using System;
using System.IO;
using MelonLoader;
using UnityEngine;

namespace ADOFAIRenderer.Util.Audio.Clip;

/// <summary>
/// Opens the <see cref="AudioClipSource"/> for a clip the game plays, keyed by the game's audioLib key (also AudioClip.name):
/// - Key recorded in <see cref="AudioClipPaths"/> and the file exists: decoded from the file with <see cref="FFmpegPCMReader"/>
///   (mono MP3 through <see cref="MP3MonoLayoutReader"/>)
///   (song files and PlaySound files of custom levels).
/// - Otherwise, or when FFmpeg cannot open the file: the Unity clip is copied with <see cref="UnityClipLoader"/>
///   (built-in hit sounds from Resources, official/DLC level songs from Addressables).
/// Main thread only (the Unity copy calls AudioClip.GetData).
/// </summary>
internal static class AudioClipResolver
{
    /// <summary>
    /// Returns the source registered under <paramref name="key"/> in <paramref name="store"/>, opening it on first use
    /// (file first, then the Unity clip; see the class summary). A key that could not be opened is remembered as null.
    /// </summary>
    /// <param name="store">Store of the current render.</param>
    /// <param name="key">audioLib key of the clip (for example "song.ogg*external" or "sndKick").</param>
    /// <param name="clip">Loaded Unity clip for the key, used when the clip has no file; may be null when the key has a file.</param>
    /// <returns>The source, or null when neither the file nor the clip can be read.</returns>
    public static AudioClipSource? GetOrAdd(AudioClipStore store, string key, AudioClip? clip)
    {
        if (store.TryGet(key, out var existing)) return existing;

        if (AudioClipPaths.TryGetPath(key, out var path) && File.Exists(path))
        {
            IPCMReader? fileReader = null;
            try
            {
                fileReader = OpenFile(path);
                if (fileReader is MP3MonoLayoutReader)
                    Melon<RenderMod>.Logger.Warning($"[AudioClipResolver] Mono MP3 '{path}' is rendered like the game: half speed, one octave lower.");
            }
            catch (Exception e)
            {
                Melon<RenderMod>.Logger.Warning($"[AudioClipResolver] FFmpeg could not open '{path}' for '{key}', using the Unity clip: {e.Message}");
            }

            // The reader opened here becomes the first decode stream; additional streams reopen the file with OpenFile.
            // When no source results (store disposed, or the source could not be created), the reader is disposed here
            // (readers allow Dispose more than once).
            if (fileReader != null)
            {
                var source = store.GetOrAdd(key, () => fileReader, () => OpenFile(path));
                if (source == null) fileReader.Dispose();
                return source;
            }
        }

        if (!clip) return store.GetOrAdd(key, () => null);
        return store.GetOrAdd(key, () => UnityClipLoader.Load(clip!, store));
    }

    /// <summary>Opens <paramref name="path"/> with FFmpeg; mono MP3 files are wrapped in <see cref="MP3MonoLayoutReader"/> (game layout).</summary>
    private static IPCMReader OpenFile(string path)
    {
        var reader = new FFmpegPCMReader(path);
        if (!reader.IsMP3 || reader.Channels != 1) return reader;
        return new MP3MonoLayoutReader(reader);
    }
}