#!/usr/bin/env node

// An implementation of the venerable cat utility [1], which concatenates one or
// more input files to stdout. Each input file is processed sequentially.
//
// When the writer is full (as when writer.write returns false), the writer is
// drained before subsequent data is read. When the reader ends (as when
// reader.ended is true), the writer is drained before the next input file is
// read, flushing the output in case an error occurs on the next file.
//
// [1] https://en.wikipedia.org/wiki/Cat_(Unix)

var rw = require("../");

var writer = rw.fileWriter("/dev/stdout");

var inputs = process.argv.slice(2);
if (inputs.length) inputs.reverse();
else inputs.push("/dev/stdin");

(function cat() {
  var input = inputs.pop();
  if (!input) return writer.end();
  var reader = rw.fileReader(input);

  reader.fill(function flow(error) {
    if (error) throw error;
    var data = reader.read();
    if (data && !writer.write(data)) return writer.drain(flow);
    if (reader.ended) return writer.drain(cat);
    reader.fill(flow);
  });
})();