/* 
 * Copyright (C) 2008 ZXing authors
 * Copyright 2011 Robert Theis
 * Copyright 2015 Jakub Kříž
 *
 * 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 cz.muni.fi.digitrecognition;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;


/**
 * Activity to display informational pages to the user in a WebView.
 * 
 * The code for this class was adapted from the ZXing project: http://code.google.com/p/zxing
 */
public final class HelpActivity extends Activity {

  private static final String TAG = HelpActivity.class.getSimpleName();

  // Use this key and one of the values below when launching this activity via intent. If not
  // present, the default page will be loaded.

  private static final String BASE_URL = "file:///android_asset/html/about.html";
  private static final String WEBVIEW_STATE_PRESENT = "webview_state_present";

  private WebView webView;

  private final Button.OnClickListener doneListener = new Button.OnClickListener() {
    @Override
    public void onClick(View view) {
      finish();
    }
  };

  @Override
  protected void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.help);

    webView = (WebView)findViewById(R.id.help_contents);
    webView.setWebViewClient(new HelpClient(this));

    // Show an OK button.
    View doneButton = findViewById(R.id.done_button);
    doneButton.setOnClickListener(doneListener);


    // Froyo has a bug with calling onCreate() twice in a row, which causes the What's New page
    // that's auto-loaded on first run to appear blank. As a workaround we only call restoreState()
    // if a valid URL was loaded at the time the previous activity was torn down.
    if (icicle != null && icicle.getBoolean(WEBVIEW_STATE_PRESENT, false)) {
        webView.restoreState(icicle);
    } else {
        webView.loadUrl(BASE_URL);
    }
  }


  @Override
  public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
      if (webView.canGoBack()) {
        webView.goBack();
        return true;
      }
    }
    return super.onKeyDown(keyCode, event);
  }

  private final class HelpClient extends WebViewClient {
    Activity context;
    public HelpClient(Activity context){
        this.context = context;
    }

    @Override
    public void onPageFinished(WebView view, String url) {
      setTitle(view.getTitle());
    }

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        // Open external URLs in Browser.
        startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
        return true;
    }
  }
}