terrasea/secret_santa.dart

## secret_santa.dart
import 'dart:html';


class Person {
  String firstname;
  String lastname;

  Person(this.firstname, this.lastname);


  @override
  String toString() {
    return firstname + " " + lastname;
  }


  @override
  bool equals(Person rhs) {
    return firstname == rhs.firstname && lastname == rhs.lastname;
  }
}


class Pair {
  Person first;
  Person second;

  Pair(this.first, this.second);
}


void main() {
  querySelector("#uploadFile")
    .onChange.listen(upload);

  querySelector("#processButton")
    .onClick.listen(createPairs);
}

void upload(Event e) {
  FileUploadInputElement input = e.currentTarget;
  FileList files = input.files;
  if(files.length > 0) {
    File file = files.item(0);
    FileReader reader = new FileReader();
    reader.addEventListener('load', (e) {
      TextAreaElement el = querySelector("#inputText");
      el.value = reader.result.toString();
    });
    reader.readAsText(file, "utf-8");
  }
}


void createPairs(Event e) {
  List<String> people = new List<String>();

  TextAreaElement el = querySelector("#inputText");
  el.value.split("\n").forEach((line) {
    people.add(line);
  });


  DivElement div = querySelector("#pairs");
  StringBuffer pairsHTML = new StringBuffer();
  matchSecretSantas(people).forEach((pair) {
    pairsHTML.write("<div><span>${pair.first}</span> - <span>${pair.second}</span></div>");
  });

  div.innerHtml = pairsHTML.toString();
}


//people items are assumed to be "firstname lastname", anything else is ignored
List<Pair> matchSecretSantas(List<String> people) {
  List<Person> potentials = new List<Person>();
  people.forEach((line) {
    List<String> nameList = line.split(" ");
    if(nameList.length == 2) {
      potentials.add(new Person(nameList[0], nameList[1]));
    }
  });

  potentials.shuffle();
  return _makePair(potentials.first, potentials);
}


//RECURSIVE function
List<Pair> _makePair(Person first, List<Person> potentials, [List<Pair> pairs]) {
  if(pairs == null) {
    pairs = new List<Pair>();
  }
  potentials.remove(first);
  Person second = potentials.firstWhere((person) => _valid(first, person));
  potentials.remove(second);
  pairs.add(new Pair(first, second));

  if(potentials.length == 0) {
    return pairs;
  } else if(potentials.length == 1) {
    Person first = potentials.first;
    Pair seconds = pairs.firstWhere((pair) => _valid(pair.first, first) || _valid(pair.second, first));
    Person second = _valid(seconds.first, first) ? seconds.first : seconds.second;
    potentials.add(second);
  }

  return _makePair(potentials.first, potentials, pairs);
}


bool _valid(Person first, Person second) {
  return _notSamePerson(first, second) && _notShareLastname(first, second);
}


bool _notSamePerson(Person first, Person second) {
  return !first.equals(second);
}


bool _notShareLastname(Person first, Person second) {
  return first.lastname != second.lastname;
}

## secret_santa.html
<!DOCTYPE html>

<html>
  <head>
    <meta charset="utf-8">
    <title>Secret Santa</title>
  </head>
  <body>
    <h1>Secret Santa</h1>

    <div>
      <input type="file" id="uploadFile">
    </div>
    <div>
      <textarea id="inputText" rows="10" cols="50"></textarea>
    </div>
    <div>
      <button id="processButton">Pair Secret Santas</button>
    </div>
    <div id="pairs">

    </div>

    <script type="application/dart" src="secret_santa.dart"></script>
    <script src="packages/browser/dart.js"></script>
  </body>
</html>
	import 'dart:html';


	class Person {
	String firstname;
	String lastname;

	Person(this.firstname, this.lastname);


	@override
	String toString() {
	return firstname + " " + lastname;
	}


	@override
	bool equals(Person rhs) {
	return firstname == rhs.firstname && lastname == rhs.lastname;
	}
	}


	class Pair {
	Person first;
	Person second;

	Pair(this.first, this.second);
	}


	void main() {
	querySelector("#uploadFile")
	.onChange.listen(upload);

	querySelector("#processButton")
	.onClick.listen(createPairs);
	}

	void upload(Event e) {
	FileUploadInputElement input = e.currentTarget;
	FileList files = input.files;
	if(files.length > 0) {
	File file = files.item(0);
	FileReader reader = new FileReader();
	reader.addEventListener('load', (e) {
	TextAreaElement el = querySelector("#inputText");
	el.value = reader.result.toString();
	});
	reader.readAsText(file, "utf-8");
	}
	}



	void createPairs(Event e) {
	List<String> people = new List<String>();

	TextAreaElement el = querySelector("#inputText");
	el.value.split("\n").forEach((line) {
	people.add(line);
	});


	DivElement div = querySelector("#pairs");
	StringBuffer pairsHTML = new StringBuffer();
	matchSecretSantas(people).forEach((pair) {
	pairsHTML.write("<div><span>${pair.first}</span> - <span>${pair.second}</span></div>");
	});

	div.innerHtml = pairsHTML.toString();
	}



	//people items are assumed to be "firstname lastname", anything else is ignored
	List<Pair> matchSecretSantas(List<String> people) {
	List<Person> potentials = new List<Person>();
	people.forEach((line) {
	List<String> nameList = line.split(" ");
	if(nameList.length == 2) {
	potentials.add(new Person(nameList[0], nameList[1]));
	}
	});

	potentials.shuffle();
	return _makePair(potentials.first, potentials);
	}


	//RECURSIVE function
	List<Pair> _makePair(Person first, List<Person> potentials, [List<Pair> pairs]) {
	if(pairs == null) {
	pairs = new List<Pair>();
	}
	potentials.remove(first);
	Person second = potentials.firstWhere((person) => _valid(first, person));
	potentials.remove(second);
	pairs.add(new Pair(first, second));

	if(potentials.length == 0) {
	return pairs;
	} else if(potentials.length == 1) {
	Person first = potentials.first;
	Pair seconds = pairs.firstWhere((pair) => _valid(pair.first, first) \|\| _valid(pair.second, first));
	Person second = _valid(seconds.first, first) ? seconds.first : seconds.second;
	potentials.add(second);
	}

	return _makePair(potentials.first, potentials, pairs);
	}


	bool _valid(Person first, Person second) {
	return _notSamePerson(first, second) && _notShareLastname(first, second);
	}


	bool _notSamePerson(Person first, Person second) {
	return !first.equals(second);
	}


	bool _notShareLastname(Person first, Person second) {
	return first.lastname != second.lastname;
	}
	<!DOCTYPE html>

	<html>
	<head>
	<meta charset="utf-8">
	<title>Secret Santa</title>
	</head>
	<body>
	<h1>Secret Santa</h1>

	<div>
	<input type="file" id="uploadFile">
	</div>
	<div>
	<textarea id="inputText" rows="10" cols="50"></textarea>
	</div>
	<div>
	<button id="processButton">Pair Secret Santas</button>
	</div>
	<div id="pairs">

	</div>

	<script type="application/dart" src="secret_santa.dart"></script>
	<script src="packages/browser/dart.js"></script>
	</body>
	</html>