/*
 * Copyright (C) 2016 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.setupwizardlib.view;

import android.content.Context;
import android.text.Annotation;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.method.MovementMethod;
import android.text.style.ClickableSpan;
import android.text.style.TextAppearanceSpan;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.TextView;
import com.android.setupwizardlib.span.LinkSpan;
import com.android.setupwizardlib.span.LinkSpan.OnLinkClickListener;
import com.android.setupwizardlib.span.SpanHelper;
import com.android.setupwizardlib.view.TouchableMovementMethod.TouchableLinkMovementMethod;

/**
 * An extension of TextView that automatically replaces the annotation tags as specified in {@link
 * SpanHelper#replaceSpan(android.text.Spannable, Object, Object)}
 *
 * <p>Note: The accessibility interaction for ClickableSpans (and therefore LinkSpans) are built
 * into platform in O, although the interaction paradigm is different. (See b/17726921). In this
 * platform version, the links are exposed in the Local Context Menu of TalkBack instead of
 * accessible directly through swiping.
 */
public class RichTextView extends TextView implements OnLinkClickListener {

  /* static section */

  private static final String TAG = "RichTextView";

  private static final String ANNOTATION_LINK = "link";
  private static final String ANNOTATION_TEXT_APPEARANCE = "textAppearance";

  /**
   * Replace &lt;annotation&gt; tags in strings to become their respective types. Currently 2 types
   * are supported:
   *
   * <ol>
   *   <li>&lt;annotation link="foobar"&gt; will create a {@link
   *       com.android.setupwizardlib.span.LinkSpan} that broadcasts with the key "foobar"
   *   <li>&lt;annotation textAppearance="TextAppearance.FooBar"&gt; will create a {@link
   *       android.text.style.TextAppearanceSpan} with @style/TextAppearance.FooBar
   * </ol>
   */
  public static CharSequence getRichText(Context context, CharSequence text) {
    if (text instanceof Spanned) {
      final SpannableString spannable = new SpannableString(text);
      final Annotation[] spans = spannable.getSpans(0, spannable.length(), Annotation.class);
      for (Annotation span : spans) {
        final String key = span.getKey();
        if (ANNOTATION_TEXT_APPEARANCE.equals(key)) {
          String textAppearance = span.getValue();
          final int style =
              context
                  .getResources()
                  .getIdentifier(textAppearance, "style", context.getPackageName());
          if (style == 0) {
            Log.w(TAG, "Cannot find resource: " + style);
          }
          final TextAppearanceSpan textAppearanceSpan = new TextAppearanceSpan(context, style);
          SpanHelper.replaceSpan(spannable, span, textAppearanceSpan);
        } else if (ANNOTATION_LINK.equals(key)) {
          LinkSpan link = new LinkSpan(span.getValue());
          SpanHelper.replaceSpan(spannable, span, link);
        }
      }
      return spannable;
    }
    return text;
  }

  /* non-static section */

  private OnLinkClickListener mOnLinkClickListener;

  public RichTextView(Context context) {
    super(context);
  }

  public RichTextView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  @Override
  public void setText(CharSequence text, BufferType type) {
    text = getRichText(getContext(), text);
    // Set text first before doing anything else because setMovementMethod internally calls
    // setText. This in turn ends up calling this method with mText as the first parameter
    super.setText(text, type);
    boolean hasLinks = hasLinks(text);

    if (hasLinks) {
      // When a TextView has a movement method, it will set the view to clickable. This makes
      // View.onTouchEvent always return true and consumes the touch event, essentially
      // nullifying any return values of MovementMethod.onTouchEvent.
      // To still allow propagating touch events to the parent when this view doesn't have
      // links, we only set the movement method here if the text contains links.
      setMovementMethod(TouchableLinkMovementMethod.getInstance());
    } else {
      setMovementMethod(null);
    }
    // ExploreByTouchHelper automatically enables focus for RichTextView
    // even though it may not have any links. Causes problems during talkback
    // as individual TextViews consume touch events and thereby reducing the focus window
    // shown by Talkback. Disable focus if there are no links
    setFocusable(hasLinks);
    // Do not "reveal" (i.e. scroll to) this view when this view is focused. Since this view is
    // focusable in touch mode, we may be focused when the screen is first shown, and starting
    // a screen halfway scrolled down is confusing to the user.
    setRevealOnFocusHint(false);
    setFocusableInTouchMode(hasLinks);
  }

  private boolean hasLinks(CharSequence text) {
    if (text instanceof Spanned) {
      final ClickableSpan[] spans =
          ((Spanned) text).getSpans(0, text.length(), ClickableSpan.class);
      return spans.length > 0;
    }
    return false;
  }

  @Override
  @SuppressWarnings("ClickableViewAccessibility") // super.onTouchEvent is called
  public boolean onTouchEvent(MotionEvent event) {
    // Since View#onTouchEvent always return true if the view is clickable (which is the case
    // when a TextView has a movement method), override the implementation to allow the movement
    // method, if it implements TouchableMovementMethod, to say that the touch is not handled,
    // allowing the event to bubble up to the parent view.
    boolean superResult = super.onTouchEvent(event);
    MovementMethod movementMethod = getMovementMethod();
    if (movementMethod instanceof TouchableMovementMethod) {
      TouchableMovementMethod touchableMovementMethod = (TouchableMovementMethod) movementMethod;
      if (touchableMovementMethod.getLastTouchEvent() == event) {
        return touchableMovementMethod.isLastTouchEventHandled();
      }
    }
    return superResult;
  }

  public void setOnLinkClickListener(OnLinkClickListener listener) {
    mOnLinkClickListener = listener;
  }

  public OnLinkClickListener getOnLinkClickListener() {
    return mOnLinkClickListener;
  }

  @Override
  public boolean onLinkClick(LinkSpan span) {
    if (mOnLinkClickListener != null) {
      return mOnLinkClickListener.onLinkClick(span);
    }
    return false;
  }
}