/*
 * Copyright (C) 2009 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 android.server.search;

import com.android.internal.app.ResolverActivity;

import android.app.SearchManager;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.os.Bundle;
import android.util.Log;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

/**
 * This class maintains the information about all searchable activities.
 */
public class Searchables {

    private static final String LOG_TAG = "Searchables";

    // static strings used for XML lookups, etc.
    // TODO how should these be documented for the developer, in a more structured way than
    // the current long wordy javadoc in SearchManager.java ?
    private static final String MD_LABEL_DEFAULT_SEARCHABLE = "android.app.default_searchable";
    private static final String MD_SEARCHABLE_SYSTEM_SEARCH = "*";

    private Context mContext;

    private HashMap<ComponentName, SearchableInfo> mSearchablesMap = null;
    private ArrayList<SearchableInfo> mSearchablesList = null;
    private ArrayList<SearchableInfo> mSearchablesInGlobalSearchList = null;
    private ArrayList<SearchableInfo> mSearchablesForWebSearchList = null;
    private SearchableInfo mDefaultSearchable = null;
    private SearchableInfo mDefaultSearchableForWebSearch = null;

    public static String GOOGLE_SEARCH_COMPONENT_NAME =
            "com.android.googlesearch/.GoogleSearch";
    public static String ENHANCED_GOOGLE_SEARCH_COMPONENT_NAME =
            "com.google.android.providers.enhancedgooglesearch/.Launcher";

    /**
     *
     * @param context Context to use for looking up activities etc.
     */
    public Searchables (Context context) {
        mContext = context;
    }

    /**
     * Look up, or construct, based on the activity.
     *
     * The activities fall into three cases, based on meta-data found in
     * the manifest entry:
     * <ol>
     * <li>The activity itself implements search.  This is indicated by the
     * presence of a "android.app.searchable" meta-data attribute.
     * The value is a reference to an XML file containing search information.</li>
     * <li>A related activity implements search.  This is indicated by the
     * presence of a "android.app.default_searchable" meta-data attribute.
     * The value is a string naming the activity implementing search.  In this
     * case the factory will "redirect" and return the searchable data.</li>
     * <li>No searchability data is provided.  We return null here and other
     * code will insert the "default" (e.g. contacts) search.
     *
     * TODO: cache the result in the map, and check the map first.
     * TODO: it might make sense to implement the searchable reference as
     * an application meta-data entry.  This way we don't have to pepper each
     * and every activity.
     * TODO: can we skip the constructor step if it's a non-searchable?
     * TODO: does it make sense to plug the default into a slot here for
     * automatic return?  Probably not, but it's one way to do it.
     *
     * @param activity The name of the current activity, or null if the
     * activity does not define any explicit searchable metadata.
     */
    public SearchableInfo getSearchableInfo(ComponentName activity) {
        // Step 1.  Is the result already hashed?  (case 1)
        SearchableInfo result;
        synchronized (this) {
            result = mSearchablesMap.get(activity);
            if (result != null) return result;
        }

        // Step 2.  See if the current activity references a searchable.
        // Note:  Conceptually, this could be a while(true) loop, but there's
        // no point in implementing reference chaining here and risking a loop.
        // References must point directly to searchable activities.

        ActivityInfo ai = null;
        try {
            ai = mContext.getPackageManager().
                       getActivityInfo(activity, PackageManager.GET_META_DATA );
            String refActivityName = null;

            // First look for activity-specific reference
            Bundle md = ai.metaData;
            if (md != null) {
                refActivityName = md.getString(MD_LABEL_DEFAULT_SEARCHABLE);
            }
            // If not found, try for app-wide reference
            if (refActivityName == null) {
                md = ai.applicationInfo.metaData;
                if (md != null) {
                    refActivityName = md.getString(MD_LABEL_DEFAULT_SEARCHABLE);
                }
            }

            // Irrespective of source, if a reference was found, follow it.
            if (refActivityName != null)
            {
                // An app or activity can declare that we should simply launch
                // "system default search" if search is invoked.
                if (refActivityName.equals(MD_SEARCHABLE_SYSTEM_SEARCH)) {
                    return getDefaultSearchable();
                }
                String pkg = activity.getPackageName();
                ComponentName referredActivity;
                if (refActivityName.charAt(0) == '.') {
                    referredActivity = new ComponentName(pkg, pkg + refActivityName);
                } else {
                    referredActivity = new ComponentName(pkg, refActivityName);
                }

                // Now try the referred activity, and if found, cache
                // it against the original name so we can skip the check
                synchronized (this) {
                    result = mSearchablesMap.get(referredActivity);
                    if (result != null) {
                        mSearchablesMap.put(activity, result);
                        return result;
                    }
                }
            }
        } catch (PackageManager.NameNotFoundException e) {
            // case 3: no metadata
        }

        // Step 3.  None found. Return null.
        return null;

    }

    /**
     * Provides the system-default search activity, which you can use
     * whenever getSearchableInfo() returns null;
     *
     * @return Returns the system-default search activity, null if never defined
     */
    public synchronized SearchableInfo getDefaultSearchable() {
        return mDefaultSearchable;
    }

    public synchronized boolean isDefaultSearchable(SearchableInfo searchable) {
        return searchable == mDefaultSearchable;
    }

    /**
     * Builds an entire list (suitable for display) of
     * activities that are searchable, by iterating the entire set of
     * ACTION_SEARCH & ACTION_WEB_SEARCH intents.
     *
     * Also clears the hash of all activities -> searches which will
     * refill as the user clicks "search".
     *
     * This should only be done at startup and again if we know that the
     * list has changed.
     *
     * TODO: every activity that provides a ACTION_SEARCH intent should
     * also provide searchability meta-data.  There are a bunch of checks here
     * that, if data is not found, silently skip to the next activity.  This
     * won't help a developer trying to figure out why their activity isn't
     * showing up in the list, but an exception here is too rough.  I would
     * like to find a better notification mechanism.
     *
     * TODO: sort the list somehow?  UI choice.
     */
    public void buildSearchableList() {
        // These will become the new values at the end of the method
        HashMap<ComponentName, SearchableInfo> newSearchablesMap
                                = new HashMap<ComponentName, SearchableInfo>();
        ArrayList<SearchableInfo> newSearchablesList
                                = new ArrayList<SearchableInfo>();
        ArrayList<SearchableInfo> newSearchablesInGlobalSearchList
                                = new ArrayList<SearchableInfo>();
        ArrayList<SearchableInfo> newSearchablesForWebSearchList
                                = new ArrayList<SearchableInfo>();

        final PackageManager pm = mContext.getPackageManager();

        // Use intent resolver to generate list of ACTION_SEARCH & ACTION_WEB_SEARCH receivers.
        List<ResolveInfo> searchList;
        final Intent intent = new Intent(Intent.ACTION_SEARCH);
        searchList = pm.queryIntentActivities(intent, PackageManager.GET_META_DATA);

        List<ResolveInfo> webSearchInfoList;
        final Intent webSearchIntent = new Intent(Intent.ACTION_WEB_SEARCH);
        webSearchInfoList = pm.queryIntentActivities(webSearchIntent, PackageManager.GET_META_DATA);

        // analyze each one, generate a Searchables record, and record
        if (searchList != null || webSearchInfoList != null) {
            int search_count = (searchList == null ? 0 : searchList.size());
            int web_search_count = (webSearchInfoList == null ? 0 : webSearchInfoList.size());
            int count = search_count + web_search_count;
            for (int ii = 0; ii < count; ii++) {
                // for each component, try to find metadata
                ResolveInfo info = (ii < search_count)
                        ? searchList.get(ii)
                        : webSearchInfoList.get(ii - search_count);
                ActivityInfo ai = info.activityInfo;
                // Check first to avoid duplicate entries.
                if (newSearchablesMap.get(new ComponentName(ai.packageName, ai.name)) == null) {
                    SearchableInfo searchable = SearchableInfo.getActivityMetaData(mContext, ai);
                    if (searchable != null) {
                        newSearchablesList.add(searchable);
                        newSearchablesMap.put(searchable.getSearchActivity(), searchable);
                        if (searchable.shouldIncludeInGlobalSearch()) {
                            newSearchablesInGlobalSearchList.add(searchable);
                        }
                    }
                }
            }
        }

        if (webSearchInfoList != null) {
            for (int i = 0; i < webSearchInfoList.size(); ++i) {
                ActivityInfo ai = webSearchInfoList.get(i).activityInfo;
                ComponentName component = new ComponentName(ai.packageName, ai.name);
                SearchableInfo searchable = newSearchablesMap.get(component);
                if (searchable == null) {
                    Log.w(LOG_TAG, "did not find component in searchables: " + component);
                } else {
                    newSearchablesForWebSearchList.add(searchable);
                }
            }
        }

        // Find the global search provider
        Intent globalSearchIntent = new Intent(SearchManager.INTENT_ACTION_GLOBAL_SEARCH);
        ComponentName globalSearchActivity = globalSearchIntent.resolveActivity(pm);
        SearchableInfo newDefaultSearchable = newSearchablesMap.get(globalSearchActivity);

        if (newDefaultSearchable == null) {
            Log.w(LOG_TAG, "No searchable info found for new default searchable activity "
                    + globalSearchActivity);
        }

        // Find the default web search provider.
        ComponentName webSearchActivity = getPreferredWebSearchActivity(mContext);
        SearchableInfo newDefaultSearchableForWebSearch = null;
        if (webSearchActivity != null) {
            newDefaultSearchableForWebSearch = newSearchablesMap.get(webSearchActivity);
        }
        if (newDefaultSearchableForWebSearch == null) {
            Log.w(LOG_TAG, "No searchable info found for new default web search activity "
                    + webSearchActivity);
        }

        // Store a consistent set of new values
        synchronized (this) {
            mSearchablesMap = newSearchablesMap;
            mSearchablesList = newSearchablesList;
            mSearchablesInGlobalSearchList = newSearchablesInGlobalSearchList;
            mSearchablesForWebSearchList = newSearchablesForWebSearchList;
            mDefaultSearchable = newDefaultSearchable;
            mDefaultSearchableForWebSearch = newDefaultSearchableForWebSearch;
        }
    }

    /**
     * Checks if the given activity component is present in the system and if so makes it the
     * preferred activity for handling ACTION_WEB_SEARCH.
     * @param component Name of the component to check and set as preferred.
     * @param action Intent action for which this activity is to be set as preferred.
     * @return true if component was detected and set as preferred activity, false if not.
     */
    private static boolean setPreferredActivity(Context context,
            ComponentName component, String action) {
        Log.d(LOG_TAG, "Checking component " + component);
        PackageManager pm = context.getPackageManager();
        ActivityInfo ai;
        try {
            ai = pm.getActivityInfo(component, 0);
        } catch (PackageManager.NameNotFoundException e) {
            return false;
        }

        // The code here to find the value for bestMatch is heavily inspired by the code
        // in ResolverActivity where the preferred activity is set.
        Intent intent = new Intent(action);
        intent.addCategory(Intent.CATEGORY_DEFAULT);
        List<ResolveInfo> webSearchActivities = pm.queryIntentActivities(intent, 0);
        ComponentName set[] = new ComponentName[webSearchActivities.size()];
        int bestMatch = 0;
        for (int i = 0; i < webSearchActivities.size(); ++i) {
            ResolveInfo ri = webSearchActivities.get(i);
            set[i] = new ComponentName(ri.activityInfo.packageName,
                                       ri.activityInfo.name);
            if (ri.match > bestMatch) bestMatch = ri.match;
        }

        Log.d(LOG_TAG, "Setting preferred web search activity to " + component);
        IntentFilter filter = new IntentFilter(action);
        filter.addCategory(Intent.CATEGORY_DEFAULT);
        pm.replacePreferredActivity(filter, bestMatch, set, component);
        return true;
    }

    private static ComponentName getPreferredWebSearchActivity(Context context) {
        // Check if we have a preferred web search activity.
        Intent intent = new Intent(Intent.ACTION_WEB_SEARCH);
        PackageManager pm = context.getPackageManager();
        ResolveInfo ri = pm.resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY);

        if (ri == null || ri.activityInfo.name.equals(ResolverActivity.class.getName())) {
            Log.d(LOG_TAG, "No preferred activity set for action web search.");

            // The components in the providers array are checked in the order of declaration so the
            // first one has the highest priority. If the component exists in the system it is set
            // as the preferred activity to handle intent action web search.
            String[] preferredActivities = context.getResources().getStringArray(
                    com.android.internal.R.array.default_web_search_providers);
            for (String componentName : preferredActivities) {
                ComponentName component = ComponentName.unflattenFromString(componentName);
                if (setPreferredActivity(context, component, Intent.ACTION_WEB_SEARCH)) {
                    return component;
                }
            }
        } else {
            // If the current preferred activity is GoogleSearch, and we detect
            // EnhancedGoogleSearch installed as well, set the latter as preferred since that
            // is a superset and provides more functionality.
            ComponentName cn = new ComponentName(ri.activityInfo.packageName, ri.activityInfo.name);
            if (cn.flattenToShortString().equals(GOOGLE_SEARCH_COMPONENT_NAME)) {
                ComponentName enhancedGoogleSearch = ComponentName.unflattenFromString(
                        ENHANCED_GOOGLE_SEARCH_COMPONENT_NAME);
                if (setPreferredActivity(context, enhancedGoogleSearch,
                        Intent.ACTION_WEB_SEARCH)) {
                    return enhancedGoogleSearch;
                }
            }
        }

        if (ri == null) return null;
        return new ComponentName(ri.activityInfo.packageName, ri.activityInfo.name);
    }

    /**
     * Returns the list of searchable activities.
     */
    public synchronized ArrayList<SearchableInfo> getSearchablesList() {
        ArrayList<SearchableInfo> result = new ArrayList<SearchableInfo>(mSearchablesList);
        return result;
    }

    /**
     * Returns a list of the searchable activities that can be included in global search.
     */
    public synchronized ArrayList<SearchableInfo> getSearchablesInGlobalSearchList() {
        return new ArrayList<SearchableInfo>(mSearchablesInGlobalSearchList);
    }

    /**
     * Returns a list of the searchable activities that handle web searches.
     */
    public synchronized ArrayList<SearchableInfo> getSearchablesForWebSearchList() {
        return new ArrayList<SearchableInfo>(mSearchablesForWebSearchList);
    }

    /**
     * Returns the default searchable activity for web searches.
     */
    public synchronized SearchableInfo getDefaultSearchableForWebSearch() {
        return mDefaultSearchableForWebSearch;
    }

    /**
     * Sets the default searchable activity for web searches.
     */
    public synchronized void setDefaultWebSearch(ComponentName component) {
        setPreferredActivity(mContext, component, Intent.ACTION_WEB_SEARCH);
        buildSearchableList();
    }
}