/*
  Copyright (C) 2013-2017 Grégory Soutadé
  
  This file is part of gPass.
  
  gPass is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  
  gPass 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 General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with gPass.  If not, see <http://www.gnu.org/licenses/>.
*/

var default_preferences = {"pbkdf2_level": 1000,
			   "account_url": "https://gpass-demo.soutade.fr/demo"};

var browser = browser || chrome;
var crypto = crypto || window.crypto;

function notify(text, data)
{
    browser.runtime.sendMessage({type: "notification", options:{"message":text}});
}

// https://stackoverflow.com/questions/6965107/converting-between-strings-and-arraybuffers
function ab2str(buf) {
    return String.fromCharCode.apply(null, new Uint8Array(buf));
}

// https://developers.google.com/web/updates/2012/06/How-to-convert-ArrayBuffer-to-and-from-String
function str2ab2(str) {
    var chars = []
    for (var i=0, strLen=str.length; i < strLen; i++) {
	chars.push(str.charCodeAt(i));
    }
    return new Uint8Array(chars);
}

function str2ab(str) {
    var buf = new ArrayBuffer(str.length); // 2 bytes for each char
    // var buf = new ArrayBuffer(str.length*2); // 2 bytes for each char
    var bufView = new Uint8Array(buf);
    for (var i=0, strLen=str.length; i < strLen; i++) {
	bufView[i] = str.charCodeAt(i);
    }
    return bufView;
}

function returnResult(result) { return result;}
function onError(error) { console.error(error); }

function pbkdf2(mkey, salt, level)
{
    debug("Process pbkdf2 with " + mkey);

    AESCBC = {
        name: "AES-CBC",
        length: 256,
    }
    level=1000;

    var key = str2ab(mkey);
    return crypto.subtle.importKey("raw", key, {name: "PBKDF2"}, false, ["deriveBits", "deriveKey"])
	.then(function(key){
            //sha-256
            return crypto.subtle.deriveKey({
		name: "PBKDF2",
		salt: str2ab(salt),
		iterations: level,
		hash: "SHA-256",
            }, key, AESCBC, false, ["encrypt", "decrypt", "unwrapKey", "wrapKey"])
		.then(function(key) {
		    return key;
		})
		.catch(function(err){
		    console.log("Error derive key " + err);
		});
	})
	.catch(function(err) {
	    console.log("Error import key" + err);
	});
}

function _encrypt(mkey, data)
{
    while ((data.length % 16))
	data += "\0";
    
    debug("Encrypt " + data);

    data = str2ab(data);

    nulliv = new Uint8Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);

    promise = mkey.then(function(mkey){
    	return crypto.subtle.encrypt({
            name: "AES-CBC",
            iv: nulliv
    	}, mkey, data)})
    	.then(function(encrypted) {
    	    return ab2str(encrypted);
    	})
    	.catch(function(encryption) {
    	    console.log("Encryption rejected " + encryption);
    	});

    return promise;
}

async function _decrypt(mkey, data)
{
    while ((data.length % 16))
	data += "\0";

    pkcs7_padding = new Uint8Array([16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16]);
    pkcs7_padding = await _encrypt(mkey, ab2str(pkcs7_padding));

    debug("Decrypt " + data);

    data = str2ab(data + pkcs7_padding);

    nulliv = new Uint8Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);

    promise = mkey.then(function(mkey){
    	return crypto.subtle.decrypt({
            name: "AES-CBC",
            iv: nulliv
    	}, mkey, data)})
    	.then(function(decrypted) {
    	    return ab2str(decrypted);
    	})
    	.catch(function(decryption) {
    	    console.log("Decryption rejected " + decryption);
    	});

    return promise;
}

async function encrypt(mkey, data)
{
    var result = "";
    
    while (data.length > 16)
    {
	res = await _encrypt(mkey, data.slice(0, 16));
	// Remove PKCS7 padding
	result += res.slice(0, 16);
	data = data.slice(16);
    }
    res = await _encrypt(mkey, data);
    result += res.slice(0, 16);

    return result;
}

async function decrypt(mkey, data)
{
    var result = "";
    
    while (data.length > 16)
    {
	res = await _decrypt(mkey, data.slice(0, 16));
	// Remove PKCS7 padding
	result += res.slice(0, 16);
	data = data.slice(16);
    }
    res = await _decrypt(mkey, data);
    result += res.slice(0, 16);

    return result;
}