<?php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
$project = 'paper'; // or waterfall
$version = getLatestVersion($project);
$build = getLatestBuild($project, $version);
$fileName = getLatestDownload($project, $version, $build);

$downloadURL = "https://papermc.io/api/v2/projects/{$project}/versions/{$version}/builds/{$build}/downloads/{$fileName}";
header("Content-Disposition: attachment; filename*=UTF-8''paper-latest.jar");
header('Content-Type: application/java-archive');
echo file_get_contents($downloadURL);


function getLatestDownload($projectName, $version, $build){
  $downloadStr = file_get_contents('https://papermc.io/api/v2/projects/'.$projectName.'/versions/'.$version.'/builds/'.$build);
  $downloads = json_decode($downloadStr);
  return $downloads->downloads->application->name;
}

function getLatestBuild($projectName, $version){
  $buildsStr = file_get_contents('https://papermc.io/api/v2/projects/'.$projectName.'/versions/'.$version);
  $builds = json_decode($buildsStr);
  $latestBuild = $builds->builds[count($builds->builds)-1];
  return $latestBuild;
}

function getLatestVersion($projectName){
  $versions = file_get_contents('https://papermc.io/api/v2/projects/'.$projectName);
  $versionJson = json_decode($versions);
  $numVersions = count($versionJson->versions) - 1;
  $latestVersion = $versionJson->versions[$numVersions];
  return $latestVersion;
}