/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.gecko;

import org.json.JSONArray;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.text.TextUtils;
import android.util.Log;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.ArrayList;

/**
 * Use network-based search suggestions.
 */
public class SuggestClient {
    private static final String LOGTAG = "GeckoSuggestClient";
    private static final String USER_AGENT = GeckoAppShell.getGeckoInterface().getDefaultUAString();

    private final Context mContext;
    private final int mTimeout;

    // should contain the string "__searchTerms__", which is replaced with the query
    private final String mSuggestTemplate;

    // the maximum number of suggestions to return
    private final int mMaxResults;

    // used by robocop for testing; referenced via reflection
    private boolean mCheckNetwork;

    // used to make suggestions appear instantly after opt-in
    private String mPrevQuery;
    private ArrayList<String> mPrevResults;

    public SuggestClient(Context context, String suggestTemplate, int timeout, int maxResults) {
        mContext = context;
        mMaxResults = maxResults;
        mSuggestTemplate = suggestTemplate;
        mTimeout = timeout;
        mCheckNetwork = true;
    }

    public SuggestClient(Context context, String suggestTemplate, int timeout) {
        this(context, suggestTemplate, timeout, Integer.MAX_VALUE);
    }

    /**
     * Queries for a given search term and returns an ArrayList of suggestions.
     */
    public ArrayList<String> query(String query) {
        if (query.equals(mPrevQuery))
            return mPrevResults;

        ArrayList<String> suggestions = new ArrayList<String>();
        if (TextUtils.isEmpty(mSuggestTemplate) || TextUtils.isEmpty(query)) {
            return suggestions;
        }

        if (!isNetworkConnected() && mCheckNetwork) {
            Log.i(LOGTAG, "Not connected to network");
            return suggestions;
        }

        try {
            String encoded = URLEncoder.encode(query, "UTF-8");
            String suggestUri = mSuggestTemplate.replace("__searchTerms__", encoded);

            URL url = new URL(suggestUri);
            String json = null;
            HttpURLConnection urlConnection = null;
            InputStream in = null;
            try {
                urlConnection = (HttpURLConnection) url.openConnection();
                urlConnection.setConnectTimeout(mTimeout);
                urlConnection.setRequestProperty("User-Agent", USER_AGENT);
                in = new BufferedInputStream(urlConnection.getInputStream());
                json = convertStreamToString(in);
            } finally {
                if (urlConnection != null)
                    urlConnection.disconnect();
                if (in != null) {
                    try {
                        in.close();
                    } catch (IOException e) {
                        Log.e(LOGTAG, "error", e);
                    }
                }
            }

            if (json != null) {
                /*
                 * Sample result:
                 * ["foo",["food network","foothill college","foot locker",...]]
                 */
                JSONArray results = new JSONArray(json);
                JSONArray jsonSuggestions = results.getJSONArray(1);
                
                int added = 0;
                for (int i = 0; (i < jsonSuggestions.length()) && (added < mMaxResults); i++) {
                    String suggestion = jsonSuggestions.getString(i);
                    if (!suggestion.equalsIgnoreCase(query)) {
                        suggestions.add(suggestion);
                        added++;
                    }
                }
            } else {
                Log.e(LOGTAG, "Suggestion query failed");
            }
        } catch (Exception e) {
            Log.e(LOGTAG, "Error", e);
        }

        mPrevQuery = query;
        mPrevResults = suggestions;
        return suggestions;
    }

    private boolean isNetworkConnected() {
        NetworkInfo networkInfo = getActiveNetworkInfo();
        return networkInfo != null && networkInfo.isConnected();
    }

    private NetworkInfo getActiveNetworkInfo() {
        ConnectivityManager connectivity = (ConnectivityManager) mContext
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        if (connectivity == null)
            return null;
        return connectivity.getActiveNetworkInfo();
    }

    private String convertStreamToString(java.io.InputStream is) {
        try {
            return new java.util.Scanner(is).useDelimiter("\\A").next();
        } catch (java.util.NoSuchElementException e) {
            return "";
        }
    }
}