"use strict"

var Buffer = require("safer-buffer").Buffer

// NOTE: Due to 'stream' module being pretty large (~100Kb, significant in browser environments),
// we opt to dependency-inject it instead of creating a hard dependency.
module.exports = function (streamModule) {
  var Transform = streamModule.Transform

  // == Encoder stream =======================================================

  function IconvLiteEncoderStream (conv, options) {
    this.conv = conv
    options = options || {}
    options.decodeStrings = false // We accept only strings, so we don't need to decode them.
    Transform.call(this, options)
  }

  IconvLiteEncoderStream.prototype = Object.create(Transform.prototype, {
    constructor: { value: IconvLiteEncoderStream }
  })

  IconvLiteEncoderStream.prototype._transform = function (chunk, encoding, done) {
    if (typeof chunk !== "string") {
      return done(new Error("Iconv encoding stream needs strings as its input."))
    }

    try {
      var res = this.conv.write(chunk)
      if (res && res.length) this.push(res)
      done()
    } catch (e) {
      done(e)
    }
  }

  IconvLiteEncoderStream.prototype._flush = function (done) {
    try {
      var res = this.conv.end()
      if (res && res.length) this.push(res)
      done()
    } catch (e) {
      done(e)
    }
  }

  IconvLiteEncoderStream.prototype.collect = function (cb) {
    var chunks = []
    this.on("error", cb)
    this.on("data", function (chunk) { chunks.push(chunk) })
    this.on("end", function () {
      cb(null, Buffer.concat(chunks))
    })
    return this
  }

  // == Decoder stream =======================================================

  function IconvLiteDecoderStream (conv, options) {
    this.conv = conv
    options = options || {}
    options.encoding = this.encoding = "utf8" // We output strings.
    Transform.call(this, options)
  }

  IconvLiteDecoderStream.prototype = Object.create(Transform.prototype, {
    constructor: { value: IconvLiteDecoderStream }
  })

  IconvLiteDecoderStream.prototype._transform = function (chunk, encoding, done) {
    if (!Buffer.isBuffer(chunk) && !(chunk instanceof Uint8Array)) { return done(new Error("Iconv decoding stream needs buffers as its input.")) }
    try {
      var res = this.conv.write(chunk)
      if (res && res.length) this.push(res, this.encoding)
      done()
    } catch (e) {
      done(e)
    }
  }

  IconvLiteDecoderStream.prototype._flush = function (done) {
    try {
      var res = this.conv.end()
      if (res && res.length) this.push(res, this.encoding)
      done()
    } catch (e) {
      done(e)
    }
  }

  IconvLiteDecoderStream.prototype.collect = function (cb) {
    var res = ""
    this.on("error", cb)
    this.on("data", function (chunk) { res += chunk })
    this.on("end", function () {
      cb(null, res)
    })
    return this
  }

  return {
    IconvLiteEncoderStream: IconvLiteEncoderStream,
    IconvLiteDecoderStream: IconvLiteDecoderStream
  }
}