namespace Webzine.Business.Seeders;

using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Text;

using Microsoft.Extensions.Options;

using Webzine.Business.DTOs.Spotify;
using Webzine.Business.Mappers.Spotify;
using Webzine.Entity;
using Webzine.Entity.Fixtures;

public class SeedDataSpotify
{
    private readonly HttpClient httpClient;
    private readonly SpotifySeederOptions options;

    public SeedDataSpotify(HttpClient httpClient, IOptions<SpotifySeederOptions> optionsAccessor)
    {
        this.httpClient = httpClient;
        this.options = optionsAccessor.Value;
    }

    public async Task<SeedDataSet> GenererJeuDeDonneesAsync(CancellationToken cancellationToken = default)
    {
        // Verification des parametres pour l'acces a Spotify.
        if (string.IsNullOrWhiteSpace(this.options.ClientId) || string.IsNullOrWhiteSpace(this.options.ClientSecret))
        {
            throw new InvalidOperationException("Renseignez SpotifySeeder:ClientId et SpotifySeeder:ClientSecret.");
        }

        var token = await this.GetTokenAsync(cancellationToken);
        var styles = new Dictionary<string, Style>();
        var artistes = new List<Artiste>();
        var titres = new List<Titre>();
        var commentaires = new List<Commentaire>();
        var artistIds = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
        int nextArtistId = 1;
        int nextStyleId = 1;
        int nextTitreId = 1;
        int nextCommentaireId = 1;

        foreach (var genre in this.options.Genres)
        {
            var artistesSpotify = await this.GetAsync<SpotifySearchArtistsResponseDto>(
                $"https://api.spotify.com/v1/search?q={Uri.EscapeDataString($"genre:\"{genre}\"")}&type=artist&market={this.options.Market}&limit={this.options.ArtistsPerGenre}",
                token,
                cancellationToken);

            foreach (var artisteSpotify in artistesSpotify?.Artists?.Items ??[])
            {
                if (string.IsNullOrWhiteSpace(artisteSpotify.Id) || !artistIds.Add(artisteSpotify.Id))
                {
                    continue;
                }

                var stylesTitre = (artisteSpotify.Genres.Count > 0 ? artisteSpotify.Genres :[genre])
                    .Select(g => SpotifyMapper.GetOrCreateStyle(styles, g, ref nextStyleId))
                    .DistinctBy(s => s.IdStyle)
                    .ToList();

                var artiste = SpotifyMapper.ToArtiste(artisteSpotify, stylesTitre, nextArtistId++);
                artistes.Add(artiste);

                var albums = await this.GetAsync<SpotifyAlbumsResponseDto>(
                    $"https://api.spotify.com/v1/artists/{artisteSpotify.Id}/albums?include_groups=album,single&market={this.options.Market}",
                    token,
                    cancellationToken);

                foreach (var album in albums?.Items.GroupBy(a => a.Name, StringComparer.OrdinalIgnoreCase).Select(g => g.First()) ??[])
                {
                    var tracks = await this.GetAsync<SpotifyTracksResponseDto>(
                        $"https://api.spotify.com/v1/albums/{album.Id}/tracks?market={this.options.Market}&limit={Math.Clamp(this.options.TracksPerAlbum, 1, 10)}",
                        token,
                        cancellationToken);

                    foreach (var track in tracks?.Items ??[])
                    {
                        var titre = SpotifyMapper.ToTitre(track, album, artiste, stylesTitre, nextTitreId++);

                        var commentairesTitre = SeedDataLocal.GenererListeCommentaire(
                            titre,
                            0,
                            Math.Clamp(this.options.MaxCommentsPerTrack, 0, 10),
                            nextCommentaireId);

                        nextCommentaireId += commentairesTitre.Count;

                        titre.Commentaires.AddRange(commentairesTitre);
                        commentaires.AddRange(commentairesTitre);
                        titres.Add(titre);
                        artiste.Titres.Add(titre);

                        foreach (var style in titre.Styles)
                        {
                            style.Titres.Add(titre);
                        }
                    }
                }
            }
        }

        return new SeedDataSet
        {
            Artistes = artistes,
            Styles = styles.Values.OrderBy(s => s.IdStyle).ToList(),
            Titres = titres,
            Commentaires = commentaires,
        };
    }

    /// <summary>
    /// Recuperation du token d'access a Spotify.
    /// </summary>
    /// <param name="cancellationToken">Permet d'annuler la requete HTTP en cas de probleme.</param>
    /// <returns>Le token d'acces a spotify.</returns>
    /// <exception cref="InvalidOperationException">Le token spotify est introuvable.</exception>
    private async Task<string> GetTokenAsync(CancellationToken cancellationToken)
    {
        using var request = new HttpRequestMessage(HttpMethod.Post, "https://accounts.spotify.com/api/token");
        request.Content = new FormUrlEncodedContent(
        [
            new KeyValuePair<string, string>("grant_type", "client_credentials"),
        ]);

        var basic = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{this.options.ClientId}:{this.options.ClientSecret}"));
        request.Headers.Authorization = new AuthenticationHeaderValue("Basic", basic);

        using var response = await this.httpClient.SendAsync(request, cancellationToken);
        response.EnsureSuccessStatusCode();

        var payload = await response.Content.ReadFromJsonAsync<SpotifyTokenResponseDto>(cancellationToken: cancellationToken);
        return payload?.AccessToken ?? throw new InvalidOperationException("Token Spotify introuvable.");
    }

    /// <summary>
    /// Recuperation d'information depuis spotify, en formattant
    /// la requete avec le Bearer Token.
    /// </summary>
    /// <typeparam name="T">DTOs Spotify.</typeparam>
    /// <param name="url">URL Spotify.</param>
    /// <param name="token">Token Bearer pour authorisation d'acces a l'api.</param>
    /// <param name="cancellationToken">Permet d'annuler la requete.</param>
    /// <returns>Reponse Spotify deserialiser.</returns>
    private async Task<T?> GetAsync<T>(string url, string token, CancellationToken cancellationToken)
    {
        // Formattage de la requete HTTP avec le Bearer token.
        using var request = new HttpRequestMessage(HttpMethod.Get, url);
        request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);

        using var response = await this.httpClient.SendAsync(request, cancellationToken);
        response.EnsureSuccessStatusCode();
        return await response.Content.ReadFromJsonAsync<T>(cancellationToken: cancellationToken);
    }
}