/*
 * Copyright (C) 2011 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.nfc;

import com.android.nfc.RegisteredComponentCache.ComponentInfo;
import com.android.nfc.handover.HandoverManager;

import android.app.Activity;
import android.app.ActivityManagerNative;
import android.app.IActivityManager;
import android.app.PendingIntent;
import android.app.PendingIntent.CanceledException;
import android.content.ComponentName;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.net.Uri;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.os.RemoteException;
import android.util.Log;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.nio.charset.Charsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

/**
 * Dispatch of NFC events to start activities
 */
public class NfcDispatcher {
    static final boolean DBG = true;
    static final String TAG = "NfcDispatcher";

    final Context mContext;
    final IActivityManager mIActivityManager;
    final RegisteredComponentCache mTechListFilters;
    final PackageManager mPackageManager;
    final ContentResolver mContentResolver;
    final HandoverManager mHandoverManager;

    // Locked on this
    PendingIntent mOverrideIntent;
    IntentFilter[] mOverrideFilters;
    String[][] mOverrideTechLists;

    public NfcDispatcher(Context context, HandoverManager handoverManager) {
        mContext = context;
        mIActivityManager = ActivityManagerNative.getDefault();
        mTechListFilters = new RegisteredComponentCache(mContext,
                NfcAdapter.ACTION_TECH_DISCOVERED, NfcAdapter.ACTION_TECH_DISCOVERED);
        mPackageManager = context.getPackageManager();
        mContentResolver = context.getContentResolver();
        mHandoverManager = handoverManager;
    }

    public synchronized void setForegroundDispatch(PendingIntent intent,
            IntentFilter[] filters, String[][] techLists) {
        if (DBG) Log.d(TAG, "Set Foreground Dispatch");
        mOverrideIntent = intent;
        mOverrideFilters = filters;
        mOverrideTechLists = techLists;
    }

    /**
     * Helper for re-used objects and methods during a single tag dispatch.
     */
    static class DispatchInfo {
        public final Intent intent;

        final Intent rootIntent;
        final Uri ndefUri;
        final String ndefMimeType;
        final PackageManager packageManager;
        final Context context;

        public DispatchInfo(Context context, Tag tag, NdefMessage message) {
            intent = new Intent();
            intent.putExtra(NfcAdapter.EXTRA_TAG, tag);
            intent.putExtra(NfcAdapter.EXTRA_ID, tag.getId());
            if (message != null) {
                intent.putExtra(NfcAdapter.EXTRA_NDEF_MESSAGES, new NdefMessage[] {message});
                ndefUri = message.getRecords()[0].toUri();
                ndefMimeType = message.getRecords()[0].toMimeType();
            } else {
                ndefUri = null;
                ndefMimeType = null;
            }

            rootIntent = new Intent(context, NfcRootActivity.class);
            rootIntent.putExtra(NfcRootActivity.EXTRA_LAUNCH_INTENT, intent);
            rootIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);

            this.context = context;
            packageManager = context.getPackageManager();
        }

        public Intent setNdefIntent() {
            intent.setAction(NfcAdapter.ACTION_NDEF_DISCOVERED);
            if (ndefUri != null) {
                intent.setData(ndefUri);
                return intent;
            } else if (ndefMimeType != null) {
                intent.setType(ndefMimeType);
                return intent;
            }
            return null;
        }

        public Intent setTechIntent() {
            intent.setData(null);
            intent.setType(null);
            intent.setAction(NfcAdapter.ACTION_TECH_DISCOVERED);
            return intent;
        }

        public Intent setTagIntent() {
            intent.setData(null);
            intent.setType(null);
            intent.setAction(NfcAdapter.ACTION_TAG_DISCOVERED);
            return intent;
        }

        /**
         * Launch the activity via a (single) NFC root task, so that it
         * creates a new task stack instead of interfering with any existing
         * task stack for that activity.
         * NfcRootActivity acts as the task root, it immediately calls
         * start activity on the intent it is passed.
         */
        boolean tryStartActivity() {
            // Ideally we'd have used startActivityForResult() to determine whether the
            // NfcRootActivity was able to launch the intent, but startActivityForResult()
            // is not available on Context. Instead, we query the PackageManager beforehand
            // to determine if there is an Activity to handle this intent, and base the
            // result of off that.
            List<ResolveInfo> activities = packageManager.queryIntentActivities(intent, 0);
            if (activities.size() > 0) {
                context.startActivity(rootIntent);
                return true;
            }
            return false;
        }

        boolean tryStartActivity(Intent intentToStart) {
            List<ResolveInfo> activities = packageManager.queryIntentActivities(intentToStart, 0);
            if (activities.size() > 0) {
                rootIntent.putExtra(NfcRootActivity.EXTRA_LAUNCH_INTENT, intentToStart);
                context.startActivity(rootIntent);
                return true;
            }
            return false;
        }
    }

    /** Returns false if no activities were found to dispatch to */
    public boolean dispatchTag(Tag tag) {
        NdefMessage message = null;
        Ndef ndef = Ndef.get(tag);
        if (ndef != null) {
            message = ndef.getCachedNdefMessage();
        }
        if (DBG) Log.d(TAG, "dispatch tag: " + tag.toString() + " message: " + message);

        PendingIntent overrideIntent;
        IntentFilter[] overrideFilters;
        String[][] overrideTechLists;

        DispatchInfo dispatch = new DispatchInfo(mContext, tag, message);
        synchronized (this) {
            overrideFilters = mOverrideFilters;
            overrideIntent = mOverrideIntent;
            overrideTechLists = mOverrideTechLists;
        }

        resumeAppSwitches();

        if (tryOverrides(dispatch, tag, message, overrideIntent, overrideFilters, overrideTechLists)) {
            return true;
        }

        if (mHandoverManager.tryHandover(message)) {
            if (DBG) Log.i(TAG, "matched BT HANDOVER");
            return true;
        }

        if (tryNdef(dispatch, message)) {
            return true;
        }

        if (tryTech(dispatch, tag)) {
            return true;
        }

        dispatch.setTagIntent();
        if (dispatch.tryStartActivity()) {
            if (DBG) Log.i(TAG, "matched TAG");
            return true;
        }

        if (DBG) Log.i(TAG, "no match");
        return false;
    }

    boolean tryOverrides(DispatchInfo dispatch, Tag tag, NdefMessage message, PendingIntent overrideIntent,
            IntentFilter[] overrideFilters, String[][] overrideTechLists) {
        if (overrideIntent == null) {
            return false;
        }
        Intent intent;

        // NDEF
        if (message != null) {
            intent = dispatch.setNdefIntent();
            if (intent != null &&
                    isFilterMatch(intent, overrideFilters, overrideTechLists != null)) {
                try {
                    overrideIntent.send(mContext, Activity.RESULT_OK, intent);
                    if (DBG) Log.i(TAG, "matched NDEF override");
                    return true;
                } catch (CanceledException e) {
                    return false;
                }
            }
        }

        // TECH
        intent = dispatch.setTechIntent();
        if (isTechMatch(tag, overrideTechLists)) {
            try {
                overrideIntent.send(mContext, Activity.RESULT_OK, intent);
                if (DBG) Log.i(TAG, "matched TECH override");
                return true;
            } catch (CanceledException e) {
                return false;
            }
        }

        // TAG
        intent = dispatch.setTagIntent();
        if (isFilterMatch(intent, overrideFilters, overrideTechLists != null)) {
            try {
                overrideIntent.send(mContext, Activity.RESULT_OK, intent);
                if (DBG) Log.i(TAG, "matched TAG override");
                return true;
            } catch (CanceledException e) {
                return false;
            }
        }
        return false;
    }

    boolean isFilterMatch(Intent intent, IntentFilter[] filters, boolean hasTechFilter) {
        if (filters != null) {
            for (IntentFilter filter : filters) {
                if (filter.match(mContentResolver, intent, false, TAG) >= 0) {
                    return true;
                }
            }
        } else if (!hasTechFilter) {
            return true;  // always match if both filters and techlists are null
        }
        return false;
    }

    boolean isTechMatch(Tag tag, String[][] techLists) {
        if (techLists == null) {
            return false;
        }

        String[] tagTechs = tag.getTechList();
        Arrays.sort(tagTechs);
        for (String[] filterTechs : techLists) {
            if (filterMatch(tagTechs, filterTechs)) {
                return true;
            }
        }
        return false;
    }

    boolean tryNdef(DispatchInfo dispatch, NdefMessage message) {
        if (message == null) {
            return false;
        }
        Intent intent = dispatch.setNdefIntent();

        // Bail out if the intent does not contain filterable NDEF data
        if (intent == null) return false;

        // Try to start AAR activity with matching filter
        List<String> aarPackages = extractAarPackages(message);
        for (String pkg : aarPackages) {
            dispatch.intent.setPackage(pkg);
            if (dispatch.tryStartActivity()) {
                if (DBG) Log.i(TAG, "matched AAR to NDEF");
                return true;
            }
        }

        // Try to perform regular launch of the first AAR
        if (aarPackages.size() > 0) {
            String firstPackage = aarPackages.get(0);
            Intent appLaunchIntent = mPackageManager.getLaunchIntentForPackage(firstPackage);
            if (appLaunchIntent != null && dispatch.tryStartActivity(appLaunchIntent)) {
                if (DBG) Log.i(TAG, "matched AAR to application launch");
                return true;
            }
            // Find the package in Market:
            Intent marketIntent = getAppSearchIntent(firstPackage);
            if (marketIntent != null && dispatch.tryStartActivity(marketIntent)) {
                if (DBG) Log.i(TAG, "matched AAR to market launch");
                return true;
            }
        }

        // regular launch
        dispatch.intent.setPackage(null);
        if (dispatch.tryStartActivity()) {
            if (DBG) Log.i(TAG, "matched NDEF");
            return true;
        }

        return false;
    }

    static List<String> extractAarPackages(NdefMessage message) {
        List<String> aarPackages = new LinkedList<String>();
        for (NdefRecord record : message.getRecords()) {
            String pkg = checkForAar(record);
            if (pkg != null) {
                aarPackages.add(pkg);
            }
        }
        return aarPackages;
    }

    boolean tryTech(DispatchInfo dispatch, Tag tag) {
        dispatch.setTechIntent();

        String[] tagTechs = tag.getTechList();
        Arrays.sort(tagTechs);

        // Standard tech dispatch path
        ArrayList<ResolveInfo> matches = new ArrayList<ResolveInfo>();
        List<ComponentInfo> registered = mTechListFilters.getComponents();

        // Check each registered activity to see if it matches
        for (ComponentInfo info : registered) {
            // Don't allow wild card matching
            if (filterMatch(tagTechs, info.techs) &&
                    isComponentEnabled(mPackageManager, info.resolveInfo)) {
                // Add the activity as a match if it's not already in the list
                if (!matches.contains(info.resolveInfo)) {
                    matches.add(info.resolveInfo);
                }
            }
        }

        if (matches.size() == 1) {
            // Single match, launch directly
            ResolveInfo info = matches.get(0);
            dispatch.intent.setClassName(info.activityInfo.packageName, info.activityInfo.name);
            if (dispatch.tryStartActivity()) {
                if (DBG) Log.i(TAG, "matched single TECH");
                return true;
            }
            dispatch.intent.setClassName((String)null, null);
        } else if (matches.size() > 1) {
            // Multiple matches, show a custom activity chooser dialog
            Intent intent = new Intent(mContext, TechListChooserActivity.class);
            intent.putExtra(Intent.EXTRA_INTENT, dispatch.intent);
            intent.putParcelableArrayListExtra(TechListChooserActivity.EXTRA_RESOLVE_INFOS,
                    matches);
            if (dispatch.tryStartActivity(intent)) {
                if (DBG) Log.i(TAG, "matched multiple TECH");
                return true;
            }
        }
        return false;
    }

    /**
     * Tells the ActivityManager to resume allowing app switches.
     *
     * If the current app called stopAppSwitches() then our startActivity() can
     * be delayed for several seconds. This happens with the default home
     * screen.  As a system service we can override this behavior with
     * resumeAppSwitches().
    */
    void resumeAppSwitches() {
        try {
            mIActivityManager.resumeAppSwitches();
        } catch (RemoteException e) { }
    }

    /** Returns true if the tech list filter matches the techs on the tag */
    boolean filterMatch(String[] tagTechs, String[] filterTechs) {
        if (filterTechs == null || filterTechs.length == 0) return false;

        for (String tech : filterTechs) {
            if (Arrays.binarySearch(tagTechs, tech) < 0) {
                return false;
            }
        }
        return true;
    }

    static String checkForAar(NdefRecord record) {
        if (record.getTnf() == NdefRecord.TNF_EXTERNAL_TYPE &&
                Arrays.equals(record.getType(), NdefRecord.RTD_ANDROID_APP)) {
            return new String(record.getPayload(), Charsets.US_ASCII);
        }
        return null;
    }

    /**
     * Returns an intent that can be used to find an application not currently
     * installed on the device.
     */
    static Intent getAppSearchIntent(String pkg) {
        Intent market = new Intent(Intent.ACTION_VIEW);
        market.setData(Uri.parse("market://details?id=" + pkg));
        return market;
    }

    static boolean isComponentEnabled(PackageManager pm, ResolveInfo info) {
        boolean enabled = false;
        ComponentName compname = new ComponentName(
                info.activityInfo.packageName, info.activityInfo.name);
        try {
            // Note that getActivityInfo() will internally call
            // isEnabledLP() to determine whether the component
            // enabled. If it's not, null is returned.
            if (pm.getActivityInfo(compname,0) != null) {
                enabled = true;
            }
        } catch (PackageManager.NameNotFoundException e) {
            enabled = false;
        }
        if (!enabled) {
            Log.d(TAG, "Component not enabled: " + compname);
        }
        return enabled;
    }

    void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
        synchronized (this) {
            pw.println("mOverrideIntent=" + mOverrideIntent);
            pw.println("mOverrideFilters=" + mOverrideFilters);
            pw.println("mOverrideTechLists=" + mOverrideTechLists);
        }
    }
}