using Microsoft.JSInterop;

namespace DeepDrftPublic.Client.Services;

public class AudioInteropService : IAsyncDisposable
{
    private readonly IJSRuntime _jsRuntime;
    private readonly Dictionary<string, IDisposable> _callbacks = new();

    public AudioInteropService(IJSRuntime jsRuntime)
    {
        _jsRuntime = jsRuntime;
    }

    public async Task<AudioOperationResult> CreatePlayerAsync(string playerId)
    {
        try
        {
            if (!await WaitForModuleReadyAsync())
            {
                return new AudioOperationResult
                {
                    Success = false,
                    Error = "Audio engine failed to load (timed out waiting for DeepDrftAudio module)."
                };
            }

            var result = await _jsRuntime.InvokeAsync<AudioOperationResult>("DeepDrftAudio.createPlayer", playerId);
            return result;
        }
        catch (Exception ex)
        {
            return new AudioOperationResult { Success = false, Error = ex.Message };
        }
    }

    // The audio engine is loaded as an ES module via a deferred `import(...)` in
    // App.razor, so on a slow WASM boot or cache miss it may not have executed by
    // the time the first track is selected. Poll its readiness probe (tolerating
    // the window before `window.DeepDrftAudio` even exists, when the call throws)
    // up to a short timeout before the first interop call.
    private async Task<bool> WaitForModuleReadyAsync()
    {
        const int timeoutMs = 5000;
        const int pollIntervalMs = 50;
        var elapsed = 0;

        while (elapsed < timeoutMs)
        {
            try
            {
                if (await _jsRuntime.InvokeAsync<bool>("DeepDrftAudio.isReady"))
                    return true;
            }
            catch
            {
                // window.DeepDrftAudio not attached yet — keep polling until timeout.
            }

            await Task.Delay(pollIntervalMs);
            elapsed += pollIntervalMs;
        }

        return false;
    }

    // Streaming methods
    public async Task<AudioOperationResult> InitializeStreaming(string playerId, long totalStreamLength, string contentType)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.initializeStreaming", playerId, totalStreamLength, contentType);
    }

    /// <summary>
    /// Probes whether this browser can stream-decode Ogg Opus via WebCodecs (<c>AudioDecoder</c> +
    /// <c>codec:'opus'</c>; Safari &lt; 16.4 / older Firefox cannot). Phase 18 capability gate (OQ2): the
    /// player only requests Opus when this returns true, otherwise it stays on the universal lossless path
    /// (AC7 — no listener ever gets silence over a codec gap). Probe failures degrade to <c>false</c>
    /// (assume incapable) so an interop error can never silence playback.
    /// </summary>
    public async Task<bool> CanDecodeOggOpus()
    {
        try
        {
            return await _jsRuntime.InvokeAsync<bool>("DeepDrftAudio.canDecodeOggOpus");
        }
        catch
        {
            return false;
        }
    }

    /// <summary>
    /// Hands the raw Opus seek/setup sidecar bytes (setup header + granule→byte seek index) to the JS player
    /// so the next Opus stream's decoder has them BEFORE init (the 18.4 set-before-init contract). The player
    /// parses and stashes them; <see cref="InitializeStreaming"/> applies them when it builds the Opus decoder.
    /// Must be called before <see cref="InitializeStreaming"/> on an Opus stream. Returns the parse result —
    /// a failure means the bytes were not a valid sidecar, and the caller falls back to lossless.
    /// </summary>
    public async Task<AudioOperationResult> SetOpusSidecar(string playerId, byte[] sidecarBytes)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.setOpusSidecar", playerId, sidecarBytes);
    }

    public async Task<StreamingResult> ProcessStreamingChunk(string playerId, byte[] audioChunk)
    {
        return await InvokeJsAsync<StreamingResult>("DeepDrftAudio.processStreamingChunk", playerId, audioChunk);
    }

    public async Task<AudioOperationResult> StartStreamingPlayback(string playerId)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.startStreamingPlayback", playerId);
    }

    public async Task<AudioOperationResult> MarkStreamCompleteAsync(string playerId)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.markStreamComplete", playerId);
    }

    public async Task<AudioOperationResult> EnsureAudioContextReady(string playerId)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.ensureAudioContextReady", playerId);
    }

    public async Task<AudioOperationResult> PlayAsync(string playerId)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.play", playerId);
    }

    public async Task<AudioOperationResult> PauseAsync(string playerId)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.pause", playerId);
    }

    public async Task<AudioOperationResult> StopAsync(string playerId)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.stop", playerId);
    }

    public async Task<AudioOperationResult> UnloadAsync(string playerId)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.unload", playerId);
    }

    public async Task<SeekResult> SeekAsync(string playerId, double position)
    {
        return await InvokeJsAsync<SeekResult>("DeepDrftAudio.seek", playerId, position);
    }

    /// <summary>
    /// Resolve the file-absolute byte offset to begin a stream at <paramref name="position"/> with no
    /// active playback or buffered audio — the "load at timestamp" seam (Phase 18 wave 18.6 format switch).
    /// Returns <see cref="SeekResult.ByteOffset"/> on success; <see cref="AudioOperationResult.Success"/> is
    /// false when the decoder cannot yet resolve an offset (e.g. a WAV stream whose header has not been
    /// parsed), so the caller can feed header bytes and retry.
    /// </summary>
    public async Task<SeekResult> ResolveStreamOffsetAsync(string playerId, double position)
    {
        return await InvokeJsAsync<SeekResult>("DeepDrftAudio.resolveStreamOffset", playerId, position);
    }

    // New methods for seek-beyond-buffer support
    public async Task<double> GetBufferedDuration(string playerId)
    {
        try
        {
            return await _jsRuntime.InvokeAsync<double>("DeepDrftAudio.getBufferedDuration", playerId);
        }
        catch
        {
            return 0;
        }
    }

    /// <summary>
    /// Phase 21.2a back-pressure poll: ask whether the scheduler is still over its forward
    /// high/low-water band. The read loop calls this only WHILE already throttled, to learn when it
    /// may resume reading — the steady-state loop reads the piggybacked <c>ProductionPaused</c> flag
    /// off each chunk result instead. Defaults to false on any interop failure so a torn-down player
    /// never wedges a loop that is exiting anyway.
    /// </summary>
    public async Task<bool> IsProductionPaused(string playerId)
    {
        try
        {
            return await _jsRuntime.InvokeAsync<bool>("DeepDrftAudio.isProductionPaused", playerId);
        }
        catch
        {
            return false;
        }
    }

    public async Task<AudioOperationResult> ReinitializeFromOffset(string playerId, long totalStreamLength, double seekPosition)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.reinitializeFromOffset", playerId, totalStreamLength, seekPosition);
    }

    /// <summary>
    /// Phase 21.3 / AC6 clean-failure recovery: after a window-miss refill (seek-back past the
    /// retained tail) fails its Range fetch or reinit, halt the starved scheduler and leave the
    /// player paused-but-loaded at <paramref name="seekPosition"/> so no silent false end fires and a
    /// retry is possible. Routes through <see cref="InvokeJsAsync{T}"/> so an interop failure during
    /// recovery still yields a failure result rather than throwing into the seek path.
    /// </summary>
    public async Task<AudioOperationResult> RecoverFromFailedRefill(string playerId, double seekPosition)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.recoverFromFailedRefill", playerId, seekPosition);
    }

    public async Task<AudioOperationResult> SetVolumeAsync(string playerId, double volume)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.setVolume", playerId, volume);
    }

    public async Task<double> GetCurrentTimeAsync(string playerId)
    {
        try
        {
            return await _jsRuntime.InvokeAsync<double>("DeepDrftAudio.getCurrentTime", playerId);
        }
        catch (Exception)
        {
            return 0;
        }
    }

    public async Task<AudioPlayerState?> GetStateAsync(string playerId)
    {
        try
        {
            return await _jsRuntime.InvokeAsync<AudioPlayerState>("DeepDrftAudio.getState", playerId);
        }
        catch (Exception)
        {
            return null;
        }
    }

    public async Task<AudioOperationResult> SetOnProgressCallbackAsync(string playerId, Func<double, Task> callback)
    {
        return await SetCallbackAsync(playerId, "_progress", "setOnProgressCallback", "OnProgressCallback", 
            wrapper => wrapper.OnProgress = callback);
    }

    public async Task<AudioOperationResult> SetOnEndCallbackAsync(string playerId, Func<Task> callback)
    {
        return await SetCallbackAsync(playerId, "_end", "setOnEndCallback", "OnEndCallback",
            wrapper => wrapper.OnEnd = callback);
    }

    // Spectrum analyzer methods
    public async Task<double[]?> GetSpectrumDataAsync(string playerId)
    {
        try
        {
            return await _jsRuntime.InvokeAsync<double[]>("DeepDrftAudio.getSpectrumData", playerId);
        }
        catch
        {
            return null;
        }
    }

    public async Task<AudioOperationResult> SetSpectrumHighPassAsync(string playerId, double freq)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.setSpectrumHighPass", playerId, freq);
    }

    public async Task<AudioOperationResult> SetSpectrumLowPassAsync(string playerId, double freq)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.setSpectrumLowPass", playerId, freq);
    }

    public async Task<AudioOperationResult> SetSpectrumSlopeAsync(string playerId, double dbPerDecade)
    {
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.setSpectrumSlope", playerId, dbPerDecade);
    }

    public async Task<AudioOperationResult> StartSpectrumAnimationAsync(string playerId, string callbackId, Func<double[], Task> callback)
    {
        try
        {
            var callbackWrapper = new SpectrumCallback { OnData = callback };
            var dotNetObjectRef = DotNetObjectReference.Create(callbackWrapper);
            _callbacks[playerId + "_spectrum_" + callbackId] = dotNetObjectRef;

            return await _jsRuntime.InvokeAsync<AudioOperationResult>(
                "DeepDrftAudio.startSpectrumAnimation",
                playerId, callbackId, dotNetObjectRef, "OnSpectrumDataCallback");
        }
        catch (Exception ex)
        {
            return new AudioOperationResult { Success = false, Error = ex.Message };
        }
    }

    public async Task<AudioOperationResult> StopSpectrumAnimationAsync(string playerId, string callbackId)
    {
        var key = playerId + "_spectrum_" + callbackId;
        if (_callbacks.TryGetValue(key, out var callback))
        {
            callback?.Dispose();
            _callbacks.Remove(key);
        }
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.stopSpectrumAnimation", playerId, callbackId);
    }

    public async Task<AudioOperationResult> StartLevelAnimationAsync(string playerId, string callbackId, Func<double, Task> callback)
    {
        try
        {
            var callbackWrapper = new LevelCallback { OnData = callback };
            var dotNetObjectRef = DotNetObjectReference.Create(callbackWrapper);
            _callbacks[playerId + "_level_" + callbackId] = dotNetObjectRef;

            return await _jsRuntime.InvokeAsync<AudioOperationResult>(
                "DeepDrftAudio.startLevelAnimation",
                playerId, callbackId, dotNetObjectRef, "OnLevelDataCallback");
        }
        catch (Exception ex)
        {
            return new AudioOperationResult { Success = false, Error = ex.Message };
        }
    }

    public async Task<AudioOperationResult> StopLevelAnimationAsync(string playerId, string callbackId)
    {
        var key = playerId + "_level_" + callbackId;
        if (_callbacks.TryGetValue(key, out var callback))
        {
            callback?.Dispose();
            _callbacks.Remove(key);
        }
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.stopLevelAnimation", playerId, callbackId);
    }

    public async Task<AudioOperationResult> DisposePlayerAsync(string playerId)
    {
        CleanupPlayerCallbacks(playerId);
        return await InvokeJsAsync<AudioOperationResult>("DeepDrftAudio.disposePlayer", playerId);
    }

    // TODO: The typeof(T) switch below requires updating whenever a new result type is added.
    // Consider introducing a shared marker interface (e.g. IAudioResult with a static factory
    // method) so InvokeJsAsync can construct the failure result generically without a type switch.
    private async Task<T> InvokeJsAsync<T>(string identifier, params object[] args)
    {
        try
        {
            return await _jsRuntime.InvokeAsync<T>(identifier, args);
        }
        catch (Exception ex)
        {
            if (typeof(T) == typeof(AudioOperationResult))
                return (T)(object)new AudioOperationResult { Success = false, Error = ex.Message };
            if (typeof(T) == typeof(StreamingResult))
                return (T)(object)new StreamingResult { Success = false, Error = ex.Message };
            if (typeof(T) == typeof(SeekResult))
                return (T)(object)new SeekResult { Success = false, Error = ex.Message };
            throw;
        }
    }

    private async Task<AudioOperationResult> SetCallbackAsync(string playerId, string suffix, string jsMethod, string callbackMethod, Action<AudioPlayerCallback> configureCallback)
    {
        try
        {
            var callbackWrapper = new AudioPlayerCallback();
            configureCallback(callbackWrapper);
            
            var dotNetObjectRef = DotNetObjectReference.Create(callbackWrapper);
            _callbacks[playerId + suffix] = dotNetObjectRef;

            return await _jsRuntime.InvokeAsync<AudioOperationResult>($"DeepDrftAudio.{jsMethod}", 
                playerId, dotNetObjectRef, callbackMethod);
        }
        catch (Exception ex)
        {
            return new AudioOperationResult { Success = false, Error = ex.Message };
        }
    }

    private void CleanupPlayerCallbacks(string playerId)
    {
        var keysToRemove = _callbacks.Keys.Where(k => k.StartsWith(playerId + "_")).ToList();
        foreach (var key in keysToRemove)
        {
            _callbacks[key]?.Dispose();
            _callbacks.Remove(key);
        }
    }

    public async ValueTask DisposeAsync()
    {
        foreach (var callback in _callbacks.Values)
        {
            callback?.Dispose();
        }
        _callbacks.Clear();
    }
}

public class AudioPlayerCallback
{
    public Func<double, Task>? OnProgress { get; set; }
    public Func<Task>? OnEnd { get; set; }

    [JSInvokable]
    public async Task OnProgressCallback(double currentTime)
    {
        if (OnProgress != null)
            await OnProgress(currentTime);
    }

    [JSInvokable]
    public async Task OnEndCallback()
    {
        if (OnEnd != null)
            await OnEnd();
    }
}

public class SpectrumCallback
{
    public Func<double[], Task>? OnData { get; set; }

    [JSInvokable]
    public async Task OnSpectrumDataCallback(double[] data)
    {
        if (OnData != null)
            await OnData(data);
    }
}

public class LevelCallback
{
    public Func<double, Task>? OnData { get; set; }

    [JSInvokable]
    public async Task OnLevelDataCallback(double db)
    {
        if (OnData != null)
            await OnData(db);
    }
}

public class AudioOperationResult
{
    public bool Success { get; set; }
    public string? Error { get; set; }
}

public class SeekResult : AudioOperationResult
{
    public bool SeekBeyondBuffer { get; set; }
    public long ByteOffset { get; set; }
}

public class StreamingResult : AudioOperationResult
{
    public bool CanStartStreaming { get; set; }
    public bool HeaderParsed { get; set; }
    public int BufferCount { get; set; }
    public double? Duration { get; set; } // Duration in seconds calculated from WAV header

    // Phase 21.2a back-pressure: true when the scheduler's forward decoded fill is over the
    // high-water mark and the C# read loop should stop calling ReadAsync until it drains. Read off
    // the chunk result the loop already awaits — no extra interop hop in the unthrottled steady state.
    public bool ProductionPaused { get; set; }
}

public class AudioPlayerState
{
    public bool IsPlaying { get; set; }
    public bool IsPaused { get; set; }
    public double CurrentTime { get; set; }
    public double Duration { get; set; }
    public double Volume { get; set; }
    public double LoadProgress { get; set; }
}