-- For Google Code In 2018 - Lua Task 7 - Date formatting
local p={}
p.valid=function(day,month,year)
day,month,year=tonumber(day),tonumber(month),tonumber(year)
local lengths={31,0,31,30,31,30,31,31,30,31,30,31}
local long=0
if year==nil then return false end
if type(year)~='number' or math.floor(year)~=year or year<1 then return false end
if month==nil then return true end
if type(month)~='number' or math.floor(month)~=month or month<1 or month>12 then return false end
if day==nil then return true end
if type(day)~='number' or math.floor(day)~=day or day<1 then return false end
if month==2 then
if year%400==0 then long=29
elseif year%100==0 then long=28
elseif year%4==0 then long=29
else long=28 end
else
long=lengths[month]
end
return day<=long
end
p.testvalid=function(frame)
return p.valid(frame.args.day,frame.args.month,frame.args.year)
end
p.convert=function(frame)
local indate=frame.args.date
local day,month,year,era,inform,circa,outdate=nil
local monthregex={"[Jj]an","[Ff]eb","[Mm]ar","[Aa]pr","[Mm]ay","[Jj]un","[Jj]ul","[Aa]ug","[Ss]ep","[Oo]ct","[Nn]ov","[Dd]ec"}
local monthnames={"January ","February ","March ","April ","May ","June ","July ","August ","September ","October ","November ","December "}
--parse indate -> inform, day, month, year; then check if valid
--first try: parse as some iso-like format
local num1,num2,num3,era=string.match(indate,"(%d+)%D+(%d+)%D+(%d+)")
if p.valid(num3,num2,num1) then day,month,year,inform=num3,num2,num1,"iso" else
if p.valid(num1,num2,num3) then day,month,year,inform=num1,num2,num3,"iso" else
if p.valid(num2,num1,num3) then day,month,year,inform=num2,num1,num3,"iso" else
if p.valid(num3,num1,num2) then day,month,year,inform=num3,num1,num2,"iso" else
if p.valid(num1,num3,num2) then day,month,year,inform=num1,num3,num2,"iso" else
if p.valid(num2,num3,num1) then day,month,year,inform=num2,num3,num1,"iso" else
if num1~=nil and num2~=nil and num3~=nil then return "Invalid entry" end
--second try: parse as some dmy-like format
local num4,num5,mon1=nil
for i=1,12 do
num4,num5=string.match(indate,"(%d+)%D+"..monthregex[i].."%D+(%d+)")
if num4~=nil then
mon1=i
break
end
end
if p.valid(num4,mon1,num5) then day,month,year,inform=num4,mon1,num5,"dmy" else
if p.valid(num5,mon1,num4) then day,month,year,inform=num5,mon1,num4,"dmy" else
if num4~=nil and mon1~=nil and num5~=nil then return "Invalid entry" end
--third try: parse as some mdy-like format
local num6,num7,mon2=nil
for i=1,12 do
num6,num7=string.match(indate,monthregex[i].."%D+(%d+)%D+(%d+)")
if num6~=nil then
mon2=i
break
end
end
if p.valid(num6,mon2,num7) then day,month,year,inform=num6,mon2,num7,"mdy" else
if p.valid(num7,mon2,num6) then day,month,year,inform=num7,mon2,num6,"mdy" else
if num6~=nil and mon2~=nil and num7~=nil then return "Invalid entry" end
--fourth try: parse as month,year-like format
local num8,mon3=nil
for i=1,12 do
num8=string.match(indate,monthregex[i].."%D+(%d+)")
if num8~=nil then
mon3=i
break
end
end
if p.valid(nil,mon3,num8) then month,year,inform=mon3,num8,"month and year" else
if mon3~=nil and num8~=nil then return "Invalid entry" end
--(the unmentioned case: day and month)
local num9,mon4=nil
for i=1,12 do
num9=string.match(indate,"(%d+)%D+"..monthregex[i])
if num9~=nil then
mon4=i
break
end
end
if mon4~=nil and p.valid(num9,mon4,2016) then day,month,inform=num9,mon4,"day and month" else
if p.valid(nil,mon4,num9) then month,year,inform=mon4,num9,"month and year" else
if mon4~=nil and num9~=nil then return "Invalid entry" end
--fifth try: parse as year
if string.match(indate,"(%d+)%D*[^% %d]%D*(%d+)") then return "Invalid entry" end
local num0=string.match("A"..indate,".*%D(%d+)")
if p.valid(nil,nil,num0) then year,inform=num0,"year" else
return "Invalid entry"
end end end end end end end end end end end end end end -- ends from all the elses
--get era
if string.find(indate,"BCE") then era=" BCE"
elseif string.find(indate,"BC") then era=" BC"
elseif string.find(indate,"CE") then era=" CE"
elseif string.find(indate,"AD") then era=" AD"
else era="" end
--get uncertainty
if string.match(indate,"around") then circa="circa "
elseif string.match(indate,"uncertain") then circa="circa "
elseif string.match(indate,"about") then circa="circa "
elseif string.match(indate,"approx") then circa="circa "
elseif string.match(indate,"circa") then circa="circa "
elseif string.match(indate,"ca%.") then circa="circa "
else circa="" end
--convert output date to input format -> outdate
local outform=frame.args.format or inform
day,month,year=tonumber(day),tonumber(month),tonumber(year)
outdate = ""
if outform=="iso" then
if era==" BC" or era==" BCE" then
circa=circa.."-"
year=year-1
end
outdate = string.format("%04d-%02d-%02d",year,month,day)
end
if outform=="dmy" then
outdate = day.." "..monthnames[month]..year..era
end
if outform=="mdy" then
outdate = monthnames[month]..day..", "..year..era
end
if outform=="month and year" then
outdate = monthnames[month]..year..era
end
if outform=="day and month" then
outdate = day.." "..monthnames[month]
end
if outform=="year" then
outdate = year..era
end
outdate = circa..outdate
return outdate
end
return p
