/*
 * Copyright (C) 2012 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.inputmethod.keyboard.internal;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.os.Message;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.util.SparseArray;
import android.widget.RelativeLayout;

import com.android.inputmethod.keyboard.PointerTracker;
import com.android.inputmethod.keyboard.internal.GesturePreviewTrail.Params;
import com.android.inputmethod.latin.CollectionUtils;
import com.android.inputmethod.latin.R;
import com.android.inputmethod.latin.StaticInnerHandlerWrapper;

public final class PreviewPlacerView extends RelativeLayout {
    // The height of extra area above the keyboard to draw gesture trails.
    // Proportional to the keyboard height.
    private static final float EXTRA_GESTURE_TRAIL_AREA_ABOVE_KEYBOARD_RATIO = 0.25f;

    private final int mGestureFloatingPreviewTextColor;
    private final int mGestureFloatingPreviewTextOffset;
    private final int mGestureFloatingPreviewColor;
    private final float mGestureFloatingPreviewHorizontalPadding;
    private final float mGestureFloatingPreviewVerticalPadding;
    private final float mGestureFloatingPreviewRoundRadius;

    private int mKeyboardViewOriginX;
    private int mKeyboardViewOriginY;

    private final SparseArray<GesturePreviewTrail> mGesturePreviewTrails =
            CollectionUtils.newSparseArray();
    private final Params mGesturePreviewTrailParams;
    private final Paint mGesturePaint;
    private boolean mDrawsGesturePreviewTrail;
    private int mOffscreenWidth;
    private int mOffscreenHeight;
    private int mOffscreenOffsetY;
    private Bitmap mOffscreenBuffer;
    private final Canvas mOffscreenCanvas = new Canvas();
    private final Rect mOffscreenDirtyRect = new Rect();
    private final Rect mGesturePreviewTrailBoundsRect = new Rect(); // per trail

    private final Paint mTextPaint;
    private String mGestureFloatingPreviewText;
    private final int mGestureFloatingPreviewTextHeight;
    // {@link RectF} is needed for {@link Canvas#drawRoundRect(RectF, float, float, Paint)}.
    private final RectF mGestureFloatingPreviewRectangle = new RectF();
    private int mLastPointerX;
    private int mLastPointerY;
    private static final char[] TEXT_HEIGHT_REFERENCE_CHAR = { 'M' };
    private boolean mDrawsGestureFloatingPreviewText;

    private final DrawingHandler mDrawingHandler;

    private static final class DrawingHandler extends StaticInnerHandlerWrapper<PreviewPlacerView> {
        private static final int MSG_DISMISS_GESTURE_FLOATING_PREVIEW_TEXT = 0;
        private static final int MSG_UPDATE_GESTURE_PREVIEW_TRAIL = 1;

        private final Params mGesturePreviewTrailParams;
        private final int mGestureFloatingPreviewTextLingerTimeout;

        public DrawingHandler(final PreviewPlacerView outerInstance,
                final Params gesturePreviewTrailParams,
                final int getstureFloatinPreviewTextLinerTimeout) {
            super(outerInstance);
            mGesturePreviewTrailParams = gesturePreviewTrailParams;
            mGestureFloatingPreviewTextLingerTimeout = getstureFloatinPreviewTextLinerTimeout;
        }

        @Override
        public void handleMessage(final Message msg) {
            final PreviewPlacerView placerView = getOuterInstance();
            if (placerView == null) return;
            switch (msg.what) {
            case MSG_DISMISS_GESTURE_FLOATING_PREVIEW_TEXT:
                placerView.setGestureFloatingPreviewText(null);
                break;
            case MSG_UPDATE_GESTURE_PREVIEW_TRAIL:
                placerView.invalidate();
                break;
            }
        }

        public void dismissGestureFloatingPreviewText() {
            removeMessages(MSG_DISMISS_GESTURE_FLOATING_PREVIEW_TEXT);
            sendMessageDelayed(obtainMessage(MSG_DISMISS_GESTURE_FLOATING_PREVIEW_TEXT),
                    mGestureFloatingPreviewTextLingerTimeout);
        }

        public void postUpdateGestureTrailPreview() {
            removeMessages(MSG_UPDATE_GESTURE_PREVIEW_TRAIL);
            sendMessageDelayed(obtainMessage(MSG_UPDATE_GESTURE_PREVIEW_TRAIL),
                    mGesturePreviewTrailParams.mUpdateInterval);
        }
    }

    public PreviewPlacerView(final Context context, final AttributeSet attrs) {
        this(context, attrs, R.attr.keyboardViewStyle);
    }

    public PreviewPlacerView(final Context context, final AttributeSet attrs, final int defStyle) {
        super(context);
        setWillNotDraw(false);

        final TypedArray keyboardViewAttr = context.obtainStyledAttributes(
                attrs, R.styleable.KeyboardView, defStyle, R.style.KeyboardView);
        final int gestureFloatingPreviewTextSize = keyboardViewAttr.getDimensionPixelSize(
                R.styleable.KeyboardView_gestureFloatingPreviewTextSize, 0);
        mGestureFloatingPreviewTextColor = keyboardViewAttr.getColor(
                R.styleable.KeyboardView_gestureFloatingPreviewTextColor, 0);
        mGestureFloatingPreviewTextOffset = keyboardViewAttr.getDimensionPixelOffset(
                R.styleable.KeyboardView_gestureFloatingPreviewTextOffset, 0);
        mGestureFloatingPreviewColor = keyboardViewAttr.getColor(
                R.styleable.KeyboardView_gestureFloatingPreviewColor, 0);
        mGestureFloatingPreviewHorizontalPadding = keyboardViewAttr.getDimension(
                R.styleable.KeyboardView_gestureFloatingPreviewHorizontalPadding, 0.0f);
        mGestureFloatingPreviewVerticalPadding = keyboardViewAttr.getDimension(
                R.styleable.KeyboardView_gestureFloatingPreviewVerticalPadding, 0.0f);
        mGestureFloatingPreviewRoundRadius = keyboardViewAttr.getDimension(
                R.styleable.KeyboardView_gestureFloatingPreviewRoundRadius, 0.0f);
        final int gestureFloatingPreviewTextLingerTimeout = keyboardViewAttr.getInt(
                R.styleable.KeyboardView_gestureFloatingPreviewTextLingerTimeout, 0);
        mGesturePreviewTrailParams = new Params(keyboardViewAttr);
        keyboardViewAttr.recycle();

        mDrawingHandler = new DrawingHandler(this, mGesturePreviewTrailParams,
                gestureFloatingPreviewTextLingerTimeout);

        final Paint gesturePaint = new Paint();
        gesturePaint.setAntiAlias(true);
        gesturePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
        mGesturePaint = gesturePaint;

        final Paint textPaint = new Paint();
        textPaint.setAntiAlias(true);
        textPaint.setTextAlign(Align.CENTER);
        textPaint.setTextSize(gestureFloatingPreviewTextSize);
        mTextPaint = textPaint;
        final Rect textRect = new Rect();
        textPaint.getTextBounds(TEXT_HEIGHT_REFERENCE_CHAR, 0, 1, textRect);
        mGestureFloatingPreviewTextHeight = textRect.height();

        final Paint layerPaint = new Paint();
        layerPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_OVER));
        setLayerType(LAYER_TYPE_HARDWARE, layerPaint);
    }

    public void setKeyboardViewGeometry(final int x, final int y, final int w, final int h) {
        mKeyboardViewOriginX = x;
        mKeyboardViewOriginY = y;
        mOffscreenOffsetY = (int)(h * EXTRA_GESTURE_TRAIL_AREA_ABOVE_KEYBOARD_RATIO);
        mOffscreenWidth = w;
        mOffscreenHeight = mOffscreenOffsetY + h;
    }

    public void setGesturePreviewMode(final boolean drawsGesturePreviewTrail,
            final boolean drawsGestureFloatingPreviewText) {
        mDrawsGesturePreviewTrail = drawsGesturePreviewTrail;
        mDrawsGestureFloatingPreviewText = drawsGestureFloatingPreviewText;
    }

    public void invalidatePointer(final PointerTracker tracker, final boolean isOldestTracker) {
        final boolean needsToUpdateLastPointer =
                isOldestTracker && mDrawsGestureFloatingPreviewText;
        if (needsToUpdateLastPointer) {
            mLastPointerX = tracker.getLastX();
            mLastPointerY = tracker.getLastY();
        }

        if (mDrawsGesturePreviewTrail) {
            GesturePreviewTrail trail;
            synchronized (mGesturePreviewTrails) {
                trail = mGesturePreviewTrails.get(tracker.mPointerId);
                if (trail == null) {
                    trail = new GesturePreviewTrail();
                    mGesturePreviewTrails.put(tracker.mPointerId, trail);
                }
            }
            trail.addStroke(tracker.getGestureStrokeWithPreviewPoints(), tracker.getDownTime());
        }

        // TODO: Should narrow the invalidate region.
        if (mDrawsGesturePreviewTrail || needsToUpdateLastPointer) {
            invalidate();
        }
    }

    @Override
    protected void onDetachedFromWindow() {
        freeOffscreenBuffer();
    }

    private void freeOffscreenBuffer() {
        if (mOffscreenBuffer != null) {
            mOffscreenBuffer.recycle();
            mOffscreenBuffer = null;
        }
    }

    private void mayAllocateOffscreenBuffer() {
        if (mOffscreenBuffer != null && mOffscreenBuffer.getWidth() == mOffscreenWidth
                && mOffscreenBuffer.getHeight() == mOffscreenHeight) {
            return;
        }
        freeOffscreenBuffer();
        mOffscreenBuffer = Bitmap.createBitmap(
                mOffscreenWidth, mOffscreenHeight, Bitmap.Config.ARGB_8888);
        mOffscreenCanvas.setBitmap(mOffscreenBuffer);
    }

    @Override
    public void onDraw(final Canvas canvas) {
        super.onDraw(canvas);
        if (mDrawsGesturePreviewTrail) {
            mayAllocateOffscreenBuffer();
            // Draw gesture trails to offscreen buffer.
            final boolean needsUpdatingGesturePreviewTrail = drawGestureTrails(
                    mOffscreenCanvas, mGesturePaint, mOffscreenDirtyRect);
            // Transfer offscreen buffer to screen.
            if (!mOffscreenDirtyRect.isEmpty()) {
                final int offsetY = mKeyboardViewOriginY - mOffscreenOffsetY;
                canvas.translate(mKeyboardViewOriginX, offsetY);
                canvas.drawBitmap(mOffscreenBuffer, mOffscreenDirtyRect, mOffscreenDirtyRect,
                        mGesturePaint);
                canvas.translate(-mKeyboardViewOriginX, -offsetY);
                // Note: Defer clearing the dirty rectangle here because we will get cleared
                // rectangle on the canvas.
            }
            if (needsUpdatingGesturePreviewTrail) {
                mDrawingHandler.postUpdateGestureTrailPreview();
            }
        }
        if (mDrawsGestureFloatingPreviewText) {
            canvas.translate(mKeyboardViewOriginX, mKeyboardViewOriginY);
            drawGestureFloatingPreviewText(canvas, mGestureFloatingPreviewText);
            canvas.translate(-mKeyboardViewOriginX, -mKeyboardViewOriginY);
        }
    }

    private boolean drawGestureTrails(final Canvas offscreenCanvas, final Paint paint,
            final Rect dirtyRect) {
        // Clear previous dirty rectangle.
        if (!dirtyRect.isEmpty()) {
            paint.setColor(Color.TRANSPARENT);
            paint.setStyle(Paint.Style.FILL);
            offscreenCanvas.drawRect(dirtyRect, paint);
        }
        dirtyRect.setEmpty();

        // Draw gesture trails to offscreen buffer.
        offscreenCanvas.translate(0, mOffscreenOffsetY);
        boolean needsUpdatingGesturePreviewTrail = false;
        synchronized (mGesturePreviewTrails) {
            // Trails count == fingers count that have ever been active.
            final int trailsCount = mGesturePreviewTrails.size();
            for (int index = 0; index < trailsCount; index++) {
                final GesturePreviewTrail trail = mGesturePreviewTrails.valueAt(index);
                needsUpdatingGesturePreviewTrail |=
                        trail.drawGestureTrail(offscreenCanvas, paint,
                                mGesturePreviewTrailBoundsRect, mGesturePreviewTrailParams);
                // {@link #mGesturePreviewTrailBoundsRect} has bounding box of the trail.
                dirtyRect.union(mGesturePreviewTrailBoundsRect);
            }
        }
        offscreenCanvas.translate(0, -mOffscreenOffsetY);

        // Clip dirty rectangle with offscreen buffer width/height.
        dirtyRect.offset(0, mOffscreenOffsetY);
        clipRect(dirtyRect, 0, 0, mOffscreenWidth, mOffscreenHeight);
        return needsUpdatingGesturePreviewTrail;
    }

    private static void clipRect(final Rect out, final int left, final int top, final int right,
            final int bottom) {
        out.set(Math.max(out.left, left), Math.max(out.top, top), Math.min(out.right, right),
                Math.min(out.bottom, bottom));
    }

    public void setGestureFloatingPreviewText(final String gestureFloatingPreviewText) {
        if (!mDrawsGestureFloatingPreviewText) return;
        mGestureFloatingPreviewText = gestureFloatingPreviewText;
        invalidate();
    }

    public void dismissGestureFloatingPreviewText() {
        mDrawingHandler.dismissGestureFloatingPreviewText();
    }

    private void drawGestureFloatingPreviewText(final Canvas canvas,
            final String gestureFloatingPreviewText) {
        if (TextUtils.isEmpty(gestureFloatingPreviewText)) {
            return;
        }

        final Paint paint = mTextPaint;
        final RectF rectangle = mGestureFloatingPreviewRectangle;
        // TODO: Figure out how we should deal with the floating preview text with multiple moving
        // fingers.

        // Paint the round rectangle background.
        final int textHeight = mGestureFloatingPreviewTextHeight;
        final float textWidth = paint.measureText(gestureFloatingPreviewText);
        final float hPad = mGestureFloatingPreviewHorizontalPadding;
        final float vPad = mGestureFloatingPreviewVerticalPadding;
        final float rectWidth = textWidth + hPad * 2.0f;
        final float rectHeight = textHeight + vPad * 2.0f;
        final int canvasWidth = canvas.getWidth();
        final float rectX = Math.min(Math.max(mLastPointerX - rectWidth / 2.0f, 0.0f),
                canvasWidth - rectWidth);
        final float rectY = mLastPointerY - mGestureFloatingPreviewTextOffset - rectHeight;
        rectangle.set(rectX, rectY, rectX + rectWidth, rectY + rectHeight);
        final float round = mGestureFloatingPreviewRoundRadius;
        paint.setColor(mGestureFloatingPreviewColor);
        canvas.drawRoundRect(rectangle, round, round, paint);
        // Paint the text preview
        paint.setColor(mGestureFloatingPreviewTextColor);
        final float textX = rectX + hPad + textWidth / 2.0f;
        final float textY = rectY + vPad + textHeight;
        canvas.drawText(gestureFloatingPreviewText, textX, textY, paint);
    }
}