<?php

/**
 * League.Uri (http://uri.thephpleague.com/parser).
 *
 * @author  Ignace Nyamagana Butera <ychag@example.com>
 * @license https://github.com/thephpleague/uri-parser/blob/master/LICENSE (MIT License)
 * @version 1.4.1
 * @link    https://uri.thephpleague.com/parser/
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

declare(strict_types=1);

namespace League\Uri;

use UnexpectedValueException;

/**
 * A class to parse a URI string according to RFC3986.
 *
 * @see     https://tools.ietf.org/html/rfc3986
 * @package League\Uri
 * @author  Ignace Nyamagana Butera <ychag@example.com>
 * @since   0.1.0
 */
class Parser
{
    /** @deprecated 1.4.0 will be removed in the next major point release */
    const INVALID_URI_CHARS = "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F\x7F";

    /** @deprecated 1.4.0 will be removed in the next major point release */
    const SCHEME_VALID_STARTING_CHARS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

    /** @deprecated 1.4.0 will be removed in the next major point release */
    const SCHEME_VALID_CHARS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+.-';

    /** @deprecated 1.4.0 will be removed in the next major point release */
    const LABEL_VALID_STARTING_CHARS = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

    /** @deprecated 1.4.0 will be removed in the next major point release */
    const LOCAL_LINK_PREFIX = '1111111010';

    const URI_COMPONENTS = [
        'scheme' => null, 'user' => null, 'pass' => null, 'host' => null,
        'port' => null, 'path' => '', 'query' => null, 'fragment' => null,
    ];

    /** @deprecated 1.4.0 will be removed in the next major point release */
    const SUB_DELIMITERS = '!$&\'()*+,;=';

    /**
     * Returns whether a scheme is valid.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-3.1
     */
    public function isScheme(string $scheme): bool
    {
        static $pattern = '/^[a-z][a-z0-9\+\.\-]*$/i';

        return '' === $scheme || 1 === preg_match($pattern, $scheme);
    }

    /**
     * Returns whether a hostname is valid.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-3.2.2
     */
    public function isHost(string $host): bool
    {
        return '' === $host
            || $this->isIpHost($host)
            || $this->isRegisteredName($host);
    }

    /**
     * Validate a IPv6/IPvfuture host.
     *
     * @see http://tools.ietf.org/html/rfc3986#section-3.2.2
     * @see http://tools.ietf.org/html/rfc6874#section-2
     * @see http://tools.ietf.org/html/rfc6874#section-4
     */
    private function isIpHost(string $host): bool
    {
        if ('[' !== ($host[0] ?? '') || ']' !== substr($host, -1)) {
            return false;
        }

        $ip = substr($host, 1, -1);
        if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
            return true;
        }

        static $ip_future = '/^
            v(?<version>[A-F0-9])+\.
            (?:
                (?<unreserved>[a-z0-9_~\-\.])|
                (?<sub_delims>[!$&\'()*+,;=:])  # also include the : character
            )+
        $/ix';
        if (1 === preg_match($ip_future, $ip, $matches) && !in_array($matches['version'], ['4', '6'], true)) {
            return true;
        }

        if (false === ($pos = strpos($ip, '%'))) {
            return false;
        }

        static $gen_delims = '/[:\/?#\[\]@ ]/'; // Also includes space.
        if (1 === preg_match($gen_delims, rawurldecode(substr($ip, $pos)))) {
            return false;
        }

        $ip = substr($ip, 0, $pos);
        if (!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
            return false;
        }

        //Only the address block fe80::/10 can have a Zone ID attach to
        //let's detect the link local significant 10 bits
        static $address_block = "\xfe\x80";

        return 0 === strpos((string) inet_pton($ip), $address_block);
    }


    /**
     * Returns whether the host is an IPv4 or a registered named.
     *
     * @see http://tools.ietf.org/html/rfc3986#section-3.2.2
     *
     * @throws MissingIdnSupport if the registered name contains non-ASCII characters
     *                           and IDN support or ICU requirement are not available or met.
     *
     */
    protected function isRegisteredName(string $host): bool
    {
        // Note that unreserved is purposely missing . as it is used to separate labels.
        static $reg_name = '/(?(DEFINE)
                (?<unreserved>[a-z0-9_~\-])
                (?<sub_delims>[!$&\'()*+,;=])
                (?<encoded>%[A-F0-9]{2})
                (?<reg_name>(?:(?&unreserved)|(?&sub_delims)|(?&encoded))*)
            )
            ^(?:(?&reg_name)\.)*(?&reg_name)\.?$/ix';
        if (1 === preg_match($reg_name, $host)) {
            return true;
        }

        //to test IDN host non-ascii characters must be present in the host
        static $idn_pattern = '/[^\x20-\x7f]/';
        if (1 !== preg_match($idn_pattern, $host)) {
            return false;
        }

        static $idn_support = null;
        $idn_support = $idn_support ?? function_exists('idn_to_ascii') && defined('INTL_IDNA_VARIANT_UTS46');

        // @codeCoverageIgnoreStart
        // added because it is not possible in travis to disabled the ext/intl extension
        // see travis issue https://github.com/travis-ci/travis-ci/issues/4701
        if (!$idn_support) {
            throw new MissingIdnSupport(sprintf('the host `%s` could not be processed for IDN. Verify that ext/intl is installed for IDN support and that ICU is at least version 4.6.', $host));
        }
        // @codeCoverageIgnoreEnd

        $ascii_host = idn_to_ascii($host, IDNA_NONTRANSITIONAL_TO_ASCII, INTL_IDNA_VARIANT_UTS46, $arr);

        // @codeCoverageIgnoreStart
        if (false === $ascii_host && 0 === $arr['errors']) {
            throw new UnexpectedValueException(sprintf('The Intl extension is misconfigured for %s, please correct this issue before proceeding.', PHP_OS));
        }
        // @codeCoverageIgnoreEnd

        return 0 === $arr['errors'];
    }

    /**
     * Returns whether a port is valid.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-3.2.2
     */
    public function isPort($port): bool
    {
        static $pattern = '/^[0-9]+$/';

        if (null === $port || '' === $port) {
            return true;
        }

        return 1 === preg_match($pattern, (string) $port);
    }

    /**
     * Parse a URI string into its components.
     *
     * @see Parser::parse
     *
     * @throws Exception if the URI contains invalid characters
     */
    public function __invoke(string $uri): array
    {
        return $this->parse($uri);
    }

    /**
     * Parse an URI string into its components.
     *
     * This method parses a URI and returns an associative array containing any
     * of the various components of the URI that are present.
     *
     * <code>
     * $components = (new Parser())->parse('http://foo@test.example.com:42?query#');
     * var_export($components);
     * //will display
     * array(
     *   'scheme' => 'http',           // the URI scheme component
     *   'user' => 'foo',              // the URI user component
     *   'pass' => null,               // the URI pass component
     *   'host' => 'test.example.com', // the URI host component
     *   'port' => 42,                 // the URI port component
     *   'path' => '',                 // the URI path component
     *   'query' => 'query',           // the URI query component
     *   'fragment' => '',             // the URI fragment component
     * );
     * </code>
     *
     * The returned array is similar to PHP's parse_url return value with the following
     * differences:
     *
     * <ul>
     * <li>All components are always present in the returned array</li>
     * <li>Empty and undefined component are treated differently. And empty component is
     *   set to the empty string while an undefined component is set to the `null` value.</li>
     * <li>The path component is never undefined</li>
     * <li>The method parses the URI following the RFC3986 rules but you are still
     *   required to validate the returned components against its related scheme specific rules.</li>
     * </ul>
     *
     * @see https://tools.ietf.org/html/rfc3986
     * @see https://tools.ietf.org/html/rfc3986#section-2
     *
     * @throws Exception if the URI contains invalid characters
     */
    public function parse(string $uri): array
    {
        static $pattern = '/[\x00-\x1f\x7f]/';

        //simple URI which do not need any parsing
        static $simple_uri = [
            '' => [],
            '#' => ['fragment' => ''],
            '?' => ['query' => ''],
            '?#' => ['query' => '', 'fragment' => ''],
            '/' => ['path' => '/'],
            '//' => ['host' => ''],
        ];

        if (isset($simple_uri[$uri])) {
            return array_merge(self::URI_COMPONENTS, $simple_uri[$uri]);
        }

        if (1 === preg_match($pattern, $uri)) {
            throw Exception::createFromInvalidCharacters($uri);
        }

        //if the first character is a known URI delimiter parsing can be simplified
        $first_char = $uri[0];

        //The URI is made of the fragment only
        if ('#' === $first_char) {
            $components = self::URI_COMPONENTS;
            $components['fragment'] = (string) substr($uri, 1);

            return $components;
        }

        //The URI is made of the query and fragment
        if ('?' === $first_char) {
            $components = self::URI_COMPONENTS;
            list($components['query'], $components['fragment']) = explode('#', substr($uri, 1), 2) + [1 => null];

            return $components;
        }

        //The URI does not contain any scheme part
        if (0 === strpos($uri, '//')) {
            return $this->parseSchemeSpecificPart($uri);
        }

        //The URI is made of a path, query and fragment
        if ('/' === $first_char || false === strpos($uri, ':')) {
            return $this->parsePathQueryAndFragment($uri);
        }

        //Fallback parser
        return $this->fallbackParser($uri);
    }

    /**
     * Extract components from a URI without a scheme part.
     *
     * The URI MUST start with the authority component
     * preceded by its delimiter the double slash ('//')
     *
     * Example: //user:pass@host:42/path?query#fragment
     *
     * The authority MUST adhere to the RFC3986 requirements.
     *
     * If the URI contains a path component, it MUST be empty or absolute
     * according to RFC3986 path classification.
     *
     * This method returns an associative array containing all URI components.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-3.2
     * @see https://tools.ietf.org/html/rfc3986#section-3.3
     *
     * @throws Exception If any component of the URI is invalid
     */
    protected function parseSchemeSpecificPart(string $uri): array
    {
        //We remove the authority delimiter
        $remaining_uri = (string) substr($uri, 2);
        $components = self::URI_COMPONENTS;

        //Parsing is done from the right upmost part to the left
        //1 - detect fragment, query and path part if any
        list($remaining_uri, $components['fragment']) = explode('#', $remaining_uri, 2) + [1 => null];
        list($remaining_uri, $components['query']) = explode('?', $remaining_uri, 2) + [1 => null];
        if (false !== strpos($remaining_uri, '/')) {
            list($remaining_uri, $components['path']) = explode('/', $remaining_uri, 2) + [1 => null];
            $components['path'] = '/'.$components['path'];
        }

        //2 - The $remaining_uri represents the authority part
        //if the authority part is empty parsing is simplified
        if ('' === $remaining_uri) {
            $components['host'] = '';

            return $components;
        }

        //otherwise we split the authority into the user information and the hostname parts
        $parts = explode('@', $remaining_uri, 2);
        $hostname = $parts[1] ?? $parts[0];
        $user_info = isset($parts[1]) ? $parts[0] : null;
        if (null !== $user_info) {
            list($components['user'], $components['pass']) = explode(':', $user_info, 2) + [1 => null];
        }
        list($components['host'], $components['port']) = $this->parseHostname($hostname);

        return $components;
    }

    /**
     * Parse and validate the URI hostname.
     *
     * @throws Exception If the hostname is invalid
     */
    protected function parseHostname(string $hostname): array
    {
        if (false === strpos($hostname, '[')) {
            list($host, $port) = explode(':', $hostname, 2) + [1 => null];

            return [$this->filterHost($host), $this->filterPort($port)];
        }

        $delimiter_offset = strpos($hostname, ']') + 1;
        if (isset($hostname[$delimiter_offset]) && ':' !== $hostname[$delimiter_offset]) {
            throw Exception::createFromInvalidHostname($hostname);
        }

        return [
            $this->filterHost(substr($hostname, 0, $delimiter_offset)),
            $this->filterPort(substr($hostname, ++$delimiter_offset)),
        ];
    }

    /**
     * validate the host component.
     *
     * @param string|null $host
     *
     * @throws Exception If the hostname is invalid
     *
     * @return string|null
     */
    protected function filterHost($host)
    {
        if (null === $host || $this->isHost($host)) {
            return $host;
        }

        throw Exception::createFromInvalidHost($host);
    }

    /**
     * Validate a port number.
     *
     * An exception is raised for ports outside the established TCP and UDP port ranges.
     *
     * @param mixed $port the port number
     *
     * @throws Exception If the port number is invalid.
     *
     * @return null|int
     */
    protected function filterPort($port)
    {
        static $pattern = '/^[0-9]+$/';

        if (null === $port || false === $port || '' === $port) {
            return null;
        }

        if (1 !== preg_match($pattern, (string) $port)) {
            throw Exception::createFromInvalidPort($port);
        }

        return (int) $port;
    }


    /**
     * Extract Components from an URI without scheme or authority part.
     *
     * The URI contains a path component and MUST adhere to path requirements
     * of RFC3986. The path can be
     *
     * <code>
     * path   = path-abempty    ; begins with "/" or is empty
     *        / path-absolute   ; begins with "/" but not "//"
     *        / path-noscheme   ; begins with a non-colon segment
     *        / path-rootless   ; begins with a segment
     *        / path-empty      ; zero characters
     * </code>
     *
     * ex: path?q#f
     * ex: /path
     * ex: /pa:th#f
     *
     * This method returns an associative array containing all URI components.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-3.3
     *
     * @throws Exception If the path component is invalid
     */
    protected function parsePathQueryAndFragment(string $uri): array
    {
        //No scheme is present so we ensure that the path respects RFC3986
        if (false !== ($pos = strpos($uri, ':')) && false === strpos(substr($uri, 0, $pos), '/')) {
            throw Exception::createFromInvalidPath($uri);
        }

        $components = self::URI_COMPONENTS;

        //Parsing is done from the right upmost part to the left
        //1 - detect the fragment part if any
        list($remaining_uri, $components['fragment']) = explode('#', $uri, 2) + [1 => null];

        //2 - detect the query and the path part
        list($components['path'], $components['query']) = explode('?', $remaining_uri, 2) + [1 => null];

        return $components;
    }

    /**
     * Extract components from an URI containing a colon.
     *
     * Depending on the colon ":" position and on the string
     * composition before the presence of the colon, the URI
     * will be considered to have an scheme or not.
     *
     * <ul>
     * <li>In case no valid scheme is found according to RFC3986 the URI will
     * be parsed as an URI without a scheme and an authority</li>
     * <li>In case an authority part is detected the URI specific part is parsed
     * as an URI without scheme</li>
     * </ul>
     *
     * ex: email:ychag@example.com?subject=Hellow%20World!
     *
     * This method returns an associative array containing all
     * the URI components.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-3.1
     * @see Parser::parsePathQueryAndFragment
     * @see Parser::parseSchemeSpecificPart
     *
     * @throws Exception If the URI scheme component is empty
     */
    protected function fallbackParser(string $uri): array
    {
        //1 - we split the URI on the first detected colon character
        $parts = explode(':', $uri, 2);
        $remaining_uri = $parts[1] ?? $parts[0];
        $scheme = isset($parts[1]) ? $parts[0] : null;

        //1.1 - a scheme can not be empty (ie a URI can not start with a colon)
        if ('' === $scheme) {
            throw Exception::createFromInvalidScheme($uri);
        }

        //2 - depending on the scheme presence and validity we will differ the parsing

        //2.1 - If the scheme part is invalid the URI may be an URI with a path-noscheme
        //      let's differ the parsing to the Parser::parsePathQueryAndFragment method
        if (!$this->isScheme($scheme)) {
            return $this->parsePathQueryAndFragment($uri);
        }

        $components = self::URI_COMPONENTS;
        $components['scheme'] = $scheme;

        //2.2 - if no scheme specific part is detect parsing is finished
        if ('' == $remaining_uri) {
            return $components;
        }

        //2.3 - if the scheme specific part is a double forward slash
        if ('//' === $remaining_uri) {
            $components['host'] = '';

            return $components;
        }

        //2.4 - if the scheme specific part starts with double forward slash
        //      we differ the remaining parsing to the Parser::parseSchemeSpecificPart method
        if (0 === strpos($remaining_uri, '//')) {
            $components = $this->parseSchemeSpecificPart($remaining_uri);
            $components['scheme'] = $scheme;

            return $components;
        }

        //2.5 - Parsing is done from the right upmost part to the left from the scheme specific part
        //2.5.1 - detect the fragment part if any
        list($remaining_uri, $components['fragment']) = explode('#', $remaining_uri, 2) + [1 => null];

        //2.5.2 - detect the part and query part if any
        list($components['path'], $components['query']) = explode('?', $remaining_uri, 2) + [1 => null];

        return $components;
    }

    /**
     * Convert a registered name label to its IDNA ASCII form.
     *
     * DEPRECATION WARNING! This method will be removed in the next major point release
     *
     * @deprecated 1.4.0 this method is no longer used to validate RFC3987 compliant host component
     * @codeCoverageIgnore
     *
     * Conversion is done only if the label contains none valid label characters
     * if a '%' sub delimiter is detected the label MUST be rawurldecode prior to
     * making the conversion
     *
     * @return string|false
     */
    protected function toAscii(string $label)
    {
        trigger_error(
            self::class.'::'.__METHOD__.' is deprecated and will be removed in the next major point release',
            E_USER_DEPRECATED
        );

        if (false !== strpos($label, '%')) {
            $label = rawurldecode($label);
        }

        static $idn_support = null;
        $idn_support = $idn_support ?? function_exists('idn_to_ascii') && defined('INTL_IDNA_VARIANT_UTS46');
        if (!$idn_support) {
            throw new MissingIdnSupport(sprintf('the label `%s` could not be processed for IDN. Verify that ext/intl is installed for IDN support and that ICU is at least version 4.6.', $label));
        }

        $ascii_host = idn_to_ascii($label, IDNA_NONTRANSITIONAL_TO_ASCII, INTL_IDNA_VARIANT_UTS46, $arr);
        if (false === $ascii_host && 0 === $arr['errors']) {
            throw new UnexpectedValueException(sprintf('The Intl extension is misconfigured for %s, please correct this issue before proceeding.', PHP_OS));
        }

        return $ascii_host;
    }

    /**
     * Returns whether the registered name label is valid.
     *
     * DEPRECATION WARNING! This method will be removed in the next major point release
     *
     * @deprecated 1.4.0 this method is no longer used to validated the host component
     * @codeCoverageIgnore
     *
     * A valid registered name label MUST conform to the following ABNF
     *
     * reg-name = *( unreserved / pct-encoded / sub-delims )
     *
     * @see https://tools.ietf.org/html/rfc3986#section-3.2.2
     *
     * @param string $label
     */
    protected function isHostLabel($label): bool
    {
        trigger_error(
            self::class.'::'.__METHOD__.' is deprecated and will be removed in the next major point release',
            E_USER_DEPRECATED
        );

        return '' != $label
            && 63 >= strlen($label)
            && strlen($label) == strspn($label, self::LABEL_VALID_STARTING_CHARS.'-_~'.self::SUB_DELIMITERS);
    }

    /**
     * Validate an IPv6 host.
     *
     * DEPRECATION WARNING! This method will be removed in the next major point release
     *
     * @deprecated 1.4.0 this method is no longer used to validated the host component
     * @codeCoverageIgnore
     *
     * @see http://tools.ietf.org/html/rfc6874#section-2
     * @see http://tools.ietf.org/html/rfc6874#section-4
     */
    protected function isIpv6Host(string $ipv6): bool
    {
        trigger_error(
            self::class.'::'.__METHOD__.' is deprecated and will be removed in the next major point release',
            E_USER_DEPRECATED
        );

        if ('[' !== ($ipv6[0] ?? '') || ']' !== substr($ipv6, -1)) {
            return false;
        }

        $ipv6 = substr($ipv6, 1, -1);
        if (false === ($pos = strpos($ipv6, '%'))) {
            return (bool) filter_var($ipv6, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6);
        }

        $scope = rawurldecode(substr($ipv6, $pos));
        if (strlen($scope) !== strcspn($scope, '?#@[]')) {
            return false;
        }

        $ipv6 = substr($ipv6, 0, $pos);
        if (!filter_var($ipv6, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
            return false;
        }

        //Only the address block fe80::/10 can have a Zone ID attach to
        //let's detect the link local significant 10 bits
        return 0 === strpos((string) inet_pton($ipv6), "\xfe\x80");
    }
}
