Module:Current events monthly archive/sandbox

-- This module generates the monthly archives [[Portal:Current events]].
-- See a sample archive at [[Portal:Current events/September 2011]].

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-- Helper functions
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-- Return true if num is a positive integer; otherwise return false
local function isPositiveInteger(num)
 return num > 0 and num == math.floor(num)
end

-- Make an ordinal number from an integer.
local function makeOrdinalNumber(num)
 local suffix
 local rem100 = num % 100
 if rem100 == 11 or rem100 == 12 or rem100 == 13 then
  suffix = 'th'
 else
  local rem10 = num % 10
  if rem10 == 1 then
   suffix = 'st'
  elseif rem10 == 2 then
   suffix = 'nd'
  elseif rem10 == 3 then
   suffix = 'rd'
  else
   suffix = 'th'
  end
 end
 return tostring(num) .. suffix
end

-- Try to parse the year and month from the current title.
local function parseYearAndMonthFromCurrentTitle()
 -- This template is used on archive pages that look like
 -- [[Portal:Current events/September 2011]], so just try to use the
 -- subpage name as a date.
 local title = mw.title.getCurrentTitle()
 local lang = mw.language.getContentLanguage()
 local success, date = pcall(function ()
  -- lang:formatDate throws errors if it gets strange input,
  -- so use pcall to catch them, as random subpage names will
  -- usually not be well-formed dates.
  return lang:formatDate('Y-m', title.subpageText)
 end)
 if not success then
  -- We couldn't parse the date, so return nil.
  return nil, nil
 end
 -- Parse the year and month numbers from the date we got from
 -- lang:formatDate. If we can't parse them, then something has gone
 -- wrong with either lang:formatDate or our pattern.
 local year, month = date:match('^(%d%d%d%d)%-(%d%d)$')
 year = tonumber(year)
 month = tonumber(month)
 if not year or not month then
  error('Internal error in [[Module:Current events '
   .. 'monthly archive]]: couldn\'t match date '
   .. 'from lang:formatDate output'
  )
 end
 return year, month
end

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-- Date info
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-- Get a table of information about the date for the monthly archive.
local function getDateInfo(year, month)
 local lang = mw.language.getContentLanguage()
 local dateFuncs = {}
 local dateInfo = setmetatable({}, {
  __index = function (t, key)
   -- Memoize values so we only have to calculate them once.
   if dateFuncs[key] then
    local val = dateFuncs[key]()
    t[key] = val
    return val
   end
  end
 })

 function dateFuncs.currentYear()
  -- The current year (number)
  return tonumber(os.date('%Y'))
 end

 function dateFuncs.currentMonthNumber()
  -- The current month (number)
  return tonumber(os.date('%m'))
 end

 function dateFuncs.year()
  -- The year (number)
  return tonumber(year) or dateInfo.currentYear
 end

 function dateFuncs.monthNumber()
  -- The month (number)
  return tonumber(month) or dateInfo.currentMonthNumber
 end

 function dateFuncs.monthNumberZeroPadded()
  -- The month, zero-padded to two digits (string)
  return string.format('%02d', dateInfo.monthNumber)
 end

 function dateFuncs.date()
  -- The date in YYYY-MM-DD format (string)
  return string.format(
   '%04d-%02d-01',
   dateInfo.year, dateInfo.monthNumber
  )
 end

 function dateFuncs.monthName()
  -- The month name, e.g. "September" (string)
  return lang:formatDate('F', dateInfo.date)
 end

 function dateFuncs.monthOrdinal()
  -- The ordinal month as an English word (string)
  local ordinals = {
   "first",   "second",   "third",
   "fourth",  "fifth",    "sixth",
   "seventh", "eighth",   "ninth",
   "tenth",   "eleventh", "twelfth and final",
  }
  return ordinals[dateInfo.monthNumber]
 end

 function dateFuncs.beVerb()
  -- If the month is the current month or a month in the future, then this
  -- is the string "is"; otherwise, "was" (string)
  if dateInfo.year > dateInfo.currentYear
   or (
    dateInfo.year == dateInfo.currentYear
    and dateInfo.monthNumber >= dateInfo.currentMonthNumber
   )
  then
   return 'is'
  else
   return 'was'
  end
 end

 function dateFuncs.leapDesc()
  -- The year's leap year status; either "common", "leap"or
  -- "century leap" (string)
  local isLeapYear = tonumber(lang:formatDate('L', dateInfo.date)) == 1
  if isLeapYear and dateInfo.year % 400 == 0 then
   return 'century leap'
  elseif isLeapYear then
   return 'leap'
  else
   return 'common'
  end
 end

 function dateFuncs.decadeNote()
  -- If the month is the first or last of a decade, century, or
  -- millennium, a note to that effect; otherwise the empty string
  -- (string)
  local function getMillennium(year)
   return math.floor((year - 1) / 1000) + 1 -- Fenceposts
  end

  local function getCentury(year)
   return math.floor((year - 1) / 100) + 1 -- Fenceposts
  end

  local year = dateInfo.year
  local month = dateInfo.monthNumber
  local firstOrLast = month == 12 and "last" or "first"

  if year % 1000 == 0 and month == 12
   or year % 1000 == 1 and month == 1
  then
   local millennium = makeOrdinalNumber(getMillennium(year))
   local century = makeOrdinalNumber(getCentury(year))
   return string.format(
    --Millenniums always overlap centuries.
    "It %s the %s month of the [[%s millennium]] and the [[%s century]].",
    dateInfo.beVerb, firstOrLast, millennium, century
   )
  elseif year % 100 == 0 and month == 12
   or year % 100 == 1 and month == 1
  then
   local century = makeOrdinalNumber(getCentury(year))
   return string.format(
    "It %s the %s month of the [[%s century]].",
    dateInfo.beVerb, firstOrLast, century
   )
  elseif year % 10 == 9 and month == 12
   or year % 10 == 0 and month == 1
  then
   local decadeNumber = math.floor(dateInfo.year / 10) * 10
   return string.format(
    "It %s the %s month of the [[%ds]] decade.",
    dateInfo.beVerb, firstOrLast, decadeNumber
   )
  end

  return ''
 end

 function dateFuncs.moonNote()
  -- If the month had no full moon, a note to that effect; otherwise the
  -- empty string (string)
  if dateInfo.monthNumber == 2 then
   -- https://www.quora.com/When-was-the-last-time-the-entire-month-of-February-passed-without-a-Full-Moon/answer/Alan-Marble
   local year = dateInfo.year
   if year == 1961
    or year == 1999
    or year == 2018
    or year == 2037
    or year == 2067
    or year == 2094
   then
    return 'This month had no full moon.'
   end
  end

  return ''
 end

 function dateFuncs.firstDayOfMonth()
  -- Weekday of the first day of the month, e.g. "Tuesday" (string)
  return lang:formatDate('l', dateInfo.date)
 end

 function dateFuncs.lastDayOfMonth()
  -- Weekday of the last day of the month, e.g. "Thursday" (string)
  return lang:formatDate('l', dateInfo.date .. ' +1 month -1 day')
 end

 function dateFuncs.daysInMonth()
  -- Number of days in the month (number)
  return tonumber(lang:formatDate(
   'j',
   dateInfo.date .. ' +1 month -1 day')
  )
 end

 function dateFuncs.mainContent()
  -- The rendered content of all the current events portal pages for the
  -- month (string)
  local ret = {}
  local frame = mw.getCurrentFrame()
  local year = dateInfo.year
  local monthName = dateInfo.monthName
  for date = 1, 31 do
   local portalTitle = mw.title.new(string.format(
    'Portal:Current events/%d %s %d',
    year, monthName, date
   ))
   if portalTitle.exists then
    table.insert(
     ret,
     frame:expandTemplate{title = portalTitle.prefixedText}
    )
   end
  end
  return table.concat(ret, '\n')
 end

 return dateInfo
end

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-- Exports
--------------------------------------------------------------------------------

local p = {}

function p.main(frame)
 -- Get the arguments
 local args = require('Module:Arguments').getArgs(frame, {
  wrappers = 'Template:Current events monthly archive',
 })
 local year = tonumber(args.year)
 local month = tonumber(args.month)

 -- Validate the arguments
 if year and not isPositiveInteger(year) then
  error('invalid year argument (must be a positive integer)', 2)
 end
 if month then
  if not isPositiveInteger(month) then
   error('invalid month argument (must be a positive integer)', 2)
  elseif month > 12 then
   error('invalid month argument (must be 12 or less)', 2)
  end
 end

 -- If we weren't passed a month or a year, try to get them from the
 -- page title.
 if not year and not month then
  year, month = parseYearAndMonthFromCurrentTitle()
 end

 -- Convert the dateInfo table values into arguments to pass to the current
 -- events monthly archive display template
 local dateInfo = getDateInfo(year, month)
 local displayArgs = {}
 displayArgs['year']                     = dateInfo.year
 displayArgs['month-name']               = dateInfo.monthName
 displayArgs['month-number']             = dateInfo.monthNumber
 displayArgs['month-number-zero-padded'] = dateInfo.monthNumberZeroPadded
 displayArgs['be-verb']                  = dateInfo.beVerb
 displayArgs['month-ordinal']            = dateInfo.monthOrdinal
 displayArgs['leap-desc']                = dateInfo.leapDesc
 displayArgs['moon-note']                = dateInfo.moonNote
 displayArgs['decade-note']              = dateInfo.decadeNote
 displayArgs['first-day-of-month']       = dateInfo.firstDayOfMonth
 displayArgs['last-day-of-month']        = dateInfo.lastDayOfMonth
 displayArgs['days-in-month']            = dateInfo.daysInMonth
 displayArgs['main-content']             = dateInfo.mainContent

 -- Expand the display template with the arguments from dateInfo, and return
 -- it
 return frame:expandTemplate{
  title = 'Current events monthly archive/display',
  args = displayArgs,
 }
end

-- Export getDateInfo so that we can use it in unit tests.
p.getDateInfo = getDateInfo

return p