Basic Upload

<html>
    <body>
        <form action="index.php" method="post" enctype="multipart/form-data">
            Select image to upload:
            <input type="file" name="upload" id="upload">
            <input type="submit" value="Upload Image" name="submit">
        </form>
    </body>
</html>

<?php

try {
    //Settings
    $target_dir = "uploads/";
    $mimes = array("jpg", "png", "jpeg", "gif");

    //Generated variables
    $file = $_FILES["upload"];
    $file_name = basename($file["name"]);
    $target_file = $target_dir . $file_name;

    if(isset($_POST["submit"])) {
        $check = getimagesize($file["tmp_name"]);
        $extension = pathinfo($target_file, PATHINFO_EXTENSION);

        if($check === false)
            throw new Exception('FILE_NOT_IMAGE');

        // Check if file already exists
        if(file_exists($target_file))
            throw new Exception('FILE_EXIST');

        // Check file size
        if($file["size"] > 5 * 1024 * 1024)
            throw new Exception('FILE_LARGE');

        // Allow certain file formats
        if(!in_array($extension, $mimes))
            throw new Exception('FILE_EXTENSION_NOT_ALLOWED');

        // Check if $uploadOk is set to 0 by an error
        if (move_uploaded_file($file["tmp_name"], $target_file))
            echo "The file ". $file_name . " has been uploaded.";
        else
            throw new Exception('FILE_ERROR');
    }
} catch (Exception $e) {
    if($e->getMessage() == 'FILE_NOT_IMAGE')
        echo "Error: File is not a image.";
    else if($e->getMessage() == 'FILE_EXIST')
        echo "Error: File already exist.";
    else if($e->getMessage() == 'FILE_EXTENSION_NOT_ALLOWED')
        echo "Error: File extension not allowed.";
    else
        echo "Epic Fail!";
}

?>