/*
 * Copyright 2017 Vorlonsoft LLC
 *
 * 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.vorlonsoft.android.http;

import android.content.Context;
import android.content.SharedPreferences;
import android.text.TextUtils;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import cz.msebera.android.httpclient.client.CookieStore;
import cz.msebera.android.httpclient.cookie.Cookie;

/**
 * A persistent cookie store which implements the Apache HttpClient {@link CookieStore} interface.
 * Cookies are stored and will persist on the user's device between application sessions since they
 * are serialized and stored in {@link SharedPreferences}. <p>&nbsp;</p> Instances of this class are
 * designed to be used with {@link AsyncHttpClient#setCookieStore}, but can also be used with a
 * regular old apache HttpClient/HttpContext if you prefer.
 */
public class PersistentCookieStore implements CookieStore {
    private static final String LOG_TAG = "PersistentCookieStore";
    private static final String COOKIE_PREFS = "CookiePrefsFile";
    private static final String COOKIE_NAME_STORE = "names";
    private static final String COOKIE_NAME_PREFIX = "cookie_";
    private final ConcurrentHashMap<String, Cookie> cookies;
    private final SharedPreferences cookiePrefs;
    private boolean omitNonPersistentCookies = false;

    /**
     * Construct a persistent cookie store.
     *
     * @param context Context to attach cookie store to
     */
    public PersistentCookieStore(Context context) {
        cookiePrefs = context.getSharedPreferences(COOKIE_PREFS, 0);
        cookies = new ConcurrentHashMap<String, Cookie>();

        // Load any previously stored cookies into the store
        String storedCookieNames = cookiePrefs.getString(COOKIE_NAME_STORE, null);
        if (storedCookieNames != null) {
            String[] cookieNames = TextUtils.split(storedCookieNames, ",");
            for (String name : cookieNames) {
                String encodedCookie = cookiePrefs.getString(COOKIE_NAME_PREFIX + name, null);
                if (encodedCookie != null) {
                    Cookie decodedCookie = decodeCookie(encodedCookie);
                    if (decodedCookie != null) {
                        cookies.put(name, decodedCookie);
                    }
                }
            }

            // Clear out expired cookies
            clearExpired(new Date());
        }
    }

    @Override
    public void addCookie(Cookie cookie) {
        if (omitNonPersistentCookies && !cookie.isPersistent())
            return;
        String name = cookie.getName() + cookie.getDomain();

        // Save cookie into local store, or remove if expired
        if (!cookie.isExpired(new Date())) {
            cookies.put(name, cookie);
        } else {
            cookies.remove(name);
        }

        // Save cookie into persistent store
        SharedPreferences.Editor prefsWriter = cookiePrefs.edit();

        // This prevents map.keySet to compile to a Java 8+ KeySetView return type
        Map<String, Cookie> map = cookies;
        prefsWriter.putString(COOKIE_NAME_STORE, TextUtils.join(",", map.keySet()));
        prefsWriter.putString(COOKIE_NAME_PREFIX + name, encodeCookie(new SerializableCookie(cookie)));
        prefsWriter.apply();
    }

    @Override
    public void clear() {
        // Clear cookies from persistent store
        SharedPreferences.Editor prefsWriter = cookiePrefs.edit();
        // This prevents map.keySet to compile to a Java 8+ KeySetView return type
        Map<String, Cookie> map = cookies;
        for (String name : map.keySet()) {
            prefsWriter.remove(COOKIE_NAME_PREFIX + name);
        }
        prefsWriter.remove(COOKIE_NAME_STORE);
        prefsWriter.apply();

        // Clear cookies from local store
        cookies.clear();
    }

    @Override
    public boolean clearExpired(Date date) {
        boolean clearedAny = false;
        SharedPreferences.Editor prefsWriter = cookiePrefs.edit();

        for (ConcurrentHashMap.Entry<String, Cookie> entry : cookies.entrySet()) {
            String name = entry.getKey();
            Cookie cookie = entry.getValue();
            if (cookie.isExpired(date)) {
                // Clear cookies from local store
                cookies.remove(name);

                // Clear cookies from persistent store
                prefsWriter.remove(COOKIE_NAME_PREFIX + name);

                // We've cleared at least one
                clearedAny = true;
            }
        }

        // Update names in persistent store
        if (clearedAny) {
            // This prevents map.keySet to compile to a Java 8+ KeySetView return type
            Map<String, Cookie> map = cookies;
            prefsWriter.putString(COOKIE_NAME_STORE, TextUtils.join(",", map.keySet()));
        }
        prefsWriter.apply();

        return clearedAny;
    }

    @Override
    public List<Cookie> getCookies() {
        return new ArrayList<Cookie>(cookies.values());
    }

    /**
     * Will make PersistentCookieStore instance ignore Cookies, which are non-persistent by
     * signature (`Cookie.isPersistent`)
     *
     * @param omitNonPersistentCookies true if non-persistent cookies should be omited
     */
    public void setOmitNonPersistentCookies(boolean omitNonPersistentCookies) {
        this.omitNonPersistentCookies = omitNonPersistentCookies;
    }

    /**
     * Non-standard helper method, to delete cookie
     *
     * @param cookie cookie to be removed
     */
    public void deleteCookie(Cookie cookie) {
        String name = cookie.getName() + cookie.getDomain();
        cookies.remove(name);
        SharedPreferences.Editor prefsWriter = cookiePrefs.edit();
        prefsWriter.remove(COOKIE_NAME_PREFIX + name);
        prefsWriter.apply();
    }

    /**
     * Serializes Cookie object into String
     *
     * @param cookie cookie to be encoded, can be null
     * @return cookie encoded as String
     */
    protected String encodeCookie(SerializableCookie cookie) {
        if (cookie == null)
            return null;
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        try {
            ObjectOutputStream outputStream = new ObjectOutputStream(os);
            outputStream.writeObject(cookie);
        } catch (IOException e) {
            AsyncHttpClient.log.d(LOG_TAG, "IOException in encodeCookie", e);
            return null;
        }

        return byteArrayToHexString(os.toByteArray());
    }

    /**
     * Returns cookie decoded from cookie string
     *
     * @param cookieString string of cookie as returned from http request
     * @return decoded cookie or null if exception occured
     */
    protected Cookie decodeCookie(String cookieString) {
        byte[] bytes = hexStringToByteArray(cookieString);
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes);
        Cookie cookie = null;
        try {
            ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
            cookie = ((SerializableCookie) objectInputStream.readObject()).getCookie();
        } catch (IOException e) {
            AsyncHttpClient.log.d(LOG_TAG, "IOException in decodeCookie", e);
        } catch (ClassNotFoundException e) {
            AsyncHttpClient.log.d(LOG_TAG, "ClassNotFoundException in decodeCookie", e);
        }

        return cookie;
    }

    /**
     * Using some super basic byte array &lt;-&gt; hex conversions so we don't have to rely on any
     * large Base64 libraries. Can be overridden if you like!
     *
     * @param bytes byte array to be converted
     * @return string containing hex values
     */
    protected String byteArrayToHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder(bytes.length * 2);
        for (byte element : bytes) {
            int v = element & 0xff;
            if (v < 16) {
                sb.append('0');
            }
            sb.append(Integer.toHexString(v));
        }
        return sb.toString().toUpperCase(Locale.US);
    }

    /**
     * Converts hex values from strings to byte arra
     *
     * @param hexString string of hex-encoded values
     * @return decoded byte array
     */
    protected byte[] hexStringToByteArray(String hexString) {
        int len = hexString.length();
        byte[] data = new byte[len / 2];
        for (int i = 0; i < len; i += 2) {
            data[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4) + Character.digit(hexString.charAt(i + 1), 16));
        }
        return data;
    }
}