/*
 * Copyright (C) 2010 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.contacts.common.list;

import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;

import com.android.contacts.common.logging.ListEvent;
import com.android.contacts.common.model.AccountTypeManager;
import com.android.contacts.common.model.account.AccountWithDataSet;

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

/**
 * Manages {@link ContactListFilter}. All methods must be called from UI thread.
 */
public abstract class ContactListFilterController {

    // singleton to cache the filter controller
    private static ContactListFilterControllerImpl sFilterController = null;

    public interface ContactListFilterListener {
        void onContactListFilterChanged();
    }

    public static ContactListFilterController getInstance(Context context) {
        // We may need to synchronize this in the future if background task will call this.
        if (sFilterController == null) {
            sFilterController = new ContactListFilterControllerImpl(context);
        }
        return sFilterController;
    }

    public abstract void addListener(ContactListFilterListener listener);

    public abstract void removeListener(ContactListFilterListener listener);

    /**
     * Return the currently-active filter.
     */
    public abstract ContactListFilter getFilter();

    public abstract int getFilterListType();

    /** Whether the persisted filter is a custom filter. */
    public abstract boolean isCustomFilterPersisted();

    /** Returns the persisted filter. */
    public abstract ContactListFilter getPersistedFilter();

    /**
     * @param filter the filter
     * @param persistent True when the given filter should be saved soon. False when the filter
     * should not be saved. The latter case may happen when some Intent requires a certain type of
     * UI (e.g. single contact) temporarily.
     */
    public abstract void setContactListFilter(ContactListFilter filter, boolean persistent);

    public abstract void selectCustomFilter();

    /**
     * Checks if the current filter is valid and reset the filter if not. It may happen when
     * an account is removed while the filter points to the account with
     * {@link ContactListFilter#FILTER_TYPE_ACCOUNT} type, for example. It may also happen if
     * the current filter is {@link ContactListFilter#FILTER_TYPE_SINGLE_CONTACT}, in
     * which case, we should switch to the last saved filter in {@link SharedPreferences}.
     */
    public abstract void checkFilterValidity(boolean notifyListeners);
}

/**
 * Stores the {@link ContactListFilter} selected by the user and saves it to
 * {@link SharedPreferences} if necessary.
 */
class ContactListFilterControllerImpl extends ContactListFilterController {
    private final Context mContext;
    private final List<ContactListFilterListener> mListeners =
            new ArrayList<ContactListFilterListener>();
    private ContactListFilter mFilter;

    public ContactListFilterControllerImpl(Context context) {
        mContext = context.getApplicationContext();
        mFilter = ContactListFilter.restoreDefaultPreferences(getSharedPreferences());
        checkFilterValidity(true /* notify listeners */);
    }

    @Override
    public void addListener(ContactListFilterListener listener) {
        mListeners.add(listener);
    }

    @Override
    public void removeListener(ContactListFilterListener listener) {
        mListeners.remove(listener);
    }

    @Override
    public ContactListFilter getFilter() {
        return mFilter;
    }

    @Override
    public int getFilterListType() {
        return mFilter == null ? ListEvent.ListType.UNKNOWN_LIST : mFilter.toListType();
    }

    @Override
    public boolean isCustomFilterPersisted() {
        final ContactListFilter filter = getPersistedFilter();
        return filter != null && filter.filterType == ContactListFilter.FILTER_TYPE_CUSTOM;
    }

    @Override
    public ContactListFilter getPersistedFilter() {
        return ContactListFilter.restoreDefaultPreferences(getSharedPreferences());
    }

    private SharedPreferences getSharedPreferences() {
        return PreferenceManager.getDefaultSharedPreferences(mContext);
    }

    @Override
    public void setContactListFilter(ContactListFilter filter, boolean persistent) {
        setContactListFilter(filter, persistent, /* notifyListeners */ true);
    }

    private void setContactListFilter(ContactListFilter filter, boolean persistent,
            boolean notifyListeners) {
        if (!filter.equals(mFilter)) {
            mFilter = filter;
            if (persistent) {
                ContactListFilter.storeToPreferences(getSharedPreferences(), mFilter);
            }
            if (notifyListeners && !mListeners.isEmpty()) {
                notifyContactListFilterChanged();
            }
        }
    }

    @Override
    public void selectCustomFilter() {
        setContactListFilter(ContactListFilter.createFilterWithType(
                ContactListFilter.FILTER_TYPE_CUSTOM), /* persistent */ true);
    }

    private void notifyContactListFilterChanged() {
        for (ContactListFilterListener listener : mListeners) {
            listener.onContactListFilterChanged();
        }
    }

    @Override
    public void checkFilterValidity(boolean notifyListeners) {
        if (mFilter == null) {
            return;
        }

        switch (mFilter.filterType) {
            case ContactListFilter.FILTER_TYPE_SINGLE_CONTACT:
                setContactListFilter(
                        ContactListFilter.restoreDefaultPreferences(getSharedPreferences()),
                        false, notifyListeners);
                break;
            case ContactListFilter.FILTER_TYPE_ACCOUNT:
                if (!filterAccountExists()) {
                    // The current account filter points to invalid account. Use "all" filter
                    // instead.
                    setContactListFilter(ContactListFilter.createFilterWithType(
                            ContactListFilter.FILTER_TYPE_ALL_ACCOUNTS), true, notifyListeners);
                }
                break;
        }
    }

    /**
     * @return true if the Account for the current filter exists.
     */
    private boolean filterAccountExists() {
        final AccountTypeManager accountTypeManager = AccountTypeManager.getInstance(mContext);
        final AccountWithDataSet filterAccount = new AccountWithDataSet(
                mFilter.accountName, mFilter.accountType, mFilter.dataSet);
        return accountTypeManager.contains(filterAccount, /* contactWritableOnly */ false);
    }
}