local p = {}

local TwitterSnowflake = require('Module:TwitterSnowflake')

local CiteWeb = require('Module:Cite web')[''



local err_msgs_t = {															-- a sequence of snowflake date error messages; all must be terminated with a semicolon (;)

	' <kbd>&#124;date=</kbd> / <kbd>&#124;number=</kbd> mismatch;',				-- [1]

	' <kbd>&#124;date=</kbd> required;',										-- [2]

	' Invalid <kbd>&#124;number=</kbd>;',										-- [3]

	' Missing or empty <kbd>&#124;number=</kbd>;',								-- [4]

	' Missing or empty <kbd>&#124;user=</kbd>;'									-- [5]

	}





--[[--------------------------< M A I N >----------------------------------------------------------------------

]]



p.main = function(frame)

	return p''](frame)

end





--[[--------------------------< S U P P R E S S _ U R L _ I N _ T I T L E >------------------------------------



This function searches for and suppresses urls in |title=, |script-title=, and |trans-title= parameters so that

{{cite web}} won't emit 'External link in |title=' error messages when rendered In the redering, urls are correctly

formed as they were in the original tweet.  The function looks for valid schemes and then wraps them in

<nowiki>..</nowiki> tags.



]]



local function suppress_url_in_title (frame, title)

	local schemes = {															-- schemes commonly found in tweets

		'https://',

		'http://',

		'ftp://',

		}



	if title then																-- when there is a title, suppress any urls with known schemes; abandon else

		for _, scheme in ipairs (schemes) do									-- spin through the list of schemes looking for a match

			title = title:gsub (scheme, frame:callParserFunction ('#tag', {'nowiki', scheme}));	-- replace the scheme with its nowiki'd form (a strip marker)

		end

	end



	return title;																-- done; return <title> modified or not

end





--[[--------------------------< D A T E _ N U M B E R _ U R L _ G E T >----------------------------------------



extract |date= and |number= parameter values if present.  Extract date from |number= and compare to |date=.



contruct |url= for {{cite web}} from the base url and |number= and |user=



returns nothing; adds date, number, url to <cite_args_t>; adds error message(s) to <errors_t>.



]]



local function date_number_url_get (args_t, cite_args_t, errors_t)

	local err_msg_index;



	cite_args_t.url = 'https://twitter.com/';									-- initialize with minimal base url because {{cite web}} requires |url=

	if not args_t.user then

		table.insert (errors_t, err_msgs_t5]);									-- error: missing or empty |user=

	end



	if not args_t.date and not args_t.number then

		err_msg_index = 4;														-- error: missing or empty |number=

	elseif tonumber (args_t.number) then										-- |number= without |date=? use number

			cite_args_t.date = TwitterSnowflake.snowflakeToDate ({ args = {id_str = args_t.number} });	-- sets cite_args_t.date post-date or to 'November 4, 2010' when tweet posted before that date

			cite_args_t.number = args_t.number;



			if args_t.user then													-- |number= appears to have a valid value; if |user= has a value

				cite_args_t.url = cite_args_t.url .. args_t.user .. '/status/' .. args_t.number;	-- construct |url= for {{cite web}}

			end

	elseif args_t.number then													-- |number= with a value that can't be converted to a number; invalid

		err_msg_index = 3;														-- error: invalid number (couldn't convert to number)

	elseif not args_t.number then												-- |date= without |number= use date

		cite_args_t.date = args_t.date;											-- |date= has a value, use it

		err_msg_index = 4;														-- error: missing or empty |number=

	end



	if err_msg_index then

		table.insert (errors_t, err_msgs_terr_msg_index]);						-- invalid number or missing necessary parameters so abandon

		return;

	end



	err_msg_index = TwitterSnowflake.datecheck ({ args = {						-- returns error message index number on error; nil else

		id_str	= args_t.number or '',

		date	= args_t.date or '',

		error1	= 1,															-- these numbers are indexes into <err_msgs_t> to override snowflake default error messages

		error2  = 2,															-- done this way to avoid long string comparison looking for

		error3	= 3																-- the undated-pre-twitter-epoch-post message

		}});



	if	2 == err_msg_index then													-- when no date and posted before twitter epoch

		cite_args_t.date = nil;													-- suppress default date because {{cite tweet}} should not claim in its own voice that the undated post was posted 2010-11-04

	end

	

	table.insert (errors_t, err_msgs_terr_msg_index]);							-- add error message

end





--[[--------------------------< p[''] >------------------------------------------------------------------------



construct parameter set for {{cite web}} from {{cite tweet}} parameters;  do some error checking



]]



p'' = function(frame)

	local args_t = require ('Module:Arguments').getArgs (frame);



	local cite_args_t = {

		title = suppress_url_in_title (frame, args_t.title),

		'script-title' = suppress_url_in_title (frame, args_t'script-title']),

		'trans-title' = suppress_url_in_title (frame, args_t'trans-title']),

		language = args_t.language,

		last1 = args_t.last1 or args_t.last,

		first1 = args_t.first1 or args_t.first,

		author1 = args_t.author1 or args_t.author,

		'author-link' = args_t'author-link' or args_t.authorlink,

		others = args_t.retweet and ('Retweeted by ' .. args_t.retweet),

		via = args_t.link == 'no' and 'Twitter' or '[[Twitter]]',

		type = args_t.link == 'no' and 'Tweet' or '[[Tweet (social media)|Tweet]]',

		location = args_t.location,												-- why |location=?  tweets are online; there is no publication place

		'access-date' = args_t'access-date' or args_t.accessdate,

		'archive-date' = args_t'archive-date' or args_t.archivedate,

		'archive-url' = args_t'archive-url' or args_t.archiveurl,

		'url-status' = args_t'url-status'],

		quote = args_t.quote,

		ref = args_t.ref,

		df = args_t.df,

		mode = args_t.mode

		}



	local errors_t = {'<span class="cs1-visible-error citation-comment"> <kbd>{{[[Template:Cite tweet|Cite tweet]]}}</kbd>:'};		-- initialize sequence of error messages with style tag

	date_number_url_get (args_t, cite_args_t, errors_t);						-- add |date=, |number=, |url= to <cite_args_t>



	local author = ((cite_args_t.last1 and cite_args_t.first1) and cite_args_t.last1 .. ', ' .. cite_args_t.first1) or	-- concatenate |last= with |first= for |author-mask=

		(cite_args_t.last1 and cite_args_t.last1) or							-- only |last= for |author-mask=

		(cite_args_t.author1 and cite_args_t.author1:gsub('^%(%((.+)%)%)$', '%1'));	-- |author= or |author1= stripped of accept-as-written markup for |author-mask=



	if author and args_t.user then

		cite_args_t'author-mask' = author .. ' [@' .. (args_t.user or '') .. ']'	-- concatenate <author> and |user= into |author-mask=

	elseif args_t.user then

		cite_args_t.author1 = '((' .. args_t.user .. '))';						-- just the user name for cs1|2 metadata

		cite_args_t'author-mask' = '@' .. args_t.user;						-- make a mask for display

	else																		-- here when neither <author> nor |user=

		cite_args_t.author1 = nil;												-- so unset

	end



	frame.args = cite_args_t;													-- overwrite frame arguments

	local rendering = CiteWeb (frame);											-- render the template



---------- error messaging ----------

	if errors_t2 then															-- errors_t[2] nil when no errors

		if rendering:find ('cs1-visible-error', 1, true) then					-- rendered {{cite web}} with errors will have this string

			errors_t1 = errors_t1]:gsub ('> <', '>; <');						-- insert semicolon to terminate cs1|2 error message string

		end



		errors_t#errors_t = errors_t#errors_t]:gsub (';$',' ([[Template:Cite_tweet#Error_detection|help]])');	-- replace trailing semicolon with help link

		table.insert (errors_t, '</span>');										-- close style span tag

		if mw.title.getCurrentTitle():inNamespace (0) then						-- mainspace only

			table.insert (errors_t, '[[Category:Cite tweet templates with errors]]');	-- add error category

		end



		rendering = rendering .. table.concat (errors_t);						-- append error messaging, help links and catagories

	end

	return rendering;

end



return p