/*
 * Copyright (C) 2010 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.browser;

import org.apache.http.Header;
import org.apache.http.HeaderIterator;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.util.EntityUtils;

import android.accounts.Account;
import android.accounts.AccountManager;
import android.accounts.AccountManagerCallback;
import android.accounts.AccountManagerFuture;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.ActivityNotFoundException;
import android.content.DialogInterface;
import android.content.DialogInterface.OnCancelListener;
import android.content.DialogInterface.OnClickListener;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.net.Uri;
import android.net.http.AndroidHttpClient;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.webkit.WebView;

import java.net.URISyntaxException;

/**
 *
 */
public class UrlHandler {

    // Use in overrideUrlLoading
    /* package */ final static String SCHEME_WTAI = "wtai://wp/";
    /* package */ final static String SCHEME_WTAI_MC = "wtai://wp/mc;";
    /* package */ final static String SCHEME_WTAI_SD = "wtai://wp/sd;";
    /* package */ final static String SCHEME_WTAI_AP = "wtai://wp/ap;";

    Controller mController;
    Activity mActivity;

    private Boolean mIsProviderPresent = null;
    private Uri mRlzUri = null;

    public UrlHandler(Controller controller) {
        mController = controller;
        mActivity = mController.getActivity();
    }

    boolean shouldOverrideUrlLoading(Tab tab, WebView view, String url) {
        if (view.isPrivateBrowsingEnabled()) {
            // Don't allow urls to leave the browser app when in
            // private browsing mode
            return false;
        }

        if (url.startsWith(SCHEME_WTAI)) {
            // wtai://wp/mc;number
            // number=string(phone-number)
            if (url.startsWith(SCHEME_WTAI_MC)) {
                Intent intent = new Intent(Intent.ACTION_VIEW,
                        Uri.parse(WebView.SCHEME_TEL +
                        url.substring(SCHEME_WTAI_MC.length())));
                mActivity.startActivity(intent);
                // before leaving BrowserActivity, close the empty child tab.
                // If a new tab is created through JavaScript open to load this
                // url, we would like to close it as we will load this url in a
                // different Activity.
                mController.closeEmptyChildTab();
                return true;
            }
            // wtai://wp/sd;dtmf
            // dtmf=string(dialstring)
            if (url.startsWith(SCHEME_WTAI_SD)) {
                // TODO: only send when there is active voice connection
                return false;
            }
            // wtai://wp/ap;number;name
            // number=string(phone-number)
            // name=string
            if (url.startsWith(SCHEME_WTAI_AP)) {
                // TODO
                return false;
            }
        }

        // The "about:" schemes are internal to the browser; don't want these to
        // be dispatched to other apps.
        if (url.startsWith("about:")) {
            return false;
        }

        // If this is a Google search, attempt to add an RLZ string
        // (if one isn't already present).
        if (rlzProviderPresent()) {
            Uri siteUri = Uri.parse(url);
            if (needsRlzString(siteUri)) {
                // Need to look up the RLZ info from a database, so do it in an
                // AsyncTask. Although we are not overriding the URL load synchronously,
                // we guarantee that we will handle this URL load after the task executes,
                // so it's safe to just return true to WebCore now to stop its own loading.
                new RLZTask(siteUri, view).execute();
                return true;
            }
        }

        // Check for service login and prompt the user for an account to use.
        if (url.startsWith("https://www.google.com/accounts/ServiceLogin?") ||
                url.startsWith("https://www.google.com/accounts/Login?")) {
            if (loginWithDeviceAccount(view, url)) {
                return true;
            }
        }

        Intent intent;
        // perform generic parsing of the URI to turn it into an Intent.
        try {
            intent = Intent.parseUri(url, Intent.URI_INTENT_SCHEME);
        } catch (URISyntaxException ex) {
            Log.w("Browser", "Bad URI " + url + ": " + ex.getMessage());
            return false;
        }

        // check whether the intent can be resolved. If not, we will see
        // whether we can download it from the Market.
        if (mActivity.getPackageManager().resolveActivity(intent, 0) == null) {
            String packagename = intent.getPackage();
            if (packagename != null) {
                intent = new Intent(Intent.ACTION_VIEW, Uri
                        .parse("market://search?q=pname:" + packagename));
                intent.addCategory(Intent.CATEGORY_BROWSABLE);
                mActivity.startActivity(intent);
                // before leaving BrowserActivity, close the empty child tab.
                // If a new tab is created through JavaScript open to load this
                // url, we would like to close it as we will load this url in a
                // different Activity.
                mController.closeEmptyChildTab();
                return true;
            } else {
                return false;
            }
        }

        // sanitize the Intent, ensuring web pages can not bypass browser
        // security (only access to BROWSABLE activities).
        intent.addCategory(Intent.CATEGORY_BROWSABLE);
        intent.setComponent(null);
        try {
            if (mActivity.startActivityIfNeeded(intent, -1)) {
                // before leaving BrowserActivity, close the empty child tab.
                // If a new tab is created through JavaScript open to load this
                // url, we would like to close it as we will load this url in a
                // different Activity.
                mController.closeEmptyChildTab();
                return true;
            }
        } catch (ActivityNotFoundException ex) {
            // ignore the error. If no application can handle the URL,
            // eg about:blank, assume the browser can handle it.
        }

        if (mController.isMenuDown()) {
            mController.openTab(tab, url, false);
            mActivity.closeOptionsMenu();
            return true;
        }
        return false;
    }

    // Url for issuing the uber token.
    private final static Uri ISSUE_AUTH_TOKEN_URL = Uri.parse(
            "https://www.google.com/accounts/IssueAuthToken?service=gaia&Session=false");
    // Url for signing into a particular service.
    private final static Uri TOKEN_AUTH_URL = Uri.parse(
            "https://www.google.com/accounts/TokenAuth");

    private class GoogleServiceLogin extends Thread implements
            AccountManagerCallback<Bundle>, OnClickListener, OnCancelListener {
        // For choosing the account.
        private final Account[] mAccounts;
        private int mCurrentAccount;  // initially 0 for the first account

        // For loading the auth token urls or the original url on error.
        private final WebView mWebView;
        private final String mUrl;

        // SID and LSID retrieval process.
        private String mSid;
        private String mLsid;
        private int mState;  // {NONE(0), SID(1), LSID(2)}

        GoogleServiceLogin(Account[] accounts, WebView view, String url) {
            mAccounts = accounts;
            mWebView = view;
            mUrl = url;
        }

        // Thread
        public void run() {
            String url = ISSUE_AUTH_TOKEN_URL.buildUpon()
                    .appendQueryParameter("SID", mSid)
                    .appendQueryParameter("LSID", mLsid)
                    .build().toString();
            // Intentionally not using Proxy.
            AndroidHttpClient client = AndroidHttpClient.newInstance(
                    mWebView.getSettings().getUserAgentString());
            HttpPost request = new HttpPost(url);

            String result = null;
            try {
                HttpResponse response = client.execute(request);
                if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
                    onCancel(null);
                    return;
                }
                HttpEntity entity = response.getEntity();
                if (entity == null) {
                    onCancel(null);
                    return;
                }
                result = EntityUtils.toString(entity, "UTF-8");
            } catch (Exception e) {
                request.abort();
                onCancel(null);
            } finally {
                client.close();
            }
            Uri parsedUri = Uri.parse(mUrl);
            String service = parsedUri.getQueryParameter("service");
            String redirect = parsedUri.getQueryParameter("continue");
            final String newUrl = TOKEN_AUTH_URL.buildUpon()
                    .appendQueryParameter("service", service)
                    .appendQueryParameter("source", "android-browser")
                    .appendQueryParameter("auth", result)
                    .appendQueryParameter("continue", redirect)
                    .build().toString();
            mActivity.runOnUiThread(new Runnable() {
                @Override public void run() {
                    mController.loadUrl(mWebView, newUrl);
                }
            });
        }

        // AccountManager callbacks.
        public void run(AccountManagerFuture<Bundle> value) {
            try {
                String id = value.getResult().getString(
                        AccountManager.KEY_AUTHTOKEN);
                switch (mState) {
                    default:
                    case 0:
                        throw new IllegalStateException(
                                "Impossible to get into this state");
                    case 1:
                        mSid = id;
                        mState = 2;  // LSID
                        AccountManager.get(mActivity).getAuthToken(
                                mAccounts[mCurrentAccount], "LSID", null,
                                mActivity, this, null);
                        break;
                    case 2:
                        mLsid = id;
                        this.start();
                        break;
                }
            } catch (Exception e) {
                // For all exceptions load the original signin page.
                // TODO: toast login failed?
                onCancel(null);
            }
        }

        // Handle picking an account and "OK."
        public void onClick(DialogInterface unused, int which) {
            if (which == DialogInterface.BUTTON_POSITIVE) {
                // TODO: toast loading...?
                Account current = mAccounts[mCurrentAccount];
                mState = 1;  // SID
                AccountManager.get(mActivity).getAuthToken(
                        mAccounts[mCurrentAccount], "SID", null,
                        mActivity, this, null);
            } else if (which == DialogInterface.BUTTON_NEGATIVE) {
                onCancel(null);
            } else {
                mCurrentAccount = which;
            }
        }

        // Handle "cancel."
        public void onCancel(DialogInterface unusued) {
            // load the original url to login manually.
            mController.loadUrl(mWebView, mUrl);
        }
    }

    private boolean loginWithDeviceAccount(WebView view, String url) {
        Uri parsedUri = Uri.parse(url);
        if ("true".equals(parsedUri.getQueryParameter("go"))) {
            return false;
        }
        Account[] accounts =
                AccountManager.get(mActivity).getAccountsByType("com.google");
        if (accounts.length == 0) {
            return false;
        }

        // Populate the account list.
        CharSequence[] names = new CharSequence[accounts.length];
        int i = 0;
        for (Account a : accounts) {
            names[i++] = a.name;
        }

        GoogleServiceLogin login = new GoogleServiceLogin(accounts, view, url);
        new AlertDialog.Builder(mActivity)
                .setTitle(R.string.account_picker_title)
                .setSingleChoiceItems(names, 0 /* first choice */, login)
                .setPositiveButton(R.string.ok, login)
                .setNegativeButton(R.string.cancel, login)
                .setCancelable(true)
                .setOnCancelListener(login)
                .show();
        return true;
    }

    private class RLZTask extends AsyncTask<Void, Void, String> {
        private Uri mSiteUri;
        private WebView mWebView;

        public RLZTask(Uri uri, WebView webView) {
            mSiteUri = uri;
            mWebView = webView;
        }

        protected String doInBackground(Void... unused) {
            String result = mSiteUri.toString();
            Cursor cur = null;
            try {
                cur = mActivity.getContentResolver()
                        .query(getRlzUri(), null, null, null, null);
                if (cur != null && cur.moveToFirst() && !cur.isNull(0)) {
                    result = mSiteUri.buildUpon()
                           .appendQueryParameter("rlz", cur.getString(0))
                           .build().toString();
                }
            } finally {
                if (cur != null) {
                    cur.close();
                }
            }
            return result;
        }

        protected void onPostExecute(String result) {
            mController.loadUrl(mWebView, result);
        }
    }

    // Determine whether the RLZ provider is present on the system.
    private boolean rlzProviderPresent() {
        if (mIsProviderPresent == null) {
            PackageManager pm = mActivity.getPackageManager();
            mIsProviderPresent = pm.resolveContentProvider(
                    BrowserSettings.RLZ_PROVIDER, 0) != null;
        }
        return mIsProviderPresent;
    }

    // Retrieve the RLZ access point string and cache the URI used to
    // retrieve RLZ values.
    private Uri getRlzUri() {
        if (mRlzUri == null) {
            String ap = mActivity.getResources()
                    .getString(R.string.rlz_access_point);
            mRlzUri = Uri.withAppendedPath(BrowserSettings.RLZ_PROVIDER_URI, ap);
        }
        return mRlzUri;
    }

    // Determine if this URI appears to be for a Google search
    // and does not have an RLZ parameter.
    // Taken largely from Chrome source, src/chrome/browser/google_url_tracker.cc
    private static boolean needsRlzString(Uri uri) {
        String scheme = uri.getScheme();
        if (("http".equals(scheme) || "https".equals(scheme)) &&
            (uri.getQueryParameter("q") != null) &&
                    (uri.getQueryParameter("rlz") == null)) {
            String host = uri.getHost();
            if (host == null) {
                return false;
            }
            String[] hostComponents = host.split("\\.");

            if (hostComponents.length < 2) {
                return false;
            }
            int googleComponent = hostComponents.length - 2;
            String component = hostComponents[googleComponent];
            if (!"google".equals(component)) {
                if (hostComponents.length < 3 ||
                        (!"co".equals(component) && !"com".equals(component))) {
                    return false;
                }
                googleComponent = hostComponents.length - 3;
                if (!"google".equals(hostComponents[googleComponent])) {
                    return false;
                }
            }

            // Google corp network handling.
            if (googleComponent > 0 && "corp".equals(
                    hostComponents[googleComponent - 1])) {
                return false;
            }

            return true;
        }
        return false;
    }

}