Module:Football manager history

 -- Implement [[Template:Football manager history]] to avoid articles being
 -- added to [[:Category:Pages where template include size is exceeded]]
 -- when the template is used many times.

 local function clean(text, default)
	-- Return text, if not empty, after trimming leading/trailing whitespace.
	-- Otherwise return default which is nil unless set by caller.
	if text then
		text = text:match("^%s*(.-)%s*$")
		if text ~= '' then
			return text
		end
	end
	return default
 end

 local function yes(parameter)
	-- Return true if parameter should be interpreted as "yes".
	-- Do not want to accept mixed upper/lowercase.
	return ({ Y = true, y = true, yes = true, T = true, ['true'] = true })[parameter]
 end

 local function collection()
	-- Return a table to hold items.
	return {
		n = 0,
		add = function (self, item)
			self.n = self.n + 1
			self[self.n] = item
		end,
		addif = function (self, item, fmt)
			if item then
				self.n = self.n + 1
				self[self.n] = fmt and string.gsub(fmt, '%%s', item) or item
			end
		end,
		join = function (self, sep)
			return table.concat(self, sep)
		end,
	}
 end

 local function message(msg, caller, nocat)
	-- Return formatted message text for an error.
	-- Can append "#FormattingError" to URL of a page with a problem to find it.
	-- If given, caller is the title of the navbox which has the error.
	local anchor = '<span id="FormattingError"></span>'
	local category
	if not nocat and mw.title.getCurrentTitle():inNamespaces(0, 10) then
		-- Category only in namespaces: 0=article, 10=template.
		category = '[[Category:Football template errors]]'
	else
		category = ''
	end
	return anchor ..
		'<strong class="error">Error: ' ..
		msg ..
		(caller and (' at [[Template:' .. caller .. ']]') or '') ..
		'</strong>' ..
		category .. '\n'
 end

 local function make_entry(name, from, to, islast)
	local result =
		'*<span class="vevent">' ..
		'<span class="agent attendee vcard">' ..
		'<span class="fn org summary">' ..
		name ..
		'</span></span>&nbsp;(<span class="dtstart">' ..
		from ..
		'</span>'
	if to then
		result = result .. '–' .. to
	elseif islast then
		result = result .. '–'
	end
	result = result .. ')</span>'
	return result
 end

 local function make_list(text, note, dissolved)
	-- Return a list of formatted items.
	-- Input is a string of multiple lines, one item per line.
	-- Each item is 'NAME FROM to TO' or 'NAME FROM', where
	-- NAME = manager name (any text)
	-- FROM = four digits (from year)
	-- TO = 1, 2, 3 or 4 digits (to year), or empty
	-- Alternatively, an item can use syntax (TEXT is any text, possibly empty):
	-- NAME from=TEXT
	-- NAME from=TEXT to=TEXT
	-- The code detects the end of NAME from the start of FROM.
	-- A dash is added to the last line (to show the manager is continuing) if
	-- no 'to' year is given, but no dash is added if the club is dissolved.
	text = text or ''
	if text:find('<span class=', 1, true) then
		-- To allow a transition period where some navboxes use the old syntax, the
		-- given text is used if it appears to have come from the old subtemplates.
		return text
	end
	-- Get the non-blank lines first so can tell when am processing the last line.
	-- Each line is left- and right-trimmed.
	local lines = collection()
	for line in string.gmatch(text .. '\n', '[\t ]*(.-)[\t\r ]*\n') do
		if line ~= '' then
			lines:add(line)
		end
	end
	if lines.n <= 0 then
		return ''
	end
	local ilast = dissolved and -1 or lines.n
	local entries = collection()
	entries:add('<div>')
	for i, line in ipairs(lines) do
		-- Need to detect lines like "Name from=1930 & 1935" (probably should
		-- not be like that, but that is not up to the template to enforce).
		local name, from, to = line:match('^([^=]-)%s+(%d%d%d%d)%s+to%s+(%d%d?%d?%d?)$')
		if not name then
			name, from = line:match('^([^=]-)%s+(%d%d%d%d)$')
			if not name then
				name, from, to = line:match('^(.-) from=(.-) to=(.*)')
				if not name then
					name, from = line:match('^(.-) from=(.*)')
				end
			end
		end
		name = clean(name)
		from = clean(from, '')
		to = clean(to)
		if ((name or '=') .. (from or '=') .. (to or '')):find('=', 1, true) then
			-- name and from must be defined (from can be ''); to is optional.
			-- Reject '=' to avoid typos in items like 'to=x' or 'from=xto=y'
			-- from being displayed.
			error('Invalid line "' .. mw.text.nowiki(line) .. '"', 0)
		end
		entries:add(make_entry(name, from, to, i == ilast))
	end
	entries:add('</div>')
	entries:addif(note)
	return entries:join('\n')
 end

 local function arg_style(bgcolor, textcolor, bordercolor)
	local result = collection()
	result:addif(clean(bgcolor), 'background:%s;')
	result:addif(clean(textcolor), 'color:%s;')
	result:addif(clean(bordercolor), 
		'box-shadow: inset 1px 1px 0 %s,' ..
		'inset -1px -1px 0 %s;')
	result:add('width: 87%;')
	return result:join(' ')
 end

 local function arg_title(title, teamname, managerlist, textcolor, american_english)
	title = clean(title)
	teamname = clean(teamname, 'MISSING "teamname"')
	managerlist = clean(managerlist)
	textcolor = clean(textcolor)
	american_english = clean(american_english)
	local spancolor = textcolor and ('<span style="color:' .. textcolor .. ';">') or '<span>'
	local mgr = spancolor .. (american_english and 'head coaches' or 'managers') .. '</span>'
	return
		'<span class="fn org">[[' .. teamname .. '|' ..
		spancolor ..
		(title or teamname) .. '</span>]]</span> – ' ..
		(managerlist and ('[[' .. managerlist .. '|' .. mgr .. ']]') or mgr)
 end

 local function _main(args)
	-- Return wikitext for a navbox.
	-- Code does not do much checking of inputs but will throw an error
	-- if input is found to be invalid.
	local style = arg_style(args.bgcolor, args.textcolor, args.bordercolor)
	local dissolved = args.dissolved
	if dissolved then
		-- May be a number of two or more digits (year club was dissolved; compatible
		-- with {{Infobox football club}}), or an alias for 'yes'.
		dissolved = dissolved:match('^%d%d+$') and true or yes(args.dissolved)
	end
	local navargs = {
		bodyclass = 'vcard',
		name = clean(args.name),
		state = clean(args.state, 'autocollapse'),
		titlestyle = style,
		title = arg_title(args.title, args.teamname, args.managerlist, args.textcolor, args.american_english),
		listclass = 'hlist',
		nowrapitems = 'yes',
		list1 = make_list(args.list, clean(args.note), dissolved),
		belowstyle = style,
		below = clean(args.below),
	}
	local navbox = require('Module:Navbox')._navbox
	return navbox(navargs)
 end

 local function main(frame)
	-- Return wikitext for a navbox or an error message.
	local args = frame:getParent().args
	-- Read arguments in order of output (Module:Navbox says this puts
	-- reference numbers in the right order).
	local _
	_ = args.title
	_ = args.list
	_ = args.below
	if not args.teamname then
		args = frame.args
		_ = args.title
		_ = args.list
		_ = args.below
	end
	local success, result = pcall(_main, args)
	if success then
		return result
	end
	return message(result, clean(args.name), clean(args.nocat))
 end

 return { main = main, _main = _main }