/**
 * Display a table of memory locations.
 * Call with [start] and [end] indices to display a range.
 * @param {Uint8Array} mem - Memory to display
 * @param {number}  [start] - A start-index, in decimal
 * @param {number}  [end] - An end-index, in decimal
 **/
const logMemory = (mem, start=0, end=mem.length) => {
  // This function can only handle
  // an even number of array entries
  if ((start % 2) === 1) { start -= 1; }
  if ((end % 2) === 1) { end += 1; }

  mem = mem.slice(start, end);
  console.log(`┌────────┬────────┬────────┐`);
  console.log(`│  addr  │   op   │   arg  │`);
  console.log(`├────────┼────────┼────────┤`);
  //for (let i = 0; i < mem.length; i += 2) { 
  for (let i = start; i < mem.length; i +=2) {
    console.log(`│   ${num2hex(i)}   │   ${num2hex(mem[i])}   │   ${num2hex(mem[i+1])}   │`);

    // Add a blank row every 4 lines:
    if (((i + 2) % 8) === 0) {
      if ((i < (mem.length - 2))) {
        console.log(`│        │        │        │`);
      }
    }
  }
  console.log(`└────────┴────────┴────────┘`);
}

const logRunningHeader = () => {
  console.log();
  let time = new Date();
  console.log( `┌─────────────────────┐`);
  console.log( `│ Running at ${time.toLocaleTimeString('en-GB')} │` );
  console.log( `└─────────────────────┘`);
}

/** 
 * @param {number} num
 * @returns {string}
 */
const num2hex = (num) => num.toString(16).toUpperCase().padStart(2, "0");

/** 
 * @param {string} hex
 * @returns {number}
 */
const hex2num = (hex) => parseInt(hex, 16);

/**
 * Convert a number to binary
 * See here for an explanation: https://stackoverflow.com/questions/9939760/how-do-i-convert-an-integer-to-binary-in-javascript
 * @param {number} num
 * @returns {string} binary representation of the input
 **/
const num2bin = (num) => (num >>> 0).toString(2).padStart(8, "0");

module.exports = {
  "logMemory": logMemory,
  "logRunningHeader": logRunningHeader,
  "num2hex": num2hex,
  "hex2num": hex2num,
  "num2bin": num2bin,
}