n.js

const fs = require('fs')
const yargs = require('yargs/yargs')

async function main() {

    // parse commandline argument -c
    // set filename to first commandline argument

    var argv = yargs(process.argv.slice(2)).argv;

    let programPath = null;
    if (argv._.length == 1) {
        programPath = argv._[0];
    }

    if (programPath === null && !("c" in argv)) {
        console.error("Must specify a program: 'n.js python.py', or an inline command: 'n.js -c \"print(1+1)\"'")
        process.exit(1);
    }

    if (programPath !== null && ("c" in argv)) {
        console.error("Can't specify both program path and inline command")
        process.exit(1);
    }

    let program = "";
    if (programPath !== null) {
        // read contents of file programPath
        program = await fs.promises.readFile(programPath, 'utf8');
    }

    if ("c" in argv) {
        program = argv.c;
    }

    if (process.env.BACALHAU_JOB_SPEC == "") {
      console.error("Must specify a BACALHAU_JOB_SPEC environment variable")
      process.exit(1);
    }

    let jobSpec

    try {
      jobSpec = JSON.parse(process.env.BACALHAU_JOB_SPEC)
    } catch(e) {
      console.error("Error processing BACALHAU_JOB_SPEC json: " + e.toString())
      process.exit(1);
    }

    // set system stdout to dev null
    // hide "Loading distutils", "Loaded distutils" messages.
    let oldStdoutWrite = process.stdout.write;
    process.stdout.write = function() {};

    let pyodide_pkg = await import("./pyodide/pyodide.js");
    let LOGGING_ON = false;
    let pyodide = await pyodide_pkg.loadPyodide({
      indexURL: "./pyodide/",
      stdout: (s) => {
         if (LOGGING_ON) {
             console.log(s)
         }
      },
      stderr: (s) => {
         if (LOGGING_ON) {
             console.log(s)
         }
      },
    });
    // await pyodide.loadPackage("micropip");

    // log any errors with fs setup
    LOGGING_ON = true;
    process.stdout.write = oldStdoutWrite;

    if (Array.isArray(jobSpec.inputs)) {
        // console.log("job spec = ", JSON.stringify(jobSpec))
        // console.log("about to mount input volumes")
        jobSpec.inputs.forEach(inputVolume => {
            const hostPath = inputVolume.path
            const wasmPath = inputVolume.path.replace('/pyodide_inputs', '')
            if (!fs.existsSync(wasmPath)) {
                // console.log(`mkdir ${wasmPath}`);
                pyodide.FS.mkdir(wasmPath);
            }
            // console.log(`mounting ${hostPath} to ${wasmPath}`)
            pyodide.FS.mount(pyodide.FS.filesystems.NODEFS, { root: hostPath }, wasmPath);
        })
        // console.log("done mounting input volumes")
    }

    if (Array.isArray(jobSpec.outputs)) {
        // console.log("about to mount output volumes")
        jobSpec.outputs.forEach(outputVolume => {
            const hostPath = outputVolume.path
            const wasmPath = outputVolume.path.replace('/pyodide_outputs', '')
            if (!fs.existsSync(wasmPath)) {
                // console.log(`mkdir ${wasmPath}`);
                pyodide.FS.mkdir(wasmPath);
            }
            // console.log(`mounting ${hostPath} to ${wasmPath}`)
            pyodide.FS.mount(pyodide.FS.filesystems.NODEFS, { root: hostPath }, wasmPath);
        })
        // console.log("done mounting input volumes")
    }

    await pyodide.runPythonAsync(program);

    // TODO: support requirements
    // TODO: expose requirements as a webserver, if needed?

    //     console.log(await pyodide.runPythonAsync(`
    // import micropip
    // micropip.install("pandas")
    // `))

    //     console.log(await pyodide.runPythonAsync(`
    // import pandas
    // from io import StringIO

    // # CSV String with out headers
    // csvString = """Spark,25000,50 Days,2000
    // Pandas,20000,35 Days,1000
    // Java,15000,,800
    // Python,15000,30 Days,500
    // PHP,18000,30 Days,800"""

    // # Convert String into StringIO
    // csvStringIO = StringIO(csvString)
    // import pandas as pd
    // df = pd.read_csv(csvStringIO, sep=",", header=None)
    // print(df)
    // `));

}

main()