Module:Calendar date

--[[ 

Display non-Gregorian holiday dates using equivalent Gregorian date

 ]]

local p = {}

--[[--------------------------< inlineError >-----------------------

     Critical error. Render output completely in red. Add to tracking category.

 ]]

local function inlineError(arg, msg, tname)

  track["Category:Holigreg template errors"] = 1
  return '<span style="font-size:100%" class="error citation-comment">Error in [[Template:' .. tname .. ']] - Check <code style="color:inherit; border:inherit; padding:inherit;">&#124;' .. arg .. '=</code>  ' .. msg .. '</span>'

end

--[[--------------------------< trimArg >-----------------------

     trimArg returns nil if arg is "" while trimArg2 returns 'true' if arg is "" 
     trimArg2 is for args that might accept an empty value, as an on/off switch like nolink=

 ]]

local function trimArg(arg)
  if arg == "" or arg == nil then
    return nil
  else
    return mw.text.trim(arg)
  end
end
local function trimArg2(arg)
  if arg == nil then
    return nil
  else
    return mw.text.trim(arg)
  end
end

--[[--------------------------< tableLength >-----------------------

      Given a 1-D table, return number of elements

  ]]

local function tableLength(T)
  local count = 0
  for _ in pairs(T) do count = count + 1 end
  return count
end

--[[--------------------------< createTracking >-----------------------

     Return data in track[] ie. tracking categories

  ]]

local function createTracking()

  local sand = ""
  if tableLength(track) > 0 then                        
    for key,_ in pairs(track) do
      sand = sand .. "[[" .. key .. "]]"
    end
  end
  return sand

end

--[[--------------------------< verifyDate >-----------------------

    Given the date arg, return true if within date range 2000-2050 else return false

 ]]
 
 local function verifyDate(date)
 
   if not date or date == "" then
     return nil
   end

    if tonumber(date) > 1999 and tonumber(date) < 2051 then
      return "true"
    else
      return nil
    end
end

--[[--------------------------< makeDate >-----------------------

     Given a zero-padded 4-digit year, 2-digit month and 2-digit day, return a full date in df format
     df = mdy, dmy, iso, ymd

 ]]

local function makeDate(year, month, day, df)

  if not year or year == "" or not month or month == "" or not day or day == "" then
    return nil
  end

  local zmonth = month                                                      -- month with leading 0
  month = month:match("0*(%d+)")                                            -- month without leading 0
  if tonumber(month) < 1 or tonumber(month) > 12 then
    return year
  end
  local nmonth = os.date("%B", os.time{year=2000, month=month, day=1} )     -- month in name form       
  if not nmonth then
    return year
  end

  local zday = day
  day = zday:match("0*(%d+)")
  if tonumber(day) < 1 or tonumber(day) > 31 then
    if df == "mdy" or df == "dmy" then
      return nmonth .. " " .. year
    elseif df == "iso" then
      return year .. "-" .. zmonth 
    elseif df == "ymd" then
      return year .. " " .. nmonth
    else
      return nmonth .. " " .. year
    end
  end                                       

  if df == "mdy" then
    return nmonth .. " " .. day .. ", " .. year         -- September 1, 2016
  elseif df == "dmy" then
    return day .. " " .. nmonth .. " " .. year          -- 1 September 2016
  elseif df == "iso" then
    return year .. "-" .. zmonth .. "-" .. zday         -- 2016-09-01
  elseif df == "ymd" then
    return year .. " " .. nmonth .. " " .. day          -- 2016 September 1
  else
    return nmonth .. " " .. day .. ", " .. year         -- September 1, 2016
  end

end

--[[--------------------------< renderHoli >-----------------------

     Render the data

  ]]
  
function renderHoli(json,holiday,date,df,format)

  local numRecords = tableLength(json.items)
  local hits = 0
  local matchdate = "^" .. date
  local startdate,enddate = ""

  for i = 1, numRecords do
    if mw.ustring.find( json.items[i].date, matchdate ) then
      if hits == 0 then
        startdate = json.items[i].date
        hits = 1
      end
      if hits >= json.days then
        enddate = json.items[i].date
        break
      end
      hits = hits + 1
    end
  end
  return startdate .. " - " .. enddate    
   
end

--[[--------------------------< holigreg >-----------------------

     Main function

  ]]

function p.holigreg(frame)

  local pframe = frame:getParent()
  local args = pframe.args

  local tname = "Holigreg"                       -- name of calling template. Change if template rename.
  local holiday = nil                            -- name of holiday
  local date = nil                               -- date of holiday 
  local df = nil                                 -- date format (mdy, dmy, iso - default: iso)
  local format = nil                             -- template display format options
  
  track = {}                                     -- global tracking-category table

  --- Determine holiday
  holiday = trimArg(args.holiday)                -- required
  if not holiday then
    return inlineError("holiday", "Missing holiday argument", tname) .. createTracking()
  end

  --- Determine date
  date = trimArg(args.date)                      -- required
  if not date then
    return inlineError("date", "Missing date argument", tname) .. createTracking()
  elseif not verifyDate(date) then
    return inlineError("date", "Invalid date", tname) .. createTracking()
  end

  --- Determine df
  df = trimArg(args.df)
  if not df then
    df = "iso"
  elseif df ~= "mdy" or df ~= "dmy" then
    df = "iso"
  end

  --- Determine format type
  format = trimArg(args.format)
  if not format then
    format = "none"
  elseif format ~= "box" or format ~= "infobox" then
    format = "none"
  end
    
  local version = mw.title.makeTitle( 'Template', 'Holigreg/holidays/' .. holiday .. '.js' )    
  local json = mw.text.jsonDecode( version:getContent() )

  rend = renderHoli(json,holiday,date,df,format)

  return rend

end

return p