/*
 * Copyright (C) 2014-2015 Dominik Schürmann <dominik@dominikschuermann.de>
 *
 * 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 org.openintents.openpgp.util;

import java.util.List;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import android.content.Context;
import android.content.Intent;
import android.content.pm.ResolveInfo;

public class OpenPgpUtils {

    public static final Pattern PGP_MESSAGE = Pattern.compile(
            ".*?(-----BEGIN PGP MESSAGE-----.*?-----END PGP MESSAGE-----).*",
            Pattern.DOTALL);

    public static final Pattern PGP_SIGNED_MESSAGE = Pattern.compile(
            ".*?(-----BEGIN PGP SIGNED MESSAGE-----.*?-----BEGIN PGP SIGNATURE-----.*?-----END PGP SIGNATURE-----).*",
            Pattern.DOTALL);

    public static final int PARSE_RESULT_NO_PGP = -1;
    public static final int PARSE_RESULT_MESSAGE = 0;
    public static final int PARSE_RESULT_SIGNED_MESSAGE = 1;

    public static int parseMessage(String message) {
        Matcher matcherSigned = PGP_SIGNED_MESSAGE.matcher(message);
        Matcher matcherMessage = PGP_MESSAGE.matcher(message);

        if (matcherMessage.matches()) {
            return PARSE_RESULT_MESSAGE;
        } else if (matcherSigned.matches()) {
            return PARSE_RESULT_SIGNED_MESSAGE;
        } else {
            return PARSE_RESULT_NO_PGP;
        }
    }

    public static boolean isAvailable(Context context) {
        Intent intent = new Intent(OpenPgpApi.SERVICE_INTENT);
        List<ResolveInfo> resInfo = context.getPackageManager().queryIntentServices(intent, 0);
        if (!resInfo.isEmpty()) {
            return true;
        } else {
            return false;
        }
    }

    public static String convertKeyIdToHex(long keyId) {
        return "0x" + convertKeyIdToHex32bit(keyId >> 32) + convertKeyIdToHex32bit(keyId);
    }

    private static String convertKeyIdToHex32bit(long keyId) {
        String hexString = Long.toHexString(keyId & 0xffffffffL).toLowerCase(Locale.ENGLISH);
        while (hexString.length() < 8) {
            hexString = "0" + hexString;
        }
        return hexString;
    }

    private static final Pattern USER_ID_PATTERN = Pattern.compile("^(.*?)(?: \\((.*)\\))?(?: <(.*)>)?$");

    /**
     * Splits userId string into naming part, email part, and comment part
     *
     * @param userId
     * @return array with naming (0), email (1), comment (2)
     */
    public static String[] splitUserId(String userId) {
        String[] result = new String[]{null, null, null};

        if (userId == null || userId.equals("")) {
            return result;
        }

        /*
         * User ID matching:
         * http://fiddle.re/t4p6f
         *
         * test cases:
         * "Max Mustermann (this is a comment) <max@example.com>"
         * "Max Mustermann <max@example.com>"
         * "Max Mustermann (this is a comment)"
         * "Max Mustermann [this is nothing]"
         */
        Matcher matcher = USER_ID_PATTERN.matcher(userId);
        if (matcher.matches()) {
            result[0] = matcher.group(1);
            result[1] = matcher.group(3);
            result[2] = matcher.group(2);
        }

        return result;
    }
}