/* gpgme.js - Javascript integration for gpgme
 * Copyright (C) 2018 Bundesamt für Sicherheit in der Informationstechnik
 *
 * This file is part of GPGME.
 *
 * GPGME is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * GPGME is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, see <http://www.gnu.org/licenses/>.
 * SPDX-License-Identifier: LGPL-2.1+
 */

/**
 * A connection port will be opened for each communication between gpgmejs and
 * gnupg. It should be alive as long as there are additional messages to be
 * expected.
 */
import { permittedOperations } from './permittedOperations'
import { gpgme_error } from "./Errors"
import { GPGME_Message, createMessage } from "./Message";

/**
 * A Connection handles the nativeMessaging interaction.
 */
export class Connection{

    constructor(){
        this.connect();
    }

    /**
     * Retrieves the information about the backend.
     * @param {Boolean} details (optional) If set to false, the promise will
     *  just return a connection status
     * @returns {Promise<Object>}
     *      {String} The property 'gpgme': Version number of gpgme
     *      {Array<Object>} 'info' Further information about the backends.
     *      Example:
     *          "protocol":     "OpenPGP",
     *          "fname":        "/usr/bin/gpg",
     *          "version":      "2.2.6",
     *          "req_version":  "1.4.0",
     *          "homedir":      "default"
     */
    checkConnection(details = true){
        if (details === true) {
            return this.post(createMessage('version'));
        } else {
            let me = this;
            return new Promise(function(resolve,reject) {
                Promise.race([
                    me.post(createMessage('version')),
                    new Promise(function(resolve, reject){
                        setTimeout(function(){
                            reject(gpgme_error('CONN_TIMEOUT'));
                        }, 500);
                    })
                ]).then(function(result){
                        resolve(true);
                }, function(reject){
                    resolve(false);
                });
            });
        }
    }

    /**
     * Immediately closes the open port.
     */
    disconnect() {
        if (this._connection){
            this._connection.disconnect();
            this._connection = null;
        }
    }

    /**
     * Opens a nativeMessaging port.
     */
    connect(){
        if (!this._connection){
            this._connection = chrome.runtime.connectNative('gpgmejson');
        }
    }

    /**
     * Sends a message and resolves with the answer.
     * @param {GPGME_Message} message
     * @returns {Promise<Object>} the gnupg answer, or rejection with error
     * information.
     */
    post(message){
        if (!this._connection) {

        }
        if (!message || !message instanceof GPGME_Message){
            return Promise.reject(gpgme_error('PARAM_WRONG'), message);
        }
        if (message.isComplete !== true){
            return Promise.reject(gpgme_error('MSG_INCOMPLETE'));
        }
        let me = this;
        return new Promise(function(resolve, reject){
            let answer = new Answer(message);
            let listener = function(msg) {
                if (!msg){
                    me._connection.onMessage.removeListener(listener)
                    reject(gpgme_error('CONN_EMPTY_GPG_ANSWER'));
                } else if (msg.type === "error"){
                    me._connection.onMessage.removeListener(listener);
                    reject(gpgme_error('GNUPG_ERROR', msg.msg));
                } else {
                    let answer_result = answer.add(msg);
                    if (answer_result !== true){
                        me._connection.onMessage.removeListener(listener);
                        reject(answer_result);
                    }
                    if (msg.more === true){
                        me._connection.postMessage({'op': 'getmore'});
                    } else {
                        me._connection.onMessage.removeListener(listener)
                        resolve(answer.message);
                    }
                }
            };

            me._connection.onMessage.addListener(listener);
            if (permittedOperations[message.operation].pinentry){
                return me._connection.postMessage(message.message);
            } else {
                return Promise.race([
                    me._connection.postMessage(message.message),
                    function(resolve, reject){
                        setTimeout(function(){
                            reject(gpgme_error('CONN_TIMEOUT'));
                        }, 5000);
                    }]).then(function(result){
                    return result;
                }, function(reject){
                    if(!reject instanceof Error) {
                        return gpgme_error('GNUPG_ERROR', reject);
                    } else {
                        return reject;
                    }
                });
            }
        });
     }
};

/**
 * A class for answer objects, checking and processing the return messages of
 * the nativeMessaging communication.
 * @param {String} operation The operation, to look up validity of returning messages
 */
class Answer{

    constructor(message){
        this.operation = message.operation;
        this.expected = message.expected;
    }

    /**
     * Add the information to the answer
     * @param {Object} msg The message as received with nativeMessaging
     * returns true if successfull, gpgme_error otherwise
     */
    add(msg){
        if (this._response === undefined){
            this._response = {};
        }
        let messageKeys = Object.keys(msg);
        let poa = permittedOperations[this.operation].answer;
        if (messageKeys.length === 0){
            return gpgme_error('CONN_UNEXPECTED_ANSWER');
        }
        for (let i= 0; i < messageKeys.length; i++){
            let key = messageKeys[i];
            switch (key) {
                case 'type':
                    if ( msg.type !== 'error' && poa.type.indexOf(msg.type) < 0){
                        return gpgme_error('CONN_UNEXPECTED_ANSWER');
                    }
                    break;
                case 'more':
                    break;
                default:
                    //data should be concatenated
                    if (poa.data.indexOf(key) >= 0){
                        if (!this._response.hasOwnProperty(key)){
                            this._response[key] = '';
                        }
                        this._response[key] += msg[key];
                    }
                    //params should not change through the message
                    else if (poa.params.indexOf(key) >= 0){
                        if (!this._response.hasOwnProperty(key)){
                            this._response[key] = msg[key];
                        }
                        else if (this._response[key] !== msg[key]){
                                return gpgme_error('CONN_UNEXPECTED_ANSWER',msg[key]);
                        }
                    }
                    //infos may be json objects etc. Not yet defined.
                    // Pushing them into arrays for now
                    else if (poa.infos.indexOf(key) >= 0){
                        if (!this._response.hasOwnProperty(key)){
                            this._response[key] = [];
                        }
                        this._response[key].push(msg[key]);
                    }
                    else {
                        return gpgme_error('CONN_UNEXPECTED_ANSWER');
                    }
                    break;
            }
        }
        return true;
    }

    /**
     * @returns {Object} the assembled message, original data assumed to be
     * (javascript-) strings
     */
    get message(){
        let keys = Object.keys(this._response);
        let msg = {};
        let poa = permittedOperations[this.operation].answer;
        for (let i=0; i < keys.length; i++) {
            if (poa.data.indexOf(keys[i]) >= 0
                && this._response.base64 === true
            ) {
                msg[keys[i]] = atob(this._response[keys[i]]);
                if (this.expected === 'base64'){
                    msg[keys[i]] = this._response[keys[i]];
                } else {
                    msg[keys[i]] = decodeURIComponent(
                        atob(this._response[keys[i]]).split('').map(function(c) {
                            return '%' +
                                ('00' + c.charCodeAt(0).toString(16)).slice(-2);
                        }).join(''));
                }
            } else {
                msg[keys[i]] = this._response[keys[i]];
            }
        }
        return msg;
    }
}