naturalDuration testing for humanize

humanize.dart

void main() {
  print("# core values");
  var dayCounts = [
    -700,
    -365,
    -90,
    -30,
    -15,
    -7,
    -2,
    -1,
    -0.5,
    0.5,
    1,
    2,
    5,
    7,
    10,
    15,
    20,
    25,
    30,
    40,
    50,
    70,
    80,
    100,
    150,
    200,
    300,
    400,
    500,
    700,
    900,
    1200
  ];
  for (var count in dayCounts) {
    var date = DateTime.now().add(Duration(hours: count * 24));
    print("$count days: " + naturalDuration(date));
  }
  print("");
  print("# without Adposition");
  dayCounts = [
    -700,
    -365,
    -90,
    -30,
    -15,
    -7,
    -5,
    -1,
    -0.5,
    0.5,
    1,
    5,
    7,
    15,
    30,
    90,
    365,
    700
  ];
  for (var count in dayCounts) {
    var date = DateTime.now().add(Duration(hours: count * 24));
    print("$count days: " + naturalDuration(date, applyAdposition: false));
  }
  print("");
  print("# AP-style");
  dayCounts = [
    -5475,
    -700,
    -365,
    -90,
    -30,
    -15,
    -7,
    -5,
    -1,
    -0.5,
    0.5,
    1,
    5,
    7,
    15,
    30,
    90,
    365,
    700,
    5475
  ];
  for (var count in dayCounts) {
    var date = DateTime.now().add(Duration(hours: count * 24));
    print("$count days: " + naturalDuration(date, applyAppNumber: true));
  }
  print("");
  print("# AP-style without Adposition");
  dayCounts = [
    -5475,
    -700,
    -365,
    -90,
    -30,
    -15,
    -7,
    -5,
    -1,
    -0.5,
    0.5,
    1,
    5,
    7,
    15,
    30,
    90,
    365,
    700,
    5475
  ];
  for (var count in dayCounts) {
    var date = DateTime.now().add(Duration(hours: count * 24));
    print("$count days: " +
        naturalDuration(date, applyAppNumber: true, applyAdposition: false));
  }
}

String appNumber(int value) {
  List values = [
    "one",
    "two",
    "three",
    "four",
    "five",
    "six",
    "seven",
    "eight",
    "nine"
  ];

  if (value < 0 || value > 10) {
    return "$value";
  } else {
    return values[value - 1];
  }
}

/// adds "in" or "ago" to a natural duration phrase. eg: "in 5 days", "2 months ago".
// this will be more useful when attempting internationalisation
String _applyAdposition(String value, bool inPast) {
  var modifier = inPast ? "ago" : "in";
  var isSuffix = inPast ? true : false;
  if (isSuffix)
    return value + " " + modifier;
  else
    return modifier + " " + value;
}

/// Present date values as a string in natural duration units like weeks, months,
/// and years relative to the current date.
/// Examples:
///   * A date 14 days in the past would return "2 weeks ago".
///   * A date 40 days in the future would return "in 6 weeks".
///   * A date 700 days in the past would return "2 years ago".
/// Supports only English duration and unit names currently.
String naturalDuration(DateTime value,
    {bool applyAdposition = true, bool applyAppNumber = false}) {
  var duration = value.difference(DateTime.now());
  var inPast = duration.inMilliseconds < 0;
  var days = duration.inDays.abs();

  // TODO: use naturalTime and naturalDay here
  if (days < 1) return inPast ? "earlier today" : "today";
  if (days < 2) return inPast ? "yesterday" : "tomorrow";

  var weeks = (days / 7).round();
  var months = (days / 30).round();
  var years = (days / 365).round();

  var phrase;
  // up to 10 days, but not 1 week exactly
  if (days < 11 && days != 7) {
    phrase = "${applyAppNumber ? appNumber(days) : days} days";
  }
  // one week
  else if (weeks == 1) {
    phrase = "${applyAppNumber ? appNumber(weeks) : weeks} week";
  }
  // multiple weeks but not 4 weeks (eg: 3 weeks, 6 weeks)
  else if (weeks != 4 && weeks < 8) {
    phrase = "${applyAppNumber ? appNumber(weeks) : weeks} weeks";
  }
  // 1 month
  else if (weeks == 4) {
    phrase = "${applyAppNumber ? appNumber(months) : months} month";
  }
  // multiple months
  else if (months < 12) {
    phrase = "${applyAppNumber ? appNumber(months) : months} months";
  }
  // 1 year
  else if (years == 1) {
    phrase = "${applyAppNumber ? appNumber(years) : years} year";
  }
  // multiple years
  else if (years > 1) {
    phrase = "${applyAppNumber ? appNumber(years) : years} years";
  }
  // TODO: raise exception if term is still null

  return applyAdposition ? _applyAdposition(phrase, inPast) : phrase;
}