saving_time.js

#!/usr/bin/env node

// Call like : node saving_time.js 9:00

/*

Idea taken from http://codegolf.com/saving-time

Take an input representing a time, like 22:15 or 04:23, and draw a clock indicating
hours and minutes, like below.

        o
    o       o

 o             o

h               o

 o             o

    m       o
        o
*/


function main() {
  var time = process.argv[2];
  var minHrs = parseTime(time);
  console.log(
    buildClock(
      mapHours(minHrs[0]),
      mapMinutes(minHrs[1])
    )
  );
}

function parseTime(time) {
  var parts = time.split(":");
  return [parseInt(parts[0]), parseInt(parts[1])];
};

// mapMinutes 0-60 -> 0-11
function mapMinutes(minutes) {
  return Math.floor(minutes/5);
}

// mapHours   0-24 -> 0-11
function mapHours(hours) {
  return hours % 12;
}

function buildClock(hourPos, minPos) {
  var template =
        "        A\n" +
        "    L       B\n\n"+
        " K             C\n\n" +
        "J               D\n\n" +
        " I             E\n\n" +
        "    H       F\n" +
        "        G";

  for (var i = 0; i <= 11; i++) {
    if (i == hourPos) {
       template = template.replace(String.fromCharCode(65 + i), 'h');
    } else if (i == minPos) {
      template = template.replace(String.fromCharCode(65 + i), 'm');
    } else {
      template = template.replace(String.fromCharCode(65 + i), 'o');
    }
  }

  return template;
}

var tests = [
  function parseTime_should_parse_time () {
    var result  = parseTime("22:10");
    assertArrayEqual(result, [22, 10]);
  },

  function mapMinutes_should_map_correctly() {
    var mappings = [
      [10, 2],
      [32, 6],
      [0, 0],
      [59, 11]
    ];

    mappings.forEach(function(mapping) {
      assertEqual(mapping[1], mapMinutes(mapping[0]));
    });
  },

  function mapHours_should_map_correctly() {
    var mappings = [
      [1, 1],
      [2, 2],
      [12, 0],
      [13, 1],
      [15, 3],
      [23, 11],
      [0, 0]
    ];

    mappings.forEach(function(mapping) {
      assertEqual(mapping[1], mapHours(mapping[0]));
    });
  },

  function test_buildClock() {
    assertEqual(
      buildClock(9, 7),
      "        o\n"+
      "    o       o\n" +
      "\n" +
      " o             o\n" +
      "\n" +
      "h               o\n" +
      "\n" +
      " o             o\n" +
      "\n" +
      "    m       o\n" +
      "        o"
    );

    assertEqual(
      buildClock(2, 7),
      "        o\n"+
      "    o       o\n" +
      "\n" +
      " o             h\n" +
      "\n" +
      "o               o\n" +
      "\n" +
      " o             o\n" +
      "\n" +
      "    m       o\n" +
      "        o"
    );
  }
];

// An improvised, poor man's testing framework

function assert(bool, message) {
  if(!bool) {
    console.log("FAIL: " + message);
    process.exit(1);
  }
}

function assertEqual(real, expected, message) {
  assert(real === expected, "Expected " + expected + ", got " + real + ' ' + (typeof(message) == 'undefined' ? '' : message));
}

function assertArrayEqual(real, expected) {
  assertEqual(real.length, expected.length, "Arrays are not the same length");
  for(var i = 0; i < real.length ; i++) {
    if (Array.isArray(real[i]) && Array.isArray(expected[i])) {
      assertArrayEqual(real[i], expected[i]);
    } else {
      assertEqual(real[i], expected[i], "difference at position " + i);
    }
  }
}

// Run the tests, this will exit if any test fails
tests.forEach(function(test) { test(); });


// Run the program
main();