<?php
$part = "";
function is_part($line) {
	global $part;
	list($this_word, $this_part, $this_defn) = preg_split("/[\t]+/", trim($line));
	return $this_part == $part;
}

$part = $_GET["part"];

# pick a random word
# pick 5 lines with same part of speech for candidate answers
$lines = file("grewords.txt");
$lines = array_filter($lines, "is_part");
shuffle($lines);
$lines = array_slice($lines, 0, 5);
list($word, $part, $defn) = preg_split("/[\t]+/", trim($lines[array_rand($lines)]));

# pack into JSON data
$json = array(
	"word" => $word,
	"part" => $part,
	"choices" => array()
);

foreach ($lines as $line) {
	list($this_word, $this_pos, $this_defn) = preg_split("/[\t]+/", trim($line));
	$json["choices"][] = array(
		"definition" => $this_defn,
		"correct" => $this_defn == $defn ? true : false
	);
}

header("Content-type: application/json");
print pretty_json(json_encode($json));


// Return a human-readable version the given JSON.
// Adapted from http://www.php.net/manual/en/function.json-encode.php#80339
function pretty_json($input) {
	$tab = "\t";
	$nl = "\n";
	$indent = 0;
	$in_string = false;

	$output = "";
	for ($i = 0; $i < strlen($input); $i++) {
		$char = $input[$i];
		$before = $after = '';
		if (!$in_string) {
			switch ($char) {
				case '{':
				case '[':
					$after = $nl . str_repeat($tab, ++$indent);
					break;

				case '}':
				case ']':
					$before = $nl . str_repeat($tab, --$indent);
					break;

				case ',':
					$after = $nl . str_repeat($tab, $indent);
					break;

				case ':':
					$after = " ";
					break;

				case '"':
					if ($i == 0 || $input[$i-1] != '\\') {
						$in_string = true;
					}
			}
		} else if ($char == '"' && $input[$i-1] != '\\') {
			$in_string = false;
		}
		$output .= $before . $char . $after;
	}

	return $output;
}