<?php

    require_once 'data.php';

    function add_user(&$dbh)
    {
        while(true)
        {
            $user_id = generate_id();
            
            $q = "INSERT INTO users (id) VALUES (?)";

            log_debug($q, $user_id);
    
            $res = $dbh->query($q, $user_id);
            
            if(PEAR::isError($res)) 
            {
                if($res->getCode() == DB_ERROR_ALREADY_EXISTS)
                    continue;
    
                die_with_code(500, "{$res->message}\n{$q}\n");
            }
            
            return get_user($dbh, $user_id);
        }
    }
        
    function get_user(&$dbh, $user_id)
    {
        $q = 'SELECT id, name, email,
                     UNIX_TIMESTAMP(created) AS created,
                     UNIX_TIMESTAMP(NOW()) - UNIX_TIMESTAMP(created) AS age
              FROM users
              WHERE id = ?';
    
        $res = $dbh->query($q, $user_id);
        
        if(PEAR::isError($res)) 
            die_with_code(500, "{$res->message}\n{$q}\n");

        return $res->fetchRow(DB_FETCHMODE_ASSOC);
    }
    
    function get_user_by_name(&$dbh, $user_name)
    {
        $q = 'SELECT id, name,
                     UNIX_TIMESTAMP(created) AS created,
                     UNIX_TIMESTAMP(NOW()) - UNIX_TIMESTAMP(created) AS age
              FROM users
              WHERE name = ?';
    
        $res = $dbh->query($q, $user_name);
        
        if(PEAR::isError($res)) 
            die_with_code(500, "{$res->message}\n{$q}\n");

        return $res->fetchRow(DB_FETCHMODE_ASSOC);
    }
    
    function set_user(&$dbh, $user)
    {
        $old_user = get_user($dbh, $user['id']);
        
        if(!$old_user)
            return false;

        $update_clauses = array();

        if(!is_null($user['name']) && $user['name'] != $old_user['name'])
            $update_clauses[] = sprintf('name = %s', $dbh->quoteSmart($user['name']));
        
        if(!is_null($user['email']) && $user['email'] != $old_user['email'])
            $update_clauses[] = sprintf('email = %s', $dbh->quoteSmart($user['email']));
        
        if(!is_null($user['password']))
            $update_clauses[] = sprintf('password = SHA1(%s)', $dbh->quoteSmart($user['password']));
        
        if(empty($update_clauses)) {
            error_log("skipping user {$user['id']} update since there's nothing to change");

        } else {
            $update_clauses = join(', ', $update_clauses);
            
            $q = "UPDATE users
                  SET {$update_clauses}
                  WHERE id = ".$dbh->quoteSmart($user['id']);
    
            error_log(preg_replace('/\s+/', ' ', $q));
    
            $res = $dbh->query($q);
            
            if(PEAR::isError($res)) 
            {
                if($res->getCode() == DB_ERROR_ALREADY_EXISTS)
                {
                    return false;
                }
    
                die_with_code(500, "{$res->message}\n{$q}\n");
            }
        }

        return get_user($dbh, $user['id']);
    }
    
    function delete_user(&$dbh, $user_id)
    {
        $q = 'DELETE FROM users
              WHERE id = ?';

        log_debug($q, $user_id);

        $res = $dbh->query($q, $user_id);
        
        if(PEAR::isError($res)) 
            die_with_code(500, "{$res->message}\n{$q}\n");

        return true;
    }
    
   /**
    * Return true if a given user ID and password match the database.
    */
    function check_user_password(&$dbh, $user_id, $password)
    {
        $q = sprintf('SELECT password = SHA1(%s)
                      FROM users
                      WHERE id = ?
                      LIMIT 1',
                      $dbh->quoteSmart($password));
    
        log_debug($q, $user_id);
        $res = $dbh->query($q, $user_id);
        
        if(PEAR::isError($res)) 
            die_with_code(500, "{$res->message}\n{$q}\n");

        $match = $res->fetchRow();
        
        return $match[0] ? true : false;
    }
    
   /**
    * Functions below all assume that session_start() has already been called.
    */

   /**
    * Is the user logged in?
    */
    function is_logged_in()
    {
        return isset($_SESSION['user_id']);
    }
    
   /**
    * If the session contains a user id, return the associated user. Otherwise,
    * return null.
    */
    function cookied_user(&$dbh)
    {
        if ($_SESSION['user_id'] && ($user = get_user($dbh, $_SESSION['user_id']))) {
            return $user;
        }

        return null;
    }
    
   /**
    * Mark the user as being logged in by stashing their id in the session.
    */
    
    function login_user_by_id(&$dbh, $user_id) {
        $_SESSION['user_id'] = $user_id;
    }
    
    function login_user_by_name(&$dbh, $user) {
        if ($user = get_user_by_name($dbh, $user)) {
            $_SESSION['user_id'] = $user['id'];
        }
    }
    
   /**
    * Log a user out.
    */
    function logout_user()
    {
        session_destroy();
    }
    
?>