using System.Net.Http.Headers;
using System.Security.Authentication;
using System.Text;
using System.Text.Json.Serialization;
using SpotifyAPI.Web;

namespace SpotiParty.Web.Services;

public sealed class AuthorizationHandler {

    private AuthResponse? _token;
    
    private class AuthResponse {
        [JsonPropertyName("access_token")]
        public string AccessToken { get; set; }
        
        [JsonPropertyName("token_type")]
        public string TokenType { get; set; }
        
        [JsonPropertyName("expires_in")]
        public int ExpiresIn { get; set; }
    }

    public async Task<SpotifyClient> ConfigureClient() {
        if (_token is null) {
            var fileLines = await File.ReadAllLinesAsync(Path.Combine(Environment.CurrentDirectory, ".dev-token"));
            var clientId = fileLines[0];
            var clientSecret = fileLines[1];

            var basicAuthToken = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{clientId}:{clientSecret}"));
            var httpClient = new HttpClient();
            httpClient.DefaultRequestHeaders.Authorization = AuthenticationHeaderValue.Parse($"Basic {basicAuthToken}");

            var response = await httpClient.PostAsync("https://accounts.spotify.com/api/token", new FormUrlEncodedContent(new[] {
                new KeyValuePair<string, string>("grant_type", "client_credentials")
            }));
            response.EnsureSuccessStatusCode();
            _token = await response.Content.ReadFromJsonAsync<AuthResponse>();

            if (_token is null) throw new AuthenticationException("Spotify auth failed!");
        }

        return new SpotifyClient(_token.AccessToken, _token.TokenType);
    }
    
}