// Copyright 2015 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#if !UNITY_EDITOR
#if UNITY_ANDROID
#define ANDROID_DEVICE
#elif UNITY_IPHONE
#define IPHONE_DEVICE
#endif
#endif

using UnityEngine;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System;

// Represents a vr device that this plugin interacts with.
// Please do not interact with this class directly, instead use the interface in Cardboard.cs.
public abstract class BaseVRDevice {
  private static BaseVRDevice device = null;

  protected BaseVRDevice() {
    Profile = CardboardProfile.Default.Clone();
  }

  public CardboardProfile Profile { get; protected set; }

  public abstract void Init();

  public virtual bool SupportsNativeDistortionCorrection(List<string> diagnostics) {
    bool support = true;
    if (!SystemInfo.supportsRenderTextures) {
      diagnostics.Add("RenderTexture (Unity Pro feature) is unavailable");
      support = false;
    }
    if (!SupportsUnityRenderEvent()) {
      diagnostics.Add("Unity 4.5+ is needed for UnityRenderEvent");
      support = false;
    }
    return support;
  }

  public virtual bool SupportsNativeUILayer(List<string> diagnostics) {
    bool support = true;
    if (!SupportsUnityRenderEvent()) {
      diagnostics.Add("Unity 4.5+ is needed for UnityRenderEvent");
      support = false;
    }
    return support;
  }

  public bool SupportsUnityRenderEvent() {
    bool support = true;
    if (Application.isMobilePlatform) {
      try {
        string version = new Regex(@"(\d+\.\d+)\..*").Replace(Application.unityVersion, "$1");
        if (new Version(version) < new Version("4.5")) {
          support = false;
        }
      } catch {
        Debug.LogWarning("Unable to determine Unity version from: " + Application.unityVersion);
      }
    }
    return support;
  }

  public virtual RenderTexture CreateStereoScreen() {
    Debug.Log("Creating new default cardboard screen texture.");
    return new RenderTexture(Screen.width, Screen.height, 16, RenderTextureFormat.RGB565);
  }

  public abstract void SetDistortionCorrectionEnabled(bool enabled);
  public abstract void SetVRModeEnabled(bool enabled);
  public abstract void SetAlignmentMarkerEnabled(bool enabled);
  public abstract void SetSettingsButtonEnabled(bool enabled);
  public abstract void SetNeckModelScale(float scale);
  public abstract void SetAutoDriftCorrectionEnabled(bool enabled);

  public abstract void SetStereoScreen(RenderTexture stereoScreen);

  public Pose3D GetHeadPose() {
    return this.headPose;
  }
  protected MutablePose3D headPose = new MutablePose3D();

  public Pose3D GetEyePose(Cardboard.Eye eye) {
    switch(eye) {
      case Cardboard.Eye.Left:
        return leftEyePose;
      case Cardboard.Eye.Right:
        return rightEyePose;
      default:
        return null;
    }
  }
  protected MutablePose3D leftEyePose = new MutablePose3D();
  protected MutablePose3D rightEyePose = new MutablePose3D();

  public Matrix4x4 GetProjection(Cardboard.Eye eye,
                                 Cardboard.Distortion distortion = Cardboard.Distortion.Distorted) {
    switch(eye) {
      case Cardboard.Eye.Left:
        return distortion == Cardboard.Distortion.Distorted ?
            leftEyeDistortedProjection : leftEyeUndistortedProjection;
      case Cardboard.Eye.Right:
        return distortion == Cardboard.Distortion.Distorted ?
            rightEyeDistortedProjection : rightEyeUndistortedProjection;
      default:
        return Matrix4x4.identity;
    }
  }
  protected Matrix4x4 leftEyeDistortedProjection;
  protected Matrix4x4 rightEyeDistortedProjection;
  protected Matrix4x4 leftEyeUndistortedProjection;
  protected Matrix4x4 rightEyeUndistortedProjection;

  public Rect GetViewport(Cardboard.Eye eye,
                          Cardboard.Distortion distortion = Cardboard.Distortion.Distorted) {
    switch(eye) {
      case Cardboard.Eye.Left:
        return distortion == Cardboard.Distortion.Distorted ?
            leftEyeDistortedViewport : leftEyeUndistortedViewport;
      case Cardboard.Eye.Right:
        return distortion == Cardboard.Distortion.Distorted ?
            rightEyeDistortedViewport : rightEyeUndistortedViewport;
      default:
        return new Rect();
    }
  }
  protected Rect leftEyeDistortedViewport;
  protected Rect rightEyeDistortedViewport;
  protected Rect leftEyeUndistortedViewport;
  protected Rect rightEyeUndistortedViewport;

  public bool triggered;
  public bool tilted;

  public abstract void UpdateState();

  public abstract void UpdateScreenData();

  public abstract void Recenter();

  public abstract void PostRender(bool vrMode);

  public virtual void SetTouchCoordinates(int x, int y) {
    // Do nothing
  }

  public virtual void OnPause(bool pause) {
    if (!pause) {
      UpdateScreenData();
    }
  }

  public virtual void OnFocus(bool focus) {
    // Do nothing.
  }

  public virtual void Reset() {
    Recenter();
  }

  public virtual void OnApplicationQuit() {
    // Do nothing.
  }

  public virtual void Destroy() {
    if (device == this) {
      device = null;
    }
  }

  // Helper functions.
  protected void ComputeEyesFromProfile() {
    // Compute left eye matrices from screen and device params
    Matrix4x4 leftEyeView = Matrix4x4.identity;
    leftEyeView[0, 3] = -Profile.device.lenses.separation / 2;
    leftEyePose.Set(leftEyeView);

    float[] rect = new float[4];
    Profile.GetLeftEyeVisibleTanAngles(ref rect);
    leftEyeDistortedProjection = MakeProjection(rect[0], rect[1], rect[2], rect[3], 1, 1000);
    Profile.GetLeftEyeNoLensTanAngles(ref rect);
    leftEyeUndistortedProjection = MakeProjection(rect[0], rect[1], rect[2], rect[3], 1, 1000);

    leftEyeUndistortedViewport = Profile.GetLeftEyeVisibleScreenRect(rect);
    leftEyeDistortedViewport = leftEyeUndistortedViewport;

    // Right eye matrices same as left ones but for some sign flippage.
    Matrix4x4 rightEyeView = leftEyeView;
    rightEyeView[0, 3] *= -1;
    rightEyePose.Set(rightEyeView);

    rightEyeDistortedProjection = leftEyeDistortedProjection;
    rightEyeDistortedProjection[0, 2] *= -1;
    rightEyeUndistortedProjection = leftEyeUndistortedProjection;
    rightEyeUndistortedProjection[0, 2] *= -1;

    rightEyeUndistortedViewport = leftEyeUndistortedViewport;
    rightEyeUndistortedViewport.x = 1 - rightEyeUndistortedViewport.xMax;
    rightEyeDistortedViewport = rightEyeUndistortedViewport;
  }

  private static Matrix4x4 MakeProjection(float l, float t, float r, float b, float n, float f) {
    Matrix4x4 m = Matrix4x4.zero;
    m[0, 0] = 2 * n / (r - l);
    m[1, 1] = 2 * n / (t - b);
    m[0, 2] = (r + l) / (r - l);
    m[1, 2] = (t + b) / (t - b);
    m[2, 2] = (n + f) / (n - f);
    m[2, 3] = 2 * n * f / (n - f);
    m[3, 2] = -1;
    return m;
  }

  public static BaseVRDevice GetDevice() {
    if (device == null) {
#if UNITY_EDITOR
      device = new UnityEditorDevice();
#elif ANDROID_DEVICE
      //device = new CardboardAndroidDevice();
      device = new AndroidVRDevice();
#elif IPHONE_DEVICE
      device = new iOSVRDevice();
#else
      throw new InvalidOperationException();
#endif
    }
    return device;
  }
}