/* --------- Comment output functions --------- */
function commentTree($comments,$parent=NULL,$layer=1) :: Builds comment tree, and calls printComment() for each comment in the correct order.
function printComment($comment,$indent) :: Outputs a comment
function parseComment($text) :: Parses comment formatting and sanitizes comment string
function parseQuote($text) :: Callback function for preg_replace for quotes in comments (not working)
function parseCode($text) :: Callback function for preg_replace for code blocks in comments (not working)

/* --------- Common functions (used throughout the site) --------- */
function timeSince($mysqltimestamp) :: returns time since given timestamp, rounded to the largest whole unit (e.g 3 hours 12 minutes ~ 3 hours)
function printHeader() :: Outputs the site header
function voteArrows($myvote,$subjectid) :: Outputs the appropriate voting arrows depending on the logged in user's vote
function pagination($page, $totalpages) :: Pagination function, takes page info from getLinks() / getComments()
function buildQueryString($qs,$suffix=NULL) :: Takes an array from parse_str, returns a query string
function buildLink($url="#", $text="link", $class=NULL, $id=NULL, $name=NULL) :: Construct an internal hyperlink
function simplifyURL($url) :: Rewrite a query string to a static URL
function spanHide() :: Returns a hidden span with the contents of all arguments in order
function urlTitle($str) :: Sanitize link title for URL
function unbase36($str) :: Return decimal value of base 36 encoded number
function base36($int) :: Return base 36 encoding of integer

/* --------- Database connection/query helper functions --------- */
function dbConn() :: Returns database link
function dbQuery($query) :: Returns result of query, logs error and returns false on failure
function dbQueryId($query) :: Returns insert id of query
function dbFirstResult($query) :: Returns first row of query result as indexed array
function dbFirstResultAssoc($query) :: Returns first row of query result as associative array
function dbResultArray($query) :: Returns query result as associative array
function dbResultExists($query) :: Returns true if a result is found, false if it isn't
function dbRowCount($query) :: Returns the number of rows in the query result
function dbEscape($string) :: Returns escaped string to prevent SQL injection attacks
function dbEscapeArray($array) :: Returns escaped array to prevent SQL injection attacks

/* --------- User table functions --------- */
function getUsername($id) :: Returns name of user with given id
function getUserid($username) :: Returns id of user with given name
function getPassword($username) :: Returns password hash of user with given name
function userExists($parameter,$value) :: Checks if a user exists, either by id, email or username
function registerUser($input) :: Writes user info to database on successful registration, returning the user id
function login($sessionid) :: Store session ID in user table
function logout() :: Remove session ID from user table and destroy session
function checkLogin($userid) :: Check session id against user table, logout if the ID is different
function getUser($userid=0) :: Returns an array containing user info, comment/link counts and points

/* --------- Link table functions --------- */
function getLink($id) :: Fetch a single link by id
function getLinks($page=1,$limit=25,$category=NULL,$user=NULL,$domain=NULL) :: Return array containing array of links, the current page and the total number of pages
function linkExists($url) :: Return true if the given URL has already been posted
function linkIdExists($id) :: return true if the link with the given id exists
function domainExists($domain) :: Return true if there are any links with the given domain
function sendLink($input) :: takes an array of sanitized input to insert into the database. On success, returns the id of the submitted link
function deleteLink($linkid) :: Delete link
function nsfw($linkid) :: Toggle nsfw status of link

/* --------- Category table functions --------- */
function categoryExists($cat) :: Return true if the given category exists
function getCategories($limit=0) :: Get an array of categories, optionally only those owned by a specific user

/* --------- Comment table functions --------- */
function sendComment($input) :: Takes an array of sanitized input. Submits comment to database and returns ID.
function getComments($linkid,$user=0,$page=1,$limit=25) :: Returns an array of comments to the given link ID
function rawComment($commentid) :: Returns raw form of comment with given ID (for comment editing)
function deleteComment($commentid) :: Deletes comment with given ID

/* --------- Vote table functions --------- */
function getMyPoints($userid) :: Get given user's total points (from their submissions and comments)
function vote($userid,$subjectid,$type,$vote) :: Enters, removes or edits a vote from user for subject, returns new vote count.

/* --------- Form output functions --------- */
function linkform($errors=array(),$input=array()) :: Outputs the link submission form with error messages and input from previous attempt (if any)
function loginform($errors=array(),$input=array()) :: Outputs the login form with error messages and input from previous attempt (if any)
function regform($errors=array(),$input=array()) :: Outputs the registration form with error messages and input from previous attempts (if any)
function commentform($id=0,$hide=0) :: Outputs a comment form for the given comment id, optionally hidden

/* --------- Link input validation/cleaning functions --------- */
function linkErrors($input) :: Takes an array of link input, returns array of errors (if any) or false on no errors.
function cleanLink($input) :: Takes an array of link data, returns same but sanitized.
function printLink($link) :: Prints a link

/* --------- Password hashing and comparison functions --------- */
function generateSalt($length = 128) :: Generate a hash salt
function hashPassword($password,$salt) :: Hash a password
function validatePassword($password,$storedhash) :: Check an entered password against a stored hash

/* --------- Validation functions --------- */
function registrationErrors($input) :: Validate registration data, return array of errors (if any), else return false
function loginErrors($input) :: Check for errors in the login form

/* --------- User info output functions --------- */
function printUser($user) :: Output user information