<?php

namespace Garfix\JsMinify;

use RuntimeException;

/**
 * This minifier removes whitespace and comments from a Javascript string.
 *
 * See docs for information.
 *
 * @author Patrick van Bergen
 */
class Minifier
{
	const FLAGGED_COMMENTS = 'flaggedComments';

	protected static $defaultOptions = [
		self::FLAGGED_COMMENTS => true
	];

	protected $options = [];

	/**
	 * Processes a javascript string and returns only the required characters,
	 * stripping out all unneeded whitespace and comments.
	 *
	 * @param string $js      The raw javascript to be minified
	 * @param array  $options Various runtime options in an associative array
	 * @throws RuntimeException
	 */
	public static function minify($js, $options = [])
	{
		$minifier = new Minifier($options);
		return $minifier->minifyUsingCallbacks($js);
	}

	public function __construct($options)
	{
		$this->options = array_merge(static::$defaultOptions, $options);
	}

	/**
	 * @param string $js    The raw javascript to be minified
	 * @return string
	 * @throws RuntimeException
	 */
	public function minifyUsingCallbacks($js)
	{
		$e = MinifierExpressions::get();

		// treat all newlines as unix newlines, to keep working with newlines simple
		$shrunkText = str_replace(["\r\n", "\r"], ["\n", "\n"], $js);

		// remove comments
		$exp1 = "~(?:" .  implode("|", $e->tokenExpressions) . ")~su";
		$shrunkText = preg_replace_callback($exp1, [$this, 'removeComments'], $shrunkText);
		MinifierError::checkRegexpError();

		// rewrite blocks by inserting whitespace placeholders
		$exp2 = "~(?:" .  implode("|", $e->allExpressions) . ")~su";
		$shrunkText = preg_replace_callback($exp2, [$this, 'processBlocks'], $shrunkText);
		MinifierError::checkRegexpError();

		// remove all remaining space (without the newlines)
		$shrunkText = preg_replace("~" . $e->someWhitespace . "~", '', $shrunkText);
		MinifierError::checkRegexpError();

		// reduce consecutive newlines to single one
		$shrunkText = preg_replace("~[\\n]+~", "\n", $shrunkText);
		MinifierError::checkRegexpError();

		// remove newlines that may safely be removed
		foreach ($e->safeNewlines as $safeNewline) {
			$shrunkText = preg_replace("~" . $safeNewline . "~", "", $shrunkText);
			MinifierError::checkRegexpError();
		}

		// replace whitespace placeholders by their original whitespace
		$shrunkText = str_replace($e->whitespaceArrayPlaceholders, $e->whitespaceArrayNewline, $shrunkText);
		MinifierError::checkRegexpError();

		// remove leading and trailing whitespace
		return trim($shrunkText);
	}

	/**
	 * Removes all comments that need to be removed
	 * The newlines that are added here may later be removed again
	 *
	 * @param $matches
	 * @return mixed|string
	 */
	protected function removeComments($matches)
	{
		$e = MinifierExpressions::get();

		// the fully matching text
		$match = $matches[0];

		if (!empty($matches['lineComment'])) {
			// not empty because this might glue words together
			return "\n";
		}
		if (!empty($matches['starComment'])) {

			// create a version without leading and trailing whitespace
			$trimmed = trim($match, $e->whitespaceCharsNewline);

			switch ($trimmed[2]) {
				case '@':
					// IE conditional comment
					return $match;
				case '!':
					if ($this->options[self::FLAGGED_COMMENTS]) {
						// option says: leave flagged comments in
						return $match;
					}
			}
			// multi line comment; not empty because this might glue words together
			return "\n";
		}

		// leave other matches unchanged
		return $match;
	}

	/**
	 * Updates the code for all blocks (they contain whitespace that should be conserved)
	 * No early returns: all code must reach `end` and have the whitespace replaced by placeholders
	 *
	 * @param $matches
	 * @return array|mixed|string|string[]
	 */
	protected function processBlocks($matches)
	{
		$e = MinifierExpressions::get();

		// the fully matching text
		$match = $matches[0];

		// create a version without leading and trailing whitespace
		$trimmed = trim($match, $e->whitespaceCharsNewline);

		// Should be handled before optional whitespace
		if (!empty($matches['requiredSpace'])) {
			$match = strpos($matches['requiredSpace'], "\n") === false ? " " : "\n";
			goto end;
		}
		// + followed by +, or - followed by -
		if (!empty($matches['plus']) || !empty($matches['min'])) {
			$match = ' ';
			goto end;
		}
		if (!empty($matches['doubleQuote'])) {
			// remove line continuation
			$match = str_replace("\\\n", "", $match);
			goto end;
		}
		if (!empty($matches['starComment'])) {
			switch ($trimmed[2]) {
				case '@':
					// IE conditional comment
					$match = $trimmed;
					goto end;
				case '!':
					if ($this->options[self::FLAGGED_COMMENTS]) {
						// ensure newlines before and after
						$match = "\n" . $trimmed . "\n";
						goto end;
					}
			}
			// simple multi line comment; will have been removed in the first step
			goto end;
		}
		if (!empty($matches['regexp'])) {
			// regular expression
			// only if the space after the regexp contains a newline, keep it
			preg_match("~^" . $e->regexp . "(?P<post>" . $e->optionalWhitespaceNewline . ")" . "$~su",
				$match, $newMatches);
			$postfix = strpos($newMatches['post'], "\n") === false ? "" : "\n";
			$match = $trimmed . $postfix;
			goto end;
		}

		end:

		return str_replace($e->whitespaceArrayNewline, $e->whitespaceArrayPlaceholders, $match);
	}
}