/*
 * Copyright (C) 2009 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.systemui;

import java.io.IOException;

import android.app.WallpaperManager;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.Region.Op;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.service.wallpaper.WallpaperService;
import android.util.Log;
import android.util.Slog;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.content.Context;
import android.content.IntentFilter;
import android.content.Intent;
import android.content.BroadcastReceiver;

/**
 * Default built-in wallpaper that simply shows a static image.
 */
public class ImageWallpaper extends WallpaperService {
    private static final String TAG = "ImageWallpaper";
    private static final boolean DEBUG = false;

    static final boolean FIXED_SIZED_SURFACE = true;

    WallpaperManager mWallpaperManager;
    private Handler mHandler;

    @Override
    public void onCreate() {
        super.onCreate();
        mWallpaperManager = (WallpaperManager) getSystemService(WALLPAPER_SERVICE);
        mHandler = new Handler();
    }

    public Engine onCreateEngine() {
        return new DrawableEngine();
    }

    class DrawableEngine extends Engine {
        private final Object mLock = new Object();
        private WallpaperObserver mReceiver;
        Drawable mBackground;
        int mBackgroundWidth = -1, mBackgroundHeight = -1;
        float mXOffset;
        float mYOffset;

        boolean mVisible = true;
        boolean mRedrawNeeded;
        boolean mOffsetsChanged;
        int mLastXTranslation;
        int mLastYTranslation;

        class WallpaperObserver extends BroadcastReceiver {
            public void onReceive(Context context, Intent intent) {
                if (DEBUG) {
                    Log.d(TAG, "onReceive");
                }

                synchronized (mLock) {
                    mBackgroundWidth = mBackgroundHeight = -1;
                    mBackground = null;
                    mRedrawNeeded = true;
                    drawFrameLocked();
                }
            }
        }

        @Override
        public void onCreate(SurfaceHolder surfaceHolder) {
            if (DEBUG) {
                Log.d(TAG, "onCreate");
            }

            super.onCreate(surfaceHolder);
            IntentFilter filter = new IntentFilter(Intent.ACTION_WALLPAPER_CHANGED);
            mReceiver = new WallpaperObserver();
            registerReceiver(mReceiver, filter, null, mHandler);

            updateSurfaceSize(surfaceHolder);
        }

        @Override
        public void onDestroy() {
            super.onDestroy();
            unregisterReceiver(mReceiver);
        }

        @Override
        public void onDesiredSizeChanged(int desiredWidth, int desiredHeight) {
            super.onDesiredSizeChanged(desiredWidth, desiredHeight);
            SurfaceHolder surfaceHolder = getSurfaceHolder();
            if (surfaceHolder != null) {
                updateSurfaceSize(surfaceHolder);
            }
        }

        void updateSurfaceSize(SurfaceHolder surfaceHolder) {
            if (FIXED_SIZED_SURFACE) {
                // Used a fixed size surface, because we are special.  We can do
                // this because we know the current design of window animations doesn't
                // cause this to break.
                surfaceHolder.setFixedSize(getDesiredMinimumWidth(), getDesiredMinimumHeight());
            } else {
                surfaceHolder.setSizeFromLayout();
            }
        }

        @Override
        public void onVisibilityChanged(boolean visible) {
            if (DEBUG) {
                Log.d(TAG, "onVisibilityChanged: visible=" + visible);
            }

            synchronized (mLock) {
                if (mVisible != visible) {
                    if (DEBUG) {
                        Log.d(TAG, "Visibility changed to visible=" + visible);
                    }
                    mVisible = visible;
                    drawFrameLocked();
                }
            }
        }

        @Override
        public void onTouchEvent(MotionEvent event) {
            super.onTouchEvent(event);
        }

        @Override
        public void onOffsetsChanged(float xOffset, float yOffset,
                float xOffsetStep, float yOffsetStep,
                int xPixels, int yPixels) {
            if (DEBUG) {
                Log.d(TAG, "onOffsetsChanged: xOffset=" + xOffset + ", yOffset=" + yOffset
                        + ", xOffsetStep=" + xOffsetStep + ", yOffsetStep=" + yOffsetStep
                        + ", xPixels=" + xPixels + ", yPixels=" + yPixels);
            }

            synchronized (mLock) {
                if (mXOffset != xOffset || mYOffset != yOffset) {
                    if (DEBUG) {
                        Log.d(TAG, "Offsets changed to (" + xOffset + "," + yOffset + ").");
                    }
                    mXOffset = xOffset;
                    mYOffset = yOffset;
                    mOffsetsChanged = true;
                }
                drawFrameLocked();
            }
        }

        @Override
        public void onSurfaceChanged(SurfaceHolder holder, int format, int width, int height) {
            if (DEBUG) {
                Log.d(TAG, "onSurfaceChanged: width=" + width + ", height=" + height);
            }

            super.onSurfaceChanged(holder, format, width, height);

            synchronized (mLock) {
                mRedrawNeeded = true;
                drawFrameLocked();
            }
        }

        void drawFrameLocked() {
            if (!mVisible) {
                if (DEBUG) {
                    Log.d(TAG, "Suppressed drawFrame since wallpaper is not visible.");
                }
                return;
            }
            if (!mRedrawNeeded && !mOffsetsChanged) {
                if (DEBUG) {
                    Log.d(TAG, "Suppressed drawFrame since redraw is not needed "
                            + "and offsets have not changed.");
                }
                return;
            }

            if (mBackgroundWidth < 0 || mBackgroundHeight < 0) {
                // If we don't yet know the size of the wallpaper bitmap,
                // we need to get it now.
                updateWallpaperLocked();
            }

            SurfaceHolder sh = getSurfaceHolder();
            final Rect frame = sh.getSurfaceFrame();
            final int dw = frame.width();
            final int dh = frame.height();
            final int availw = dw - mBackgroundWidth;
            final int availh = dh - mBackgroundHeight;
            int xPixels = availw < 0 ? (int)(availw * mXOffset + .5f) : (availw / 2);
            int yPixels = availh < 0 ? (int)(availh * mYOffset + .5f) : (availh / 2);

            mOffsetsChanged = false;
            if (!mRedrawNeeded
                    && xPixels == mLastXTranslation && yPixels == mLastYTranslation) {
                if (DEBUG) {
                    Log.d(TAG, "Suppressed drawFrame since the image has not "
                            + "actually moved an integral number of pixels.");
                }
                return;
            }
            mRedrawNeeded = false;
            mLastXTranslation = xPixels;
            mLastYTranslation = yPixels;

            if (mBackground == null) {
                // If we somehow got to this point after we have last flushed
                // the wallpaper, well we really need it to draw again.  So
                // seems like we need to reload it.  Ouch.
                updateWallpaperLocked();
            }

            //Slog.i(TAG, "************** DRAWING WALLAPER ******************");
            Canvas c = sh.lockCanvas();
            if (c != null) {
                try {
                    if (DEBUG) {
                        Log.d(TAG, "Redrawing: xPixels=" + xPixels + ", yPixels=" + yPixels);
                    }

                    c.translate(xPixels, yPixels);
                    if (availw < 0 || availh < 0) {
                        c.save(Canvas.CLIP_SAVE_FLAG);
                        c.clipRect(0, 0, mBackgroundWidth, mBackgroundHeight, Op.DIFFERENCE);
                        c.drawColor(0xff000000);
                        c.restore();
                    }
                    if (mBackground != null) {
                        mBackground.draw(c);
                    }
                } finally {
                    sh.unlockCanvasAndPost(c);
                }
            }

            if (FIXED_SIZED_SURFACE) {
                // If the surface is fixed-size, we should only need to
                // draw it once and then we'll let the window manager
                // position it appropriately.  As such, we no longer needed
                // the loaded bitmap.  Yay!
                mBackground = null;
                mWallpaperManager.forgetLoadedWallpaper();
            }
        }

        void updateWallpaperLocked() {
            //Slog.i(TAG, "************** LOADING WALLAPER ******************");
            Throwable exception = null;
            try {
                mBackground = mWallpaperManager.getFastDrawable();
            } catch (RuntimeException e) {
                exception = e;
            } catch (OutOfMemoryError e) {
                exception = e;
            }
            if (exception != null) {
                mBackground = null;
                // Note that if we do fail at this, and the default wallpaper can't
                // be loaded, we will go into a cycle.  Don't do a build where the
                // default wallpaper can't be loaded.
                Log.w(TAG, "Unable to load wallpaper!", exception);
                try {
                    mWallpaperManager.clear();
                } catch (IOException ex) {
                    // now we're really screwed.
                    Log.w(TAG, "Unable reset to default wallpaper!", ex);
                }
            }
            mBackgroundWidth = mBackground != null ? mBackground.getIntrinsicWidth() : 0;
            mBackgroundHeight = mBackground != null ? mBackground.getIntrinsicHeight() : 0;
        }
    }
}