using System.Collections.ObjectModel;
using System.IO;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace VideoDownloader.App.Browser.Features;

/// <summary>재생목록 트랙. Kind: Direct/Hls/Dash/Social.</summary>
public sealed record MediaTrack(
    string Url,
    string Title,
    string Kind,
    DateTime AddedAt,
    bool Played = false,
    string? Referer = null,
    string? LocalFile = null);

/// <summary>
/// T2-10 미디어 재생목록(Brave Playlist 패턴): 브라우저에서 감지된 미디어를
/// 쌓아두고 앱 내에서 연속 재생. JSON 영속(playlist.json).
/// </summary>
public sealed class MediaPlaylist
{
    public ObservableCollection<MediaTrack> Tracks { get; } = new();

    public int CurrentIndex { get; set; } = -1;

    [JsonIgnore]
    public MediaTrack? Current => CurrentIndex >= 0 && CurrentIndex < Tracks.Count ? Tracks[CurrentIndex] : null;

    public event Action? Changed;

    /// <summary>추가(중복 URL 무시). 새 항목이 첫 트랙이면 자동 선택.</summary>
    public void Add(MediaTrack track)
    {
        if (Tracks.Any(t => t.Url == track.Url)) return;
        Tracks.Add(track);
        if (CurrentIndex < 0) CurrentIndex = Tracks.Count - 1;
        Changed?.Invoke();
    }

    public void Remove(MediaTrack track)
    {
        var idx = Tracks.IndexOf(track);
        if (idx < 0) return;
        Tracks.RemoveAt(idx);
        if (CurrentIndex >= Tracks.Count) CurrentIndex = Tracks.Count - 1;
        Changed?.Invoke();
    }

    public void Clear()
    {
        Tracks.Clear();
        CurrentIndex = -1;
        Changed?.Invoke();
    }

    /// <summary>다음 트랙 인덱스(순환). 반환 후 CurrentIndex 갱신.</summary>
    public int Next()
    {
        if (Tracks.Count == 0) return -1;
        CurrentIndex = (CurrentIndex + 1) % Tracks.Count;
        return CurrentIndex;
    }

    /// <summary>이전 트랙 인덱스(순환).</summary>
    public int Previous()
    {
        if (Tracks.Count == 0) return -1;
        CurrentIndex = (CurrentIndex - 1 + Tracks.Count) % Tracks.Count;
        return CurrentIndex;
    }

    public void MarkPlayed(MediaTrack track)
    {
        var idx = Tracks.IndexOf(track);
        if (idx < 0) return;
        Tracks[idx] = track with { Played = true };
        Changed?.Invoke();
    }

    public void Save(string path)
    {
        try
        {
            Directory.CreateDirectory(Path.GetDirectoryName(path)!);
            var dto = new { tracks = Tracks.ToList(), currentIndex = CurrentIndex };
            var tmp = path + ".tmp";
            File.WriteAllText(tmp, JsonSerializer.Serialize(dto));
            File.Move(tmp, path, overwrite: true);
        }
        catch { }
    }

    public void Load(string path)
    {
        try
        {
            if (!File.Exists(path)) return;
            using var doc = JsonDocument.Parse(File.ReadAllText(path));
            var root = doc.RootElement;
            Tracks.Clear();
            if (root.TryGetProperty("tracks", out var arr))
                foreach (var t in arr.EnumerateArray())
                {
                    var track = t.Deserialize<MediaTrack>();
                    if (track != null) Tracks.Add(track);
                }
            CurrentIndex = root.TryGetProperty("currentIndex", out var ci) ? ci.GetInt32() : -1;
            if (CurrentIndex >= Tracks.Count) CurrentIndex = Tracks.Count - 1;
        }
        catch
        {
            Tracks.Clear();
            CurrentIndex = -1;
        }
    }
}