class PhpFileCleaner

class PhpFileCleaner {
    
    /** @var array<array{name: string, length: int, pattern: non-empty-string}> */
    private static $typeConfig;
    
    /** @var non-empty-string */
    private static $restPattern;
    
    /**
     * @readonly
     * @var string
     */
    private $contents;
    
    /**
     * @readonly
     * @var int
     */
    private $len;
    
    /**
     * @readonly
     * @var int
     */
    private $maxMatches;
    
    /** @var int */
    private $index = 0;
    
    /**
     * @param string[] $types
     */
    public static function setTypeConfig(array $types) : void {
        foreach ($types as $type) {
            self::$typeConfig[$type[0]] = array(
                'name' => $type,
                'length' => \strlen($type),
                'pattern' => '{.\\b(?<![\\$:>])' . $type . '\\s++[a-zA-Z_\\x7f-\\xff:][a-zA-Z0-9_\\x7f-\\xff:\\-]*+}Ais',
            );
        }
        self::$restPattern = '{[^?"\'</' . implode('', array_keys(self::$typeConfig)) . ']+}A';
    }
    public function __construct(string $contents, int $maxMatches) {
        $this->contents = $contents;
        $this->len = \strlen($this->contents);
        $this->maxMatches = $maxMatches;
    }
    public function clean() : string {
        $clean = '';
        while ($this->index < $this->len) {
            $this->skipToPhp();
            $clean .= '<?';
            while ($this->index < $this->len) {
                $char = $this->contents[$this->index];
                if ($char === '?' && $this->peek('>')) {
                    $clean .= '?>';
                    $this->index += 2;
                    continue 2;
                }
                if ($char === '"') {
                    $this->skipString('"');
                    $clean .= 'null';
                    continue;
                }
                if ($char === "'") {
                    $this->skipString("'");
                    $clean .= 'null';
                    continue;
                }
                if ($char === "<" && $this->peek('<') && $this->match('{<<<[ \\t]*+([\'"]?)([a-zA-Z_\\x80-\\xff][a-zA-Z0-9_\\x80-\\xff]*+)\\1(?:\\r\\n|\\n|\\r)}A', $match)) {
                    $this->index += \strlen($match[0]);
                    $this->skipHeredoc($match[2]);
                    $clean .= 'null';
                    continue;
                }
                if ($char === '/') {
                    if ($this->peek('/')) {
                        $this->skipToNewline();
                        continue;
                    }
                    if ($this->peek('*')) {
                        $this->skipComment();
                        continue;
                    }
                }
                if ($this->maxMatches === 1 && isset(self::$typeConfig[$char])) {
                    $type = self::$typeConfig[$char];
                    if (\substr($this->contents, $this->index, $type['length']) === $type['name'] && Preg::isMatch($type['pattern'], $this->contents, $match, 0, $this->index - 1)) {
                        $clean .= $match[0];
                        return $clean;
                    }
                }
                $this->index += 1;
                if ($this->match(self::$restPattern, $match)) {
                    $clean .= $char . $match[0];
                    $this->index += \strlen($match[0]);
                }
                else {
                    $clean .= $char;
                }
            }
        }
        return $clean;
    }
    private function skipToPhp() : void {
        while ($this->index < $this->len) {
            if ($this->contents[$this->index] === '<' && $this->peek('?')) {
                $this->index += 2;
                break;
            }
            $this->index += 1;
        }
    }
    private function skipString(string $delimiter) : void {
        $this->index += 1;
        while ($this->index < $this->len) {
            if ($this->contents[$this->index] === '\\' && ($this->peek('\\') || $this->peek($delimiter))) {
                $this->index += 2;
                continue;
            }
            if ($this->contents[$this->index] === $delimiter) {
                $this->index += 1;
                break;
            }
            $this->index += 1;
        }
    }
    private function skipComment() : void {
        $this->index += 2;
        while ($this->index < $this->len) {
            if ($this->contents[$this->index] === '*' && $this->peek('/')) {
                $this->index += 2;
                break;
            }
            $this->index += 1;
        }
    }
    private function skipToNewline() : void {
        while ($this->index < $this->len) {
            if ($this->contents[$this->index] === "\r" || $this->contents[$this->index] === "\n") {
                return;
            }
            $this->index += 1;
        }
    }
    private function skipHeredoc(string $delimiter) : void {
        $firstDelimiterChar = $delimiter[0];
        $delimiterLength = \strlen($delimiter);
        $delimiterPattern = '{' . preg_quote($delimiter) . '(?![a-zA-Z0-9_\\x80-\\xff])}A';
        while ($this->index < $this->len) {
            // check if we find the delimiter after some spaces/tabs
            switch ($this->contents[$this->index]) {
                case "\t":
                case " ":
                    $this->index += 1;
                    continue 2;
                case $firstDelimiterChar:
                    if (\substr($this->contents, $this->index, $delimiterLength) === $delimiter && $this->match($delimiterPattern)) {
                        $this->index += $delimiterLength;
                        return;
                    }
                    break;
            }
            // skip the rest of the line
            while ($this->index < $this->len) {
                $this->skipToNewline();
                // skip newlines
                while ($this->index < $this->len && ($this->contents[$this->index] === "\r" || $this->contents[$this->index] === "\n")) {
                    $this->index += 1;
                }
                break;
            }
        }
    }
    private function peek(string $char) : bool {
        return $this->index + 1 < $this->len && $this->contents[$this->index + 1] === $char;
    }
    
    /**
     * @param non-empty-string $regex
     * @param null|array<mixed> $match
     * @param-out array<int|string, string> $match
     */
    private function match(string $regex, ?array &$match = null) : bool {
        return Preg::isMatchStrictGroups($regex, $this->contents, $match, 0, $this->index);
    }

}