Module:Infobox date field metadata: Difference between revisions

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This module allows infoboxes using {{Infobox date field metadata}} to automatically produce machine-readable metadata in form of microformats (see also WP Microformats) from infobox fields using recognized dates, times, and date ranges. Unrecognized, ambiguous and incomplete values are skipped and some will produce an error tracking category.

Usage

This module is not intended to be used directly other than from its parent template {{Infobox date field metadata}}. See that template for description.

Parameters

• First paramater is always the input string – this should be the infobox's date field value
• |dtstart=yes specifies that hCalendar (WP:UF#hCalendar) dtstart (event start date) class is to be output if possible
• |dtend=yes specifies that hCalendar dtend (event end date) class is to be output if possible
• |trackingCat=yes specifies that Category:Articles with automatically detected infobox date metadata should be added to every article where metadata was successfully emitted
• |noErrorCats=yes specifies that parsing error categories (currently Category:Articles with incomplete date ranges for automatic metadata) should not be added by default

Examples

See Module talk:Infobox date field metadata/testcases

The above documentation is transcluded from Module:Infobox date field metadata/doc. (edit | history)
Editors can experiment in this module's sandbox (create | mirror) and testcases (edit | run) pages.
Subpages of this module.

local main = {};

local monthIndices = {
    ['january'] = 1,
    ['february'] = 2,
    ['march'] = 3,
    ['april'] = 4,
    ['may'] = 5,
    ['june'] = 6,
    ['july'] = 7,
    ['august'] = 8,
    ['september'] = 9,
    ['october'] = 10,
    ['november'] = 11,
    ['december'] = 12
}

local monthShortIndices = {
    ['jan'] = 1,
    ['feb'] = 2,
    ['mar'] = 3,
    ['apr'] = 4,
    ['may'] = 5, -- long one would have caught this already
    ['jun'] = 6,
    ['jul'] = 7,
    ['aug'] = 8,
    ['sep'] = 9,
    ['oct'] = 10,
    ['nov'] = 11,
    ['dec'] = 12
}

local monthDays = {
    [1] = 31,
    [2] = 29, -- will check below
    [3] = 31,
    [4] = 30,
    [5] = 31,
    [6] = 30,
    [7] = 31,
    [8] = 31,
    [9] = 30,
    [10] = 31,
    [11] = 30,
    [12] = 31
}

function checkIfDayValid(day, month, year)
    -- First check that the month can have at least this many days
    if (day > monthDays[month]) then return false end

    -- February leap year check
    if (month == 2) then
        if (day == 29 and not ((year % 4 == 0) and (year % 100 ~= 0) or (year % 400 == 0))) then
             return false
        end
    end

    return true
end

function checkIfMonthValid(month)
    return month ~= 0 and month <= 12  -- <0 never happens with [0-9] pattern
end

function checkIfYearValid(year)
    return year >= 1583 -- up to 9999
end

function checkIfHourValid(hour)
    return hour < 24 -- <0 never happens with [0-9] pattern
end

function checkIfMinuteValid(minute)
    return minute < 60 -- <0 never happens with [0-9] pattern
end

function checkIfSecondValid(second)
    return second < 60 -- <0 never happens with [0-9] pattern
end

local PARSERESULT_OKAY = 1
local PARSERESULT_FAIL = 2 -- whatever we encountered isn't expected for any pattern
local PARSERESULT_UNCRECOGNIZED = 3 -- 14 May 12, 2014 (all elements okay, no pattern)
local PARSERESULT_INCOMPLETE = 4 -- May 3
local PARSERESULT_INCOMPLETERANGE = 5 -- 3 May 2012 - June 2013
local PARSERESULT_INVALID = 6 -- May 32
local PARSERESULT_INVALIDRANGE = 7 -- May 3 - May 2

-- This will first verify that we have a valid date and time and then output an ISO datetime string
function checkAndOutput(year, month, day, hour, minute, second, year2, month2, day2, hour2, minute2, second2)

    local s

    if (year and not checkIfYearValid(year)) then return PARSERESULT_INVALID; end
    if (month and not checkIfMonthValid(month)) then return PARSERESULT_INVALID; end
    if (day and not checkIfDayValid(day, month, year)) then return PARSERESULT_INVALID; end
    if (hour and not checkIfHourValid(hour)) then return PARSERESULT_INVALID; end
    if (minute and not checkIfMinuteValid(minute)) then return PARSERESULT_INVALID; end
    if (second and not checkIfSecondValid(second)) then return PARSERESULT_INVALID; end

    if (year2 and not checkIfYearValid(year2)) then return PARSERESULT_INVALID; end
    if (month2 and not checkIfMonthValid(month2)) then return PARSERESULT_INVALID; end
    if (day2 and not checkIfDayValid(day2, month2, year2)) then return PARSERESULT_INVALID; end
    if (hour2 and not checkIfHourValid(hour2)) then return PARSERESULT_INVALID; end
    if (minute2 and not checkIfMinuteValid(minute2)) then return PARSERESULT_INVALID; end
    if (second2 and not checkIfSecondValid(second2)) then return PARSERESULT_INVALID; end

    -- Check that end date is actually after start date
    if (year2 and year) then
        if (year2 < year) then return PARSERESULT_INVALIDRANGE end
        if (year2 == year) then
            if (month2 and month) then
                if (month2 < month) then return PARSERESULT_INVALIDRANGE end
                if (month2 == month) then
                    if (day2 and day) then
                        if (day2 < day) then return PARSERESULT_INVALIDRANGE end
                        -- TODO: compare time
                    end
                end
            end
        end
    end

    -- Check that the date is actually complete even if valid
    if (month and month2 and not year) then return PARSERESULT_INCOMPLETERANGE end -- any of 'd-dM', 'dM-dM', 'Md-d', 'Md-Md'
    if (month and not year) then return PARSERESULT_INCOMPLETE end -- 'May', 'May 15', '15 May'
    if (month2 and not year2) then return PARSERESULT_INCOMPLETE end -- same but other end
    -- While technically there are more cases, none should have been matched and been given to us
    
    local date1, time1, date2, time2

    -- time only
    if (second and not year) then time1 = string.format('%02d:%02d:%02d', hour, minute, second)
    elseif (minute and not year) then time1 = string.format('%02d:%02d', hour, minute)
    elseif (hour and not year) then time1 = string.format('%02d', hour)

    -- date and time
    elseif (second) then date1 = string.format('%d-%02d-%02d', year, month, day) time1 = string.format('%02d:%02d:%02d', hour, minute, second)
    elseif (minute) then date1 = string.format('%d-%02d-%02d', year, month, day) time1 = string.format('%02d:%02d', hour, minute)
    elseif (hour) then date1 = string.format('%d-%02d-%02d', year, month, day) time1 = string.format('%02d', hour)

    -- date only
    elseif (day) then date1 = string.format('%d-%02d-%02d', year, month, day)
    elseif (month) then date1 = string.format('%d-%02d', year, month)
    elseif (year) then date1 = string.format('%d', year)
    end

    -- time only
    if (second2 and not year2) then time2 = string.format('%02d:%02d:%02d', hour2, minute2, second2)
    elseif (minute2 and not year2) then time2 = string.format('%02d:%02d', hour2, minute2)
    elseif (hour2 and not year2) then time2 = string.format('%02d', hour2)

    -- date and time
    elseif (second2) then date2 = string.format('%d-%02d-%02d', year2, month2, day2) time2 = string.format('%02d:%02d:%02d', hour2, minute2, second2)
    elseif (minute2) then date2 = string.format('%d-%02d-%02d', year2, month2, day2) time2 = string.format('%02d:%02d', hour2, minute2)
    elseif (hour2) then date2 = string.format('%d-%02d-%02d', year2, month2, day2) time2 = string.format('%02d', hour2)

    -- date only
    elseif (day2) then date2 = string.format('%d-%02d-%02d', year2, month2, day2)
    elseif (month2) then date2 = string.format('%d-%02d', year2, month2)
    elseif (year2) then date2 = string.format('%d', year2)
    end

    return PARSERESULT_OKAY, date1, time1, date2, time2 -- this function wouldn't be called withotu matching pattern, so at least 1 value should have been filled

end

function periodHourAdd(period)
    if (period == 'pm' or period == 'p.m' or period == 'pm.' or period == 'p.m.') then -- random '.' is pattern match artifact
        return 12
    else
        return 0
    end
end

local seekString -- this is our local seek string, so we don't have to pass it as parameter every time

local currentPosition -- this keeps track of where we are in seeking our current string

-- These are the element type "constants" for readability mostly
local ELEMENT_INVALID = 1
local ELEMENT_ONETWODIGITS = 2
local ELEMENT_FOURDIGITS = 3
local ELEMENT_WHITESPACE = 4
local ELEMENT_MONTHWORD = 5
local ELEMENT_COMMA = 6
local ELEMENT_DASH = 7
local ELEMENT_DATESEPARATOR = 8
local ELEMENT_TIMESEPARATOR = 9
local ELEMENT_TIMEPERIOD = 10

function seekNextElement()
    
    -- Profiler says mw.ustring.find is the bottleneck, probably because it's unicode; not sure how to improve though besides writing my own pattern matcher

    -- Digits
    local foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^([0-9]+)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location

        -- Additionally check how many digits we actually have, as arbitrary number isn't valid
        if (#foundMatch <= 2) then -- most likely a day number or time number
            return ELEMENT_ONETWODIGITS, tonumber(foundMatch), (currentPosition > mw.ustring.len(seekString))
        elseif (#foundMatch == 4) then -- most likely a year
            return ELEMENT_FOURDIGITS, tonumber(foundMatch), (currentPosition > mw.ustring.len(seekString))
        else
            return ELEMENT_INVALID -- just the invalid, the number of digits (3 or 5+) won't match any patterns
        end
    end

    -- Time period - a.m./p.m. (before letters)
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^%s*([ap]%.?m%.?)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_TIMEPERIOD, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end

    -- Word
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^([A-Za-z]+)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location

        if (#foundMatch >= 3) then

            -- Find the possible month name index
            monthIndex = monthIndices[mw.ustring.lower(foundMatch)]
            if (not monthIndex) then monthIndex = monthShortIndices[mw.ustring.lower(foundMatch)] end

            if (monthIndex) then
                return ELEMENT_MONTHWORD, monthIndex, (currentPosition > mw.ustring.len(seekString))
            else
                return ELEMENT_INVALID -- just the invalid, the word didn't match a valid month name
            end
        else
            -- TODO LETTERS
            return ELEMENT_INVALID -- just the invalid, the word was too short to be valid month name
        end
    end

    -- Time separator (colon without whitespace)
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^(:)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_TIMESEPARATOR, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end

    -- Comma and any following whitespace
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^(,%s*)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_COMMA, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end
    
    -- Dash with possible whitespace or Date separator (dash without whitespace)
    -- Both non-breaking spaces - '&nbsp;-&nbsp;'
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^(&nbsp;[%-–—]&nbsp;)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_DASH, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end
    -- Non-breaking space - '&nbsp;- '
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^(&nbsp;[%-–—]%s*)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_DASH, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end
    -- Dash entity code and both non-breaking spaces - '&nbsp;&ndash;&nbsp;'
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^(&nbsp;&[nm]dash;&nbsp;)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_DASH, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end
    -- Dash entity code and non-breaking space - '&nbsp;&ndash; '
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^(&nbsp;&[nm]dash;%s*)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_DASH, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end  
    -- Dash entity code - ' &ndash; '
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^(%s*&[nm]dash;%s*)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_DASH, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end 
    -- Regular whitespace
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^(%s*[%-–—]%s*)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        
        if (foundMatch == '-') then -- nothing else is date separator, no hyphens no stuff like that
            return ELEMENT_DATESEPARATOR, foundMatch, (currentPosition > mw.ustring.len(seekString))
        else
            return ELEMENT_DASH, foundMatch, (currentPosition > mw.ustring.len(seekString)) -- we will actually need to check for DATESEPARATOR as well, as that one stole the '-' case
        end
    end

    -- Whitespace (after all others that capture whitespace)
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^(%s+)', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_WHITESPACE, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end
    -- Whitespace -- same as above but using &nbsp; (other that for dashes)
    foundPositionStart, foundPositionEnd, foundMatch = mw.ustring.find(seekString, '^&nbsp;', currentPosition)
    if (foundPositionStart) then
        currentPosition = foundPositionEnd + 1 -- this is our new start location
        return ELEMENT_WHITESPACE, foundMatch, (currentPosition > mw.ustring.len(seekString))
    end

    return ELEMENT_INVALID -- just the invalid, we won't be parsing this further

end

function parseDateString(input)

    -- Reset our seek string and position
    seekString = input
    currentPosition = 1

    local elements = {}
    local values = {}

    -- Seek the entire string now
    local numberOfElements = 0
    repeat

        foundElement, foundValue, eos = seekNextElement()

        -- If we found something we can't process, return as unparsable
        if (foundElement == ELEMENT_INVALID) then return nil end

        numberOfElements = numberOfElements + 1
        elements[numberOfElements] = foundElement
        values[numberOfElements] = foundValue

    until eos

    --[[
    local s = input .. ' -> ' .. numberOfElements .. ' elements: '

    for currentElementIndex = 1, numberOfElements do
        s = s .. ' #' .. elements[currentElementIndex] .. '=' .. values[currentElementIndex]
    end

    do return s end  
    ]]

    -- Now comes an uber-deep if-then-else tree
    -- This is roughly the most efficient step-by-step parsing, something like log(N)
    -- Doing each combination via pattern/"Regex" is way slower
    -- Having each combination a clean function/preset means checking every element, so way slower
    -- Only immediate big improvement is to only seekNextElement() when actually checking that deep, though this will make a (even bigger) mess

    if (elements[1] == ELEMENT_ONETWODIGITS) then -- '3' or '10'
        if (elements[2] == ELEMENT_WHITESPACE) then -- '3 '
            if (elements[3] == ELEMENT_MONTHWORD) then -- '3 May'
                if (numberOfElements == 3) then return checkAndOutput(nil, values[3], values[1], nil, nil, nil) end
                if (elements[4] == ELEMENT_WHITESPACE) then -- '3 May '
                    if (elements[5] == ELEMENT_FOURDIGITS) then -- '3 May 2013'
                        if (numberOfElements == 5) then return checkAndOutput(values[5], values[3], values[1], nil, nil, nil) end
                        if (elements[6] == ELEMENT_WHITESPACE or elements[6] == ELEMENT_COMMA) then -- '3 May 2013, '
                            if (elements[7] == ELEMENT_ONETWODIGITS) then -- '3 May 2013, 10'
                                if (elements[8] == ELEMENT_TIMEPERIOD) then -- '3 May 2013, 10 am'
                                    if (numberOfElements == 8) then return checkAndOutput(values[5], values[3], values[1], values[7] + periodHourAdd(values[8]), nil, nil) end
                                elseif (elements[8] == ELEMENT_TIMESEPARATOR) then -- '3 May 2013, 10:'
                                    if (elements[9] == ELEMENT_ONETWODIGITS) then -- '3 May 2013, 10:38'
                                        if (numberOfElements == 9) then return checkAndOutput(values[5], values[3], values[1], values[7], values[9], nil) end
                                        if (elements[10] == ELEMENT_TIMEPERIOD) then -- '3 May 2013, 10:38 am'
                                            if (numberOfElements == 10) then return checkAndOutput(values[5], values[3], values[1], values[7] + periodHourAdd(values[10]), values[9], nil) end
                                        elseif (elements[10] == ELEMENT_TIMESEPARATOR) then -- '3 May 2013, 10:38:'
                                            if (elements[11] == ELEMENT_ONETWODIGITS) then -- '3 May 2013, 10:38:27'
                                                if (numberOfElements == 11) then return checkAndOutput(values[5], values[3], values[1], values[7], values[9], values[11]) end
                                                if (elements[12] == ELEMENT_TIMEPERIOD) then -- '3 May 2013, 10:38:27 am'
                                                    if (numberOfElements == 12) then return checkAndOutput(values[5], values[3], values[1], values[7] + periodHourAdd(values[12]), values[9], values[11]) end
                                                end
                                            end                                            
                                        end                                        
                                    end                                    
                                end                                
                            end
                        elseif (elements[6] == ELEMENT_DASH or elements[6] == ELEMENT_DATESEPARATOR) then -- '3 May 2013 - '
                            if (elements[7] == ELEMENT_ONETWODIGITS) then -- '3 May 2013 - 12'
                                if (elements[8] == ELEMENT_WHITESPACE) then -- '3 May 2013 - 12 '
                                    if (elements[9] == ELEMENT_MONTHWORD) then -- '3 May 2013 - 12 February'
                                        if (elements[10] == ELEMENT_WHITESPACE) then -- '3 May 2013 - 12 February '
                                            if (elements[11] == ELEMENT_FOURDIGITS) then -- '3 May 2013 - 12 February 2014'
                                                if (numberOfElements == 11) then return checkAndOutput(values[5], values[3], values[1], nil, nil, nil, values[11], values[9], values[7], nil, nil, nil) end
                                            end
                                        end
                                    end
                                end
                            end
                        end
                    end                
                elseif (elements[4] == ELEMENT_DASH or elements[4] == ELEMENT_DATESEPARATOR) then -- '3 May - '
                    if (elements[5] == ELEMENT_ONETWODIGITS) then -- '3 May - 12'
                        if (elements[6] == ELEMENT_WHITESPACE) then -- '3 May - 12 '
                            if (elements[7] == ELEMENT_MONTHWORD) then -- '3 May - 12 October'
                                if (numberOfElements == 7) then return checkAndOutput(nil, values[3], values[1], nil, nil, nil, nil, values[7], values[5], nil, nil, nil) end
                                if (elements[8] == ELEMENT_COMMA or elements[8] == ELEMENT_WHITESPACE) then -- '3 May - 12 October '
                                    if (elements[9] == ELEMENT_FOURDIGITS) then -- '3 May - 12 October 2013'
                                        if (numberOfElements == 9) then return checkAndOutput(values[9], values[3], values[1], nil, nil, nil, values[9], values[7], values[5], nil, nil, nil) end
                                    end
                                end
                            end
                        end
                    end
                end
            end
        elseif (elements[2] == ELEMENT_DASH or elements[2] == ELEMENT_DATESEPARATOR) then -- '3 - '
            if (elements[3] == ELEMENT_ONETWODIGITS) then -- '3 - 12'
                if (elements[4] == ELEMENT_WHITESPACE) then -- '3 - 12 '
                    if (elements[5] == ELEMENT_MONTHWORD) then -- '3 - 12 May'
                        if (numberOfElements == 5) then return checkAndOutput(nil, values[5], values[1], nil, nil, nil, nil, values[5], values[3], nil, nil, nil) end
                        if (elements[6] == ELEMENT_COMMA or elements[6] == ELEMENT_WHITESPACE) then -- '3 - 12 May '
                            if (elements[7] == ELEMENT_FOURDIGITS) then -- '3 - 12 May 2013'
                                if (numberOfElements == 7) then return checkAndOutput(values[7], values[5], values[1], nil, nil, nil, values[7], values[5], values[3], nil, nil, nil) end
                            end
                        end
                    end
                end
            end
        end

        -- Here's a case where we want to optimize or rather add readability and trim redundancy
        -- Basically, any time '10am', '10:28', '10:28am', '10:28:27', '10:28:27am' can be followed by a date, which means 5 copies of 30+ lines (urgh)
        -- Instead we will only check once, but using a different element index offset if needed, so date might start at element 4 or 5 or 6 etc.
        -- Currently we only have '10', but if it turns out to be a time we will be checking if it's followed by a date

        local wasTime = false -- by default we didn't find a valid time syntax, we have '10' and that's not a time by itself without 'am/pm' or further precision
        local possibleHour, possibleMinute, possibleSecond -- temporary values that we will fill as far as we can when parsing time and use for time+date combo if one is found
        local i = 0 -- this is our offset from the closest possible location for date seeking

        if (elements[2] == ELEMENT_TIMESEPARATOR) then -- '10:'            
            possibleHour = values[1] -- only once we see ':' (or 'am' below) it is likely a time
            if (elements[3] == ELEMENT_ONETWODIGITS) then -- '10:28'
                if (numberOfElements == 3) then return checkAndOutput(nil, nil, nil, values[1], values[3], nil) end
                possibleMinute = values[3]
                wasTime = true -- this is a valid final time, so we can check date appended to this
                i = 1 -- '10', ':' and '28' are three elements, so we start 1 further from 3
                if (elements[4] == ELEMENT_TIMESEPARATOR) then -- '10:28:'
                    wasTime = false -- a time can't end with separator, so if this is last match, we aren't appending any dates
                    if (elements[5] == ELEMENT_ONETWODIGITS) then -- '10:28:27'
                        if (numberOfElements == 5) then return checkAndOutput(nil, nil, nil, values[1], values[3], values[5]) end
                        possibleSecond = values[5]
                        wasTime = true -- this is a valid final time, so we can check date appended to this
                        i = 3 -- '10', ':', '28', ':' and '27' are five elements, so we start 3 further from 3
                        if (elements[6] == ELEMENT_TIMEPERIOD) then -- '10:28:27 am'
                            if (numberOfElements == 6) then return checkAndOutput(nil, nil, nil, values[1] + periodHourAdd(values[6]), values[3], values[5]) end
                            possibleHour = values[1] + periodHourAdd(values[6]) -- hour now needs possible adjusting since we saw a time period
                            -- wasTime = true -- already set
                            i = 4 -- '10', ':', '28', ':', '27' and 'am' are six elements, so we start 4 further from 3
                        end
                    end
                elseif (elements[4] == ELEMENT_TIMEPERIOD) then -- '10:28 am'
                    if (numberOfElements == 4) then return checkAndOutput(nil, nil, nil, values[1] + periodHourAdd(values[4]), values[3], nil) end
                    wasTime = true -- this is a valid final time, so we can check date appended to this
                    possibleHour = values[1] + periodHourAdd(values[4]) -- hour now needs possible adjusting since we saw a time period
                    i = 2 -- '10', ':', '28' and 'am' are four elements, so we start 2 further from 3
                end
            end
        elseif (elements[2] == ELEMENT_TIMEPERIOD) then -- '10 am'
            if (numberOfElements == 2) then return checkAndOutput(nil, nil, nil, values[1] + periodHourAdd(values[2]), nil, nil) end
            possibleHour = values[1] + periodHourAdd(values[2]) -- only once we see 'am' (or ':' above) it is likely a time
            wasTime = true -- this is a valid final time, so we can check date appended to this
            i = 0 -- '10' and 'am' are two elements, so we start at 3 - default
        end

        if (wasTime) then -- '10am', '10:28', '10:28am', '10:28:27', '10:28:27am' (using just '10:28:27...' below)
            -- Now we will try to append a date to the time
            if (elements[3+i] == ELEMENT_WHITESPACE or elements[3+i] == ELEMENT_COMMA) then -- '10:28:27, '
                if (elements[4+i] == ELEMENT_ONETWODIGITS) then -- '10:28:27, 3'
                    if (elements[5+i] == ELEMENT_WHITESPACE) then -- '10:28:27, 3 '
                        if (elements[6+i] == ELEMENT_MONTHWORD) then -- '10:28:27, 3 May'
                            if (elements[7+i] == ELEMENT_WHITESPACE) then -- '10:28:27, 3 May '
                                if (elements[8+i] == ELEMENT_FOURDIGITS) then -- '10:28:27, 3 May 2013'
                                    if (numberOfElements == 8+i) then return checkAndOutput(values[8+i], values[6+i], values[4+i], possibleHour, possibleMinute, possibleSecond) end
                                end
                            end
                        end
                    end
                elseif (elements[4+i] == ELEMENT_MONTHWORD) then -- '10:28:27, May'
                    if (elements[5+i] == ELEMENT_WHITESPACE) then -- '10:28:27, May '
                        if (elements[6+i] == ELEMENT_ONETWODIGITS) then -- '10:28:27, May 3'
                            if (elements[7+i] == ELEMENT_COMMA or elements[7+i] == ELEMENT_WHITESPACE) then -- '10:28:27, May 3, '
                                if (elements[8+i] == ELEMENT_FOURDIGITS) then -- '10:28:27, May 3, 2013'
                                    if (numberOfElements == 8+i) then return checkAndOutput(values[8+i], values[4+i], values[6+i], possibleHour, possibleMinute, possibleSecond) end
                                end
                            end
                        end
                    end
                elseif (elements[4+i] == ELEMENT_FOURDIGITS) then -- '10:28:27, 2013'
                    if (elements[5+i] == ELEMENT_DATESEPARATOR) then -- '10:28:27, 2013-'
                        if (elements[6+i] == ELEMENT_ONETWODIGITS) then -- '10:28:27, 2013-05'
                            if (elements[7+i] == ELEMENT_DATESEPARATOR) then -- '10:28:27, 2013-05-'
                                if (elements[8+i] == ELEMENT_ONETWODIGITS) then -- '10:28:27, 2013-05-03'
                                    if (numberOfElements == 8+i) then return checkAndOutput(values[4+i], values[6+i], values[8+i], possibleHour, possibleMinute, possibleSecond) end
                                end
                            end
                        end
                    end
                end
            end
        end

    elseif (elements[1] == ELEMENT_FOURDIGITS) then -- '2013'
        if (numberOfElements == 1) then return checkAndOutput(values[1], nil, nil, nil, nil, nil) end
        if (elements[2] == ELEMENT_DATESEPARATOR) then -- '2013-'
            if (elements[3] == ELEMENT_ONETWODIGITS) then -- '2013-05'
                if (numberOfElements == 3) then return checkAndOutput(values[1], values[3], nil, nil, nil, nil) end
                if (elements[4] == ELEMENT_DATESEPARATOR) then -- '2013-05-'
                    if (elements[5] == ELEMENT_ONETWODIGITS) then -- '2013-05-03'
                        if (numberOfElements == 5) then return checkAndOutput(values[1], values[3], values[5], nil, nil, nil) end
                        if (elements[6] == ELEMENT_WHITESPACE or elements[6] == ELEMENT_COMMA) then -- '2013-05-03, '
                            if (elements[7] == ELEMENT_ONETWODIGITS) then -- '2013-05-03, 10'
                                if (elements[8] == ELEMENT_TIMEPERIOD) then -- '2013-05-03, 10 am'
                                    if (numberOfElements == 8) then return checkAndOutput(values[1], values[3], values[5], values[7] + periodHourAdd(values[8]), nil, nil) end
                                elseif (elements[8] == ELEMENT_TIMESEPARATOR) then -- '2013-05-03, 10:'
                                    if (elements[9] == ELEMENT_ONETWODIGITS) then -- '2013-05-03, 10:38'
                                        if (numberOfElements == 9) then return checkAndOutput(values[1], values[3], values[5], values[7], values[9], nil) end
                                        if (elements[10] == ELEMENT_TIMEPERIOD) then -- '2013-05-03, 10:38 am'
                                            if (numberOfElements == 10) then return checkAndOutput(values[1], values[3], values[5], values[7] + periodHourAdd(values[10]), values[9], nil) end
                                        elseif (elements[10] == ELEMENT_TIMESEPARATOR) then -- '2013-05-03, 10:38:'
                                            if (elements[11] == ELEMENT_ONETWODIGITS) then -- '2013-05-03, 10:38:27'
                                                if (numberOfElements == 11) then return checkAndOutput(values[1], values[3], values[5], values[7], values[9], values[11]) end
                                                if (elements[12] == ELEMENT_TIMEPERIOD) then -- '2013-05-03, 10:38:27 am'
                                                    if (numberOfElements == 12) then return checkAndOutput(values[1], values[3], values[5], values[7] + periodHourAdd(values[12]), values[9], values[11]) end
                                                end
                                            end
                                        end
                                    end
                                end
                            end
                        end
                    end
                end
            end
        end -- can't elseif, because we have ELEMENT_DATESEPARATOR, which repeats above
        if (elements[2] == ELEMENT_DASH or elements[2] == ELEMENT_DATESEPARATOR) then -- '2013 - '
            if (elements[3] == ELEMENT_FOURDIGITS) then -- '2013 - 2014'
                if (numberOfElements == 3) then return checkAndOutput(values[1], nil, nil, nil, nil, nil, values[3], nil, nil, nil, nil, nil) end
            end
        elseif (elements[2] == ELEMENT_WHITESPACE) then -- '2013 '
            if (elements[3] == ELEMENT_MONTHWORD) then -- '2013 May'
                if (numberOfElements == 3) then return checkAndOutput(values[1], values[3], nil, nil, nil, nil) end
                -- 2013 May - 2013 April (let's see first if this is ever used real-world)
            end
        end

    elseif (elements[1] == ELEMENT_MONTHWORD) then -- 'May'
        if (numberOfElements == 1) then return checkAndOutput(nil, values[1], nil, nil, nil, nil) end
        if (elements[2] == ELEMENT_WHITESPACE) then -- 'May '
            if (elements[3] == ELEMENT_ONETWODIGITS) then -- 'May 3'
                if (numberOfElements == 3) then return checkAndOutput(nil, values[1], values[3], nil, nil, nil) end
                if (elements[4] == ELEMENT_COMMA or elements[4] == ELEMENT_WHITESPACE) then -- 'May 3, '
                    if (elements[5] == ELEMENT_FOURDIGITS) then -- 'May 3, 2013'
                        if (numberOfElements == 5) then return checkAndOutput(values[5], values[1], values[3], nil, nil, nil) end
                        if (elements[6] == ELEMENT_WHITESPACE or elements[6] == ELEMENT_COMMA) then -- ''May 3, 2013, '
                            if (elements[7] == ELEMENT_ONETWODIGITS) then -- ''May 3, 2013, 10'
                                if (elements[8] == ELEMENT_TIMEPERIOD) then -- ''May 3, 2013, 10 am'
                                    if (numberOfElements == 8) then return checkAndOutput(values[5], values[1], values[3], values[7] + periodHourAdd(values[8]), nil, nil) end
                                elseif (elements[8] == ELEMENT_TIMESEPARATOR) then -- ''May 3, 2013, 10:'
                                    if (elements[9] == ELEMENT_ONETWODIGITS) then -- ''May 3, 2013, 10:38'
                                        if (numberOfElements == 9) then return checkAndOutput(values[5], values[1], values[3], values[7], values[9], nil) end
                                        if (elements[10] == ELEMENT_TIMEPERIOD) then -- ''May 3, 2013, 10:38 am'
                                            if (numberOfElements == 10) then return checkAndOutput(values[5], values[1], values[3], values[7] + periodHourAdd(values[10]), values[9], nil) end
                                        elseif (elements[10] == ELEMENT_TIMESEPARATOR) then -- ''May 3, 2013, 10:38:'
                                            if (elements[11] == ELEMENT_ONETWODIGITS) then -- ''May 3, 2013, 10:38:27'
                                                if (numberOfElements == 11) then return checkAndOutput(values[5], values[1], values[3], values[7], values[9], values[11]) end
                                                if (elements[12] == ELEMENT_TIMEPERIOD) then -- ''May 3, 2013, 10:38:27 am'
                                                    if (numberOfElements == 12) then return checkAndOutput(values[5], values[1], values[3], values[7] + periodHourAdd(values[12]), values[9], values[11]) end
                                                end
                                            end
                                        end
                                    end
                                end
                            end
                        elseif (elements[6] == ELEMENT_DASH or elements[6] == ELEMENT_DATESEPARATOR) then -- 'May 3, 2013 - '
                            if (elements[7] == ELEMENT_MONTHWORD) then -- 'May 3, 2013 - February'
                                if (elements[8] == ELEMENT_WHITESPACE) then -- 'May 3, 2013 - February '
                                    if (elements[9] == ELEMENT_ONETWODIGITS) then -- 'May 3, 2013 - February 12'
                                        if (elements[10] == ELEMENT_COMMA or elements[10] == ELEMENT_WHITESPACE) then -- 'May 3, 2013 - February 12, '
                                            if (elements[11] == ELEMENT_FOURDIGITS) then -- 'May 3, 2013 - February 12, 2014'
                                                if (numberOfElements == 11) then return checkAndOutput(values[5], values[1], values[3], nil, nil, nil, values[11], values[7], values[9], nil, nil, nil) end
                                            end
                                        end
                                    end
                                end
                            end
                        end
                    end
                elseif (elements[4] == ELEMENT_DASH or elements[4] == ELEMENT_DATESEPARATOR) then -- 'May 3 - '
                    if (elements[5] == ELEMENT_MONTHWORD) then -- 'May 3 - June'
                        if (elements[6] == ELEMENT_WHITESPACE) then -- 'May 3 - June '
                            if (elements[7] == ELEMENT_ONETWODIGITS) then -- 'May 3 - June 12'
                                if (numberOfElements == 7) then return checkAndOutput(nil, values[1], values[3], nil, nil, nil, nil, values[5], values[7], nil, nil, nil) end
                                if (elements[8] == ELEMENT_COMMA or elements[8] == ELEMENT_WHITESPACE) then -- 'May 3 - June 12, '
                                    if (elements[9] == ELEMENT_FOURDIGITS) then -- 'May 3 - June 12, 2014'
                                        if (numberOfElements == 9) then return checkAndOutput(values[9], values[1], values[3], nil, nil, nil, values[9], values[5], values[7], nil, nil, nil) end
                                    end
                                end
                            end
                        end
                    elseif (elements[5] == ELEMENT_ONETWODIGITS) then -- 'May 3 - 12'
                        if (numberOfElements == 5) then return checkAndOutput(nil, values[1], values[3], nil, nil, nil, nil, values[1], values[5], nil, nil, nil) end
                        if (elements[6] == ELEMENT_COMMA or elements[6] == ELEMENT_WHITESPACE) then -- 'May 3 - 12, '
                            if (elements[7] == ELEMENT_FOURDIGITS) then -- 'May 3 - 12, 2013'
                                if (numberOfElements == 7) then return checkAndOutput(values[7], values[1], values[3], nil, nil, nil, values[7], values[1], values[5], nil, nil, nil) end
                            end
                        end
                    end
                end
            elseif (elements[3] == ELEMENT_FOURDIGITS) then -- 'May 2013'
                if (numberOfElements == 3) then return checkAndOutput(values[3], values[1], nil, nil, nil, nil) end
                if (elements[4] == ELEMENT_DASH or elements[4] == ELEMENT_DATESEPARATOR) then -- 'May 2013 -'
                    if (elements[5] == ELEMENT_MONTHWORD) then -- 'May 2013 - June'
                        if (elements[6] == ELEMENT_WHITESPACE) then -- 'May 2013 - June '
                            if (elements[7] == ELEMENT_FOURDIGITS) then -- 'May 2013 - June 2013'
                                if (numberOfElements == 7) then return checkAndOutput(values[3], values[1], nil, nil, nil, nil, values[7], values[5], nil, nil, nil, nil) end
                            end
                        end
                    end
                end
            end
        elseif (elements[2] == ELEMENT_DASH or elements[2] == ELEMENT_DATESEPARATOR) then -- 'May - '
            if (elements[3] == ELEMENT_MONTHWORD) then -- 'May - June'
                if (elements[4] == ELEMENT_WHITESPACE) then -- 'May - June '
                    if (elements[5] == ELEMENT_FOURDIGITS) then -- 'May - June 2013'
                        if (numberOfElements == 5) then return checkAndOutput(values[5], values[1], nil, nil, nil, nil, values[5], values[3], nil, nil, nil, nil) end
                    end
                end
            end
        end

    else
        return PARSERESULT_UNRECOGNIZED -- the combination of elements was not a recognized one
    end

end

-- This function will return a raw string for generic checks and unit test, including defined parse errors
function main.parseDateOutputRaw(frame)

    local result, startDate, startTime, endDate, endTime = parseDateString(frame.args[1])

    if (result == PARSERESULT_FAIL) then if (frame.args[2] == 'pretty') then return frame:preprocess('\'\'{{gray|Failed parse}}\'\'') else return 'Failed parse' end end
    if (result == PARSERESULT_UNRECOGNIZED) then if (frame.args[2] == 'pretty') then return frame:preprocess('\'\'{{gray|Unrecognized pattern}}\'\'') else return 'Unrecognized pattern' end end
    if (result == PARSERESULT_INVALID) then if (frame.args[2] == 'pretty') then return frame:preprocess('\'\'{{maroon|Invalid date/time}}\'\'') else return 'Invalid date/time' end end
    if (result == PARSERESULT_INVALIDRANGE) then if (frame.args[2] == 'pretty') then return frame:preprocess('\'\'{{maroon|Invalid date range}}\'\'') else return 'Invalid date range' end end
    if (result == PARSERESULT_INCOMPLETE) then if (frame.args[2] == 'pretty') then return frame:preprocess('\'\'{{cyan|Incomplete date}}\'\'') else return 'Incomplete date' end end
    if (result == PARSERESULT_INCOMPLETERANGE) then if (frame.args[2] == 'pretty') then return frame:preprocess('\'\'{{cyan|Incomplete date range}}\'\'') else return 'Incomplete date range' end end

    local s
    
    if (startDate) then s = startDate end
    if (startTime) then if (startDate) then s = s .. ' ' .. startTime else s = startTime end end
    if (endDate) then s = s .. '; ' .. endDate end -- currently end date implies start date
    -- currently no end time

    return s

end

function main.emitMetadata(frame)

    -- First parse the date and see if we get a valid output date
    local result, startDate, startTime, endDate, endTime = parseDateString(frame.args[1])
    
    if (not frame.args.noErrorCats or frame.args.noErrorCats ~= 'yes') then
        --if (result == PARSERESULT_FAIL) then return frame:preprocess('<includeonly>[[Category:]]</includeonly>') end
        --if (result == PARSERESULT_UNRECOGNIZED) then return frame:preprocess('<includeonly>[[Category:]]</includeonly>') end
        --if (result == PARSERESULT_INVALID) then return frame:preprocess('<includeonly>[[Category:]]</includeonly>') end
        --if (result == PARSERESULT_INVALIDRANGE) then return frame:preprocess('<includeonly>[[Category:]]</includeonly>') end
        --if (result == PARSERESULT_INCOMPLETE) then return frame:preprocess('<includeonly>[[Category:]]</includeonly>') end
        if (result == PARSERESULT_INCOMPLETERANGE) then return frame:preprocess('<includeonly>[[Category:Articles with incomplete date ranges for automatic metadata]]</includeonly>') end
    end

    -- We are only doing the rest for a valid date
    if (result ~= PARSERESULT_OKAY) then return nil end

    local dtstartSpan, dtendSpan
    
    -- If we have a start value and we're told to output it
    if ((startDate or startTime) and frame.args.dtstart and frame.args.dtstart == 'yes') then 
        if (startDate and startTime) then dtstartSpan = '<span class="dtstart">' .. startDate .. 'T' .. startTime .. '</span>'
        elseif (startDate) then dtstartSpan = '<span class="dtstart">' .. startDate .. '</span>'
        else dtstartSpan = '<span class="dtstart">' .. startTime .. '</span>' end
    end

    -- If we have an end value and we're told to output it
    if ((endDate or endTime) and frame.args.dtend and frame.args.dtend == 'yes') then -- end values only happen when start values happen
        if (endDate and endTime) then dtendSpan = '<span class="dtend">' .. endDate .. 'T' .. endTime .. '</span>'
        elseif (endDate) then dtendSpan = '<span class="dtend">' .. endDate .. '</span>'
        else dtendSpan = '<span class="dtend">' .. endTime .. '</span>' end
    end

    local trackingCat = ''
    if (frame.args.trackingCat and frame.args.trackingCat == 'yes') then
        trackingCat = '[[Category:Articles with automatically detected infobox date metadata]]'
    end

    if (dtstartSpan and dtendSpan) then return '<span style="display:none">&#160;(' .. dtstartSpan .. dtendSpan .. ')</span>' .. trackingCat
    elseif (dtstartSpan) then return '<span style="display:none">&#160;(' .. dtstartSpan .. ')</span>' .. trackingCat
    elseif (dtendSpan) then return '<span style="display:none">&#160;(' .. dtendSpan .. ')</span>' .. trackingCat
    else return nil end

end

return main