<?php

namespace WellRESTed\Message;

use InvalidArgumentException;
use Psr\Http\Message\UriInterface;

/**
 * Value object representing a URI.
 *
 * This interface is meant to represent URIs according to RFC 3986 and to
 * provide methods for most common operations. Additional functionality for
 * working with URIs can be provided on top of the interface or externally.
 * Its primary use is for HTTP requests, but may also be used in other
 * contexts.
 *
 * @link http://tools.ietf.org/html/rfc3986 (the URI specification)
 */
class Uri implements UriInterface
{
    const MIN_PORT = 0;
    const MAX_PORT = 65535;

    /** @var string */
    private $scheme = '';
    /** @var string  */
    private $user = '';
    /** @var string|null */
    private $password;
    /** @var string  */
    private $host = '';
    /** @var int|null */
    private $port;
    /** @var string  */
    private $path = '';
    /** @var string  */
    private $query = '';
    /** @var string  */
    private $fragment = '';

    /**
     * @param string $uri A string representation of a URI.
     */
    public function __construct(string $uri = '')
    {
        $parsed = parse_url($uri);
        if (!$parsed) {
            return;
        }

        if (isset($parsed['scheme'])) {
            $this->scheme = $parsed['scheme'];
        }
        if (isset($parsed['host'])) {
            $this->host = strtolower($parsed['host']);
        }
        if (isset($parsed['port'])) {
            $this->port = $parsed['port'];
        }
        if (isset($parsed['user'])) {
            $this->user = $parsed['user'];
        }
        if (isset($parsed['pass'])) {
            $this->password = $parsed['pass'];
        }
        if (isset($parsed['path'])) {
            $this->path = $parsed['path'];
        }
        if (isset($parsed['query'])) {
            $this->query = $parsed['query'];
        }
        if (isset($parsed['fragment'])) {
            $this->fragment = $parsed['fragment'];
        }
    }

    /**
     * Retrieve the scheme component of the URI.
     *
     * If no scheme is present, this method will return an empty string.
     *
     * The value returned will be normalized to lowercase, per RFC 3986
     * Section 3.1.
     *
     * The trailing ":" character is not part of the scheme and will not be
     * added.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-3.1
     * @return string The URI scheme.
     */
    public function getScheme()
    {
        return $this->scheme;
    }

    /**
     * Retrieve the authority component of the URI.
     *
     * If no authority information is present, this method will return an empty
     * string.
     *
     * The authority syntax of the URI is:
     *
     * <pre>
     * [user-info@]host[:port]
     * </pre>
     *
     * If the port component is not set or is the standard port for the current
     * scheme, it will not be included.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-3.2
     * @return string The URI authority, in "[user-info@]host[:port]" format.
     */
    public function getAuthority()
    {
        $host = $this->getHost();
        if (!$host) {
            return '';
        }

        $authority = '';

        // User Info
        $userInfo = $this->getUserInfo();
        if ($userInfo) {
            $authority .= $userInfo . '@';
        }

        // Host
        $authority .= $host;

        // Port: Include only if non-standard
        if ($this->nonStandardPort()) {
            $authority .= ':' . $this->getPort();
        }

        return $authority;
    }

    private function nonStandardPort(): bool
    {
        $port = $this->getPort();
        $scheme = $this->getScheme();
        return $scheme === 'http' && $port !== 80
            || $scheme === 'https' && $port !== 443;
    }

    /**
     * Retrieve the user information component of the URI.
     *
     * If no user information is present, this method will return an empty
     * string.
     *
     * If a user is present in the URI, this will return that value;
     * additionally, if the password is also present, it will be appended to the
     * user value, with a colon (":") separating the values.
     *
     * The trailing "@" character is not part of the user information and will
     * not be added.
     *
     * @return string The URI user information, in "username[:password]" format.
     */
    public function getUserInfo()
    {
        $userInfo = $this->user;
        if ($userInfo && $this->password) {
            $userInfo .= ':' . $this->password;
        }
        return $userInfo;
    }

    /**
     * Retrieve the host component of the URI.
     *
     * If no host is present, this method will return an empty string.
     *
     * The value returned will be normalized to lowercase, per RFC 3986
     * Section 3.2.2.
     *
     * @see http://tools.ietf.org/html/rfc3986#section-3.2.2
     * @return string The URI host.
     */
    public function getHost()
    {
        return $this->host;
    }

    /**
     * Retrieve the port component of the URI.
     *
     * If a port is present, and it is non-standard for the current scheme,
     * this method MUST return it as an integer. If the port is the standard port
     * used with the current scheme, this method SHOULD return null.
     *
     * If no port is present, and no scheme is present, this method MUST return
     * a null value.
     *
     * If no port is present, but a scheme is present, this method MAY return
     * the standard port for that scheme, but SHOULD return null.
     *
     * @return null|int The URI port.
     */
    public function getPort()
    {
        if ($this->port === null) {
            switch ($this->scheme) {
                case 'http':
                    return 80;
                case 'https':
                    return 443;
                default:
                    return null;
            }
        }
        return $this->port;
    }

    /**
     * Retrieve the path component of the URI.
     *
     * The path can either be empty or absolute (starting with a slash) or
     * rootless (not starting with a slash). Implementations MUST support all
     * three syntaxes.
     *
     * Normally, the empty path "" and absolute path "/" are considered equal as
     * defined in RFC 7230 Section 2.7.3. But this method MUST NOT automatically
     * do this normalization because in contexts with a trimmed base path, e.g.
     * the front controller, this difference becomes significant. It's the task
     * of the user to handle both "" and "/".
     *
     * The value returned MUST be percent-encoded, but MUST NOT double-encode
     * any characters. To determine what characters to encode, please refer to
     * RFC 3986, Sections 2 and 3.3.
     *
     * As an example, if the value should include a slash ("/") not intended as
     * delimiter between path segments, that value MUST be passed in encoded
     * form (e.g., "%2F") to the instance.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-2
     * @see https://tools.ietf.org/html/rfc3986#section-3.3
     * @return string The URI path.
     */
    public function getPath()
    {
        if ($this->path === '*') {
            return $this->path;
        }
        return $this->percentEncode($this->path);
    }

    /**
     * Retrieve the query string of the URI.
     *
     * If no query string is present, this method MUST return an empty string.
     *
     * The leading "?" character is not part of the query and MUST NOT be
     * added.
     *
     * The value returned MUST be percent-encoded, but MUST NOT double-encode
     * any characters. To determine what characters to encode, please refer to
     * RFC 3986, Sections 2 and 3.4.
     *
     * As an example, if a value in a key/value pair of the query string should
     * include an ampersand ("&") not intended as a delimiter between values,
     * that value MUST be passed in encoded form (e.g., "%26") to the instance.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-2
     * @see https://tools.ietf.org/html/rfc3986#section-3.4
     * @return string The URI query string.
     */
    public function getQuery()
    {
        return $this->percentEncode($this->query);
    }

    /**
     * Retrieve the fragment component of the URI.
     *
     * If no fragment is present, this method MUST return an empty string.
     *
     * The leading "#" character is not part of the fragment and MUST NOT be
     * added.
     *
     * The value returned MUST be percent-encoded, but MUST NOT double-encode
     * any characters. To determine what characters to encode, please refer to
     * RFC 3986, Sections 2 and 3.5.
     *
     * @see https://tools.ietf.org/html/rfc3986#section-2
     * @see https://tools.ietf.org/html/rfc3986#section-3.5
     * @return string The URI fragment.
     */
    public function getFragment()
    {
        return $this->percentEncode($this->fragment);
    }

    /**
     * Return an instance with the specified scheme.
     *
     * This method MUST retain the state of the current instance, and return
     * an instance that contains the specified scheme.
     *
     * Implementations MUST support the schemes "http" and "https" case
     * insensitively, and MAY accommodate other schemes if required.
     *
     * An empty scheme is equivalent to removing the scheme.
     *
     * @param string $scheme The scheme to use with the new instance.
     * @return static A new instance with the specified scheme.
     * @throws InvalidArgumentException for invalid or unsupported schemes.
     */
    public function withScheme($scheme)
    {
        $scheme = $scheme ? strtolower($scheme) : '';
        if (!in_array($scheme, ['', 'http', 'https'])) {
            throw new InvalidArgumentException('Scheme must be http, https, or empty.');
        }
        $uri = clone $this;
        $uri->scheme = $scheme;
        return $uri;
    }

    /**
     * Return an instance with the specified user information.
     *
     * This method MUST retain the state of the current instance, and return
     * an instance that contains the specified user information.
     *
     * Password is optional, but the user information MUST include the
     * user; an empty string for the user is equivalent to removing user
     * information.
     *
     * @param string $user The user name to use for authority.
     * @param null|string $password The password associated with $user.
     * @return static A new instance with the specified user information.
     */
    public function withUserInfo($user, $password = null)
    {
        $uri = clone $this;
        $uri->user = $user;
        $uri->password = $password;
        return $uri;
    }

    /**
     * Return an instance with the specified host.
     *
     * This method MUST retain the state of the current instance, and return
     * an instance that contains the specified host.
     *
     * An empty host value is equivalent to removing the host.
     *
     * @param string $host The hostname to use with the new instance.
     * @return static A new instance with the specified host.
     * @throws InvalidArgumentException for invalid hostnames.
     */
    public function withHost($host)
    {
        if (!is_string($host)) {
            throw new InvalidArgumentException('Host must be a string.');
        }

        $uri = clone $this;
        $uri->host = strtolower($host);
        return $uri;
    }

    /**
     * Return an instance with the specified port.
     *
     * This method MUST retain the state of the current instance, and return
     * an instance that contains the specified port.
     *
     * Implementations MUST raise an exception for ports outside the
     * established TCP and UDP port ranges.
     *
     * A null value provided for the port is equivalent to removing the port
     * information.
     *
     * @param null|int $port The port to use with the new instance; a null value
     *     removes the port information.
     * @return static A new instance with the specified port.
     * @throws InvalidArgumentException for invalid ports.
     */
    public function withPort($port)
    {
        if (is_numeric($port)) {
            if ($port < self::MIN_PORT || $port > self::MAX_PORT) {
                $message = sprintf('Port must be between %s and %s.', self::MIN_PORT, self::MAX_PORT);
                throw new InvalidArgumentException($message);
            }
            $port = (int) $port;
        } elseif ($port !== null) {
            throw new InvalidArgumentException('Port must be an int or null.');
        }

        $uri = clone $this;
        $uri->port = $port;
        return $uri;
    }

    /**
     * Return an instance with the specified path.
     *
     * This method MUST retain the state of the current instance, and return
     * an instance that contains the specified path.
     *
     * The path can either be empty or absolute (starting with a slash) or
     * rootless (not starting with a slash). Implementations MUST support all
     * three syntaxes.
     *
     * Users can provide both encoded and decoded path characters.
     * Implementations ensure the correct encoding as outlined in getPath().
     *
     * @param string $path The path to use with the new instance.
     * @return static A new instance with the specified path.
     * @throws InvalidArgumentException for invalid paths.
     */
    public function withPath($path)
    {
        if (!is_string($path)) {
            throw new InvalidArgumentException('Path must be a string');
        }
        $uri = clone $this;
        $uri->path = $path;
        return $uri;
    }

    /**
     * Return an instance with the specified query string.
     *
     * This method MUST retain the state of the current instance, and return
     * an instance that contains the specified query string.
     *
     * Users can provide both encoded and decoded query characters.
     * Implementations ensure the correct encoding as outlined in getQuery().
     *
     * An empty query string value is equivalent to removing the query string.
     *
     * @param string $query The query string to use with the new instance.
     * @return static A new instance with the specified query string.
     * @throws InvalidArgumentException for invalid query strings.
     */
    public function withQuery($query)
    {
        $uri = clone $this;
        $uri->query = $query;
        return $uri;
    }

    /**
     * Return an instance with the specified URI fragment.
     *
     * This method MUST retain the state of the current instance, and return
     * an instance that contains the specified URI fragment.
     *
     * Users can provide both encoded and decoded fragment characters.
     * Implementations ensure the correct encoding as outlined in getFragment().
     *
     * An empty fragment value is equivalent to removing the fragment.
     *
     * @param string $fragment The fragment to use with the new instance.
     * @return static A new instance with the specified fragment.
     */
    public function withFragment($fragment)
    {
        $uri = clone $this;
        $uri->fragment = $fragment;
        return $uri;
    }

    /**
     * Return the string representation as a URI reference.
     *
     * Depending on which components of the URI are present, the resulting
     * string is either a full URI or relative reference according to RFC 3985,
     * Section 4.1. The method concatenates the various components of the URI,
     * using the appropriate delimiters:
     *
     * - If a scheme is present, it MUST be suffixed by ":".
     * - If an authority is present, it MUST be prefixed by "//".
     * - The path can be concatenated without delimiters. But there are two
     *   cases where the path has to be adjusted to make the URI reference
     *   valid as PHP does not allow to throw an exception in __toString():
     *     - If the path is rootless and an authority is present, the path MUST
     *       be prefixed by "/".
     *     - If the path is starting with more than one "/" and no authority is
     *       present, the starting slashes MUST be reduced to one.
     * - If a query is present, it MUST be prefixed by "?".
     * - If a fragment is present, it MUST be prefixed by "#".
     *
     * @see http://tools.ietf.org/html/rfc3986#section-4.1
     * @return string
     */
    public function __toString()
    {
        $string = '';

        $authority = $this->getAuthority();
        if ($authority !== '') {
            $scheme = $this->getScheme();
            if ($scheme !== '') {
                $string = $scheme . ':';
            }
            $string .= "//$authority";
        }

        $path = $this->getPath();
        if ($path !== '') {
            $string .= $path;
        }

        $query = $this->getQuery();
        if ($query !== '') {
            $string .= "?$query";
        }

        $fragment = $this->getFragment();
        if ($fragment !== '') {
            $string .= "#$fragment";
        }

        return $string;
    }

    /**
     * Return a percent-encoded string.
     *
     * This method encode each character that is not:
     * - A percent sign ("%") that is followed by a hex character (0-9, a-f, A-F)
     * - An "unreserved character" per RFC 3986 (see below)
     * - A "reserved character" per RFC 3986 (see below)
     *
     * unreserved  = ALPHA / DIGIT / "-" / "." / "_" / "~"
     * reserved = gen-delims / sub-delims
     * gen-delims  = ":" / "/" / "?" / "#" / "[" / "]" / "@"
     * sub-delims  = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
     *
     * @param string $subject
     * @return string
     */
    private function percentEncode($subject)
    {
        $reserved = ':/?#[]@!$&\'()*+,;=';
        $reserved = preg_quote($reserved);
        $pattern = '~(?:%(?![a-fA-F0-9]{2}))|(?:[^%a-zA-Z0-9\-\.\_\~' . $reserved . ']{1})~';
        $callback = function (array $matches): string {
            return urlencode($matches[0]);
        };
        return preg_replace_callback($pattern, $callback, $subject);
    }
}