#!/usr/bin/env node
/**
 * @author Boolean263 [boolean263@protonmail.com]
 * @copyright Crown Copyright 2020
 * @license Apache-2.0
 */
"use strict";

const fs = require("fs");

/* * * * * Helper Functions * * * * */

/**
 * Slurp the contents of a stream up into a Buffer to pass to CyberChef
 *
 * @param {Stream} istream
 */
const slurpStream = (istream) => { // {{{1
    const ret = [];
    let len = 0;
    return new Promise(resolve => {
        istream.on("readable", () => {
            let chunk;
            while ((chunk = istream.read()) !== null) {
                ret.push(chunk);
                len += chunk.length;
            }
            resolve(Buffer.concat(ret, len));
        });
    });
}; // }}}1

/**
 * Slurp the contents of a file (or stdin) into a Buffer
 *
 * @param {String} fname
 */
const slurp = (fname) => { // {{{1
    let istream;

    if (fname === undefined || fname === "-") {
        istream = process.stdin;
        if (istream.isTTY) {
            return Promise.reject(new Error("TTY input not supported"));
        }
    } else {
        istream = fs.createReadStream(fname, { flags: "r" });
    }
    return slurpStream(istream);
}; // }}}1

/**
 * Get a valid port number from the command line
 *
 * Used by commander
 *
 * @param {String} value
 * @param {String} dummyPrevious
 */
const getPort = (value, dummyPrevious) => { // {{{1
    const ret = parseInt(value, 10);
    if (ret < 1 || ret > 65535) {
        throw new Error("invalid port number");
    }
    return ret;
};
// }}}1

/* * * * * MAIN * * * * */ // {{{1

const chef = require("cyberchef");
const program = require("commander");

program
    .version(require("./package.json").version)
    .description("Bake data from files and/or TCP clients " +
        "using a CyberChef recipe.")
    .usage("[options] [file [file ...]]")
    .requiredOption("-r, --recipe-file <file>",
        "recipe JSON file")
    .option("-l, --listen [port]",
        "listen on TCP port for data (random if not given)", getPort, false)
    .option("-o, --output <file-or-dir>",
        "where to write result (file input only; default:stdout)");

try {
    program.exitOverride().parse(process.argv);
} catch (e) {
    if (e.code !== "commander.helpDisplayed") {
        console.error("Run with \"--help\" for usage");
    }
    process.exit(1);
}

// If we get no inputs and we aren't running a server,
// make stdin our single input
let inputs = program.args;
if (inputs.length === 0 && !program.listen) {
    inputs = ["-"];
}

// Likewise stdout for our output
let ostream;
let path;
let outputIsDir = false;
if (program.output === undefined && !program.listen) {
    ostream = process.stdout;
} else if (inputs.length > 0) {
    // See if our output is a directory
    let st;
    try {
        st = fs.statSync(program.output);
        outputIsDir = st.isDirectory();
    } catch (err) {
        // We"re fine if the output doesn"t exist yet
        if (err.code !== "ENOENT") throw err;
    }
    if (!outputIsDir) {
        ostream = fs.createWriteStream(program.output);
    }
}
if (outputIsDir) path = require("path");

let recipe;
slurp(program.recipeFile).then((data) => {
    recipe = JSON.parse(data);
})
    .catch((err) => {
        console.error(`Error parsing recipe: ${err.message}`);
        process.exit(2);
    })
    .then(() => {
        // First, deal with any files we want to read
        for (const i of inputs) {
            slurp(i).then((data) => {
                const output = chef.bake(data, recipe);
                if (outputIsDir) {
                    let outFileName = path.basename(i);
                    if (outFileName === "-") outFileName = "from-stdin";
                    ostream = fs.createWriteStream(
                        path.join(program.output, outFileName));
                }
                ostream.write(output.presentAs("string", true));
                if (outputIsDir) ostream.end();
            },
            (err) => {
                console.error(err.message);
                process.exitCode = 2;
            })
                .catch((err) => {
                    console.error(err.message);
                    process.exitCode = 2;
                });
        }

        // Next, listen for TCP requests.
        // This is intentionally hardcoded to localhost to discourage
        // the use of this script as a production system.
        if (program.listen) {
            const net = require("net");
            const server = net.createServer((socket) => {
                slurpStream(socket).then((data) => {
                    const output = chef.bake(data, recipe);
                    socket.write(output.presentAs("string", true));
                    socket.end();
                })
                    .catch((err) => {
                        console.error(err);
                    });
            });

            // If no port given by user, let the OS choose one
            if (program.listen === true) program.listen = 0;
            server.listen(program.listen, "127.0.0.1")
                .on("listening", () => {
                    console.log("Now listening on " +
                        server.address().address +
                        ":" + server.address().port);
                });

            // Exit gracefully
            process.on("SIGINT", () => {
                console.log("Exiting");
                server.close();
            });
        }
    })
    .catch((err) => {
        console.error(err);
        process.exit(3);
    });