<?php

/**
 * @package KantPHP
 * @author  Zhenqiang Zhang <zhenqiang.zhang@hotmail.com>
 * @copyright (c) KantPHP Studio, All rights reserved.
 * @license http://www.opensource.org/licenses/BSD-3-Clause  The BSD 3-Clause License
 */
namespace Kant\Http;

/**
 * Represents an Accept-* header.
 *
 * An accept header is compound with a list of items,
 * sorted by descending quality.
 *
 * @author Jean-François Simon <contact@jfsimon.fr>
 */
class AcceptHeader
{

    /**
     *
     * @var AcceptHeaderItem[]
     */
    private $items = array();

    /**
     *
     * @var bool
     */
    private $sorted = true;

    /**
     * Constructor.
     *
     * @param AcceptHeaderItem[] $items            
     */
    public function __construct(array $items)
    {
        foreach ($items as $item) {
            $this->add($item);
        }
    }

    /**
     * Builds an AcceptHeader instance from a string.
     *
     * @param string $headerValue            
     *
     * @return self
     */
    public static function fromString($headerValue)
    {
        $index = 0;
        
        return new self(array_map(function ($itemValue) use(&$index) {
            $item = AcceptHeaderItem::fromString($itemValue);
            $item->setIndex($index ++);
            
            return $item;
        }, preg_split('/\s*(?:,*("[^"]+"),*|,*(\'[^\']+\'),*|,+)\s*/', $headerValue, 0, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE)));
    }

    /**
     * Returns header value's string representation.
     *
     * @return string
     */
    public function __toString()
    {
        return implode(',', $this->items);
    }

    /**
     * Tests if header has given value.
     *
     * @param string $value            
     *
     * @return bool
     */
    public function has($value)
    {
        return isset($this->items[$value]);
    }

    /**
     * Returns given value's item, if exists.
     *
     * @param string $value            
     *
     * @return AcceptHeaderItem|null
     */
    public function get($value)
    {
        return isset($this->items[$value]) ? $this->items[$value] : null;
    }

    /**
     * Adds an item.
     *
     * @param AcceptHeaderItem $item            
     *
     * @return $this
     */
    public function add(AcceptHeaderItem $item)
    {
        $this->items[$item->getValue()] = $item;
        $this->sorted = false;
        
        return $this;
    }

    /**
     * Returns all items.
     *
     * @return AcceptHeaderItem[]
     */
    public function all()
    {
        $this->sort();
        
        return $this->items;
    }

    /**
     * Filters items on their value using given regex.
     *
     * @param string $pattern            
     *
     * @return self
     */
    public function filter($pattern)
    {
        return new self(array_filter($this->items, function (AcceptHeaderItem $item) use($pattern) {
            return preg_match($pattern, $item->getValue());
        }));
    }

    /**
     * Returns first item.
     *
     * @return AcceptHeaderItem|null
     */
    public function first()
    {
        $this->sort();
        
        return ! empty($this->items) ? reset($this->items) : null;
    }

    /**
     * Sorts items by descending quality.
     */
    private function sort()
    {
        if (!$this->sorted) {
            uasort($this->items, function ($a, $b) {
                $qA = $a->getQuality();
                $qB = $b->getQuality();
                
                if ($qA === $qB) {
                    return $a->getIndex() > $b->getIndex() ? 1 : - 1;
                }
                
                return $qA > $qB ? - 1 : 1;
            });
            
            $this->sorted = true;
        }
    }
}
