<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\HttpFoundation;

/**
 * HeaderBag is a container for HTTP headers.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class HeaderBag implements \IteratorAggregate, \Countable
{
    protected $headers = [];
    protected $cacheControl = [];

    /**
     * @param array $headers An array of HTTP headers
     */
    public function __construct(array $headers = [])
    {
        foreach ($headers as $key => $values) {
            $this->set($key, $values);
        }
    }

    /**
     * Returns the headers as a string.
     *
     * @return string The headers
     */
    public function __toString()
    {
        if (!$headers = $this->all()) {
            return '';
        }

        ksort($headers);
        $max = max(array_map('strlen', array_keys($headers))) + 1;
        $content = '';
        foreach ($headers as $name => $values) {
            $name = ucwords($name, '-');
            foreach ($values as $value) {
                $content .= sprintf("%-{$max}s %s\r\n", $name.':', $value);
            }
        }

        return $content;
    }

    /**
     * Returns the headers.
     *
     * @return array An array of headers
     */
    public function all()
    {
        return $this->headers;
    }

    /**
     * Returns the parameter keys.
     *
     * @return array An array of parameter keys
     */
    public function keys()
    {
        return array_keys($this->all());
    }

    /**
     * Replaces the current HTTP headers by a new set.
     *
     * @param array $headers An array of HTTP headers
     */
    public function replace(array $headers = [])
    {
        $this->headers = [];
        $this->add($headers);
    }

    /**
     * Adds new headers the current HTTP headers set.
     *
     * @param array $headers An array of HTTP headers
     */
    public function add(array $headers)
    {
        foreach ($headers as $key => $values) {
            $this->set($key, $values);
        }
    }

    /**
     * Returns a header value by name.
     *
     * @param string      $key     The header name
     * @param string|null $default The default value
     * @param bool        $first   Whether to return the first value or all header values
     *
     * @return string|string[]|null The first header value or default value if $first is true, an array of values otherwise
     */
    public function get($key, $default = null, $first = true)
    {
        $key = str_replace('_', '-', strtolower($key));
        $headers = $this->all();

        if (!array_key_exists($key, $headers)) {
            if (null === $default) {
                return $first ? null : [];
            }

            return $first ? $default : [$default];
        }

        if ($first) {
            return \count($headers[$key]) ? $headers[$key][0] : $default;
        }

        return $headers[$key];
    }

    /**
     * Sets a header by name.
     *
     * @param string          $key     The key
     * @param string|string[] $values  The value or an array of values
     * @param bool            $replace Whether to replace the actual value or not (true by default)
     */
    public function set($key, $values, $replace = true)
    {
        $key = str_replace('_', '-', strtolower($key));

        if (\is_array($values)) {
            $values = array_values($values);

            if (true === $replace || !isset($this->headers[$key])) {
                $this->headers[$key] = $values;
            } else {
                $this->headers[$key] = array_merge($this->headers[$key], $values);
            }
        } else {
            if (true === $replace || !isset($this->headers[$key])) {
                $this->headers[$key] = [$values];
            } else {
                $this->headers[$key][] = $values;
            }
        }

        if ('cache-control' === $key) {
            $this->cacheControl = $this->parseCacheControl(implode(', ', $this->headers[$key]));
        }
    }

    /**
     * Returns true if the HTTP header is defined.
     *
     * @param string $key The HTTP header
     *
     * @return bool true if the parameter exists, false otherwise
     */
    public function has($key)
    {
        return array_key_exists(str_replace('_', '-', strtolower($key)), $this->all());
    }

    /**
     * Returns true if the given HTTP header contains the given value.
     *
     * @param string $key   The HTTP header name
     * @param string $value The HTTP value
     *
     * @return bool true if the value is contained in the header, false otherwise
     */
    public function contains($key, $value)
    {
        return \in_array($value, $this->get($key, null, false));
    }

    /**
     * Removes a header.
     *
     * @param string $key The HTTP header name
     */
    public function remove($key)
    {
        $key = str_replace('_', '-', strtolower($key));

        unset($this->headers[$key]);

        if ('cache-control' === $key) {
            $this->cacheControl = [];
        }
    }

    /**
     * Returns the HTTP header value converted to a date.
     *
     * @param string    $key     The parameter key
     * @param \DateTime $default The default value
     *
     * @return \DateTime|null The parsed DateTime or the default value if the header does not exist
     *
     * @throws \RuntimeException When the HTTP header is not parseable
     */
    public function getDate($key, \DateTime $default = null)
    {
        if (null === $value = $this->get($key)) {
            return $default;
        }

        if (false === $date = \DateTime::createFromFormat(DATE_RFC2822, $value)) {
            throw new \RuntimeException(sprintf('The %s HTTP header is not parseable (%s).', $key, $value));
        }

        return $date;
    }

    /**
     * Adds a custom Cache-Control directive.
     *
     * @param string $key   The Cache-Control directive name
     * @param mixed  $value The Cache-Control directive value
     */
    public function addCacheControlDirective($key, $value = true)
    {
        $this->cacheControl[$key] = $value;

        $this->set('Cache-Control', $this->getCacheControlHeader());
    }

    /**
     * Returns true if the Cache-Control directive is defined.
     *
     * @param string $key The Cache-Control directive
     *
     * @return bool true if the directive exists, false otherwise
     */
    public function hasCacheControlDirective($key)
    {
        return array_key_exists($key, $this->cacheControl);
    }

    /**
     * Returns a Cache-Control directive value by name.
     *
     * @param string $key The directive name
     *
     * @return mixed|null The directive value if defined, null otherwise
     */
    public function getCacheControlDirective($key)
    {
        return array_key_exists($key, $this->cacheControl) ? $this->cacheControl[$key] : null;
    }

    /**
     * Removes a Cache-Control directive.
     *
     * @param string $key The Cache-Control directive
     */
    public function removeCacheControlDirective($key)
    {
        unset($this->cacheControl[$key]);

        $this->set('Cache-Control', $this->getCacheControlHeader());
    }

    /**
     * Returns an iterator for headers.
     *
     * @return \ArrayIterator An \ArrayIterator instance
     */
    public function getIterator()
    {
        return new \ArrayIterator($this->headers);
    }

    /**
     * Returns the number of headers.
     *
     * @return int The number of headers
     */
    public function count()
    {
        return \count($this->headers);
    }

    protected function getCacheControlHeader()
    {
        ksort($this->cacheControl);

        return HeaderUtils::toString($this->cacheControl, ',');
    }

    /**
     * Parses a Cache-Control HTTP header.
     *
     * @param string $header The value of the Cache-Control HTTP header
     *
     * @return array An array representing the attribute values
     */
    protected function parseCacheControl($header)
    {
        $parts = HeaderUtils::split($header, ',=');

        return HeaderUtils::combine($parts);
    }
}