/*
 * 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.contacts.editor;

import android.accounts.Account;
import android.accounts.AccountManager;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.text.TextUtils;
import android.util.Log;

import com.android.contacts.common.R;
import com.android.contacts.common.testing.NeededForTesting;
import com.android.contacts.common.model.AccountTypeManager;
import com.android.contacts.common.model.account.AccountType;
import com.android.contacts.common.model.account.AccountWithDataSet;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Sets;

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

/**
 * Utility methods for the "account changed" notification in the new contact creation flow.
 */
@NeededForTesting
public class ContactEditorUtils {
    private static final String TAG = "ContactEditorUtils";

    private static final String KEY_KNOWN_ACCOUNTS = "ContactEditorUtils_known_accounts";

    private static final List<AccountWithDataSet> EMPTY_ACCOUNTS = ImmutableList.of();

    private static ContactEditorUtils sInstance;

    private final Context mContext;
    private final SharedPreferences mPrefs;
    private final AccountTypeManager mAccountTypes;
    private final String mDefaultAccountKey;
    // Key to tell the first time launch.
    private final String mAnythingSavedKey;

    private ContactEditorUtils(Context context) {
        this(context, AccountTypeManager.getInstance(context));
    }

    @VisibleForTesting
    ContactEditorUtils(Context context, AccountTypeManager accountTypes) {
        mContext = context.getApplicationContext();
        mPrefs = mContext.getSharedPreferences(context.getPackageName(), Context.MODE_PRIVATE);
        mAccountTypes = accountTypes;
        mDefaultAccountKey = mContext.getResources().getString(
                R.string.contact_editor_default_account_key);
        mAnythingSavedKey = mContext.getResources().getString(
                R.string.contact_editor_anything_saved_key);
    }

    public static synchronized ContactEditorUtils getInstance(Context context) {
        if (sInstance == null) {
            sInstance = new ContactEditorUtils(context.getApplicationContext());
        }
        return sInstance;
    }

    @NeededForTesting
    void cleanupForTest() {
        mPrefs.edit().remove(mDefaultAccountKey).remove(KEY_KNOWN_ACCOUNTS)
                .remove(mAnythingSavedKey).apply();
    }

    @NeededForTesting
    void removeDefaultAccountForTest() {
        mPrefs.edit().remove(mDefaultAccountKey).apply();
    }

    /**
     * Sets the {@link #KEY_KNOWN_ACCOUNTS} and {@link #mDefaultAccountKey} preference values to
     * empty strings to reset the state of the preferences file.
     */
    private void resetPreferenceValues() {
        mPrefs.edit().putString(KEY_KNOWN_ACCOUNTS, "").putString(mDefaultAccountKey, "").apply();
    }

    private List<AccountWithDataSet> getWritableAccounts() {
        return mAccountTypes.getAccounts(true);
    }

    /**
     * @return true if it's the first launch and {@link #saveDefaultAndAllAccounts} has never
     *     been called.
     */
    private boolean isFirstLaunch() {
        return !mPrefs.getBoolean(mAnythingSavedKey, false);
    }

    /**
     * Saves all writable accounts and the default account, which can later be obtained
     * with {@link #getDefaultAccount}.
     *
     * This should be called when saving a newly created contact.
     *
     * @param defaultAccount the account used to save a newly created contact.  Or pass {@code null}
     *     If the user selected "local only".
     */
    @NeededForTesting
    public void saveDefaultAndAllAccounts(AccountWithDataSet defaultAccount) {
        final SharedPreferences.Editor editor = mPrefs.edit()
                .putBoolean(mAnythingSavedKey, true);

        if (defaultAccount == null || defaultAccount.isLocalAccount()) {
            // If the default is "local only", there should be no writable accounts.
            // This should always be the case with our spec, but because we load the account list
            // asynchronously using a worker thread, it is possible that there are accounts at this
            // point. So if the default is null always clear the account list.
            editor.remove(KEY_KNOWN_ACCOUNTS);
            editor.remove(mDefaultAccountKey);
        } else {
            editor.putString(KEY_KNOWN_ACCOUNTS,
                    AccountWithDataSet.stringifyList(getWritableAccounts()));
            editor.putString(mDefaultAccountKey, defaultAccount.stringify());
        }
        editor.apply();
    }

    /**
     * @return the default account saved with {@link #saveDefaultAndAllAccounts}.
     *
     * Note the {@code null} return value can mean either {@link #saveDefaultAndAllAccounts} has
     * never been called, or {@code null} was passed to {@link #saveDefaultAndAllAccounts} --
     * i.e. the user selected "local only".
     *
     * Also note that the returned account may have been removed already.
     */
    public AccountWithDataSet getDefaultAccount() {
        final List<AccountWithDataSet> currentWritableAccounts = getWritableAccounts();
        if (currentWritableAccounts.size() == 1) {
            return currentWritableAccounts.get(0);
        }

        final String saved = mPrefs.getString(mDefaultAccountKey, null);
        if (TextUtils.isEmpty(saved)) {
            return null;
        }
        try {
            return AccountWithDataSet.unstringify(saved);
        } catch (IllegalArgumentException exception) {
            Log.e(TAG, "Error with retrieving default account " + exception.toString());
            // unstringify()can throw an exception if the string is not in an expected format.
            // Hence, if the preferences file is corrupt, just reset the preference values
            resetPreferenceValues();
            return null;
        }
    }

    /**
     * @return true if an account still exists.  {@code null} is considered "local only" here,
     *    so it's valid too.
     */
    @VisibleForTesting
    boolean isValidAccount(AccountWithDataSet account) {
        if (account == null || account.isLocalAccount()) {
            return true; // It's "local only" account, which is valid.
        }
        return getWritableAccounts().contains(account);
    }

    /**
     * @return saved known accounts, or an empty list if none has been saved yet.
     */
    @VisibleForTesting
    List<AccountWithDataSet> getSavedAccounts() {
        final String saved = mPrefs.getString(KEY_KNOWN_ACCOUNTS, null);
        if (TextUtils.isEmpty(saved)) {
            return EMPTY_ACCOUNTS;
        }
        try {
            return AccountWithDataSet.unstringifyList(saved);
        } catch (IllegalArgumentException exception) {
            Log.e(TAG, "Error with retrieving saved accounts " + exception.toString());
            // unstringifyList()can throw an exception if the string is not in an expected format.
            // Hence, if the preferences file is corrupt, just reset the preference values
            resetPreferenceValues();
            return EMPTY_ACCOUNTS;
        }
    }

    /**
     * @return true if the contact editor should show the "accounts changed" notification, that is:
     * - If it's the first launch.
     * - Or, if the default account has been removed.
     * (And some extra sanity check)
     *
     * Note if this method returns {@code false}, the caller can safely assume that
     * {@link #getDefaultAccount} will return a valid account.  (Either an account which still
     * exists, or {@code null} which should be interpreted as "local only".)
     */
    @NeededForTesting
    public boolean shouldShowAccountChangedNotification() {
        if (isFirstLaunch()) {
            return true;
        }

        final List<AccountWithDataSet> currentWritableAccounts = getWritableAccounts();

        final AccountWithDataSet defaultAccount = getDefaultAccount();

        // Does default account still exist?
        if (!isValidAccount(defaultAccount)) {
            return true;
        }

        // If there is an inconsistent state in the preferences file - default account is null
        // ("local" account) while there are multiple accounts, then show the notification dialog.
        // This shouldn't ever happen, but this should allow the user can get back into a normal
        // state after they respond to the notification.
        if ((defaultAccount == null || defaultAccount.isLocalAccount())
                && currentWritableAccounts.size() > 0) {
            Log.e(TAG, "Preferences file in an inconsistent state, request that the default account"
                    + " and current writable accounts be saved again");
            return true;
        }

        // All good.
        return false;
    }

    @VisibleForTesting
    String[] getWritableAccountTypeStrings() {
        final Set<String> types = Sets.newHashSet();
        for (AccountType type : mAccountTypes.getAccountTypes(true)) {
            types.add(type.accountType);
        }
        return types.toArray(new String[types.size()]);
    }

    /**
     * Create an {@link Intent} to start "add new account" setup wizard.  Selectable account
     * types will be limited to ones that supports editing contacts.
     *
     * Use {@link Activity#startActivityForResult} or
     * {@link android.app.Fragment#startActivityForResult} to start the wizard, and
     * {@link Activity#onActivityResult} or {@link android.app.Fragment#onActivityResult} to
     * get the result.
     */
    public Intent createAddWritableAccountIntent() {
        return AccountManager.newChooseAccountIntent(
                null, // selectedAccount
                new ArrayList<Account>(), // allowableAccounts
                getWritableAccountTypeStrings(), // allowableAccountTypes
                false, // alwaysPromptForAccount
                null, // descriptionOverrideText
                null, // addAccountAuthTokenType
                null, // addAccountRequiredFeatures
                null // addAccountOptions
                );
    }

    /**
     * Parses a result from {@link #createAddWritableAccountIntent} and returns the created
     * {@link Account}, or null if the user has canceled the wizard.  Pass the {@code resultCode}
     * and {@code data} parameters passed to {@link Activity#onActivityResult} or
     * {@link android.app.Fragment#onActivityResult}.
     *
     * Note although the return type is {@link AccountWithDataSet}, return values from this method
     * will never have {@link AccountWithDataSet#dataSet} set, as there's no way to create an
     * extension package account from setup wizard.
     */
    public AccountWithDataSet getCreatedAccount(int resultCode, Intent resultData) {
        // Javadoc doesn't say anything about resultCode but that the data intent will be non null
        // on success.
        if (resultData == null) return null;

        final String accountType = resultData.getStringExtra(AccountManager.KEY_ACCOUNT_TYPE);
        final String accountName = resultData.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);

        // Just in case
        if (TextUtils.isEmpty(accountType) || TextUtils.isEmpty(accountName)) return null;

        return new AccountWithDataSet(accountName, accountType, null);
    }
}