// Copyright (c) 2021 homuler
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.Rendering;

using Stopwatch = System.Diagnostics.Stopwatch;

namespace Mediapipe.Unity
{
  public abstract class GraphRunner : MonoBehaviour
  {
    public enum ConfigType
    {
      None,
      CPU,
      GPU,
      OpenGLES,
    }

#pragma warning disable IDE1006
    // TODO: make it static
    protected string TAG => GetType().Name;
#pragma warning restore IDE1006

    [SerializeField] private TextAsset _cpuConfig = null;
    [SerializeField] private TextAsset _gpuConfig = null;
    [SerializeField] private TextAsset _openGlEsConfig = null;
    [SerializeField] private long _timeoutMicrosec = 0;

    private static readonly GlobalInstanceTable<int, GraphRunner> _InstanceTable = new GlobalInstanceTable<int, GraphRunner>(5);
    private static readonly Dictionary<IntPtr, int> _NameTable = new Dictionary<IntPtr, int>();

    protected RunningMode runningMode { get; private set; } = RunningMode.Async;
    private bool _isRunning = false;

    public InferenceMode inferenceMode => configType == ConfigType.CPU ? InferenceMode.CPU : InferenceMode.GPU;
    public virtual ConfigType configType
    {
      get
      {
        if (GpuManager.IsInitialized)
        {
#if UNITY_ANDROID
          if (SystemInfo.graphicsDeviceType == GraphicsDeviceType.OpenGLES3 && _openGlEsConfig != null)
          {
            return ConfigType.OpenGLES;
          }
#endif
          if (_gpuConfig != null)
          {
            return ConfigType.GPU;
          }
        }
        return _cpuConfig != null ? ConfigType.CPU : ConfigType.None;
      }
    }
    public TextAsset textConfig
    {
      get
      {
        switch (configType)
        {
          case ConfigType.CPU: return _cpuConfig;
          case ConfigType.GPU: return _gpuConfig;
          case ConfigType.OpenGLES: return _openGlEsConfig;
          case ConfigType.None:
          default: return null;
        }
      }
    }

    public long timeoutMicrosec
    {
      get => _timeoutMicrosec;
      set => _timeoutMicrosec = (long)Mathf.Max(0, value);
    }
    public long timeoutMillisec
    {
      get => timeoutMicrosec / 1000;
      set => timeoutMicrosec = value * 1000;
    }

    public RotationAngle rotation { get; private set; } = 0;

    private Stopwatch _stopwatch;
    protected CalculatorGraph calculatorGraph { get; private set; }
    protected Timestamp latestTimestamp;

    protected virtual void Start()
    {
      _InstanceTable.Add(GetInstanceID(), this);
    }

    protected virtual void OnDestroy()
    {
      Stop();
    }

    public WaitForResult WaitForInit(RunningMode runningMode)
    {
      return new WaitForResult(this, Initialize(runningMode));
    }

    public virtual IEnumerator Initialize(RunningMode runningMode)
    {
      this.runningMode = runningMode;

      Logger.LogInfo(TAG, $"Config Type = {configType}");
      Logger.LogInfo(TAG, $"Running Mode = {runningMode}");

      InitializeCalculatorGraph().AssertOk();
      _stopwatch = new Stopwatch();
      _stopwatch.Start();

      Logger.LogInfo(TAG, "Loading dependent assets...");
      var assetRequests = RequestDependentAssets();
      yield return new WaitWhile(() => assetRequests.Any((request) => request.keepWaiting));

      var errors = assetRequests.Where((request) => request.isError).Select((request) => request.error).ToList();
      if (errors.Count > 0)
      {
        foreach (var error in errors)
        {
          Logger.LogError(TAG, error);
        }
        throw new InternalException("Failed to prepare dependent assets");
      }
    }

    public abstract void StartRun(ImageSource imageSource);

    protected void StartRun(SidePacket sidePacket)
    {
      calculatorGraph.StartRun(sidePacket).AssertOk();
      _isRunning = true;
    }

    public virtual void Stop()
    {
      if (calculatorGraph != null)
      {
        if (_isRunning)
        {
          using (var status = calculatorGraph.CloseAllPacketSources())
          {
            if (!status.Ok())
            {
              Logger.LogError(TAG, status.ToString());
            }
          }

          using (var status = calculatorGraph.WaitUntilDone())
          {
            if (!status.Ok())
            {
              Logger.LogError(TAG, status.ToString());
            }
          }
        }

        _isRunning = false;
        var _ = _NameTable.Remove(calculatorGraph.mpPtr);
        calculatorGraph.Dispose();
        calculatorGraph = null;
      }

      if (_stopwatch != null && _stopwatch.IsRunning)
      {
        _stopwatch.Stop();
      }
    }

    protected void AddPacketToInputStream<T>(string streamName, Packet<T> packet)
    {
      calculatorGraph.AddPacketToInputStream(streamName, packet).AssertOk();
    }

    protected void AddTextureFrameToInputStream(string streamName, TextureFrame textureFrame)
    {
      latestTimestamp = GetCurrentTimestamp();

      if (configType == ConfigType.OpenGLES)
      {
        var gpuBuffer = textureFrame.BuildGpuBuffer(GpuManager.GlCalculatorHelper.GetGlContext());
        AddPacketToInputStream(streamName, new GpuBufferPacket(gpuBuffer, latestTimestamp));
        return;
      }

      var imageFrame = textureFrame.BuildImageFrame();
      textureFrame.Release();

      AddPacketToInputStream(streamName, new ImageFramePacket(imageFrame, latestTimestamp));
    }

    protected bool TryGetNext<TPacket, TValue>(OutputStream<TPacket, TValue> stream, out TValue value, bool allowBlock, long currentTimestampMicrosec) where TPacket : Packet<TValue>, new()
    {
      var result = stream.TryGetNext(out value, allowBlock);
      return result || allowBlock || stream.ResetTimestampIfTimedOut(currentTimestampMicrosec, timeoutMicrosec);
    }

    protected long GetCurrentTimestampMicrosec()
    {
      return _stopwatch == null || !_stopwatch.IsRunning ? -1 : _stopwatch.ElapsedTicks / (TimeSpan.TicksPerMillisecond / 1000);
    }

    protected Timestamp GetCurrentTimestamp()
    {
      var microsec = GetCurrentTimestampMicrosec();
      return microsec < 0 ? Timestamp.Unset() : new Timestamp(microsec);
    }

    protected Status InitializeCalculatorGraph()
    {
      calculatorGraph = new CalculatorGraph();
      _NameTable.Add(calculatorGraph.mpPtr, GetInstanceID());

      // NOTE: There's a simpler way to initialize CalculatorGraph.
      //
      //     calculatorGraph = new CalculatorGraph(config.text);
      //
      //   However, if the config format is invalid, this code does not initialize CalculatorGraph and does not throw exceptions either.
      //   The problem is that if you call ObserveStreamOutput in this state, the program will crash.
      //   The following code is not very efficient, but it will return Non-OK status when an invalid configuration is given.
      try
      {
        var baseConfig = textConfig == null ? null : CalculatorGraphConfig.Parser.ParseFromTextFormat(textConfig.text);
        if (baseConfig == null)
        {
          throw new InvalidOperationException("Failed to get the text config. Check if the config is set to GraphRunner");
        }
        var status = ConfigureCalculatorGraph(baseConfig);
        return !status.Ok() || inferenceMode == InferenceMode.CPU ? status : calculatorGraph.SetGpuResources(GpuManager.GpuResources);
      }
      catch (Exception e)
      {
        return Status.FailedPrecondition(e.ToString());
      }
    }

    /// <summary>
    ///   Configure and initialize the <see cref="CalculatorGraph" />.
    /// </summary>
    /// <remarks>
    ///   This is the main process in <see cref="InitializeCalculatorGraph" />.<br />
    ///   At least, <c>calculatorGraph.Initialize</c> must be called here.
    ///   In addition to that, <see cref="OutputStream" /> instances should be initialized.
    /// </remarks>
    /// <param name="config">
    ///   A <see cref="CalculatorGraphConfig" /> instance corresponding to <see cref="textConfig" />.<br />
    ///   It can be dynamically modified here.
    /// </param>
    protected virtual Status ConfigureCalculatorGraph(CalculatorGraphConfig config)
    {
      return calculatorGraph.Initialize(config);
    }

    protected void SetImageTransformationOptions(SidePacket sidePacket, ImageSource imageSource, bool expectedToBeMirrored = false)
    {
      // NOTE: The origin is left-bottom corner in Unity, and right-top corner in MediaPipe.
      rotation = imageSource.rotation.Reverse();
      var inputRotation = rotation;
      var isInverted = CoordinateSystem.ImageCoordinate.IsInverted(rotation);
      var shouldBeMirrored = imageSource.isHorizontallyFlipped ^ expectedToBeMirrored;
      var inputHorizontallyFlipped = isInverted ^ shouldBeMirrored;
      var inputVerticallyFlipped = !isInverted;

      if ((inputHorizontallyFlipped && inputVerticallyFlipped) || rotation == RotationAngle.Rotation180)
      {
        inputRotation = inputRotation.Add(RotationAngle.Rotation180);
        inputHorizontallyFlipped = !inputHorizontallyFlipped;
        inputVerticallyFlipped = !inputVerticallyFlipped;
      }

      Logger.LogDebug($"input_rotation = {inputRotation}, input_horizontally_flipped = {inputHorizontallyFlipped}, input_vertically_flipped = {inputVerticallyFlipped}");

      sidePacket.Emplace("input_rotation", new IntPacket((int)inputRotation));
      sidePacket.Emplace("input_horizontally_flipped", new BoolPacket(inputHorizontallyFlipped));
      sidePacket.Emplace("input_vertically_flipped", new BoolPacket(inputVerticallyFlipped));
    }

    protected WaitForResult WaitForAsset(string assetName, string uniqueKey, long timeoutMillisec, bool overwrite = false)
    {
      return new WaitForResult(this, AssetLoader.PrepareAssetAsync(assetName, uniqueKey, overwrite), timeoutMillisec);
    }

    protected WaitForResult WaitForAsset(string assetName, long timeoutMillisec, bool overwrite = false)
    {
      return WaitForAsset(assetName, assetName, timeoutMillisec, overwrite);
    }

    protected WaitForResult WaitForAsset(string assetName, string uniqueKey, bool overwrite = false)
    {
      return new WaitForResult(this, AssetLoader.PrepareAssetAsync(assetName, uniqueKey, overwrite));
    }

    protected WaitForResult WaitForAsset(string assetName, bool overwrite = false)
    {
      return WaitForAsset(assetName, assetName, overwrite);
    }

    protected abstract IList<WaitForResult> RequestDependentAssets();
  }
}