// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package org.chromium.chromoting;

import android.accounts.Account;
import android.accounts.AccountManager;
import android.accounts.AccountManagerCallback;
import android.accounts.AccountManagerFuture;
import android.accounts.AuthenticatorException;
import android.accounts.OperationCanceledException;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.text.Html;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import android.widget.ListView;
import android.widget.Toast;

import org.chromium.chromoting.jni.JniInterface;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Scanner;

/**
 * The user interface for querying and displaying a user's host list from the directory server. It
 * also requests and renews authentication tokens using the system account manager.
 */
public class Chromoting extends Activity {
    /** Only accounts of this type will be selectable for authentication. */
    private static final String ACCOUNT_TYPE = "com.google";

    /** Scopes at which the authentication token we request will be valid. */
    private static final String TOKEN_SCOPE = "oauth2:https://www.googleapis.com/auth/chromoting " +
            "https://www.googleapis.com/auth/googletalk";

    /** Path from which to download a user's host list JSON object. */
    private static final String HOST_LIST_PATH =
            "https://www.googleapis.com/chromoting/v1/@me/hosts?key=";

    /** Color to use for hosts that are online. */
    private static final String HOST_COLOR_ONLINE = "green";

    /** Color to use for hosts that are offline. */
    private static final String HOST_COLOR_OFFLINE = "red";

    /** User's account details. */
    private Account mAccount;

    /** Account auth token. */
    private String mToken;

    /** List of hosts. */
    private JSONArray mHosts;

    /** Account switcher. */
    private MenuItem mAccountSwitcher;

    /** Greeting at the top of the displayed list. */
    private TextView mGreeting;

    /** Host list as it appears to the user. */
    private ListView mList;

    /** Callback handler to be used for network operations. */
    private Handler mNetwork;

    /**
     * Called when the activity is first created. Loads the native library and requests an
     * authentication token from the system.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Get ahold of our view widgets.
        mGreeting = (TextView)findViewById(R.id.hostList_greeting);
        mList = (ListView)findViewById(R.id.hostList_chooser);

        // Bring native components online.
        JniInterface.loadLibrary(this);

        // Thread responsible for downloading/displaying host list.
        HandlerThread thread = new HandlerThread("auth_callback");
        thread.start();
        mNetwork = new Handler(thread.getLooper());

        SharedPreferences prefs = getPreferences(MODE_PRIVATE);
        if (prefs.contains("account_name") && prefs.contains("account_type")) {
            // Perform authentication using saved account selection.
            mAccount = new Account(prefs.getString("account_name", null),
                    prefs.getString("account_type", null));
            AccountManager.get(this).getAuthToken(mAccount, TOKEN_SCOPE, null, this,
                    new HostListDirectoryGrabber(this), mNetwork);
            if (mAccountSwitcher != null) {
                mAccountSwitcher.setTitle(mAccount.name);
            }
        } else {
            // Request auth callback once user has chosen an account.
            Log.i("auth", "Requesting auth token from system");
            AccountManager.get(this).getAuthTokenByFeatures(
                    ACCOUNT_TYPE,
                    TOKEN_SCOPE,
                    null,
                    this,
                    null,
                    null,
                    new HostListDirectoryGrabber(this),
                    mNetwork
                );
        }
    }

    /** Called when the activity is finally finished. */
    @Override
    public void onDestroy() {
        super.onDestroy();
        JniInterface.disconnectFromHost();
    }

    /** Called to initialize the action bar. */
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.chromoting_actionbar, menu);
        mAccountSwitcher = menu.findItem(R.id.actionbar_accountswitcher);
        if (mAccount != null) {
            mAccountSwitcher.setTitle(mAccount.name);
        }

        return super.onCreateOptionsMenu(menu);
    }

    /** Called whenever an action bar button is pressed. */
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // The only button is the account switcher, so defer to the android accounts system now.
        AccountManager.get(this).getAuthTokenByFeatures(
                ACCOUNT_TYPE,
                TOKEN_SCOPE,
                null,
                this,
                null,
                null,
                new HostListDirectoryGrabber(this),
                mNetwork
            );
        return true;
    }

    /**
     * Processes the authentication token once the system provides it. Once in possession of such a
     * token, attempts to request a host list from the directory server. In case of a bad response,
     * this is retried once in case the system's cached auth token had expired.
     */
    private class HostListDirectoryGrabber implements AccountManagerCallback<Bundle> {
        /** Whether authentication has already been attempted. */
        private boolean mAlreadyTried;

        /** Communication with the screen. */
        private Activity mUi;

        /** Constructor. */
        public HostListDirectoryGrabber(Activity ui) {
            mAlreadyTried = false;
            mUi = ui;
        }

        /**
         * Retrieves the host list from the directory server. This method performs
         * network operations and must be run an a non-UI thread.
         */
        @Override
        public void run(AccountManagerFuture<Bundle> future) {
            Log.i("auth", "User finished with auth dialogs");
            try {
                // Here comes our auth token from the Android system.
                Bundle result = future.getResult();
                String accountName = result.getString(AccountManager.KEY_ACCOUNT_NAME);
                String accountType = result.getString(AccountManager.KEY_ACCOUNT_TYPE);
                String authToken = result.getString(AccountManager.KEY_AUTHTOKEN);
                Log.i("auth", "Received an auth token from system");

                synchronized (mUi) {
                    mAccount = new Account(accountName, accountType);
                    mToken = authToken;
                    getPreferences(MODE_PRIVATE).edit().putString("account_name", accountName).
                            putString("account_type", accountType).apply();
                }

                // Send our HTTP request to the directory server.
                URLConnection link =
                        new URL(HOST_LIST_PATH + JniInterface.getApiKey()).openConnection();
                link.addRequestProperty("client_id", JniInterface.getClientId());
                link.addRequestProperty("client_secret", JniInterface.getClientSecret());
                link.setRequestProperty("Authorization", "OAuth " + authToken);

                // Listen for the server to respond.
                StringBuilder response = new StringBuilder();
                Scanner incoming = new Scanner(link.getInputStream());
                Log.i("auth", "Successfully authenticated to directory server");
                while (incoming.hasNext()) {
                    response.append(incoming.nextLine());
                }
                incoming.close();

                // Interpret what the directory server told us.
                JSONObject data = new JSONObject(String.valueOf(response)).getJSONObject("data");
                mHosts = data.getJSONArray("items");
                Log.i("hostlist", "Received host listing from directory server");
            } catch (RuntimeException ex) {
                // Make sure any other failure is reported to the user (as an unknown error).
                throw ex;
            } catch (Exception ex) {
                // Assemble error message to display to the user.
                String explanation = getString(R.string.error_unknown);
                if (ex instanceof OperationCanceledException) {
                    explanation = getString(R.string.error_auth_canceled);
                } else if (ex instanceof AuthenticatorException) {
                    explanation = getString(R.string.error_no_accounts);
                } else if (ex instanceof IOException) {
                    if (!mAlreadyTried) {  // This was our first connection attempt.
                        Log.w("auth", "Unable to authenticate with (expired?) token");

                        // Ask system to renew the auth token in case it expired.
                        AccountManager authenticator = AccountManager.get(mUi);
                        synchronized (mUi) {
                            authenticator.invalidateAuthToken(mAccount.type, mToken);
                            mToken = null;
                            Log.i("auth", "Requesting auth token renewal");
                            authenticator.getAuthToken(
                                    mAccount, TOKEN_SCOPE, null, mUi, this, mNetwork);
                        }

                        // We're not in an error state *yet*.
                        mAlreadyTried = true;
                        return;
                    } else {  // Authentication truly failed.
                        Log.e("auth", "Fresh auth token was also rejected");
                        explanation = getString(R.string.error_auth_failed);
                    }
                } else if (ex instanceof JSONException) {
                    explanation = getString(R.string.error_unexpected_response);
                    runOnUiThread(new HostListDisplayer(mUi));
                }

                mHosts = null;
                Log.w("auth", ex);
                Toast.makeText(mUi, explanation, Toast.LENGTH_LONG).show();
            }

            // Share our findings with the user.
            runOnUiThread(new HostListDisplayer(mUi));
        }
    }

    /** Formats the host list and offers it to the user. */
    private class HostListDisplayer implements Runnable {
        /** Communication with the screen. */
        private Activity mUi;

        /** Constructor. */
        public HostListDisplayer(Activity ui) {
            mUi = ui;
        }

        /**
         * Updates the infotext and host list display.
         * This method affects the UI and must be run on its same thread.
         */
        @Override
        public void run() {
            synchronized (mUi) {
                mAccountSwitcher.setTitle(mAccount.name);
            }

            if (mHosts == null) {
                mGreeting.setText(getString(R.string.inst_empty_list));
                mList.setAdapter(null);
                return;
            }

            mGreeting.setText(getString(R.string.inst_host_list));

            ArrayAdapter<JSONObject> displayer = new HostListAdapter(mUi, R.layout.host);
            Log.i("hostlist", "About to populate host list display");
            try {
                int index = 0;
                while (!mHosts.isNull(index)) {
                    displayer.add(mHosts.getJSONObject(index));
                    ++index;
                }
                mList.setAdapter(displayer);
            }
            catch(JSONException ex) {
                Log.w("hostlist", ex);
                Toast.makeText(
                        mUi, getString(R.string.error_cataloging_hosts), Toast.LENGTH_LONG).show();

                // Close the application.
                finish();
            }
        }
    }

    /** Describes the appearance and behavior of each host list entry. */
    private class HostListAdapter extends ArrayAdapter<JSONObject> {
        /** Constructor. */
        public HostListAdapter(Context context, int textViewResourceId) {
            super(context, textViewResourceId);
        }

        /** Generates a View corresponding to this particular host. */
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            TextView target = (TextView)super.getView(position, convertView, parent);

            try {
                final JSONObject host = getItem(position);
                target.setText(Html.fromHtml(host.getString("hostName") + " (<font color = \"" +
                        (host.getString("status").equals("ONLINE") ? HOST_COLOR_ONLINE :
                        HOST_COLOR_OFFLINE) + "\">" + host.getString("status") + "</font>)"));

                if (host.getString("status").equals("ONLINE")) {  // Host is online.
                    target.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View v) {
                                try {
                                    synchronized (getContext()) {
                                        JniInterface.connectToHost(mAccount.name, mToken,
                                                host.getString("jabberId"),
                                                host.getString("hostId"),
                                                host.getString("publicKey"),
                                                new Runnable() {
                                            @Override
                                            public void run() {
                                                startActivity(
                                                        new Intent(getContext(), Desktop.class));
                                            }
                                        });
                                    }
                                }
                                catch(JSONException ex) {
                                    Log.w("host", ex);
                                    Toast.makeText(getContext(),
                                            getString(R.string.error_reading_host),
                                            Toast.LENGTH_LONG).show();

                                    // Close the application.
                                    finish();
                                }
                            }
                        });
                } else {  // Host is offline.
                    // Disallow interaction with this entry.
                    target.setEnabled(false);
                }
            }
            catch(JSONException ex) {
                Log.w("hostlist", ex);
                Toast.makeText(getContext(),
                        getString(R.string.error_displaying_host),
                        Toast.LENGTH_LONG).show();

                // Close the application.
                finish();
            }

            return target;
        }
    }
}