Ignace Knops

<?php

/**
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author Ignace Knops <developer.ignace@gmail.com>
 * @license http://www.gnu.org/licenses/gpl.txt GNU GPL v3
 */
class ContentNegotiation
{
    /**
     *
     * @var <array>
     */
    protected $_mimeTypes = array();

    /**
     *
     * @var <array>
     */
    protected $_languages = array();

    /**
     *
     * @var <array>
     */
    protected $_encodings = array();

    /**
     *
     * @var <array>
     */
    protected $_charsets = array();

    /**
     * Class constructor
     */
    public function __construct() {
        $this->_parseAcceptHeader();
        $this->_parseAcceptLanguageHeader();
        $this->_parseAcceptEncodingHeader();
        $this->_parseAcceptCharsetHeader();
    }

    /**
     *
     * @return <array>
     */
    public function getMimeTypes() {
        return $this->_mimeTypes;
    }

    /**
     *
     * @return <array>
     */
    public function getLanguages() {
        return $this->_languages;
    }

    /**
     *
     * @return <array>
     */
    public function getEncodings() {
        return $this->_encodings;
    }

    /**
     *
     * @return <array>
     */
    public function getCharsets() {
        return $this->_charsets;
    }

    /**
     * Returns the optimal mime-type
     *
     * @param <string> $mimeTypesString
     * @return <string>
     */
    public function returnOptimalMimeType($mimeTypesString) {
        return $this->_returnOptimal($mimeTypesString, $this->getMimeTypes());
    }

    /**
     * Returns the optimal language
     *
     * @param <string> $languagesString
     * @return <string>
     */
    public function returnOptimalLanguage($languagesString) {
        return $this->_returnOptimal($languagesString, $this->getLanguages());
    }

    /**
     * Returns the optimal encoding
     *
     * @param <string> $encodingsString
     * @return <string>
     */
    public function returnOptimalEncoding($encodingsString) {
        return $this->_returnOptimal($encodingsString, $this->getEncodings());
    }

    /**
     * Returns the optimal charset
     *
     * @param <string> $charsetsString
     * @return <string>
     */
    public function returnOptimalCharset($charsetsString) {
        return $this->_returnOptimal($charsetsString, $this->getCharsets());
    }

    /**
     * Returns the item with the best quality value
     *
     * @param <string> $str
     * @param <array> $array
     * @return <string>
     */
    protected function _returnOptimal($str, $array) {
        $optimalItem = '';
        foreach (explode(',', $str) as $item) {
            if (empty($optimalItem)) {
                $optimalItem = $item;
                continue;
            }
            $q1 = $this->_getQuality($item, $array);
            $q2 = $this->_getQuality($optimalItem, $array);
            if ($this->_compare($q1, $q2) < 0) {
                $optimalItem = $item;
            }
        }
        return $optimalItem;
    }

    /**
     * Returns -1 if $mt1 is greater, 0 if they are equal and 1 if $mt2 is greater
     *
     * @param <string> $mt1
     * @param <string> $mt2
     */
    public function compareMimeTypeQuality($mt1, $mt2) {
        $q1 = $this->_getMimeTypeQuality($mt1);
        $q2 = $this->_getMimeTypeQuality($mt2);
        return $this->_compare($q1, $q2);
    }

    /**
     * Returns -1 if $mt1 is greater, 0 if they are equal and 1 if $mt2 is greater
     *
     * @param <string> $lang1
     * @param <string> $lang2
     */
    public function compareLanguageQuality($lang1, $lang2) {
        $q1 = $this->_getLanguageQuality($lang1);
        $q2 = $this->_getLanguageQuality($lang2);
        return $this->_compare($q1, $q2);
    }

    /**
     * Returns -1 if $mt1 is greater, 0 if they are equal and 1 if $mt2 is greater
     *
     * @param <string> $enc1
     * @param <string> $enc2
     */
    public function compareEncodingQuality($enc1, $enc2) {
        $q1 = $this->_getEncodingQuality($enc1);
        $q2 = $this->_getEncodingQuality($enc2);
        return $this->_compare($q1, $q2);
    }

    /**
     * Returns -1 if $mt1 is greater, 0 if they are equal and 1 if $mt2 is greater
     *
     * @param <string> $char1
     * @param <string> $char2
     */
    public function compareCharsetQuality($char1, $char2) {
        $q1 = $this->_getCharsetQuality($char1);
        $q2 = $this->_getCharsetQuality($char2);
        return $this->_compare($q1, $q2);
    }

    /**
     * Compares and returns results in a unified format
     *
     * @param <int> $qualityValue1
     * @param <int> $qualityValue2
     * @return <int>
     */
    protected function _compare($qualityValue1, $qualityValue2) {
        if ($qualityValue1 > $qualityValue2) {
            return -1;
        } else if ($qualityValue2 > $qualityValue1) {
            return 1;
        } else {
            return 0;
        }
    }

    /**
     * Returns the mime-type quality
     *
     * @param <string> $mimeType
     * @return <int>
     */
    protected function _getMimeTypeQuality($mimeType) {
        return $this->_getQuality($mimeType, $this->getMimeTypes());
    }

    /**
     * Returns the language quality
     *
     * @param <string> $language
     * @return <int>
     */
    protected function _getLanguageQuality($language) {
        return $this->_getQuality($language, $this->getLanguages());
    }

    /**
     * Returns the encoding quality
     *
     * @param <string> $encoding
     * @return <int>
     */
    protected function _getEncodingQuality($encoding) {
        return $this->_getQuality($encoding, $this->getEncodings());
    }

    /**
     * Returns the charset quality
     *
     * @param <string> $charset
     * @return <int>
     */
    protected function _getCharsetQuality($charset) {
        return $this->_getQuality($charset, $this->getCharsets());
    }

    /**
     * Retrieves the quality from $search and returns $default otherwise
     *
     * @param <string> $item
     * @param <array> $search
     * @param <mixed> $default
     * @return <int>
     */
    protected function _getQuality($item, $search, $default = 0) {
        $item = strtoupper($item);
        return array_key_exists($item, $search) ? $search[$item] : $default;
    }

    /**
     * Parses the HTTP_ACCEPT header and merges it with $this->_mimeTypes
     */
    protected function _parseAcceptHeader() {
        $this->_mergeMimeTypes($this->_parse($_SERVER['HTTP_ACCEPT']));
    }

    /**
     * Parses the HTTP_ACCEPT_LANGUAGE header and merges it with $this->_languages
     */
    protected function _parseAcceptLanguageHeader() {
        $this->_mergeLanguages($this->_parse($_SERVER['HTTP_ACCEPT_LANGUAGE']));
    }

    /**
     * Parses the HTTP_ACCEPT_ENCODING header and merges it with $this->_encodings
     */
    protected function _parseAcceptEncodingHeader() {
        $this->_mergeEncodings($this->_parse($_SERVER['HTTP_ACCEPT_ENCODING']));
    }

    /**
     * Parses the HTTP_ACCEPT_CHARSET header and merges it with $this->_charsets
     */
    protected function _parseAcceptCharsetHeader() {
        $this->_mergeCharsets($this->_parse($_SERVER['HTTP_ACCEPT_CHARSET']));
    }

    /**
     * Performs the actual parsing of accept headers
     *
     * @param <string> $str
     * @return <array>
     */
    protected function _parse($str) {
        $mimeTypesQuality = array();
        $mimeTypes = explode(',', $str);
        foreach ($mimeTypes as $mimeType) {
            if (strpos($mimeType, ';')) {
                list($mimeType, $qualityValue) = explode(';', $mimeType);
                list(, $qualityValue) = explode('=', $qualityValue);
            } else {
                $qualityValue = 1;
            }
            if (strpos($mimeType, '*')) {
                continue;
            }
            $mimeTypesQuality[strtoupper($mimeType)] = $qualityValue;
        }
        return $mimeTypesQuality;
    }

    /**
     * Merges $mimeTypes with $this->_mimeTypes
     *
     * @param <array> $mimeTypes
     */
    protected function _mergeMimeTypes($mimeTypes) {
        $this->_mimeTypes = $this->_merge($this->getMimeTypes(), $mimeTypes);
    }

    /**
     * Merges $languages with $this->_languages
     *
     * @param <array> $languages
     */
    protected function _mergeLanguages($languages) {
        $this->_languages = $this->_merge($this->getLanguages(), $languages);
    }

    /**
     * Merges $encodings with $this->_encodings
     *
     * @param <array> $encodings
     */
    protected function _mergeEncodings($encodings) {
        $this->_encodings = $this->_merge($this->getEncodings(), $encodings);
    }

    /**
     * Merges $charsets with $this->_charsets
     *
     * @param <array> $charsets
     */
    protected function _mergeCharsets($charsets) {
        $this->_charsets = $this->_merge($this->getCharsets(), $charsets);
    }

    /**
     * Merges two arrays
     *
     * @param <array> $array1
     * @param <array> $array2
     * @return <array>
     */
    protected function _merge($array1, $array2) {
        return array_merge($array1, $array2);
    }
}