const proc = require('child_process');
const Transform = require('stream').Transform;

module.exports = function (cb) {
  var ids = []
  var maxBlobSize = 5242879
  var add, len = 0
  var onAddDone
  function startAdd() {
    return proc.execFile('sbotc', ['blobs.add'], (err, stdout, stderr) => {
      if (err) return console.error(stderr), cb(err)
      var id = stdout.trim()
      ids.push(id)
      if (onAddDone) onAddDone(id), onAddDone = null
      else console.trace(id)
    })
  }
  return new Transform({
    transform: function transform(data, encoding, cb) {
      if (!add) add = startAdd()
      var buf = Buffer.from(data, encoding)
      if (buf.length === 0) return cb()
      var remainingSpace = maxBlobSize - len
      if (buf.length < remainingSpace) {
        len += buf.length
        return add.stdin.write(buf, cb)
      }
      var endBuf = buf.slice(0, remainingSpace)
      var nextBuf = buf.slice(remainingSpace)
      len += endBuf.length
      var waiting = 2
      onAddDone = function (id) {
        if (!--waiting) next()
      }
      var stdin = add.stdin
      add = null
      len = 0
      stdin.end(endBuf, function (err) {
        if (err) return cb(err)
        if (!--waiting) next()
      })
      function next() {
        transform(nextBuf, null, cb)
      }
    },
    flush: (_cb) => {
      if (!add) {
        _cb()
        return cb(null, ids)
      }
      var waiting = 2
      onAddDone = function (id) {
        if (!--waiting) next()
      }
      add.stdin.end(function (err) {
        if (err) return cb(err)
        if (!--waiting) next()
      })
      function next() {
        _cb()
        cb(null, ids)
      }
    }
  })
}