#!/usr/bin/env node

// Usage: ./run-cpu.js -f code.asm [--debug] [--step] [--pretty]

const fs = require('fs');
const computer = require('./cpu.js');
const assembler = require('./assembler.js');
const { logRunningHeader } = require('./logging.js');

// Load file...

let filename;
try {
  filename = getArgumentValue('-f', `Missing filename`);
} catch (error) {
  console.error(error.message);
  process.exit()
}

const inputFile_str = fs.readFileSync(filename, 'utf8');


// Check optional arguments...

let debug = false;
let singleStep = false;
let prettyPrint = false;
process.argv.forEach((arg) => { if (arg === '--debug')  { debug = true } });
process.argv.forEach((arg) => { if (arg === '--step')   { singleStep = true } });
process.argv.forEach((arg) => { if (arg === '--pretty') { prettyPrint = true } });

let speed = null;
process.argv.forEach((arg, index) => {
  if (arg === '--speed' && process.argv.length > (index -1)) {
    speed = parseInt(process.argv[index + 1]);
  }
});


let assemblerOutput = assembler.assemble(inputFile_str);
logRunningHeader();
computer.runProgram(
  assemblerOutput.machineCode,
  assemblerOutput.debugInfo,
  debug,
  singleStep,
  prettyPrint,
  speed
);


// CLI args TODO
// - check if value is the name of another arg
// - usage info
// - catch nonexistant flags

/**
 * @param {string}   flag    - The command line flag, eg. '-f'
 * @param {string}    errorMessage  - The error to throw if a value isn't found
 * @returns {string}
 **/
function getArgumentValue(flag, errorMessage) {
  let value = null;
  process.argv.forEach((arg, index) => {
    if (arg === flag && process.argv.length > (index -1)) {
      value = process.argv[index + 1];
    }
  });
  if (!value) throw new Error(errorMessage);
  return value;
}