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_ = require 'underscore'

class Degrees

A Factory Method Class

  of: (given , base = true) ->
    switch base
      when true then new DegreesBase given
      when 'lon', 'longitude' then new CelestialLongitude given
      else throw "Unknown kind of #{base} degrees."

Alias for @of x, 'lon' - nice, short, consistent.

  lon: (given, rep) ->

Takes an optional representation - 1 for the Ram to 12 for the Fishes.

    if rep?
      if _.isNumber(rep) and 1 <= rep <= 12
        rep = Math.floor rep
        add = (rep - 1) * 30

        if _.isNumber given then given += add
        else if _.isArray given and _.isNumber given[0] then given[0] += add

The degrees and representation must be numbers / valid.

        else throw "The given #{given} degrees can't be added to."
      else throw "Invalid representation #{rep}."

    @of given, 'lon'

Sometimes using more than one degrees instance within this module too.

degrees = new Degrees

class DegreesBase

Unacceptable initial value.

  dec: NaN

Requirements to be overriden by sub-classes as needed.

  abs: false # must be / remain absolute (i.e. a positive value)

Ensuring a @dec (decimal degrees) number to work with.

  constructor: (@given) ->

    if _.isNumber @given then @dec = @given

DMS: [degrees] or [degrees, minutes] or [degrees, minutes, seconds]. Note: chain-call @neg to get a negative @dec from dms. All of the degrees, minutes or seconds are being taken as absolute values. TODO: consider taking decimal degrees or minutes, even through the array?

    else if _.isArray @given
      unless 1 <= @given.length <= 3
        throw "The given array must at least have degrees, and at most seconds."

TODO: figure out why the following validation isn't working:

unless _.all @given, (x) -> _.isNumber x
  throw "Expecting the given array #{@given} to be all-number(s)."

Note: integers are expected, discarding aything after the decimal.

      @dec =  Math.floor(Math.abs @given[0])
      @dec += Math.floor(Math.abs @given[1]) / 60   if @given.length > 1 # mins
      @dec += Math.floor(Math.abs @given[2]) / 3600 if @given.length > 2 # secs

    else throw "Unexpected '#{typeof(@given)}' type of degrees given."

The positive (i.e. absolute) angle - whole int or decimal.

    if @abs then @dec = Math.abs @dec

Ensures the degrees are negative. Useful for geo-coordinates. This was introduced for easier instantiation with a dms array. The @pos opposite could also be added, but that means variable degrees... So far this is the only method besides the constructor(s) that modify @dec. Therefore a one-time-deal without undo.

  neg: ->
    unless @abs then @dec = 0 - Math.abs @dec

Just so one can get the decimal degrees with a method call rather than with @deg (the only property). So that to have less of special cases... See CelestialLongitude.representation('the') as an example of wanting more.

  the: -> @dec


  rad: ->
    @dec * Math.PI / 180

Array of [sign, degrees, minutes, seconds] for the standard acronym. Note: that we can't do fractional seconds (as a result of not taking them).

  dms: ->

Empty string for plus will make it easier to display.

    n = if @dec < 0 then '-' else ''
    dec = Math.abs @dec
    d = Math.floor  dec
    m = Math.floor((dec * 60)   % 60) # 0 <= m < 60
    s = Math.floor((dec * 3600) % 60) # 0 <= s < 60
    [ n, d, m, s ]

A string (with unicode characters after the degrees, minutes and seconds). Fist, but not least, it starts with '-' (minus) if negative.

  str: ->
    [ n, d, m, s ] = @dms()

  unimplemented: (method) ->

mod x = degrees % modulo
num n = convert to the n-th harmonic

    throw "The wanted '#{method}' method is not implemented yet."

class CelestialLongitude extends DegreesBase

See DegreesBase.

  abs: true # absolutely always positive

These are only for rep-based longitude, though alignment could be refactored for BaseDegrees as well - need to take into account variation of 1-3 digits.

  aligns: false # set filler character to ' ' or '0' for dms() / str() alignment
  representations: ['♈', '♉', '♊', '♋', '♌', '♍', '♎', '♏', '♐', '♑', '♒', '♓']

Longitude degrees are special.

  constructor: (@given) ->
    super @given

Ensure [0..360] range, however the pure 0 can't be had. It throws off various calculations, think about doing the same for base... unless @dec is 0 # the only way to have 0 is be given a 0 (no longer true)

    @dec %= 360 # smaller modulos can be done with `mod n` modification
    @dec = 360 if @dec is 0 # exact multiples of 360 equal 360 degrees, again

Note that @rep aligns by default. Set to '' (empty string) if not wanted.

  align: (fill = ' ') ->
    fill = "#{fill}" if _.isNumber fill # so that 0 doesn't have to be quoted
    @aligns = fill # take any value, but the useful are 0, space, '' or false
    @ # chain-able

Longitude @dms function is special: * it cannot be negative (so it discards the sign) * it can be aligned with a prepended character - the [d,m,s] become strings The @aligns filling must be set (best by pre-chaining call of @align) and is consumed / cleared with @dms() use.

  dms: ->
    [n, d, m, s] = super()
    if _.isString(@aligns)
      @aligns = @aligns.charAt(0) if @aligns.length > 1
      d = "#{@aligns}#{d}" if d < 10
      m = "#{@aligns}#{m}" if m < 10
      s = "#{@aligns}#{s}" if s < 10
    @aligns = false
    [d, m, s]

Is portion (or degree in modern parlance).

  top: ->
    portion = Math.ceil @dec
    portion = 360 if portion is 0 # there is no zero portion (= whole circle)

  portion: ->

The 1 to 12 for image / representation (modern "sign" number). Request more and get a representation-first array, followed by that more, where more is a string that matches a method name (e.g. 'top', 'dms') for further getting the rest of the @dec degrees in a representation context.

  rep: (more) ->
    rep = if @dec is 0 or @dec is 360 then 12 else Math.ceil(@dec / 30)

    switch more
      when undefined then rep
      when "sym" then @representations[rep - 1]
      when "str"
        rest = @dec - (rep - 1) * 30

Pass on & reset the @aligns, or else align by default if not set. The usual false is ignored - so use blank '' in order to not align.

        [a, @aligns] = [(if _.isString(@aligns) then @aligns else null), false]
        [ d, m, s ] = degrees.lon(rest).align(a).dms()
        "#{@representations[rep - 1]}  #{d}\u00B0#{m}\u2032#{s}\u2033"
      when "the", "top" then [rep, (@[more]() - (rep - 1) * 30)]
      else throw "Unsupported: rep('#{more}')"

  representation: (more) ->

The 12th part higher-level representation (1 to 12 again).

  _12: (exact = false) ->

is p12: -> #better?


module.exports = degrees