config.php

<?php


// must match the main HTML file
$dest = "xrb_1ytjfqxmz5zabt39qxcz3nphabstegddqqbhjgau13stfxz6fq7rkmceih7i";


$files = [
	"item-1" => [
		"name" => "Random File text",
		"file-name" => "Jupiter", //the file name the user will see
		"file-path" => "random-file.mp3", //hidden file, keep the name difficult to guess! Won't be shown to the user. (Recommended to have a subdirectory)
		"price" => 0.01, // price in USD (must match what the user is paying in the main HTML file),
		"description" => "Buy an MP3"
	],

	"image-1" => [
		"name" => "Random Image",
		"file-name" => "my-donald-image.jpg",
		"file-path" => "donald.jpg",
		"price" => 0.01
	]
];

?>

pay-api.php

<?php
include("config.php");

session_start();

$token = isset($_POST["token"]) ? $_POST["token"] : $_GET["token"];
$id = isset($_POST['id']) ? $_POST['id'] : $_GET['id'];

if($token == null){
	exit("Token is null");
}

if($id == null){
	exit("Id is null");
}

echo $_SESSION["state"];

$url = "https://api.brainblocks.io/api/session/$token/verify";

$status = file_get_contents($url);
$json = json_decode($status);

if(isset($_POST["action"]) && $_POST["action"] == "token"){
	if($json->fulfilled == false){
		$_SESSION["state"] = "WAITING";
		exit("OK");
	}
}

$file = $files[ $id ];

if($file == null){
	exit("Invalid file id");
}

if(	$json->fulfilled == true &&
	$json->destination == $dest &&
	$json->currency == "usd" &&
	((float)$json->amount) >= (float)$file["price"] ){

	if($_SESSION["state"] == "WAITING"){

		if(isset($_GET["download"]) && $_GET["download"] == "true"){

			header("Content-Disposition: attachment; filename=\"" . basename($file['file-name']) . "\"");
			header("Content-Type: text/html");
			header("Content-Length: " . filesize($file['file-path']));
			header("Connection: close");

			exit(readfile( $file['file-path'] ));

		}

	}else{
		exit( "Invalid payment hash" );
	}

}else{
	exit( "Invalid payment" );
}


$download_url = "?token=$token&id=$id&download=true";

?>


<h2>Thank you for buying <?php echo $file['name']; ?>!</h2>

<?php
// optional
if(isset($file['description'])){
	echo $file['description'];
}
?>
<br>
<a href="<?php echo $download_url; ?>">Click to download</a>