var LineReader = require('node-line-reader').LineReader;
const fs = require('fs');

let registers = [{name: 'ACC', val: 0}, {name: 'R0', val: 0}];
let mem = [6,9,4,2,7,8,1];
let marks = [];
let counter = 0;

fs.readFile('code.txt', {encoding: 'utf-8'}, function(err, data) {
    if (!err) {
        let code = data.replace(/,/g,'').replace(/\r/g,'').split('\n');
        let filtered = code.filter((val, i, arr) => {
            return val != '';
        });
        runProgram(filtered);
    } else {
        console.log(err);
    }
});

const runProgram = (sourceCode) => {
    while(counter < sourceCode.length - 1) {
        if (sourceCode[counter].includes(':')) {
            marks.push({pos: counter, val: sourceCode[counter].replace(/:/g,'')});
        } else {
            processCommand(sourceCode[counter], sourceCode[counter - 1]);
        }
        counter++;
    }
    console.log(registers);
}

const processCommand = (line, previousLine) => {
    let data = line.split(' ');
    let prevData = previousLine.split(' ');
    switch(data[0]) {
        case 'MOV' : processMov(data);
        break;
        case 'ADD' : processAdd(data);
        break;
        case 'DEC' : processDec(data);
        break;
        case 'JNE' : processJne(data, processCmp(prevData));
        break;
    }
}

const processJne = (data, condition) => {
    if (!condition) {
        marks.forEach((mark, i) => {
            if (mark.val === 'loop') { counter = mark.pos }
        });
    }
}

const processCmp = (data) => {
    let regValue = registers[findRegister(data[1])].val;
    return regValue <= data[2];
}

const processDec = (data) => {
    let index = findRegister(data[1]);
    registers[index].val -= 1;
}

const processAdd = (data) => {
    registers[0].val += memAccess(data[1]);
}

const processMov = (data) => {
    if (data[2].includes('[') && data[2].includes(']')) {
        registers[findRegister(data[1])].val = memAccess(data[2]);
    } else {
        registers[findRegister(data[1])].val = parseInt(data[2]);
    }
}

const memAccess = (sector) => {
    const numbers = /^[0-9]+$/
    let sectorData = sector.replace(/\[|\]/g,'');
    if (sectorData.match(numbers)) {
        return mem[parseInt(sectorData, 10)];
    }
    else {
        let reg = registers[findRegister(sectorData)];
        return mem[reg.val];
    }
}

const findRegister = (name) => {
    let index = -1;
    registers.forEach((register, i) => {
        if (register.name === name) { index = i; }
    });
    return index;
}