Module:Find sources

Documentation for this module may be created at Module:Find sources/doc

-- This module implements {{find sources}} and other similar templates, and also
-- provides a mechanism to easily create new source-finding templates.
--
-- Template settings are found in subpages of [[Module:Find sources/templates]].
-- Link functions are defined in subpages of [[Module:Find sources/links]].
-- Functions shared between the link modules are stored at
-- [[Module:Find sources/shared]].

local ROOT_PAGE = 'Module:Find sources'
local TEMPLATE_ROOT = ROOT_PAGE .. '/templates/'
local LINK_ROOT = ROOT_PAGE .. '/links/'
local DEFAULT_SEPARATOR = ', '

local checkType = require('libraryUtils').checkType

local p = {}

local function maybeLoadData(page)
	local success, data = pcall(mw.loadData, page)
	if success then
		return data
	else
		return nil
	end
end

local function substituteParams(msg, ...)
	local params = {...}
	if params[1] then
		return mw.message.newRawMessage(msg):params(params):plain()
	else
		return msg
	end
end

local function renderLink(code, searchStrings, display)
	-- Get link config.
	local linkCfg = maybeLoadData(LINK_ROOT .. code)
	if not linkCfg then
		error(string.format(
			"invalid link code '%s'; no link config found at [[%s]]",
			code,
			LINK_ROOT .. code
		))
	end

	-- Make URL.
	local url
	do
		local firstFormat = linkCfg.firstFormat or '"$1"'
		searchStrings[1] = substituteParams(firstFormat, searchStrings[1])
		local separator = linkCfg.separator or "+"
		local searchString = table.concat(searchStrings, separator)
		url = linkCfg.url or error(string.format(
			"no 'url' field found in the link config at [[%s]]",
			LINK_ROOT .. code
		))
		url = substituteParams(url, searchString)
	end
	
	-- Fetch display.
	display = display or linkCfg.display or error(string.format(
		"no 'display' field found in the link config at [[%s]]",
		LINK_ROOT .. code
	))

	return string.format('[%s %s]', url, display)
end

local function checkTemplateCfgLinkTable(cfgPage, key, t)
	if type(t) ~= 'table' then
		error(string.format(
			"invalid link table found in key '%s' of template config at [[%s]] " ..
				"(expected type table, got type %s)",
			key, cfgPage, type(t)
		))
	elseif type(t[1]) ~= 'string' then
		error(string.format(
			"invalid link table found in key '%s' of template config at [[%s]] " ..
				"(the first table value must be a string)",
			key, cfgPage
		))
	elseif t[2] and type(t[2]) ~= 'string' then
		error(string.format(
			"invalid link table found in key '%s' of template config at [[%s]] " ..
				"(if the second table value is specified, it must be a string)",
			key, cfgPage
		))
	end
end

function p._main(template, args)
	checkType('_main', 1, template, 'string')
	checkType('_main', 2, args, 'table', true)
	args = args or {}
	local title = mw.title.getCurrentTitle()
	
	-- Get the template config.
	local templateCfgPage = TEMPLATE_ROOT .. template
	local templateCfg = maybeLoadData(templateCfgPage)
	if not templateCfg then
		error(string.format(
			"invalid template name '%s'; no template config found at [[%s]]",
			template, templateCfgPage
		))
	end

	-- Template config sanity check.
	if templateCfg.introLink then
		checkTemplateCfgLinkTable(templateCfgPage, 'introLink', templateCfg.introLink)
	end
	if type(templateCfg.links) ~= 'table' then
		error(string.format(
			"type error in the 'links' field of the template config at [[%s]] " ..
				"(expected table, got %s)",
			templateCfgPage, type(templateCfg.links)
		))
	end
	for _, t in ipairs(templateCfg.links) do
		checkTemplateCfgLinkTable(templateCfgPage, 'links', t)
	end

	-- Get the search strings from the arguments.
	local searchStrings = {}
	for i, s in ipairs(args) do
		searchStrings[i] = mw.uri.encode(s)
	end
	searchStrings[1] = searchStrings[1] or title.subpageText
	
	-- Make the intro link
	local introLink
	if templateCfg.introLink then
		local code = templateCfg.introLink[1]
		local display = templateCfg.introLink[2]
		introLink = renderLink(code, searchStrings, display)
	else
		introLink = ''
	end

	-- Make the other links
	local links = {}
	for i, t in ipairs(templateCfg.links) do
		local code = t[1]
		local display = t[2]
		links[i] = renderLink(code, searchStrings, display)
	end
	links = table.concat(links, templateCfg.separator or DEFAULT_SEPARATOR)
end

setmetatable(p, { __index = function(t, template)
	return function(frame)
		local args = require('Module:Arguments').getArgs(frame, {
			wrappers = mw.site.namespaces[10].name .. ':' .. template
		})
		return t._main(template, args)
	end
end})

return p