Module:MostRecentValue

Documentation for this module may be created at Module:MostRecentValue/doc

local monthNames = {
    ["january"] = "01",
    ["february"] = "02",
    ["march"] = "03",
    ["april"] = "04",
    ["may"] = "05",
    ["june"] = "06",
    ["july"] = "07",
    ["august"] = "08",
    ["september"] = "09",
    ["october"] = "10",
    ["november"] = "11",
    ["december"] = "12",
    ["jan"] = "01",
    ["feb"] = "02",
    ["mar"] = "03",
    ["apr"] = "04",
    ["jun"] = "06",
    ["jul"] = "07",
    ["aug"] = "08",
    ["sep"] = "09",
    ["oct"] = "10",
    ["nov"] = "11",
    ["dec"] = "12"
}


local dmyPattern = "^(%d+)%s+(%w+)%s+(%d+)$"
local mdyPattern = "^(%w+)%s+(%d+),?%s+(%d+)$"
local myPattern = "^(%w+)%s+(%d+)$"

function dateToISO(dateString)
   local day, month, year = dateString:lower():match(dmyPattern)
   if year == nil then
      -- failed to parse try again
      month, day, year = dateString:lower():match(mdyPattern)
      if year == nil then
	     -- failed to parse try again
	     month, year = dateString:lower():match(myPattern)
      end
   end
   month = monthNames[month]

   if month == nil or year == nil then
      return nil
   end

   if day == nil or day == '' then
      day = "01"
   elseif tonumber(day) < 10 then
      -- pad with a zero
      day = "0" .. tonumber(day)
   end

   return year.."-"..month.."-"..day
end

local p = {}

function p.mostRecentValue( frame )
   v1 = frame.args["v1"]
   d1 = frame.args["d1"]
   v2 = frame.args["v2"]
   d2 = frame.args["d2"]


   d1Iso = dateToISO(d1)
   d2Iso = dateToISO(d2)

   if d1Iso == nil and d2Iso == nil then
      error("Failed to parse both dates given")
   elseif d2Iso == nil then
      return v1
   elseif d1Iso == nil then
      return v2
   end

   if d1Iso < d2Iso then
      return v2
   else
      return v1
   end
end

return p