString()));
			claims.Add(new Claim("amr", "pwd"));
			var securityKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_key));
			var credentials = new SigningCredentials(securityKey, SecurityAlgorithms.HmacSha256Signature);
			var tokenDescriptor = new JwtSecurityToken(_issuer, _audience, claims, expires: validUntil, signingCredentials: credentials);
			return new JwtSecurityTokenHandler().WriteToken(tokenDescriptor);
		}

		public bool ValidateToken(string token, out ClaimsPrincipal claims)
		{
			var mySecret = Encoding.UTF8.GetBytes(_key);
			var mySecurityKey = new SymmetricSecurityKey(mySecret);
			var tokenHandler = new JwtSecurityTokenHandler();
			try
			{
				claims = tokenHandler.ValidateToken(token,
				new TokenValidationParameters
				{
					ValidateIssuerSigningKey = true,
					ValidateIssuer = true,
					ValidateAudience = true,
					ValidIssuer = _issuer,
					ValidAudience = _audience,
					IssuerSigningKey = mySecurityKey,
				}, out SecurityToken validatedToken);
			}
			catch
			{
				claims = null;
				return false;
			}

			return true;
		}
	}

}