/*
 * Copyright (C) 2012 Google Inc.
 * Licensed to 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.mail.ui;

import android.os.Bundle;

import com.android.mail.analytics.Analytics;
import com.android.mail.utils.LogUtils;
import com.google.common.collect.Lists;

import java.util.ArrayList;

/**
 * Represents the view mode for the tablet Gmail activity.
 * Transitions between modes should be done through this central object, and UI components that are
 * dependent on the mode should listen to changes on this object.
 */
public class ViewMode {
    /**
     * A listener for changes on a ViewMode. To listen to mode changes, implement this
     * interface and register your object with the single ViewMode held by the ActivityController
     * instance. On mode changes, the onViewModeChanged method will be called with the new mode.
     */
    public interface ModeChangeListener {
        /**
         * Called when the mode has changed.
         */
        void onViewModeChanged(int newMode);
    }

    /**
     * Mode when showing a single conversation.
     */
    public static final int CONVERSATION = 1;
    /**
     * Mode when showing a list of conversations
     */
    public static final int CONVERSATION_LIST = 2;
    /**
     * Mode when showing results from user search.
     */
    public static final int SEARCH_RESULTS_LIST = 3;
    /**
     * Mode when showing results from user search.
     */
    public static final int SEARCH_RESULTS_CONVERSATION = 4;
    /**
     * Mode when showing the "waiting for sync" message.
     */
    public static final int WAITING_FOR_ACCOUNT_INITIALIZATION = 5;
    /**
     * Mode when showing ads.
     */
    public static final int AD = 6;
    /**
     * Uncertain mode. The mode has not been initialized.
     */
    public static final int UNKNOWN = 0;

    // Key used to save this {@link ViewMode}.
    private static final String VIEW_MODE_KEY = "view-mode";
    private final ArrayList<ModeChangeListener> mListeners = Lists.newArrayList();
    /**
     * The actual mode the activity is in. We start out with an UNKNOWN mode, and require entering
     * a valid mode after the object has been created.
     */
    private int mMode = UNKNOWN;

    public static final String LOG_TAG = "ViewMode";

    // friendly names (not user-facing) for each view mode, indexed by ordinal value.
    private static final String[] MODE_NAMES = {
        "Unknown",
        "Conversation",
        "Conversation list",
        "Search results list",
        "Search results conversation",
        "Waiting for sync",
        "Ad"
    };

    public ViewMode() {
        // Do nothing
    }

    @Override
    public String toString() {
        return "[mode=" + MODE_NAMES[mMode] + "]";
    }

    public String getModeString() {
        return MODE_NAMES[mMode];
    }

    /**
     * Adds a listener from this view mode.
     * Must happen in the UI thread.
     */
    public void addListener(ModeChangeListener listener) {
        mListeners.add(listener);
    }

    /**
     * Dispatches a change event for the mode.
     * Always happens in the UI thread.
     */
    private void dispatchModeChange() {
        ArrayList<ModeChangeListener> list = new ArrayList<ModeChangeListener>(mListeners);
        for (ModeChangeListener listener : list) {
            assert (listener != null);
            listener.onViewModeChanged(mMode);
        }
    }

    /**
     * Requests a transition of the mode to show the conversation list as the prominent view.
     *
     */
    public void enterConversationListMode() {
        setModeInternal(CONVERSATION_LIST);
    }

    /**
     * Requests a transition of the mode to show a conversation as the prominent view.
     *
     */
    public void enterConversationMode() {
        setModeInternal(CONVERSATION);
    }

    /**
     * Requests a transition of the mode to show a list of search results as the
     * prominent view.
     *
     */
    public void enterSearchResultsListMode() {
        setModeInternal(SEARCH_RESULTS_LIST);
    }

    /**
     * Requests a transition of the mode to show a conversation that was part of
     * search results.
     *
     */
    public void enterSearchResultsConversationMode() {
        setModeInternal(SEARCH_RESULTS_CONVERSATION);
    }

    /**
     * Requests a transition of the mode to show the "waiting for sync" messages
     *
     */
    public void enterWaitingForInitializationMode() {
        setModeInternal(WAITING_FOR_ACCOUNT_INITIALIZATION);
    }

    /**
     * Requests a transition of the mode to show an ad.
     */
    public void enterAdMode() {
        setModeInternal(AD);
    }

    /**
     * @return The current mode.
     */
    public int getMode() {
        return mMode;
    }

    /**
     * Return whether the current mode is considered a list mode.
     */
    public boolean isListMode() {
        return isListMode(mMode);
    }

    public static boolean isListMode(final int mode) {
        return mode == CONVERSATION_LIST || mode == SEARCH_RESULTS_LIST;
    }

    public boolean isConversationMode() {
        return isConversationMode(mMode);
    }

    public static boolean isConversationMode(final int mode) {
        return mode == CONVERSATION || mode == SEARCH_RESULTS_CONVERSATION;
    }

    public static boolean isSearchMode(final int mode) {
        return mode == SEARCH_RESULTS_LIST || mode == SEARCH_RESULTS_CONVERSATION;
    }

    public boolean isWaitingForSync() {
        return isWaitingForSync(mMode);
    }

    public static boolean isWaitingForSync(final int mode) {
        return mode == WAITING_FOR_ACCOUNT_INITIALIZATION;
    }

    public boolean isAdMode() {
        return isAdMode(mMode);
    }

    public static boolean isAdMode(final int mode) {
        return mode == AD;
    }

    /**
     * Restoring from a saved state restores only the mode. It does not restore the listeners of
     * this object.
     * @param inState
     */
    public void handleRestore(Bundle inState) {
        if (inState == null) {
            return;
        }
        // Restore the previous mode, and UNKNOWN if nothing exists.
        final int newMode = inState.getInt(VIEW_MODE_KEY, UNKNOWN);
        if (newMode != UNKNOWN) {
            setModeInternal(newMode);
        }
    }

    /**
     * Save the existing mode only. Does not save the existing listeners.
     * @param outState
     */
    public void handleSaveInstanceState(Bundle outState) {
        if (outState == null) {
            return;
        }
        outState.putInt(VIEW_MODE_KEY, mMode);
    }

    /**
     * Removes a listener from this view mode.
     * Must happen in the UI thread.
     */
    public void removeListener(ModeChangeListener listener) {
        mListeners.remove(listener);
    }

    /**
     * Sets the internal mode.
     * @return Whether or not a change occurred.
     */
    private boolean setModeInternal(int mode) {
        if (mMode == mode) {
            if (LogUtils.isLoggable(LOG_TAG, LogUtils.DEBUG)) {
                LogUtils.d(LOG_TAG, new Error(), "ViewMode: debouncing change attempt mode=%s",
                        mode);
            } else {
                LogUtils.i(LOG_TAG, "ViewMode: debouncing change attempt mode=%s", mode);
            }
            return false;
        }

        if (LogUtils.isLoggable(LOG_TAG, LogUtils.DEBUG)) {
            LogUtils.d(LOG_TAG, new Error(), "ViewMode: executing change old=%s new=%s", mMode,
                    mode);
        } else {
            LogUtils.i(LOG_TAG, "ViewMode: executing change old=%s new=%s", mMode, mode);
        }

        mMode = mode;
        dispatchModeChange();
        Analytics.getInstance().sendView("ViewMode" + toString());
        return true;
    }
}