module.exports.clone = (obj) ->
  return obj if obj is null or typeof (obj) isnt 'object'
  temp = obj.constructor()
  for key of obj
    temp[key] = module.exports.clone(obj[key])
  temp

module.exports.combineAncestralObject = (obj, propertyName) ->
  combined = {}
  while obj?[propertyName]
    for key, value of obj[propertyName]
      continue if combined[key]
      combined[key] = value
    if obj.__proto__
      obj = obj.__proto__
    else
      # IE has no __proto__. TODO: does this even work? At most it doesn't crash.
      obj = Object.getPrototypeOf(obj)
  combined

module.exports.normalizeFunc = (func_thing, object) ->
  # func could be a string to a function in this class
  # or a function in its own right
  object ?= {}
  if _.isString(func_thing)
    func = object[func_thing]
    if not func
      console.error "Could not find method #{func_thing} in object", object
      return => null # always return a func, or Mediator will go boom
    func_thing = func
  return func_thing

module.exports.hexToHSL = (hex) ->
  rgbToHsl(hexToR(hex), hexToG(hex), hexToB(hex))

hexToR = (h) -> parseInt (cutHex(h)).substring(0, 2), 16
hexToG = (h) -> parseInt (cutHex(h)).substring(2, 4), 16
hexToB = (h) -> parseInt (cutHex(h)).substring(4, 6), 16
cutHex = (h) -> (if (h.charAt(0) is '#') then h.substring(1, 7) else h)

module.exports.hslToHex = (hsl) ->
  '#' + (toHex(n) for n in hslToRgb(hsl...)).join('')

toHex = (n) ->
  h = Math.floor(n).toString(16)
  h = '0'+h if h.length is 1
  h

module.exports.i18n = (say, target, language=me.get('preferredLanguage', true), fallback='en') ->
  generalResult = null
  fallbackResult = null
  fallforwardResult = null # If a general language isn't available, the first specific one will do
  matches = (/\w+/gi).exec(language)
  generalName = matches[0] if matches

  for localeName, locale of say.i18n
    continue if localeName is '-'
    if target of locale
      result = locale[target]
    else continue
    return result if localeName is language
    generalResult = result if localeName is generalName
    fallbackResult = result if localeName is fallback
    fallforwardResult = result if localeName.indexOf(language) is 0 and not fallforwardResult?

  return generalResult if generalResult?
  return fallforwardResult if fallforwardResult?
  return fallbackResult if fallbackResult?
  return say[target] if target of say
  null

module.exports.getByPath = (target, path) ->
  throw new Error 'Expected an object to match a query against, instead got null' unless target
  pieces = path.split('.')
  obj = target
  for piece in pieces
    return undefined unless piece of obj
    obj = obj[piece]
  obj

module.exports.isID = (id) -> _.isString(id) and id.length is 24 and id.match(/[a-f0-9]/gi)?.length is 24

module.exports.round = _.curry (digits, n) ->
  n = +n.toFixed(digits)

positify = (func) -> (params) -> (x) -> if x > 0 then func(params)(x) else 0

# f(x) = ax + b
createLinearFunc = (params) ->
  (x) -> (params.a or 1) * x + (params.b or 0)

# f(x) = ax² + bx + c
createQuadraticFunc = (params) ->
  (x) -> (params.a or 1) * x * x + (params.b or 1) * x + (params.c or 0)

# f(x) = a log(b (x + c)) + d
createLogFunc = (params) ->
  (x) -> if x > 0 then (params.a or 1) * Math.log((params.b or 1) * (x + (params.c or 0))) + (params.d or 0) else 0

module.exports.functionCreators =
  linear: positify(createLinearFunc)
  quadratic: positify(createQuadraticFunc)
  logarithmic: positify(createLogFunc)

# Call done with true to satisfy the 'until' goal and stop repeating func
module.exports.keepDoingUntil = (func, wait=100, totalWait=5000) ->
  waitSoFar = 0
  (done = (success) ->
    if (waitSoFar += wait) <= totalWait and not success
      _.delay (-> func done), wait) false

module.exports.grayscale = (imageData) ->
  d = imageData.data
  for i in [0..d.length] by 4
    r = d[i]
    g = d[i+1]
    b = d[i+2]
    v = 0.2126*r + 0.7152*g + 0.0722*b
    d[i] = d[i+1] = d[i+2] = v
  imageData

# Deep compares l with r, with the exception that undefined values are considered equal to missing values
# Very practical for comparing Mongoose documents where undefined is not allowed, instead fields get deleted
module.exports.kindaEqual = compare = (l, r) ->
  if _.isObject(l) and _.isObject(r)
    for key in _.union Object.keys(l), Object.keys(r)
      return false unless compare l[key], r[key]
    return true
  else if l is r
    return true
  else
    return false

# Return UTC string "YYYYMMDD" for today + offset
module.exports.getUTCDay = (offset=0) ->
  day = new Date()
  day.setDate(day.getUTCDate() + offset)
  partYear = day.getUTCFullYear()
  partMonth = (day.getUTCMonth() + 1)
  partMonth = "0" + partMonth if partMonth < 10
  partDay = day.getUTCDate()
  partDay = "0" + partDay if partDay < 10
  "#{partYear}#{partMonth}#{partDay}"

# Fast, basic way to replace text in an element when you don't need much.
# http://stackoverflow.com/a/4962398/540620
if document?.createElement
  dummy = document.createElement 'div'
  dummy.innerHTML = 'text'
  TEXT = if dummy.textContent is 'text' then 'textContent' else 'innerText'
  module.exports.replaceText = (elems, text) ->
    elem[TEXT] = text for elem in elems
    null

# Add a stylesheet rule
# http://stackoverflow.com/questions/524696/how-to-create-a-style-tag-with-javascript/26230472#26230472
# Don't use wantonly, or we'll have to implement a simple mechanism for clearing out old rules.
if document?.createElement
  module.exports.injectCSS = ((doc) ->
    # wrapper for all injected styles and temp el to create them
    wrap = doc.createElement("div")
    temp = doc.createElement("div")
    # rules like "a {color: red}" etc.
    return (cssRules) ->
      # append wrapper to the body on the first call
      unless wrap.id
        wrap.id = "injected-css"
        wrap.style.display = "none"
        doc.body.appendChild wrap
      # <br> for IE: http://goo.gl/vLY4x7
      temp.innerHTML = "<br><style>" + cssRules + "</style>"
      wrap.appendChild temp.children[1]
      return
  )(document)