printservice.js

#!/usr/bin/env node
/*
  This program watches the directory as specified in
  zero.config.label_out_dir (config.js) for new png
  files, prints them and moves them to the dir 
  specified in zero.config.label_in_dir.

  If files are in label_out_dir when this program
  starts, then they are also printed and moved.
*/

var fs = require('fs');
var path = require('path');
var util = require('util');
var zero = require('./zero.js').initialize(true);

var name = "Mycelia Zero printservice";
var version = '0.0.1';

if(process.argv[2] == '-h') {
    process.stderr.write("Usage: "+process.argv[1]+" [--purge]\n\n");
    process.stderr.write("  --purge: Moves all png files in the to_print dir to the printed dir\n           without printing and then continues to listen for new\n           png files normally.\n\n");
    process.stderr.write("  -v: Print version info and exit.\n");
    process.stderr.write("  -h: Print this help screen.\n\n");
    process.exit(0);
} else if(process.argv[2] == '-v') {
    process.stderr.write(name+" version "+version+"\n");
    process.exit(0);
}

function print(filename) {

    if(!filename) {
        return;
    }

    console.log("Printing: " + filename);

    var filepath = path.join(zero.config.label_out_dir, filename);
    zero.print_file(filepath, function(err) {
        if(err) {
            console.log("Printing of " + filename + " failed: " + err);
        }
        console.log("Printed " + filename);

        if(zero.config.label_out_dir != zero.config.label_in_dir) {
            // TODO does not work across filesystems
            // but encountered problem with the mv package
            fs.renameSync(filepath, path.join(zero.config.label_in_dir, filename));
            console.log("Moved file to " + zero.config.label_in_dir);
        }
    });
}

if(process.argv[2] != '--purge') {

    var files = fs.readdirSync(zero.config.label_out_dir);
    if(files.length > 0) {
        console.log("Printing existing files.");
        var i;
        for(i=0; i < files.length; i++) {
            if(!files[i].match(/.*\.png$/)) {
                continue;
            }
            print(files[i]);
        }
    }
} else {
    var files = fs.readdirSync(zero.config.label_out_dir);
    if(files.length > 0) {
        console.log("Purging existing files.");
        var i;
        for(i=0; i < files.length; i++) {
            if(!files[i].match(/.*\.png$/)) {
                continue;
            }
            fs.renameSync(path.join(zero.config.label_out_dir, files[i]), path.join(zero.config.label_in_dir, files[i]));
            console.log("Purged " + files[i]);
        }
    }
}
console.log("Listening for new png files in: " + zero.config.label_out_dir);

var last_renamed = null;

// there is no "new file" event
// rather, a new file appears as a rename followed by a change
var watcher = fs.watch(zero.config.label_out_dir, function(event, filename) {
    if(event == 'rename') {
        last_renamed = filename;
        return
    }

    if(event != 'change') {
        last_renamed = null;
        return;
    }
    
    if(last_renamed != filename) {
        return;
    }
            
    if(!filename.match(/.*\.png$/)) {
        return;
    }

    print(filename);
});