<?php
/**
 * Zend Framework (http://framework.zend.com/)
 *
 * @link      http://github.com/zendframework/zf2 for the canonical source repository
 * @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
 * @license   http://framework.zend.com/license/new-bsd New BSD License
 */

namespace Zend\View\Helper\Navigation;

use RecursiveIteratorIterator;
use Traversable;
use Zend\Navigation\AbstractContainer;
use Zend\Navigation\Page\AbstractPage;
use Zend\Stdlib\ArrayUtils;
use Zend\Stdlib\ErrorHandler;
use Zend\View\Exception;

/**
 * Helper for printing <link> elements
 */
class Links extends AbstractHelper
{
    /**
     * Constants used for specifying which link types to find and render
     *
     * @var int
     */
    const RENDER_ALTERNATE  = 0x0001;
    const RENDER_STYLESHEET = 0x0002;
    const RENDER_START      = 0x0004;
    const RENDER_NEXT       = 0x0008;
    const RENDER_PREV       = 0x0010;
    const RENDER_CONTENTS   = 0x0020;
    const RENDER_INDEX      = 0x0040;
    const RENDER_GLOSSARY   = 0x0080;
    const RENDER_COPYRIGHT  = 0x0100;
    const RENDER_CHAPTER    = 0x0200;
    const RENDER_SECTION    = 0x0400;
    const RENDER_SUBSECTION = 0x0800;
    const RENDER_APPENDIX   = 0x1000;
    const RENDER_HELP       = 0x2000;
    const RENDER_BOOKMARK   = 0x4000;
    const RENDER_CUSTOM     = 0x8000;
    const RENDER_ALL        = 0xffff;

    /**
     * Maps render constants to W3C link types
     *
     * @var array
     */
    protected static $RELATIONS = [
        self::RENDER_ALTERNATE  => 'alternate',
        self::RENDER_STYLESHEET => 'stylesheet',
        self::RENDER_START      => 'start',
        self::RENDER_NEXT       => 'next',
        self::RENDER_PREV       => 'prev',
        self::RENDER_CONTENTS   => 'contents',
        self::RENDER_INDEX      => 'index',
        self::RENDER_GLOSSARY   => 'glossary',
        self::RENDER_COPYRIGHT  => 'copyright',
        self::RENDER_CHAPTER    => 'chapter',
        self::RENDER_SECTION    => 'section',
        self::RENDER_SUBSECTION => 'subsection',
        self::RENDER_APPENDIX   => 'appendix',
        self::RENDER_HELP       => 'help',
        self::RENDER_BOOKMARK   => 'bookmark',
    ];

    /**
     * The helper's render flag
     *
     * @see render()
     * @see setRenderFlag()
     * @var int
     */
    protected $renderFlag = self::RENDER_ALL;

    /**
     * Root container
     *
     * Used for preventing methods to traverse above the container given to
     * the {@link render()} method.
     *
     * @see _findRoot()
     * @var AbstractContainer
     */
    protected $root;

    /**
     * Helper entry point
     *
     * @param  string|AbstractContainer $container container to operate on
     * @return Links
     */
    public function __invoke($container = null)
    {
        if (null !== $container) {
            $this->setContainer($container);
        }

        return $this;
    }

    /**
     * Magic overload: Proxy calls to {@link findRelation()} or container
     *
     * Examples of finder calls:
     * <code>
     * // METHOD                  // SAME AS
     * $h->findRelNext($page);    // $h->findRelation($page, 'rel', 'next')
     * $h->findRevSection($page); // $h->findRelation($page, 'rev', 'section');
     * $h->findRelFoo($page);     // $h->findRelation($page, 'rel', 'foo');
     * </code>
     *
     * @param  string $method
     * @param  array  $arguments
     * @return mixed
     * @throws Exception\ExceptionInterface
     */
    public function __call($method, array $arguments = [])
    {
        ErrorHandler::start(E_WARNING);
        $result = preg_match('/find(Rel|Rev)(.+)/', $method, $match);
        ErrorHandler::stop();
        if ($result) {
            return $this->findRelation($arguments[0], strtolower($match[1]), strtolower($match[2]));
        }

        return parent::__call($method, $arguments);
    }

    /**
     * Renders helper
     *
     * Implements {@link HelperInterface::render()}.
     *
     * @param  AbstractContainer|string|null $container [optional] container to render.
     *                                         Default is to render the
     *                                         container registered in the
     *                                         helper.
     * @return string
     */
    public function render($container = null)
    {
        $this->parseContainer($container);
        if (null === $container) {
            $container = $this->getContainer();
        }

        $active = $this->findActive($container);
        if ($active) {
            $active = $active['page'];
        } else {
            // no active page
            return '';
        }

        $output = '';
        $indent = $this->getIndent();
        $this->root = $container;

        $result = $this->findAllRelations($active, $this->getRenderFlag());
        foreach ($result as $attrib => $types) {
            foreach ($types as $relation => $pages) {
                foreach ($pages as $page) {
                    $r = $this->renderLink($page, $attrib, $relation);
                    if ($r) {
                        $output .= $indent . $r . PHP_EOL;
                    }
                }
            }
        }

        $this->root = null;

        // return output (trim last newline by spec)
        return strlen($output) ? rtrim($output, PHP_EOL) : '';
    }

    /**
     * Renders the given $page as a link element, with $attrib = $relation
     *
     * @param  AbstractPage $page     the page to render the link for
     * @param  string       $attrib   the attribute to use for $type,
     *                                either 'rel' or 'rev'
     * @param  string       $relation relation type, muse be one of;
     *                                alternate, appendix, bookmark,
     *                                chapter, contents, copyright,
     *                                glossary, help, home, index, next,
     *                                prev, section, start, stylesheet,
     *                                subsection
     * @return string
     * @throws Exception\DomainException
     */
    public function renderLink(AbstractPage $page, $attrib, $relation)
    {
        if (! in_array($attrib, ['rel', 'rev'])) {
            throw new Exception\DomainException(sprintf(
                'Invalid relation attribute "%s", must be "rel" or "rev"',
                $attrib
            ));
        }

        if (! $href = $page->getHref()) {
            return '';
        }

        // TODO: add more attribs
        // http://www.w3.org/TR/html401/struct/links.html#h-12.2
        $attribs = [
            $attrib  => $relation,
            'href'   => $href,
            'title'  => $page->getLabel()
        ];

        return '<link' .
            $this->htmlAttribs($attribs) .
            $this->getClosingBracket();
    }

    // Finder methods:

    /**
     * Finds all relations (forward and reverse) for the given $page
     *
     * The form of the returned array:
     * <code>
     * // $page denotes an instance of Zend\Navigation\Page\AbstractPage
     * $returned = array(
     *     'rel' => array(
     *         'alternate' => array($page, $page, $page),
     *         'start'     => array($page),
     *         'next'      => array($page),
     *         'prev'      => array($page),
     *         'canonical' => array($page)
     *     ),
     *     'rev' => array(
     *         'section'   => array($page)
     *     )
     * );
     * </code>
     *
     * @param  AbstractPage $page  page to find links for
     * @param  null|int
     * @return array
     */
    public function findAllRelations(AbstractPage $page, $flag = null)
    {
        if (! is_int($flag)) {
            $flag = self::RENDER_ALL;
        }

        $result = ['rel' => [], 'rev' => []];
        $native = array_values(static::$RELATIONS);

        foreach (array_keys($result) as $rel) {
            $meth = 'getDefined' . ucfirst($rel);
            $types = array_merge($native, array_diff($page->$meth(), $native));

            foreach ($types as $type) {
                if (! $relFlag = array_search($type, static::$RELATIONS)) {
                    $relFlag = self::RENDER_CUSTOM;
                }
                if (! ($flag & $relFlag)) {
                    continue;
                }

                $found = $this->findRelation($page, $rel, $type);
                if ($found) {
                    if (! is_array($found)) {
                        $found = [$found];
                    }
                    $result[$rel][$type] = $found;
                }
            }
        }

        return $result;
    }

    /**
     * Finds relations of the given $rel=$type from $page
     *
     * This method will first look for relations in the page instance, then
     * by searching the root container if nothing was found in the page.
     *
     * @param  AbstractPage $page page to find relations for
     * @param  string       $rel  relation, "rel" or "rev"
     * @param  string       $type link type, e.g. 'start', 'next'
     * @return AbstractPage|array|null
     * @throws Exception\DomainException if $rel is not "rel" or "rev"
     */
    public function findRelation(AbstractPage $page, $rel, $type)
    {
        if (! in_array($rel, ['rel', 'rev'])) {
            throw new Exception\DomainException(sprintf(
                'Invalid argument: $rel must be "rel" or "rev"; "%s" given',
                $rel
            ));
        }

        if (! $result = $this->findFromProperty($page, $rel, $type)) {
            $result = $this->findFromSearch($page, $rel, $type);
        }

        return $result;
    }

    /**
     * Finds relations of given $type for $page by checking if the
     * relation is specified as a property of $page
     *
     * @param  AbstractPage $page  page to find relations for
     * @param  string       $rel   relation, 'rel' or 'rev'
     * @param  string       $type  link type, e.g. 'start', 'next'
     * @return AbstractPage|array|null
     */
    protected function findFromProperty(AbstractPage $page, $rel, $type)
    {
        $method = 'get' . ucfirst($rel);
        $result = $page->$method($type);
        if ($result) {
            $result = $this->convertToPages($result);
            if ($result) {
                if (! is_array($result)) {
                    $result = [$result];
                }

                foreach ($result as $key => $page) {
                    if (! $this->accept($page)) {
                        unset($result[$key]);
                    }
                }

                return count($result) == 1 ? $result[0] : $result;
            }
        }

        return;
    }

    /**
     * Finds relations of given $rel=$type for $page by using the helper to
     * search for the relation in the root container
     *
     * @param  AbstractPage $page page to find relations for
     * @param  string       $rel  relation, 'rel' or 'rev'
     * @param  string       $type link type, e.g. 'start', 'next', etc
     * @return array|null
     */
    protected function findFromSearch(AbstractPage $page, $rel, $type)
    {
        $found = null;

        $method = 'search' . ucfirst($rel) . ucfirst($type);
        if (method_exists($this, $method)) {
            $found = $this->$method($page);
        }

        return $found;
    }

    // Search methods:

    /**
     * Searches the root container for the forward 'start' relation of the given
     * $page
     *
     * From {@link http://www.w3.org/TR/html4/types.html#type-links}:
     * Refers to the first document in a collection of documents. This link type
     * tells search engines which document is considered by the author to be the
     * starting point of the collection.
     *
     * @param  AbstractPage $page
     * @return AbstractPage|null
     */
    public function searchRelStart(AbstractPage $page)
    {
        $found = $this->findRoot($page);
        if (! $found instanceof AbstractPage) {
            $found->rewind();
            $found = $found->current();
        }

        if ($found === $page || ! $this->accept($found)) {
            $found = null;
        }

        return $found;
    }

    /**
     * Searches the root container for the forward 'next' relation of the given
     * $page
     *
     * From {@link http://www.w3.org/TR/html4/types.html#type-links}:
     * Refers to the next document in a linear sequence of documents. User
     * agents may choose to preload the "next" document, to reduce the perceived
     * load time.
     *
     * @param  AbstractPage $page
     * @return AbstractPage|null
     */
    public function searchRelNext(AbstractPage $page)
    {
        $found = null;
        $break = false;
        $iterator = new RecursiveIteratorIterator($this->findRoot($page), RecursiveIteratorIterator::SELF_FIRST);
        foreach ($iterator as $intermediate) {
            if ($intermediate === $page) {
                // current page; break at next accepted page
                $break = true;
                continue;
            }

            if ($break && $this->accept($intermediate)) {
                $found = $intermediate;
                break;
            }
        }

        return $found;
    }

    /**
     * Searches the root container for the forward 'prev' relation of the given
     * $page
     *
     * From {@link http://www.w3.org/TR/html4/types.html#type-links}:
     * Refers to the previous document in an ordered series of documents. Some
     * user agents also support the synonym "Previous".
     *
     * @param  AbstractPage $page
     * @return AbstractPage|null
     */
    public function searchRelPrev(AbstractPage $page)
    {
        $found = null;
        $prev = null;
        $iterator = new RecursiveIteratorIterator(
            $this->findRoot($page),
            RecursiveIteratorIterator::SELF_FIRST
        );
        foreach ($iterator as $intermediate) {
            if (! $this->accept($intermediate)) {
                continue;
            }
            if ($intermediate === $page) {
                $found = $prev;
                break;
            }

            $prev = $intermediate;
        }

        return $found;
    }

    /**
     * Searches the root container for forward 'chapter' relations of the given
     * $page
     *
     * From {@link http://www.w3.org/TR/html4/types.html#type-links}:
     * Refers to a document serving as a chapter in a collection of documents.
     *
     * @param  AbstractPage $page
     * @return AbstractPage|array|null
     */
    public function searchRelChapter(AbstractPage $page)
    {
        $found = [];

        // find first level of pages
        $root = $this->findRoot($page);

        // find start page(s)
        $start = $this->findRelation($page, 'rel', 'start');
        if (! is_array($start)) {
            $start = [$start];
        }

        foreach ($root as $chapter) {
            // exclude self and start page from chapters
            if ($chapter !== $page &&
                ! in_array($chapter, $start) &&
                $this->accept($chapter)) {
                $found[] = $chapter;
            }
        }

        switch (count($found)) {
            case 0:
                return;
            case 1:
                return $found[0];
            default:
                return $found;
        }
    }

    /**
     * Searches the root container for forward 'section' relations of the given
     * $page
     *
     * From {@link http://www.w3.org/TR/html4/types.html#type-links}:
     * Refers to a document serving as a section in a collection of documents.
     *
     * @param  AbstractPage $page
     * @return AbstractPage|array|null
     */
    public function searchRelSection(AbstractPage $page)
    {
        $found = [];

        // check if given page has pages and is a chapter page
        if ($page->hasPages() && $this->findRoot($page)->hasPage($page)) {
            foreach ($page as $section) {
                if ($this->accept($section)) {
                    $found[] = $section;
                }
            }
        }

        switch (count($found)) {
            case 0:
                return;
            case 1:
                return $found[0];
            default:
                return $found;
        }
    }

    /**
     * Searches the root container for forward 'subsection' relations of the
     * given $page
     *
     * From {@link http://www.w3.org/TR/html4/types.html#type-links}:
     * Refers to a document serving as a subsection in a collection of
     * documents.
     *
     * @param  AbstractPage $page
     * @return AbstractPage|array|null
     */
    public function searchRelSubsection(AbstractPage $page)
    {
        $found = [];

        if ($page->hasPages()) {
            // given page has child pages, loop chapters
            foreach ($this->findRoot($page) as $chapter) {
                // is page a section?
                if ($chapter->hasPage($page)) {
                    foreach ($page as $subsection) {
                        if ($this->accept($subsection)) {
                            $found[] = $subsection;
                        }
                    }
                }
            }
        }

        switch (count($found)) {
            case 0:
                return;
            case 1:
                return $found[0];
            default:
                return $found;
        }
    }

    /**
     * Searches the root container for the reverse 'section' relation of the
     * given $page
     *
     * From {@link http://www.w3.org/TR/html4/types.html#type-links}:
     * Refers to a document serving as a section in a collection of documents.
     *
     * @param  AbstractPage $page
     * @return AbstractPage|null
     */
    public function searchRevSection(AbstractPage $page)
    {
        $found  = null;
        $parent = $page->getParent();
        if ($parent) {
            if ($parent instanceof AbstractPage &&
                $this->findRoot($page)->hasPage($parent)) {
                $found = $parent;
            }
        }

        return $found;
    }

    /**
     * Searches the root container for the reverse 'section' relation of the
     * given $page
     *
     * From {@link http://www.w3.org/TR/html4/types.html#type-links}:
     * Refers to a document serving as a subsection in a collection of
     * documents.
     *
     * @param  AbstractPage $page
     * @return AbstractPage|null
     */
    public function searchRevSubsection(AbstractPage $page)
    {
        $found  = null;
        $parent = $page->getParent();
        if ($parent) {
            if ($parent instanceof AbstractPage) {
                $root = $this->findRoot($page);
                foreach ($root as $chapter) {
                    if ($chapter->hasPage($parent)) {
                        $found = $parent;
                        break;
                    }
                }
            }
        }

        return $found;
    }

    // Util methods:

    /**
     * Returns the root container of the given page
     *
     * When rendering a container, the render method still store the given
     * container as the root container, and unset it when done rendering. This
     * makes sure finder methods will not traverse above the container given
     * to the render method.
     *
     * @param  AbstractPage $page
     * @return AbstractContainer
     */
    protected function findRoot(AbstractPage $page)
    {
        if ($this->root) {
            return $this->root;
        }

        $root = $page;

        while ($parent = $page->getParent()) {
            $root = $parent;
            if ($parent instanceof AbstractPage) {
                $page = $parent;
            } else {
                break;
            }
        }

        return $root;
    }

    /**
     * Converts a $mixed value to an array of pages
     *
     * @param  mixed $mixed     mixed value to get page(s) from
     * @param  bool  $recursive whether $value should be looped
     *                          if it is an array or a config
     * @return AbstractPage|array|null
     */
    protected function convertToPages($mixed, $recursive = true)
    {
        if ($mixed instanceof AbstractPage) {
            // value is a page instance; return directly
            return $mixed;
        } elseif ($mixed instanceof AbstractContainer) {
            // value is a container; return pages in it
            $pages = [];
            foreach ($mixed as $page) {
                $pages[] = $page;
            }
            return $pages;
        } elseif ($mixed instanceof Traversable) {
            $mixed = ArrayUtils::iteratorToArray($mixed);
        } elseif (is_string($mixed)) {
            // value is a string; make a URI page
            return AbstractPage::factory([
                'type' => 'uri',
                'uri'  => $mixed
            ]);
        }

        if (is_array($mixed) && ! empty($mixed)) {
            if ($recursive && is_numeric(key($mixed))) {
                // first key is numeric; assume several pages
                $pages = [];
                foreach ($mixed as $value) {
                    $value = $this->convertToPages($value, false);
                    if ($value) {
                        $pages[] = $value;
                    }
                }
                return $pages;
            } else {
                // pass array to factory directly
                try {
                    $page = AbstractPage::factory($mixed);
                    return $page;
                } catch (\Exception $e) {
                }
            }
        }

        // nothing found
        return;
    }

    /**
     * Sets the helper's render flag
     *
     * The helper uses the bitwise '&' operator against the hex values of the
     * render constants. This means that the flag can is "bitwised" value of
     * the render constants. Examples:
     * <code>
     * // render all links except glossary
     * $flag = Links:RENDER_ALL ^ Links:RENDER_GLOSSARY;
     * $helper->setRenderFlag($flag);
     *
     * // render only chapters and sections
     * $flag = Links:RENDER_CHAPTER | Links:RENDER_SECTION;
     * $helper->setRenderFlag($flag);
     *
     * // render only relations that are not native W3C relations
     * $helper->setRenderFlag(Links:RENDER_CUSTOM);
     *
     * // render all relations (default)
     * $helper->setRenderFlag(Links:RENDER_ALL);
     * </code>
     *
     * Note that custom relations can also be rendered directly using the
     * {@link renderLink()} method.
     *
     * @param  int $renderFlag
     * @return Links
     */
    public function setRenderFlag($renderFlag)
    {
        $this->renderFlag = (int) $renderFlag;

        return $this;
    }

    /**
     * Returns the helper's render flag
     *
     * @return int
     */
    public function getRenderFlag()
    {
        return $this->renderFlag;
    }
}
