/*
 * Copyright (C) 2008 Esmertec AG.
 * Copyright (C) 2008 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.google.android.mms.util;

import android.content.ContentUris;
import android.content.UriMatcher;
import android.net.Uri;
import android.provider.Telephony.Mms;
import android.util.Config;
import android.util.Log;

import java.util.HashMap;
import java.util.HashSet;

public final class PduCache extends AbstractCache<Uri, PduCacheEntry> {
    private static final String TAG = "PduCache";
    private static final boolean DEBUG = false;
    private static final boolean LOCAL_LOGV = DEBUG ? Config.LOGD : Config.LOGV;

    private static final int MMS_ALL             = 0;
    private static final int MMS_ALL_ID          = 1;
    private static final int MMS_INBOX           = 2;
    private static final int MMS_INBOX_ID        = 3;
    private static final int MMS_SENT            = 4;
    private static final int MMS_SENT_ID         = 5;
    private static final int MMS_DRAFTS          = 6;
    private static final int MMS_DRAFTS_ID       = 7;
    private static final int MMS_OUTBOX          = 8;
    private static final int MMS_OUTBOX_ID       = 9;
    private static final int MMS_CONVERSATION    = 10;
    private static final int MMS_CONVERSATION_ID = 11;

    private static final UriMatcher URI_MATCHER;
    private static final HashMap<Integer, Integer> MATCH_TO_MSGBOX_ID_MAP;

    private static PduCache sInstance;

    static {
        URI_MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
        URI_MATCHER.addURI("mms", null,         MMS_ALL);
        URI_MATCHER.addURI("mms", "#",          MMS_ALL_ID);
        URI_MATCHER.addURI("mms", "inbox",      MMS_INBOX);
        URI_MATCHER.addURI("mms", "inbox/#",    MMS_INBOX_ID);
        URI_MATCHER.addURI("mms", "sent",       MMS_SENT);
        URI_MATCHER.addURI("mms", "sent/#",     MMS_SENT_ID);
        URI_MATCHER.addURI("mms", "drafts",     MMS_DRAFTS);
        URI_MATCHER.addURI("mms", "drafts/#",   MMS_DRAFTS_ID);
        URI_MATCHER.addURI("mms", "outbox",     MMS_OUTBOX);
        URI_MATCHER.addURI("mms", "outbox/#",   MMS_OUTBOX_ID);
        URI_MATCHER.addURI("mms-sms", "conversations",   MMS_CONVERSATION);
        URI_MATCHER.addURI("mms-sms", "conversations/#", MMS_CONVERSATION_ID);

        MATCH_TO_MSGBOX_ID_MAP = new HashMap<Integer, Integer>();
        MATCH_TO_MSGBOX_ID_MAP.put(MMS_INBOX,  Mms.MESSAGE_BOX_INBOX);
        MATCH_TO_MSGBOX_ID_MAP.put(MMS_SENT,   Mms.MESSAGE_BOX_SENT);
        MATCH_TO_MSGBOX_ID_MAP.put(MMS_DRAFTS, Mms.MESSAGE_BOX_DRAFTS);
        MATCH_TO_MSGBOX_ID_MAP.put(MMS_OUTBOX, Mms.MESSAGE_BOX_OUTBOX);
    }

    private final HashMap<Integer, HashSet<Uri>> mMessageBoxes;
    private final HashMap<Long, HashSet<Uri>> mThreads;

    private PduCache() {
        mMessageBoxes = new HashMap<Integer, HashSet<Uri>>();
        mThreads = new HashMap<Long, HashSet<Uri>>();
    }

    synchronized public static final PduCache getInstance() {
        if (sInstance == null) {
            if (LOCAL_LOGV) {
                Log.v(TAG, "Constructing new PduCache instance.");
            }
            sInstance = new PduCache();
        }
        return sInstance;
    }

    @Override
    synchronized public boolean put(Uri uri, PduCacheEntry entry) {
        int msgBoxId = entry.getMessageBox();
        HashSet<Uri> msgBox = mMessageBoxes.get(msgBoxId);
        if (msgBox == null) {
            msgBox = new HashSet<Uri>();
            mMessageBoxes.put(msgBoxId, msgBox);
        }

        long threadId = entry.getThreadId();
        HashSet<Uri> thread = mThreads.get(threadId);
        if (thread == null) {
            thread = new HashSet<Uri>();
            mThreads.put(threadId, thread);
        }

        Uri finalKey = normalizeKey(uri);
        boolean result = super.put(finalKey, entry);
        if (result) {
            msgBox.add(finalKey);
            thread.add(finalKey);
        }
        return result;
    }

    @Override
    synchronized public PduCacheEntry purge(Uri uri) {
        int match = URI_MATCHER.match(uri);
        switch (match) {
            case MMS_ALL_ID:
                return purgeSingleEntry(uri);
            case MMS_INBOX_ID:
            case MMS_SENT_ID:
            case MMS_DRAFTS_ID:
            case MMS_OUTBOX_ID:
                String msgId = uri.getLastPathSegment();
                return purgeSingleEntry(Uri.withAppendedPath(Mms.CONTENT_URI, msgId));
            // Implicit batch of purge, return null.
            case MMS_ALL:
            case MMS_CONVERSATION:
                purgeAll();
                return null;
            case MMS_INBOX:
            case MMS_SENT:
            case MMS_DRAFTS:
            case MMS_OUTBOX:
                purgeByMessageBox(MATCH_TO_MSGBOX_ID_MAP.get(match));
                return null;
            case MMS_CONVERSATION_ID:
                purgeByThreadId(ContentUris.parseId(uri));
                return null;
            default:
                return null;
        }
    }

    private PduCacheEntry purgeSingleEntry(Uri key) {
        PduCacheEntry entry = super.purge(key);
        if (entry != null) {
            removeFromThreads(key, entry);
            removeFromMessageBoxes(key, entry);
            return entry;
        }
        return null;
    }

    @Override
    synchronized public void purgeAll() {
        super.purgeAll();

        mMessageBoxes.clear();
        mThreads.clear();
    }

    /**
     * @param uri The Uri to be normalized.
     * @return Uri The normalized key of cached entry.
     */
    private Uri normalizeKey(Uri uri) {
        int match = URI_MATCHER.match(uri);
        Uri normalizedKey = null;

        switch (match) {
            case MMS_ALL_ID:
                normalizedKey = uri;
                break;
            case MMS_INBOX_ID:
            case MMS_SENT_ID:
            case MMS_DRAFTS_ID:
            case MMS_OUTBOX_ID:
                String msgId = uri.getLastPathSegment();
                normalizedKey = Uri.withAppendedPath(Mms.CONTENT_URI, msgId);
                break;
            default:
                return null;
        }

        if (LOCAL_LOGV) {
            Log.v(TAG, uri + " -> " + normalizedKey);
        }
        return normalizedKey;
    }

    private void purgeByMessageBox(Integer msgBoxId) {
        if (LOCAL_LOGV) {
            Log.v(TAG, "Purge cache in message box: " + msgBoxId);
        }

        if (msgBoxId != null) {
            HashSet<Uri> msgBox = mMessageBoxes.remove(msgBoxId);
            if (msgBox != null) {
                for (Uri key : msgBox) {
                    PduCacheEntry entry = super.purge(key);
                    if (entry != null) {
                        removeFromThreads(key, entry);
                    }
                }
            }
        }
    }

    private void removeFromThreads(Uri key, PduCacheEntry entry) {
        HashSet<Uri> thread = mThreads.get(entry.getThreadId());
        if (thread != null) {
            thread.remove(key);
        }
    }

    private void purgeByThreadId(long threadId) {
        if (LOCAL_LOGV) {
            Log.v(TAG, "Purge cache in thread: " + threadId);
        }

        HashSet<Uri> thread = mThreads.remove(threadId);
        if (thread != null) {
            for (Uri key : thread) {
                PduCacheEntry entry = super.purge(key);
                if (entry != null) {
                    removeFromMessageBoxes(key, entry);
                }
            }
        }
    }

    private void removeFromMessageBoxes(Uri key, PduCacheEntry entry) {
        HashSet<Uri> msgBox = mThreads.get(Long.valueOf(entry.getMessageBox()));
        if (msgBox != null) {
            msgBox.remove(key);
        }
    }
}