package com.example.wordbook;

/*
 * Copyright (C) 2008 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.
 */

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.SharedPreferences;

/**
 * Displays an EULA ("End User License Agreement") that the user has to accept
 * before using the application. Your application should call
 * {@link Eula#show(android.app.Activity)} in the onCreate() method of the first
 * activity. If the user accepts the EULA, it will never be shown again. If the
 * user refuses, {@link android.app.Activity#finish()} is invoked on your
 * activity.
 */
class Eula {

	private static final String PREFERENCES_EULA = "eula";
	private static final String PREFERENCE_EULA_ACCEPTED = "eula.accepted";

	/**
	 * callback to let the activity know when the user has accepted the EULA.
	 */
	interface OnEulaAgreedTo {
		/**
		 * Called when the user has accepted the EULA and the dialog closes.
		 */
		void onEulaAgreedTo();
	}

	/**
	 * Displays the EULA if necessary. This method should be called from the
	 * onCreate() method of your main Activity.
	 * 
	 * @param activity
	 *            The Activity to finish if the user rejects the EULA.
	 * @return Whether the user has agreed already.
	 */
	static boolean show(final Activity activity) {
		final SharedPreferences preferences = activity.getSharedPreferences(
				PREFERENCES_EULA, Context.MODE_PRIVATE);
		if (!preferences.getBoolean(PREFERENCE_EULA_ACCEPTED, false)) {
			final AlertDialog.Builder builder = new AlertDialog.Builder(
					activity);
			builder.setTitle(R.string.eula_title);
			builder.setCancelable(true);
			builder.setPositiveButton(R.string.eula_accept,
					new DialogInterface.OnClickListener() {
						@Override
						public void onClick(DialogInterface dialog, int which) {
							accept(preferences);
							if (activity instanceof OnEulaAgreedTo) {
								((OnEulaAgreedTo) activity).onEulaAgreedTo();
							}
						}
					});
			builder.setNegativeButton(R.string.eula_refuse,
					new DialogInterface.OnClickListener() {
						@Override
						public void onClick(DialogInterface dialog, int which) {
							refuse(activity);
						}
					});
			builder.setOnCancelListener(new DialogInterface.OnCancelListener() {
				@Override
				public void onCancel(DialogInterface dialog) {
					refuse(activity);
				}
			});
			builder.setMessage(readEula(activity));
			builder.create().show();
			return false;
		}
		return true;
	}

	private static void accept(SharedPreferences preferences) {
		preferences.edit().putBoolean(PREFERENCE_EULA_ACCEPTED, true).commit();
	}

	private static void refuse(Activity activity) {
		activity.finish();
	}

	private static CharSequence readEula(Activity activity) {
		BufferedReader in = null;
		try {
			in = new BufferedReader(new InputStreamReader(activity.getAssets()
					.open(activity.getString(R.string.eula_file)), "UTF-8"));
			String line;
			StringBuilder buffer = new StringBuilder();
			while ((line = in.readLine()) != null) {
				buffer.append(line).append('\n');
			}
			return buffer;
		} catch (IOException e) {
			e.printStackTrace();
			return "";
		} finally {
			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

}