just-build/src/which-local.js

A simple task runner that doesn't bloat your package

const path = require('path');
const fs = require('fs');
const {getPackageRoot, getBinLocation} = require('./dirutils');
const {tokenize, surroundWithQuotes} = require('./tokenize');
const debug = require('./debug');

function whichLocal (cmd, cwd) {
    debug.log(`whichLocal(${JSON.stringify(cwd)}, ${JSON.stringify(cmd)})`);
    const binScript = getBinLocation(cwd, cmd);
    debug.log(`binScript = ${JSON.stringify(binScript)}`);
    if (!binScript) return null;
    const binDir = path.dirname (binScript);
    debug.log(`binDir = ${JSON.stringify(binDir)}`);
    const node_modules = path.normalize(path.resolve(binDir, ".."));
    debug.log(`node_modules = ${JSON.stringify(node_modules)}`);

    if (!fs.existsSync(binScript)) return null;

    const scriptLines = fs.readFileSync(binScript, "utf-8").split('\n');
    if (scriptLines.length === 0) return null;
    const shebang = scriptLines[0].trim();
    debug.log(`shebang = ${shebang}`);
    if (shebang[0] != "#") return null;
    if (shebang.indexOf("bin/sh") === -1) {
        // Not a shellscript (cygwin starter)
        if (scriptLines[0].indexOf(' node') !== -1) {
            // A node script by itself
            debug.log(`A node script by itself`);
            return path.normalize(binScript);
        }
        debug.log(`whichLocal return null since bin/sh not found in shebang.`);
        return null;
    }
    const invokerLines = scriptLines.filter(line => line.indexOf('node ') !== -1);
    debug.log(`invokerLines = ${JSON.stringify(invokerLines)}`);
    // Expected to find: `  node  "$basedir/../uglify-js/bin/uglifyjs" "$@"`
    if (invokerLines.length < 1) return null;
    const tokenized = tokenize(invokerLines[0]);
    // Expected: "node", "$basedir/../uglify-js/bin/uglifyjs", "$@" or
    //           "exec", "node", "$basedir/../typescript/bin/tsc", "$@" or
    //           "exec", "$basedir/node", "$basedir/../typescript/bin/tsc". "$@""
    if (tokenized.length < 3) return null;
    const binFilePath = tokenized.find(part =>
        part !== 'exec' &&
        part !== 'node' &&
        !part.endsWith('/node')
    );
    let splitted = binFilePath.split('/');
    while (splitted.length > 0 && (
        splitted[0].indexOf('$') === 0 || // $basedir
        //splitted[0] === '..' || // ".."
        splitted[0] === '.')) // just for optional future changes
    {
        splitted = splitted.slice(1);
    }

    const jsScriptPath = path.normalize(path.resolve(binDir, splitted.join('/')));
    debug.log(`jsScriptPath = ${JSON.stringify(jsScriptPath)}`);
    if (splitted.length === 0) return null;
    
    return jsScriptPath;
}

module.exports = { whichLocal };