<?php

namespace Program\Parser;

use Program\Word;

class WordParser
{
	/**
	 * @param string $filename
	 * @return Word[]
	 */
	public function parseFile(string $filename): array
	{
		$lines = explode(PHP_EOL, file_get_contents($filename));
		$lines = array_filter($lines);

		return $this->parse($lines);
	}


	/**
	 * @param string[] $lines
	 * @return Word[]
	 */
	public function parse(array $lines): array
	{
		/** @var Word[] $words */
		$words = [];
		foreach ($lines as $line) {
			$characters = str_split(trim($line) . ' ');
			$state = 'NONE';
			$wordBuffer = [];
			foreach ($characters as $character) {
				if ('READING' === $state) {
					if ('-' === $character || is_numeric($character)) {
						$wordBuffer['value'] .= $character;
						continue;
					}
					// Word is finished
					$words[] = new Word($wordBuffer['register'], $wordBuffer['value']);
					$wordBuffer = [];
					$state = 'NONE';
				}

				if ('NONE' === $state && ctype_alpha($character)) {
					$state = 'READING';
					$wordBuffer = ['register' => $character, 'value' => ''];
					continue;
				}

				if (strpos($line, 'EOF') !== false) {
					break 2; // End of program reached
				}

				if (';' === $character) {
					break; // Rest of line is a comment
				}
			}
		}

		return $words;
	}
}