HttpAcceptNegotiator.php

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<?php
 
namespace Wikimedia\Http;
 
class HttpAcceptNegotiator {
 
    private $supportedValues;
 
    private $defaultValue;
 
    public function __construct( array $supported ) {
        $this->supportedValues = $supported;
        $this->defaultValue = reset( $supported );
    }
 
    public function getBestSupportedKey( array $weights, $default = null ) {
        // Make sure we correctly bias against wildcards and ranges, see RFC2616, section 14.
        foreach ( $weights as $name => &$weight ) {
            if ( $name === '*' || $name === '*/*' ) {
                $weight -= 0.000002;
            } elseif ( substr( $name, -2 ) === '/*' ) {
                $weight -= 0.000001;
            }
        }
 
        // Sort $weights by value and...
        asort( $weights );
 
        // remove any keys with values equal to 0 or false (HTTP/1.1 section 3.9)
        $weights = array_filter( $weights );
 
        // ...use the ordered list of keys
        $preferences = array_reverse( array_keys( $weights ) );
 
        $value = $this->getFirstSupportedValue( $preferences, $default );
        return $value;
    }
 
    public function getFirstSupportedValue( array $preferences, $default = null ) {
        foreach ( $preferences as $value ) {
            foreach ( $this->supportedValues as $supported ) {
                if ( $this->valueMatches( $value, $supported ) ) {
                    return $supported;
                }
            }
        }
 
        return $default;
    }
 
    private function valueMatches( $accepted, $supported ) {
        // RDF 2045: MIME types are case insensitive.
        // full match
        if ( strcasecmp( $accepted, $supported ) === 0 ) {
            return true;
        }
 
        // wildcard match (HTTP/1.1 section 14.1, 14.2, 14.3)
        if ( $accepted === '*' || $accepted === '*/*' ) {
            return true;
        }
 
        // wildcard match (HTTP/1.1 section 14.1)
        if ( substr( $accepted, -2 ) === '/*'
            && strncasecmp( $accepted, $supported, strlen( $accepted ) - 2 ) === 0
        ) {
            return true;
        }
 
        return false;
    }
 
}