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.objectIdToDate = (objectID) ->
  new Date(parseInt(objectID.toString().slice(0,8), 16)*1000)

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.
  fallSidewaysResult = null  # If a specific language isn't available, its sibling specific language 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?
    fallSidewaysResult = result if localeName.indexOf(generalName) is 0 and not fallSidewaysResult?

  return generalResult if generalResult?
  return fallForwardResult if fallForwardResult?
  return fallSidewaysResult if fallSidewaysResult?
  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

# f(x) = ax^b + c
createPowFunc = (params) ->
  (x) -> (params.a or 1) * Math.pow(x, params.b or 1) + (params.c or 0)

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

# 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)

module.exports.getQueryVariable = getQueryVariable = (param, defaultValue) ->
  query = document.location.search.substring 1
  pairs = (pair.split('=') for pair in query.split '&')
  for pair in pairs when pair[0] is param
    return {'true': true, 'false': false}[pair[1]] ? decodeURIComponent(pair[1])
  defaultValue

module.exports.getSponsoredSubsAmount = getSponsoredSubsAmount = (price=999, subCount=0, personalSub=false) ->
  # 1 100%
  # 2-11 80%
  # 12+ 60%
  # TODO: make this less confusing
  return 0 unless subCount > 0
  offset = if personalSub then 1 else 0
  if subCount <= 1 - offset
    price
  else if subCount <= 11 - offset
    Math.round((1 - offset) * price + (subCount - 1 + offset) * price * 0.8)
  else
    Math.round((1 - offset) * price + 10 * price * 0.8 + (subCount - 11 + offset) * price * 0.6)

module.exports.getCourseBundlePrice = getCourseBundlePrice = (coursePrices, seats=20) ->
  totalPricePerSeat = coursePrices.reduce ((a, b) -> a + b), 0
  if coursePrices.length > 2
    pricePerSeat = Math.round(totalPricePerSeat / 2.0)
  else
    pricePerSeat = parseInt(totalPricePerSeat)
  seats * pricePerSeat

module.exports.getCoursePraise = getCoursePraise = ->
  praise = [
    {
      quote:  "The kids love it."
      source: "Leo Joseph Tran, Athlos Leadership Academy"
    },
    {
      quote: "My students have been using the site for a couple of weeks and they love it."
      source: "Scott Hatfield, Computer Applications Teacher, School Technology Coordinator, Eastside Middle School"
    },
    {
      quote: "Thanks for the captivating site. My eighth graders love it."
      source: "Janet Cook, Ansbach Middle/High School"
    },
    {
      quote: "My students have started working on CodeCombat and love it! I love that they are learning coding and problem solving skills without them even knowing it!!"
      source: "Kristin Huff, Special Education Teacher, Webb City School District"
    },
    {
      quote: "I recently introduced Code Combat to a few of my fifth graders and they are loving it!"
      source: "Shauna Hamman, Fifth Grade Teacher, Four Peaks Elementary School"
    },
    {
      quote: "Overall I think it's a fantastic service. Variables, arrays, loops, all covered in very fun and imaginative ways. Every kid who has tried it is a fan."
      source: "Aibinder Andrew, Technology Teacher"
    },
    {
      quote: "I love what you have created. The kids are so engaged."
      source: "Desmond Smith, 4KS Academy"
    },
    {
      quote: "My students love the website and I hope on having content structured around it in the near future."
      source: "Michael Leonard, Science Teacher, Clearwater Central Catholic High School"
    }
  ]
  praise[_.random(0, praise.length - 1)]

module.exports.getPrepaidCodeAmount = getPrepaidCodeAmount = (price=0, users=0, months=0) ->
  return 0 unless users > 0 and months > 0
  total = price * users * months
  total

startsWithVowel = (s) -> s[0] in 'aeiouAEIOU'
module.exports.filterMarkdownCodeLanguages = (text, language) ->
  return '' unless text
  currentLanguage = language or me.get('aceConfig')?.language or 'python'
  excludedLanguages = _.without ['javascript', 'python', 'coffeescript', 'clojure', 'lua', 'java', 'io'], currentLanguage
  # Exclude language-specific code blocks like ```python (... code ...)``` for each non-target language.
  codeBlockExclusionRegex = new RegExp "```(#{excludedLanguages.join('|')})\n[^`]+```\n?", 'gm'
  # Exclude language-specific images like ![python - image description](image url) for each non-target language.
  imageExclusionRegex = new RegExp "!\\[(#{excludedLanguages.join('|')}) - .+?\\]\\(.+?\\)\n?", 'gm'
  text = text.replace(codeBlockExclusionRegex, '').replace(imageExclusionRegex, '')

  commonLanguageReplacements =
    python: [
      ['true', 'True'], ['false', 'False'], ['null', 'None'],
      ['object', 'dictionary'], ['Object', 'Dictionary'],
      ['array', 'list'], ['Array', 'List'],
    ]
    lua: [
      ['null', 'nil'],
      ['object', 'table'], ['Object', 'Table'],
      ['array', 'table'], ['Array', 'Table'],
    ]
  for [from, to] in commonLanguageReplacements[currentLanguage] ? []
    # Convert JS-specific keywords and types to Python ones, if in simple `code` tags.
    # This won't cover it when it's not in an inline code tag by itself or when it's not in English.
    text = text.replace ///`#{from}`///g, "`#{to}`"
    # Now change "An `dictionary`" to "A `dictionary`", etc.
    if startsWithVowel(from) and not startsWithVowel(to)
      text = text.replace ///(\ a|A)n(\ `#{to}`)///g, "$1$2"
    if not startsWithVowel(from) and startsWithVowel(to)
      text = text.replace ///(\ a|A)(\ `#{to}`)///g, "$1n$2"

  return text

module.exports.aceEditModes = aceEditModes =
  'javascript': 'ace/mode/javascript'
  'coffeescript': 'ace/mode/coffee'
  'python': 'ace/mode/python'
  'java': 'ace/mode/java'
  'lua': 'ace/mode/lua'
  'java': 'ace/mode/java'

module.exports.initializeACE = (el, codeLanguage) ->
  contents = $(el).text().trim()
  editor = ace.edit el
  editor.setOptions maxLines: Infinity
  editor.setReadOnly true
  editor.setTheme 'ace/theme/textmate'
  editor.setShowPrintMargin false
  editor.setShowFoldWidgets false
  editor.setHighlightActiveLine false
  editor.setHighlightActiveLine false
  editor.setBehavioursEnabled false
  editor.renderer.setShowGutter false
  editor.setValue contents
  editor.clearSelection()
  session = editor.getSession()
  session.setUseWorker false
  session.setMode aceEditModes[codeLanguage]
  session.setWrapLimitRange null
  session.setUseWrapMode true
  session.setNewLineMode 'unix'
  return editor

module.exports.capitalLanguages = capitalLanguages =
  'javascript': 'JavaScript'
  'coffeescript': 'CoffeeScript'
  'python': 'Python'
  'java': 'Java'
  'lua': 'Lua'