index.js

const core = require('@actions/core');
const tc = require('@actions/tool-cache');
const io = require('@actions/io');
const exec = require('@actions/exec');
const path = require('path');
const github = require('@actions/github');

// Main entry function
//
async function main(){

  try {

    // Get inputs
    const token = core.getInput('github-token');

    var fpmVersion = core.getInput('fpm-version');
    console.log(`fpm-version: ${fpmVersion}`);

    const fpmRepo = core.getInput('fpm-repository');
    console.log(`fpm-repository: ${fpmRepo}`);

    // Get latest version if requested
    if (fpmVersion === 'latest'){

      if (token === 'none') {
        core.setFailed('To fetch the latest fpm version, please supply a github token. Alternatively you can specify the fpm release version manually.');
      }

      try {

        fpmVersion = await getLatestReleaseVersion(token);

      } catch (error) {

        core.setFailed('Error while querying the latest fpm release version - please check your github token.');

      }

    }

    // Build download path
    const fetchPath = fpmRepo + '/releases/download/' + fpmVersion + '/';
    const filename = getFPMFilename(fpmVersion,process.platform);

    console.log(`This platform is ${process.platform}`);
    console.log(`Fetching fpm from ${fetchPath}${filename}`);

    // Download release
    var fpmPath;
    try {

      fpmPath = await tc.downloadTool(fetchPath+filename);

    } catch (error) {

      core.setFailed(`Error while trying to fetch fpm - please check that a version exists at the above release url.`);

    }

    console.log(fpmPath);
    const downloadDir = path.dirname(fpmPath);

    // Add executable flag on unix
    if (process.platform === 'linux' || process.platform === 'darwin'){

      await exec.exec('chmod u+x '+fpmPath);

    }

    // Rename to 'fpm'
    if (process.platform === 'win32') {

      await io.mv(fpmPath, downloadDir + '/' + 'fpm.exe');

    } else {

      await io.mv(fpmPath, downloadDir + '/' + 'fpm');

    }

    // Add to path
    core.addPath( downloadDir );
    console.log(`fpm added to path at ${downloadDir}`);

  } catch (error) {

    core.setFailed(error.message);

  }
};


// Construct the filename for an fpm release
//
//  fpm-<version>-<os>-<arch>[.exe]
//
//  <version> is a string of form X.Y.Z corresponding to a release of fpm
//  <os> is either 'linux', 'macos', or 'windows'
//  <arch> here is always 'x86_64'
//
function getFPMFilename(fpmVersion,platform){

  var filename = 'fpm-';

  filename += fpmVersion.replace('v','') + '-';

  if (platform === 'linux') {

    filename += 'linux-x86_64';

  } else if (platform === 'darwin') {

    filename += 'macos-x86_64';

  } else if (platform === 'win32') {

    filename += 'windows-x86_64.exe';

  } else {

    core.setFailed('Unknown platform');

  }

  return filename;

}

// Query github API to find the tag for the latest release
//
async function getLatestReleaseVersion(token){

  const octokit = github.getOctokit(token);

  const {data: latest} = await octokit.request('GET /repos/{owner}/{repo}/releases/latest', {
                            owner: 'fortran-lang',
                            repo: 'fpm'});

  return latest.tag_name;

}


// Call entry function
main();