/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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.
 */

package com.android.wallpaperpicker;

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.Point;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.ScaleGestureDetector.OnScaleGestureListener;
import android.view.ViewConfiguration;
import android.view.ViewTreeObserver;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;

import com.android.photos.views.TiledImageRenderer.TileSource;
import com.android.photos.views.TiledImageView;

public class CropView extends TiledImageView implements OnScaleGestureListener {

    private ScaleGestureDetector mScaleGestureDetector;
    private long mTouchDownTime;
    private float mFirstX, mFirstY;
    private float mLastX, mLastY;
    private float mCenterX, mCenterY;
    private float mMinScale;
    private boolean mTouchEnabled = true;
    private RectF mTempEdges = new RectF();
    private float[] mTempPoint = new float[] { 0, 0 };
    private float[] mTempCoef = new float[] { 0, 0 };
    private float[] mTempAdjustment = new float[] { 0, 0 };
    private float[] mTempImageDims = new float[] { 0, 0 };
    private float[] mTempRendererCenter = new float[] { 0, 0 };
    TouchCallback mTouchCallback;
    Matrix mRotateMatrix;
    Matrix mInverseRotateMatrix;

    public interface TouchCallback {
        void onTouchDown();
        void onTap();
        void onTouchUp();
    }

    public CropView(Context context) {
        this(context, null);
    }

    public CropView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mScaleGestureDetector = new ScaleGestureDetector(context, this);
        mRotateMatrix = new Matrix();
        mInverseRotateMatrix = new Matrix();
    }

    private float[] getImageDims() {
        final float imageWidth = mRenderer.source.getImageWidth();
        final float imageHeight = mRenderer.source.getImageHeight();
        float[] imageDims = mTempImageDims;
        imageDims[0] = imageWidth;
        imageDims[1] = imageHeight;
        mRotateMatrix.mapPoints(imageDims);
        imageDims[0] = Math.abs(imageDims[0]);
        imageDims[1] = Math.abs(imageDims[1]);
        return imageDims;
    }

    private void getEdgesHelper(RectF edgesOut) {
        final float width = getWidth();
        final float height = getHeight();
        final float[] imageDims = getImageDims();
        final float imageWidth = imageDims[0];
        final float imageHeight = imageDims[1];

        float initialCenterX = mRenderer.source.getImageWidth() / 2f;
        float initialCenterY = mRenderer.source.getImageHeight() / 2f;

        float[] rendererCenter = mTempRendererCenter;
        rendererCenter[0] = mCenterX - initialCenterX;
        rendererCenter[1] = mCenterY - initialCenterY;
        mRotateMatrix.mapPoints(rendererCenter);
        rendererCenter[0] += imageWidth / 2;
        rendererCenter[1] += imageHeight / 2;

        final float scale = mRenderer.scale;
        float centerX = (width / 2f - rendererCenter[0] + (imageWidth - width) / 2f)
                * scale + width / 2f;
        float centerY = (height / 2f - rendererCenter[1] + (imageHeight - height) / 2f)
                * scale + height / 2f;
        float leftEdge = centerX - imageWidth / 2f * scale;
        float rightEdge = centerX + imageWidth / 2f * scale;
        float topEdge = centerY - imageHeight / 2f * scale;
        float bottomEdge = centerY + imageHeight / 2f * scale;

        edgesOut.left = leftEdge;
        edgesOut.right = rightEdge;
        edgesOut.top = topEdge;
        edgesOut.bottom = bottomEdge;
    }

    public int getImageRotation() {
        return mRenderer.rotation;
    }

    public RectF getCrop() {
        final RectF edges = mTempEdges;
        getEdgesHelper(edges);
        final float scale = mRenderer.scale;

        float cropLeft = -edges.left / scale;
        float cropTop = -edges.top / scale;
        float cropRight = cropLeft + getWidth() / scale;
        float cropBottom = cropTop + getHeight() / scale;

        return new RectF(cropLeft, cropTop, cropRight, cropBottom);
    }

    public Point getSourceDimensions() {
        return new Point(mRenderer.source.getImageWidth(), mRenderer.source.getImageHeight());
    }

    public void setTileSource(TileSource source, Runnable isReadyCallback) {
        super.setTileSource(source, isReadyCallback);
        mCenterX = mRenderer.centerX;
        mCenterY = mRenderer.centerY;
        mRotateMatrix.reset();
        mRotateMatrix.setRotate(mRenderer.rotation);
        mInverseRotateMatrix.reset();
        mInverseRotateMatrix.setRotate(-mRenderer.rotation);
        updateMinScale(getWidth(), getHeight(), source, true);
    }

    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        updateMinScale(w, h, mRenderer.source, false);
    }

    public void setScale(float scale) {
        synchronized (mLock) {
            mRenderer.scale = scale;
        }
    }

    private void updateMinScale(int w, int h, TileSource source, boolean resetScale) {
        synchronized (mLock) {
            if (resetScale) {
                mRenderer.scale = 1;
            }
            if (source != null) {
                final float[] imageDims = getImageDims();
                final float imageWidth = imageDims[0];
                final float imageHeight = imageDims[1];
                mMinScale = Math.max(w / imageWidth, h / imageHeight);
                mRenderer.scale =
                        Math.max(mMinScale, resetScale ? Float.MIN_VALUE : mRenderer.scale);
            }
        }
    }

    @Override
    public boolean onScaleBegin(ScaleGestureDetector detector) {
        return true;
    }

    @Override
    public boolean onScale(ScaleGestureDetector detector) {
        // Don't need the lock because this will only fire inside of
        // onTouchEvent
        mRenderer.scale *= detector.getScaleFactor();
        mRenderer.scale = Math.max(mMinScale, mRenderer.scale);
        invalidate();
        return true;
    }

    @Override
    public void onScaleEnd(ScaleGestureDetector detector) {
    }

    /**
     * Offsets wallpaper preview according to the state it will be displayed in upon returning home.
     * @param offset Ranges from 0 to 1, where 0 is the leftmost parallax and 1 is the rightmost.
     */
    public void setParallaxOffset(float offset, RectF crop) {
        offset = Math.max(0, Math.min(offset, 1)); // Make sure the offset is in the correct range.
        float screenWidth = getWidth() / mRenderer.scale;
        mCenterX = screenWidth / 2 + offset * (crop.width() - screenWidth) + crop.left;
        updateCenter();
    }

    public void moveToLeft() {
        if (getWidth() == 0 || getHeight() == 0) {
            final ViewTreeObserver observer = getViewTreeObserver();
            observer.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
                    public void onGlobalLayout() {
                        moveToLeft();
                        getViewTreeObserver().removeOnGlobalLayoutListener(this);
                    }
                });
        }
        final RectF edges = mTempEdges;
        getEdgesHelper(edges);
        final float scale = mRenderer.scale;
        mCenterX += Math.ceil(edges.left / scale);
        updateCenter();
    }

    private void updateCenter() {
        mRenderer.centerX = Math.round(mCenterX);
        mRenderer.centerY = Math.round(mCenterY);
    }

    public void setTouchEnabled(boolean enabled) {
        mTouchEnabled = enabled;
    }

    public void setTouchCallback(TouchCallback cb) {
        mTouchCallback = cb;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int action = event.getActionMasked();
        final boolean pointerUp = action == MotionEvent.ACTION_POINTER_UP;
        final int skipIndex = pointerUp ? event.getActionIndex() : -1;

        // Determine focal point
        float sumX = 0, sumY = 0;
        final int count = event.getPointerCount();
        for (int i = 0; i < count; i++) {
            if (skipIndex == i)
                continue;
            sumX += event.getX(i);
            sumY += event.getY(i);
        }
        final int div = pointerUp ? count - 1 : count;
        float x = sumX / div;
        float y = sumY / div;

        if (action == MotionEvent.ACTION_DOWN) {
            mFirstX = x;
            mFirstY = y;
            mTouchDownTime = System.currentTimeMillis();
            if (mTouchCallback != null) {
                mTouchCallback.onTouchDown();
            }
        } else if (action == MotionEvent.ACTION_UP) {
            ViewConfiguration config = ViewConfiguration.get(getContext());

            float squaredDist = (mFirstX - x) * (mFirstX - x) + (mFirstY - y) * (mFirstY - y);
            float slop = config.getScaledTouchSlop() * config.getScaledTouchSlop();
            long now = System.currentTimeMillis();
            if (mTouchCallback != null) {
                // only do this if it's a small movement
                if (squaredDist < slop &&
                        now < mTouchDownTime + ViewConfiguration.getTapTimeout()) {
                    mTouchCallback.onTap();
                }
                mTouchCallback.onTouchUp();
            }
        }

        if (!mTouchEnabled) {
            return true;
        }

        synchronized (mLock) {
            mScaleGestureDetector.onTouchEvent(event);
            switch (action) {
                case MotionEvent.ACTION_MOVE:
                    float[] point = mTempPoint;
                    point[0] = (mLastX - x) / mRenderer.scale;
                    point[1] = (mLastY - y) / mRenderer.scale;
                    mInverseRotateMatrix.mapPoints(point);
                    mCenterX += point[0];
                    mCenterY += point[1];
                    updateCenter();
                    invalidate();
                    break;
            }
            if (mRenderer.source != null) {
                // Adjust position so that the wallpaper covers the entire area
                // of the screen
                final RectF edges = mTempEdges;
                getEdgesHelper(edges);
                final float scale = mRenderer.scale;

                float[] coef = mTempCoef;
                coef[0] = 1;
                coef[1] = 1;
                mRotateMatrix.mapPoints(coef);
                float[] adjustment = mTempAdjustment;
                mTempAdjustment[0] = 0;
                mTempAdjustment[1] = 0;
                if (edges.left > 0) {
                    adjustment[0] = edges.left / scale;
                } else if (edges.right < getWidth()) {
                    adjustment[0] = (edges.right - getWidth()) / scale;
                }
                if (edges.top > 0) {
                    adjustment[1] = (float) Math.ceil(edges.top / scale);
                } else if (edges.bottom < getHeight()) {
                    adjustment[1] = (edges.bottom - getHeight()) / scale;
                }
                for (int dim = 0; dim <= 1; dim++) {
                    if (coef[dim] > 0) adjustment[dim] = (float) Math.ceil(adjustment[dim]);
                }

                mInverseRotateMatrix.mapPoints(adjustment);
                mCenterX += adjustment[0];
                mCenterY += adjustment[1];
                updateCenter();
            }
        }

        mLastX = x;
        mLastY = y;
        return true;
    }
}