ethics-canvas/canvas/php/add-collaborator.php

<?php
    require_once("../../php/db_utils.php");
    
    try {
        // Declarations
        $collaboratorIsMember = false;
        $collaboratorExists = false;
        
        // Connect to the database
        $database = db_connect();
        
        // Incoming data
        $canvasId = $_POST["canvas_id"];
        $collaborator = $_POST["collaborator"];
        
        // Check if the collaborator is a member
        $query = 'SELECT username FROM user WHERE username = "' . $collaborator . '";';
        $recordSet = db_query_return($database, $query);
        
        $record = mysqli_fetch_assoc($recordSet);
        
        if(isset($record["username"])) {
            $collaboratorIsMember = true;
        }
        
        mysqli_free_result($recordSet);
        
        // Check if the collaborator already exists
        $query = 'SELECT * FROM collaborators WHERE canvas_id = "' . $canvasId . '" AND collaborator = "' . $collaborator . '";';
        
        $recordSet = db_query_return($database, $query);
        
        $record = mysqli_fetch_assoc($recordSet);
        
        if(isset($record["collaborator"])) {
            $collaboratorExists = true;
        }
        
        mysqli_free_result($recordSet);
        
        // If the collaborator is not already a member
        if($collaboratorIsMember == false) {
            echo(1);
        }
        // If the collaborator is already a collaborator
        else if($collaboratorExists == true) {
            echo(2);
        }
        else if($collaboratorIsMember == true && $collaboratorExists == false) {
            // Add collaborator
            $query = 'INSERT INTO collaborators (canvas_id, collaborator) VALUES ("' . $canvasId . '", "' . $collaborator . '");';
            
            echo(3);
        }
        
        // Insert new or update old description
        db_query_no_return($database, $query);
        
        // Close the connection to the database
        db_close($database);
    }
    catch(Exception $e) {
        $errorMsg = $e->getMessage();
        print_r($errorMsg);
    }
?>