/*
 * ConnectBot: simple, powerful, open-source SSH client for Android
 * Copyright 2007 Kenny Root, Jeffrey Sharkey
 *
 * 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.five_ten_sg.connectbot;

import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.five_ten_sg.connectbot.bean.SelectionArea;
import com.five_ten_sg.connectbot.service.FontSizeChangedListener;
import com.five_ten_sg.connectbot.service.TerminalBridge;
import com.five_ten_sg.connectbot.service.TerminalKeyListener;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ResolveInfo;
import android.database.Cursor;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PixelXorXfermode;
import android.graphics.RectF;
import android.net.Uri;
import android.os.AsyncTask;
import android.view.KeyEvent;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityManager;
import android.view.inputmethod.BaseInputConnection;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.InputConnection;
import android.view.ScaleGestureDetector;
import android.widget.Toast;
import de.mud.terminal.VDUBuffer;

/**
 * User interface {@link View} for showing a TerminalBridge in an
 * {@link Activity}. Handles drawing bitmap updates and passing keystrokes down
 * to terminal.
 *
 * @author jsharkey
 */
public class TerminalView extends View implements FontSizeChangedListener {

    private final Context context;
    public  final TerminalBridge bridge;
    private final Paint paint;
    private final Paint cursorPaint;
    private final Paint cursorStrokePaint;

    // Cursor paints to distinguish modes
    private Path ctrlCursor, altCursor, shiftCursor;
    private RectF tempSrc, tempDst;
    private Matrix scaleMatrix;
    private static final Matrix.ScaleToFit scaleType = Matrix.ScaleToFit.FILL;

    private Toast notification = null;
    private String lastNotification = null;
    private volatile boolean notifications = true;

    // Related to Accessibility Features
    private boolean mAccessibilityInitialized = false;
    private boolean mAccessibilityActive = true;
    private Object[] mAccessibilityLock = new Object[0];
    private StringBuffer mAccessibilityBuffer;
    private Pattern mControlCodes = null;
    private Matcher mCodeMatcher = null;
    private AccessibilityEventSender mEventSender = null;


    private static final String BACKSPACE_CODE = "\\x08\\x1b\\[K";
    private static final String CONTROL_CODE_PATTERN = "\\x1b\\[K[^m]+[m|:]";

    private static final int ACCESSIBILITY_EVENT_THRESHOLD = 1000;
    private static final String SCREENREADER_INTENT_ACTION = "android.accessibilityservice.AccessibilityService";
    private static final String SCREENREADER_INTENT_CATEGORY = "android.accessibilityservice.category.FEEDBACK_SPOKEN";

    public ScaleGestureDetector mScaleDetector;

    public TerminalView(Context context, TerminalBridge bridge) {
        super(context);
        this.context       = context;
        this.bridge        = bridge;
        paint = new Paint();
        setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
        setFocusable(true);
        setFocusableInTouchMode(true);
        cursorPaint = new Paint();
        cursorPaint.setColor(bridge.color[bridge.defaultFg]);
        cursorPaint.setXfermode(new PixelXorXfermode(bridge.color[bridge.defaultBg]));
        cursorPaint.setAntiAlias(true);
        cursorStrokePaint = new Paint(cursorPaint);
        cursorStrokePaint.setStrokeWidth(0.1f);
        cursorStrokePaint.setStyle(Paint.Style.STROKE);
        /*
         * Set up our cursor indicators on a 1x1 Path object which we can later
         * transform to our character width and height
         */
        // TODO make this into a resource somehow
        shiftCursor = new Path();
        shiftCursor.lineTo(0.5f, 0.33f);
        shiftCursor.lineTo(1.0f, 0.0f);
        altCursor = new Path();
        altCursor.moveTo(0.0f, 1.0f);
        altCursor.lineTo(0.5f, 0.66f);
        altCursor.lineTo(1.0f, 1.0f);
        ctrlCursor = new Path();
        ctrlCursor.moveTo(0.0f, 0.25f);
        ctrlCursor.lineTo(1.0f, 0.5f);
        ctrlCursor.lineTo(0.0f, 0.75f);
        // For creating the transform when the terminal resizes
        tempSrc = new RectF();
        tempSrc.set(0.0f, 0.0f, 1.0f, 1.0f);
        tempDst = new RectF();
        scaleMatrix = new Matrix();
        bridge.addFontSizeChangedListener(this);
        // connect our view up to the bridge
        setOnKeyListener(bridge.getKeyHandler());
        mAccessibilityBuffer = new StringBuffer();
        // Enable accessibility features if a screen reader is active.
        new AccessibilityStateTester().execute((Void) null);
        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
    }

    public void destroy() {
        // tell bridge to destroy its bitmap
        bridge.parentDestroyed();
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        bridge.parentChanged(this);
        scaleCursors();
    }

    public void onFontSizeChanged(float size) {
        scaleCursors();
    }

    private void scaleCursors() {
        // Create a scale matrix to scale our 1x1 representation of the cursor
        tempDst.set(0.0f, 0.0f, bridge.charWidth, bridge.charHeight);
        scaleMatrix.setRectToRect(tempSrc, tempDst, scaleType);
    }

    @Override
    public void onDraw(Canvas canvas) {
        if (bridge.bitmap != null) {
            // draw the bitmap
            bridge.onDraw();
            // draw the bridge bitmap if it exists
            canvas.drawBitmap(bridge.bitmap, 0, 0, paint);

            // also draw cursor if visible
            if (bridge.buffer.isCursorVisible()) {
                int cursorColumn = bridge.buffer.getCursorColumn();
                final int cursorRow = bridge.buffer.getCursorRow();
                final int columns = bridge.buffer.getColumns();

                if (cursorColumn == columns)
                    cursorColumn = columns - 1;

                if (cursorColumn < 0 || cursorRow < 0)
                    return;

                int currentAttribute = bridge.buffer.getAttributes(
                                           cursorColumn, cursorRow);
                boolean onWideCharacter = (currentAttribute & VDUBuffer.FULLWIDTH) != 0;
                int x = cursorColumn * bridge.charWidth;
                int y = (bridge.buffer.getCursorRow()
                         + bridge.buffer.screenBase - bridge.buffer.windowBase)
                        * bridge.charHeight;
                // Save the current clip and translation
                canvas.save();
                canvas.translate(x, y);
                canvas.clipRect(0, 0,
                                bridge.charWidth * (onWideCharacter ? 2 : 1),
                                bridge.charHeight);
                canvas.drawPaint(cursorPaint);
                final int deadKey = bridge.getKeyHandler().getDeadKey();

                if (deadKey != 0) {
                    canvas.drawText(new char[] { (char)deadKey }, 0, 1, 0, 0, cursorStrokePaint);
                }

                // Make sure we scale our decorations to the correct size.
                canvas.concat(scaleMatrix);
                int metaState = bridge.getKeyHandler().getMetaState();

                if ((metaState & TerminalKeyListener.META_SHIFT_ON) != 0)
                    canvas.drawPath(shiftCursor, cursorStrokePaint);
                else if ((metaState & TerminalKeyListener.META_SHIFT_LOCK) != 0)
                    canvas.drawPath(shiftCursor, cursorPaint);

                if ((metaState & TerminalKeyListener.META_ALT_ON) != 0)
                    canvas.drawPath(altCursor, cursorStrokePaint);
                else if ((metaState & TerminalKeyListener.META_ALT_LOCK) != 0)
                    canvas.drawPath(altCursor, cursorPaint);

                if ((metaState & TerminalKeyListener.META_CTRL_ON) != 0)
                    canvas.drawPath(ctrlCursor, cursorStrokePaint);
                else if ((metaState & TerminalKeyListener.META_CTRL_LOCK) != 0)
                    canvas.drawPath(ctrlCursor, cursorPaint);

                // Restore previous clip region
                canvas.restore();
            }

            // draw any highlighted area
            if (bridge.isSelectingForCopy()) {
                SelectionArea area = bridge.getSelectionArea();
                canvas.save(Canvas.CLIP_SAVE_FLAG);
                canvas.clipRect(
                    area.getLeft() * bridge.charWidth,
                    area.getTop() * bridge.charHeight,
                    (area.getRight() + 1) * bridge.charWidth,
                    (area.getBottom() + 1) * bridge.charHeight
                );
                canvas.drawPaint(cursorPaint);
                canvas.restore();
            }
        }
    }

    public void notifyUser(String message) {
        if (!notifications)
            return;

        if (notification != null) {
            // Don't keep telling the user the same thing.
            if (lastNotification != null && lastNotification.equals(message))
                return;

            notification.setText(message);
            notification.show();
        }
        else {
            notification = Toast.makeText(context, message, Toast.LENGTH_SHORT);
            notification.show();
        }

        lastNotification = message;
    }

    /**
     * Ask the {@link TerminalBridge} we're connected to to resize to a specific size.
     * @param width
     * @param height
     */
    public void forceSize(int width, int height) {
        bridge.resizeComputed(width, height, getWidth(), getHeight());
    }

    /**
     * Sets the ability for the TerminalView to display Toast notifications to the user.
     * @param value whether to enable notifications or not
     */
    public void setNotifications(boolean value) {
        notifications = value;
    }

    @Override
    public boolean onCheckIsTextEditor() {
        return true;
    }

    @Override
    public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
        outAttrs.imeOptions |=
            EditorInfo.IME_FLAG_NO_EXTRACT_UI |
            EditorInfo.IME_FLAG_NO_ENTER_ACTION |
            EditorInfo.IME_ACTION_NONE;
        outAttrs.inputType = EditorInfo.TYPE_NULL;
        return new BaseInputConnection(this, false) {
            @Override
            public boolean deleteSurroundingText(int leftLength, int rightLength) {
                if (rightLength == 0 && leftLength == 0) {
                    return this.sendKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_DEL));
                }

                for (int i = 0; i < leftLength; i++) {
                    this.sendKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_DEL));
                }

                // TODO: forward delete
                return true;
            }
        };
    }

    public void propagateConsoleText(char[] rawText, int length) {
        if (mAccessibilityActive) {
            synchronized (mAccessibilityLock) {
                mAccessibilityBuffer.append(rawText, 0, length);
            }

            if (mAccessibilityInitialized) {
                if (mEventSender != null) {
                    removeCallbacks(mEventSender);
                }
                else {
                    mEventSender = new AccessibilityEventSender();
                }

                postDelayed(mEventSender, ACCESSIBILITY_EVENT_THRESHOLD);
            }
        }
    }

    private class AccessibilityEventSender implements Runnable {
        public void run() {
            synchronized (mAccessibilityLock) {
                if (mCodeMatcher == null) {
                    mCodeMatcher = mControlCodes.matcher(mAccessibilityBuffer);
                }
                else {
                    mCodeMatcher.reset(mAccessibilityBuffer);
                }

                // Strip all control codes out.
                mAccessibilityBuffer = new StringBuffer(mCodeMatcher.replaceAll(" "));
                // Apply Backspaces using backspace character sequence
                int i = mAccessibilityBuffer.indexOf(BACKSPACE_CODE);

                while (i != -1) {
                    mAccessibilityBuffer = mAccessibilityBuffer.replace(i == 0 ? 0 : i - 1, i
                                           + BACKSPACE_CODE.length(), "");
                    i = mAccessibilityBuffer.indexOf(BACKSPACE_CODE);
                }

                if (mAccessibilityBuffer.length() > 0) {
                    AccessibilityEvent event = AccessibilityEvent.obtain(
                                                   AccessibilityEvent.TYPE_VIEW_TEXT_CHANGED);
                    event.setFromIndex(0);
                    event.setAddedCount(mAccessibilityBuffer.length());
                    event.getText().add(mAccessibilityBuffer);
                    sendAccessibilityEventUnchecked(event);
                    mAccessibilityBuffer.setLength(0);
                }
            }
        }
    }

    private class AccessibilityStateTester extends AsyncTask<Void, Void, Boolean> {
        @Override
        protected Boolean doInBackground(Void... params) {
            /*
             * Presumably if the accessibility manager is not enabled, we don't
             * need to send accessibility events.
             */
            final AccessibilityManager accessibility = (AccessibilityManager) context
                    .getSystemService(Context.ACCESSIBILITY_SERVICE);

            if (!accessibility.isEnabled()) {
                return false;
            }

            /*
             * Restrict the set of intents to only accessibility services that
             * have the category FEEDBACK_SPOKEN (aka, screen readers).
             */
            final Intent screenReaderIntent = new Intent(SCREENREADER_INTENT_ACTION);
            screenReaderIntent.addCategory(SCREENREADER_INTENT_CATEGORY);
            final ContentResolver cr = context.getContentResolver();
            final List<ResolveInfo> screenReaders = context.getPackageManager().queryIntentServices(
                    screenReaderIntent, 0);
            boolean foundScreenReader = false;
            final int N = screenReaders.size();

            for (int i = 0; i < N; i++) {
                final ResolveInfo screenReader = screenReaders.get(i);
                /*
                 * All screen readers are expected to implement a content
                 * provider that responds to:
                 * content://<nameofpackage>.providers.StatusProvider
                 */
                final Cursor cursor = cr.query(
                                          Uri.parse("content://" + screenReader.serviceInfo.packageName
                                                    + ".providers.StatusProvider"), null, null, null, null);

                if (cursor != null && cursor.moveToFirst()) {
                    /*
                     * These content providers use a special cursor that only has
                     * one element, an integer that is 1 if the screen reader is
                     * running.
                     */
                    final int status = cursor.getInt(0);
                    cursor.close();

                    if (status == 1) {
                        foundScreenReader = true;
                        break;
                    }
                }
            }

            if (foundScreenReader) {
                mControlCodes = Pattern.compile(CONTROL_CODE_PATTERN);
            }

            return foundScreenReader;
        }

        @Override
        protected void onPostExecute(Boolean result) {
            mAccessibilityActive = result;
            mAccessibilityInitialized = true;

            if (result) {
                mEventSender = new AccessibilityEventSender();
                postDelayed(mEventSender, ACCESSIBILITY_EVENT_THRESHOLD);
            }
            else {
                mAccessibilityBuffer = null;
            }
        }
    }

    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            float mScaleFactor = detector.getScaleFactor();

            if (mScaleFactor > 1.1) {
                bridge.increaseFontSize();
                return true;
            }
            else if (mScaleFactor < 0.9) {
                bridge.decreaseFontSize();
                return true;
            }

            return (false);
        }
    }

}