WSHHashFunc

/**
 * Created by KoMeDiAnT on 4/12/2017.
 */

function printHelp() {
    WSH.echo('usage: CScript //nologo WSHHash.js input_file.txt \
    \n//nologo: Prevent logo display: No banner will be shown at execution time \
    \ninput_file: name of input file')
}

//@return {number}
function SimpleHash(str) {
    var hash = 0;

    for (var i = 0; i < str.length; i++){
        hash += str.charCodeAt(i);
    }

    return hash;
}

//@return {number}
function SquareHash(str) {
    var hash = 0;

    for (var i = 0; i < str.length; i++){
        hash += str.charCodeAt(i)*str.charCodeAt(i);
    }

    return hash;
}

function FindBySimpleHash(str, subStr) {
    var collision = 0;
    var strHash = 0;
    var subStrHash = SimpleHash(subStr);

    for (var i = 0; i < str.length - subStr.length + 1; i++){
        if(i === 0){
            strHash = SimpleHash(str.substr(0, subStr.length));
        }
        else{
            strHash += str.charCodeAt(i + subStr.length - 1) - str.charCodeAt(i - 1);
        }

        if (strHash === subStrHash){
            var j = 0;

            while(str.charAt(i + j) === subStr.charAt(j)){
                j++;

                if (j === subStr.length){
                    var end = i + j - 1;
                    WSH.echo('Begin: ' + i + '   End: ' + end);
                    collision -= 1;
                    break;
                }
            }

            collision++;
        }
    }

    WSH.echo('Amount of collisions: ' + collision);
}

function FindBySquareHash(str, subStr) {
    var collision = 0;
    var strHash = 0;
    var subStrHash = SquareHash(subStr);

    for (var i = 0; i < str.length - subStr.length + 1; i++){
        if (i === 0){
            strHash = SquareHash(str.substr(0, subStr.length));
        }
        else{
            strHash += str.charCodeAt(i + subStr.length - 1)*str.charCodeAt(i + subStr.length - 1)
                - str.charCodeAt(i - 1)*str.charCodeAt(i - 1);
        }

        if (strHash === subStrHash){
            var j = 0;

            while(str.charAt(i + j) === subStr.charAt(j)){
                j++;

                if (j === subStr.length){
                    var end = i + j - 1;
                    WSH.echo('Begin: ' + i + '   End: ' + end);
                    collision--;
                    break;
                }
            }

            collision++;
        }
    }

   WSH.echo('Amount of collisions: ' + collision);
}

function FindByRAndCHash(str, subStr) {
    var collision = 0;
    var strHash = 0;
    var subStrHash = 0;

    for (var i = 0; i < subStr.length; i++){
        strHash += str.charCodeAt(i)*Math.pow(2, subStr.length - i - 1);
        subStrHash += subStr.charCodeAt(i)*Math.pow(2, subStr.length - i - 1);
    }

    var i = 0;

    while(i < str.length - subStr.length + 1){

        if (strHash === subStrHash){
            var j = 0;

            while(str.charAt(i + j) === subStr.charAt(j)){
                j++;

                if (j === subStr.length){
                    var end = i + j - 1;
                    WSH.echo('Begin: ' + i + '   End: ' + end);
                    collision--;
                    break;
                }
            }
            collision++;
        }
        i++;
        strHash = (strHash - str.charCodeAt(i - 1)*Math.pow(2, subStr.length - 1))*2 + str.charCodeAt(i + subStr.length - 1);
    }

    WSH.echo('Amount of collisions: ' + collision);
}

function main() {
    if (WSH.Arguments.length === 0){
        printHelp();
        return;
    }

    var fso = new ActiveXObject('Scripting.FileSystemObject')
    var ts = fso.OpenTextFile(WSH.Arguments(0));
    var inputData = ts.ReadAll();

    // Раскомментируй, если хочешь проверку работы скрипта
    // WSH.echo('Type string, please')
    // var inputData = WScript.StdIn.ReadLine();

    if (inputData === ''){
        WSH.echo('Input file is empty');
        return;
    }

    WSH.echo('Type substring')
    var subStr = WScript.StdIn.ReadLine();

    if (subStr === ''){
        WSH.echo('Wrong input substring');
        return;
    }
    var start;
    var end;
    var time;

    WSH.echo('\nBy Simple Hash:');
    start = new Date().getTime();
    FindBySimpleHash(inputData, subStr);
    end = new Date().getTime();
    time = end - start;
    WSH.echo('Time for Simple Hash: '+ time + '\n');

    WSH.echo('By Square Hash:');
    start = new Date().getTime();
    FindBySquareHash(inputData, subStr);
    end = new Date().getTime();
    time = end - start;
    WSH.echo('Time for Square Hash: ' + time + '\n');

    WSH.echo('By Rabin And Carp Hash:');
    start = new Date().getTime();
    FindByRAndCHash(inputData, subStr);
    end = new Date().getTime();
    time = end - start;
    WSH.echo('Time for Rabin And Carp Hash: ' + time + '\n');
}

main();