<?php
/**
* Data storage for links.
*
* This object behaves like an associative array.
*
* Example:
* $myLinks = new LinkDB();
* echo $myLinks[350]['title'];
* foreach ($myLinks as $link)
* echo $link['title'].' at url '.$link['url'].'; description:'.$link['description'];
*
* Available keys:
* - id: primary key, incremental integer identifier (persistent)
* - description: description of the entry
* - created: creation date of this entry, DateTime object.
* - updated: last modification date of this entry, DateTime object.
* - private: Is this link private? 0=no, other value=yes
* - tags: tags attached to this entry (separated by spaces)
* - title Title of the link
* - url URL of the link. Used for displayable links (no redirector, relative, etc.).
* Can be absolute or relative.
* Relative URLs are permalinks (e.g.'?m-ukcw')
* - real_url Absolute processed URL.
* - shorturl Permalink smallhash
*
* Implements 3 interfaces:
* - ArrayAccess: behaves like an associative array;
* - Countable: there is a count() method;
* - Iterator: usable in foreach () loops.
*
* ID mechanism:
* ArrayAccess is implemented in a way that will allow to access a link
* with the unique identifier ID directly with $link[ID].
* Note that it's not the real key of the link array attribute.
* This mechanism is in place to have persistent link IDs,
* even though the internal array is reordered by date.
* Example:
* - DB: link #1 (2010-01-01) link #2 (2016-01-01)
* - Order: #2 #1
* - Import links containing: link #3 (2013-01-01)
* - New DB: link #1 (2010-01-01) link #2 (2016-01-01) link #3 (2013-01-01)
* - Real order: #2 #3 #1
*/
class LinkDB implements Iterator, Countable, ArrayAccess
{
// Links are stored as a PHP serialized string
private $datastore;
// Link date storage format
const LINK_DATE_FORMAT = 'Ymd_His';
// List of links (associative array)
// - key: link date (e.g. "20110823_124546"),
// - value: associative array (keys: title, description...)
private $links;
// List of all recorded URLs (key=url, value=link offset)
// for fast reserve search (url-->link offset)
private $urls;
/**
* @var array List of all links IDS mapped with their array offset.
* Map: id->offset.
*/
protected $ids;
// List of offset keys (for the Iterator interface implementation)
private $keys;
// Position in the $this->keys array (for the Iterator interface)
private $position;
// Is the user logged in? (used to filter private links)
private $loggedIn;
// Hide public links
private $hidePublicLinks;
// link redirector set in user settings.
private $redirector;
/**
* Set this to `true` to urlencode link behind redirector link, `false` to leave it untouched.
*
* Example:
* anonym.to needs clean URL while dereferer.org needs urlencoded URL.
*
* @var boolean $redirectorEncode parameter: true or false
*/
private $redirectorEncode;
/**
* Creates a new LinkDB
*
* Checks if the datastore exists; else, attempts to create a dummy one.
*
* @param string $datastore datastore file path.
* @param boolean $isLoggedIn is the user logged in?
* @param boolean $hidePublicLinks if true all links are private.
* @param string $redirector link redirector set in user settings.
* @param boolean $redirectorEncode Enable urlencode on redirected urls (default: true).
*/
public function __construct(
$datastore,
$isLoggedIn,
$hidePublicLinks,
$redirector = '',
$redirectorEncode = true
)
{
$this->datastore = $datastore;
$this->loggedIn = $isLoggedIn;
$this->hidePublicLinks = $hidePublicLinks;
$this->redirector = $redirector;
$this->redirectorEncode = $redirectorEncode === true;
$this->check();
$this->read();
}
/**
* Countable - Counts elements of an object
*/
public function count()
{
return count($this->links);
}
/**
* ArrayAccess - Assigns a value to the specified offset
*/
public function offsetSet($offset, $value)
{
// TODO: use exceptions instead of "die"
if (!$this->loggedIn) {
die('You are not authorized to add a link.');
}
if (!isset($value['id']) || empty($value['url'])) {
die('Internal Error: A link should always have an id and URL.');
}
if (($offset !== null && ! is_int($offset)) || ! is_int($value['id'])) {
die('You must specify an integer as a key.');
}
if ($offset !== null && $offset !== $value['id']) {
die('Array offset and link ID must be equal.');
}
// If the link exists, we reuse the real offset, otherwise new entry
$existing = $this->getLinkOffset($offset);
if ($existing !== null) {
$offset = $existing;
} else {
$offset = count($this->links);
}
$this->links[$offset] = $value;
$this->urls[$value['url']] = $offset;
$this->ids[$value['id']] = $offset;
}
/**
* ArrayAccess - Whether or not an offset exists
*/
public function offsetExists($offset)
{
return array_key_exists($this->getLinkOffset($offset), $this->links);
}
/**
* ArrayAccess - Unsets an offset
*/
public function offsetUnset($offset)
{
if (!$this->loggedIn) {
// TODO: raise an exception
die('You are not authorized to delete a link.');
}
$realOffset = $this->getLinkOffset($offset);
$url = $this->links[$realOffset]['url'];
unset($this->urls[$url]);
unset($this->ids[$realOffset]);
unset($this->links[$realOffset]);
}
/**
* ArrayAccess - Returns the value at specified offset
*/
public function offsetGet($offset)
{
$realOffset = $this->getLinkOffset($offset);
return isset($this->links[$realOffset]) ? $this->links[$realOffset] : null;
}
/**
* Iterator - Returns the current element
*/
public function current()
{
return $this[$this->keys[$this->position]];
}
/**
* Iterator - Returns the key of the current element
*/
public function key()
{
return $this->keys[$this->position];
}
/**
* Iterator - Moves forward to next element
*/
public function next()
{
++$this->position;
}
/**
* Iterator - Rewinds the Iterator to the first element
*
* Entries are sorted by date (latest first)
*/
public function rewind()
{
$this->keys = array_keys($this->ids);
$this->position = 0;
}
/**
* Iterator - Checks if current position is valid
*/
public function valid()
{
return isset($this->keys[$this->position]);
}
/**
* Checks if the DB directory and file exist
*
* If no DB file is found, creates a dummy DB.
*/
private function check()
{
if (file_exists($this->datastore)) {
return;
}
// Create a dummy database for example
$this->links = array();
$link = array(
'id' => 1,
'title'=>' Shaarli: the personal, minimalist, super-fast, no-database delicious clone',
'url'=>'https://github.com/shaarli/Shaarli/wiki',
'description'=>'Welcome to Shaarli! This is your first public bookmark. To edit or delete me, you must first login.
To learn how to use Shaarli, consult the link "Help/documentation" at the bottom of this page.
You use the community supported version of the original Shaarli project, by Sebastien Sauvage.',
'private'=>0,
'created'=> new DateTime(),
'tags'=>'opensource software'
);
$link['shorturl'] = link_small_hash($link['created'], $link['id']);
$this->links[1] = $link;
$link = array(
'id' => 0,
'title'=>'My secret stuff... - Pastebin.com',
'url'=>'http://sebsauvage.net/paste/?8434b27936c09649#bR7XsXhoTiLcqCpQbmOpBi3rq2zzQUC5hBI7ZT1O3x8=',
'description'=>'Shhhh! I\'m a private link only YOU can see. You can delete me too.',
'private'=>1,
'created'=> new DateTime('1 minute ago'),
'tags'=>'secretstuff',
);
$link['shorturl'] = link_small_hash($link['created'], $link['id']);
$this->links[0] = $link;
// Write database to disk
$this->write();
}
/**
* Reads database from disk to memory
*/
private function read()
{
// Public links are hidden and user not logged in => nothing to show
if ($this->hidePublicLinks && !$this->loggedIn) {
$this->links = array();
return;
}
$this->links = FileUtils::readFlatDB($this->datastore, []);
$toremove = array();
foreach ($this->links as $key => &$link) {
if (! $this->loggedIn && $link['private'] != 0) {
// Transition for not upgraded databases.
$toremove[] = $key;
continue;
}
// Sanitize data fields.
sanitizeLink($link);
// Remove private tags if the user is not logged in.
if (! $this->loggedIn) {
$link['tags'] = preg_replace('/(^|\s+)\.[^($|\s)]+\s*/', ' ', $link['tags']);
}
// Do not use the redirector for internal links (Shaarli note URL starting with a '?').
if (!empty($this->redirector) && !startsWith($link['url'], '?')) {
$link['real_url'] = $this->redirector;
if ($this->redirectorEncode) {
$link['real_url'] .= urlencode(unescape($link['url']));
} else {
$link['real_url'] .= $link['url'];
}
}
else {
$link['real_url'] = $link['url'];
}
// To be able to load links before running the update, and prepare the update
if (! isset($link['created'])) {
$link['id'] = $link['linkdate'];
$link['created'] = DateTime::createFromFormat(self::LINK_DATE_FORMAT, $link['linkdate']);
if (! empty($link['updated'])) {
$link['updated'] = DateTime::createFromFormat(self::LINK_DATE_FORMAT, $link['updated']);
}
$link['shorturl'] = smallHash($link['linkdate']);
}
}
// If user is not logged in, filter private links.
foreach ($toremove as $offset) {
unset($this->links[$offset]);
}
$this->reorder();
}
/**
* Saves the database from memory to disk
*
* @throws IOException the datastore is not writable
*/
private function write()
{
FileUtils::writeFlatDB($this->datastore, $this->links);
}
/**
* Saves the database from memory to disk
*
* @param string $pageCacheDir page cache directory
*/
public function save($pageCacheDir)
{
if (!$this->loggedIn) {
// TODO: raise an Exception instead
die('You are not authorized to change the database.');
}
$this->write();
invalidateCaches($pageCacheDir);
}
/**
* Returns the link for a given URL, or False if it does not exist.
*
* @param string $url URL to search for
*
* @return mixed the existing link if it exists, else 'false'
*/
public function getLinkFromUrl($url)
{
if (isset($this->urls[$url])) {
return $this->links[$this->urls[$url]];
}
return false;
}
/**
* Returns the shaare corresponding to a smallHash.
*
* @param string $request QUERY_STRING server parameter.
*
* @return array $filtered array containing permalink data.
*
* @throws LinkNotFoundException if the smallhash is malformed or doesn't match any link.
*/
public function filterHash($request)
{
$request = substr($request, 0, 6);
$linkFilter = new LinkFilter($this->links);
return $linkFilter->filter(LinkFilter::$FILTER_HASH, $request);
}
/**
* Returns the list of articles for a given day.
*
* @param string $request day to filter. Format: YYYYMMDD.
*
* @return array list of shaare found.
*/
public function filterDay($request) {
$linkFilter = new LinkFilter($this->links);
return $linkFilter->filter(LinkFilter::$FILTER_DAY, $request);
}
/**
* Filter links according to search parameters.
*
* @param array $filterRequest Search request content. Supported keys:
* - searchtags: list of tags
* - searchterm: term search
* @param bool $casesensitive Optional: Perform case sensitive filter
* @param string $visibility return only all/private/public links
*
* @return array filtered links, all links if no suitable filter was provided.
*/
public function filterSearch($filterRequest = array(), $casesensitive = false, $visibility = 'all')
{
// Filter link database according to parameters.
$searchtags = isset($filterRequest['searchtags']) ? escape($filterRequest['searchtags']) : '';
$searchterm = isset($filterRequest['searchterm']) ? escape($filterRequest['searchterm']) : '';
// Search tags + fullsearch - blank string parameter will return all links.
$type = LinkFilter::$FILTER_TAG | LinkFilter::$FILTER_TEXT;
$request = [$searchtags, $searchterm];
$linkFilter = new LinkFilter($this);
return $linkFilter->filter($type, $request, $casesensitive, $visibility);
}
/**
* Returns the list tags appearing in the links with the given tags
* @param $filteringTags: tags selecting the links to consider
* @param $visibility: process only all/private/public links
* @return: a tag=>linksCount array
*/
public function linksCountPerTag($filteringTags = [], $visibility = 'all')
{
$links = empty($filteringTags) ? $this->links : $this->filterSearch(['searchtags' => $filteringTags], false, $visibility);
$tags = array();
$caseMapping = array();
foreach ($links as $link) {
foreach (preg_split('/\s+/', $link['tags'], 0, PREG_SPLIT_NO_EMPTY) as $tag) {
if (empty($tag)) {
continue;
}
// The first case found will be displayed.
if (!isset($caseMapping[strtolower($tag)])) {
$caseMapping[strtolower($tag)] = $tag;
$tags[$caseMapping[strtolower($tag)]] = 0;
}
$tags[$caseMapping[strtolower($tag)]]++;
}
}
// Sort tags by usage (most used tag first)
arsort($tags);
return $tags;
}
/**
* Returns the list of days containing articles (oldest first)
* Output: An array containing days (in format YYYYMMDD).
*/
public function days()
{
$linkDays = array();
foreach ($this->links as $link) {
$linkDays[$link['created']->format('Ymd')] = 0;
}
$linkDays = array_keys($linkDays);
sort($linkDays);
return $linkDays;
}
/**
* Reorder links by creation date (newest first).
*
* Also update the urls and ids mapping arrays.
*
* @param string $order ASC|DESC
*/
public function reorder($order = 'DESC')
{
$order = $order === 'ASC' ? -1 : 1;
// Reorder array by dates.
usort($this->links, function($a, $b) use ($order) {
return $a['created'] < $b['created'] ? 1 * $order : -1 * $order;
});
$this->urls = array();
$this->ids = array();
foreach ($this->links as $key => $link) {
$this->urls[$link['url']] = $key;
$this->ids[$link['id']] = $key;
}
}
/**
* Return the next key for link creation.
* E.g. If the last ID is 597, the next will be 598.
*
* @return int next ID.
*/
public function getNextId()
{
if (!empty($this->ids)) {
return max(array_keys($this->ids)) + 1;
}
return 0;
}
/**
* Returns a link offset in links array from its unique ID.
*
* @param int $id Persistent ID of a link.
*
* @return int Real offset in local array, or null if doesn't exist.
*/
protected function getLinkOffset($id)
{
if (isset($this->ids[$id])) {
return $this->ids[$id];
}
return null;
}
}
