--------------------------------------------------------------------------------
--                                                                            --
--      This meta-module which automatically detects namespaces, and allows   --
--      for a great deal of customisation. It can easily be ported to other   --
--      wikis by changing the values in the [[Module:Pagetype/config]].       --
--                                                                            --
--------------------------------------------------------------------------------
-- Load config.
local cfg = mw.loadData('Module:Pagetype/config')

-- Load required modules.
local yesno = require('Module:Yesno')
local p = {}

-- Look up a namespace argument in the args table.
local function lookUpNamespaceArg(args, key)
	local arg = args[key]
	-- Convert "yes", "1" etc. to true, "no", "0" etc. to false, and leave
	-- other values the same.
	return yesno(arg, arg)
end

-- Append multiple values to an array
local function appendMultiple(target, source)
	for _, value in ipairs(source) do
		table.insert(target, value)
	end
end

-- Get argument keys for a title's namespace
local function getNamespaceArgKeys(title)
	local nsInfo = mw.site.namespaces[title.namespace]
	local customAliases = cfg.customNamespaceAliases[title.namespace] or {}
	local keys = {}
	if nsInfo.name ~= '' then
		table.insert(keys, nsInfo.name)
	end
	if nsInfo.canonicalName ~= nsInfo.name and nsInfo.canonicalName ~= '' then
		table.insert(keys, nsInfo.canonicalName)
	end
	appendMultiple(keys, nsInfo.aliases)
	appendMultiple(keys, customAliases)
	return keys
end

-- Get the argument for a title's namespace, if it was specified in the args table.
local function getNamespaceArg(title, args)
	if title.isTalkPage then
		return lookUpNamespaceArg(args, cfg.talk)
	end
	for _, key in ipairs(getNamespaceArgKeys(title)) do
		local arg = lookUpNamespaceArg(args, mw.ustring.lower(key))
		if arg ~= nil then
			return arg
		end
	end
	return nil
end

-- Look up a page type specific to the title's namespace
local function getExplicitPageType(title)
	if title.isTalkPage then
		return cfg.talkDefault
	else
		return cfg.pagetypes[title.namespace]
	end
end

-- Get a default page type that is not specific to the title's namespace
local function getDefaultPageType(args)
	local other = lookUpNamespaceArg(args, cfg.other)
	if type(other) == 'string' then
		return other
	else
		return cfg.otherDefault
	end
end

local function detectRedirects(title, args)
	local redirect = lookUpNamespaceArg(args, cfg.redirect)
	if redirect == false then
		-- Don't detect redirects if they have been specifically disallowed.
		return nil
	end

	-- Allow custom values for redirects.
	if not title.isRedirect then
		return nil
	elseif type(redirect) == 'string' then
		return redirect
	else
		return cfg.redirectDefault
	end
end

local function capitalize(pageType)
	local first = mw.ustring.sub(pageType, 1, 1)
	local rest = mw.ustring.sub(pageType, 2)
	return mw.ustring.upper(first) .. rest
end

local function pluralize(pageType)
	if cfg.irregularPlurals[pageType] then
		return cfg.irregularPlurals[pageType]
	else
		return pageType .. cfg.plural -- often 's'
	end
end

local function parseContent(title, args, optionsList)
	if title.namespace==828 and title.subpageText~='doc' -- don't detect modules
		or not title.exists -- can't check unless page exists
	then
		return nil
	end
	local content = title:getContent()
	if content == nil then
		return nil
	end
	local templates -- lazily evaluated
	for _, options in next, optionsList do
		local list, parameter, default, articleOnly = unpack(options, 1, 4)
		if not articleOnly or title.namespace==0 then -- only check for templates if we should...
			local out = lookUpNamespaceArg(args, parameter)
			if type(out) == "string" or (out ~= false and default) then -- ...and if we actually have anything to say about them
				if not templates then
					templates = {} -- do our delayed evaluation now that we are required to
					content = require('Module:Wikitext Parsing').PrepareText(content) -- disregard templates which do not have any affect
					for template in string.gmatch(content, "{{%s*([^|}]-)%s*[|}]") do
						templates[#templates+1] = capitalize(template)
					end
				end
				local wantedTemplates = mw.loadData('Module:Pagetype/' .. list)
				local templateFound = false
				for _, template in next, templates do
					if wantedTemplates[template] then
						templateFound = true
						break
					end
				end
				if templateFound then
					if type(out)=='string' then
						return out
					elseif out ~= false and default then
						return default
					end
				end
			end
		end
	end
end

-- Find pages which do not exist
local function nonExistent(title, args)
	local arg = lookUpNamespaceArg(args, cfg.ne)
	if arg == false then
		return nil
	end
	local exists = false
	if title.exists then -- not an article if it does not exist
		exists = true
	elseif title.namespace==8 and mw.message.new(title.text):exists() then
		exists = true
	elseif title.namespace==6 and title.fileExists then
		exists = true
	end
	if not exists then
		if type(arg) == 'string' then
			return arg
		else
			return cfg.naDefault
		end
	end
end

-- Get page types for mainspaces pages with an explicit class specified
local function getMainNamespaceClassPageType(title, args)
	local class = args[1]
	if type(class) == 'string' then	-- Put in lower case so e.g. "na" and "NA" will both match
		class = mw.ustring.lower(class)
	end
	local arg = lookUpNamespaceArg(args, cfg.na)
	if arg == false then -- don't check for this class if it is specifically disallowed
		return nil
	end
	if cfg.naAliases[class] then
		if type(arg) == 'string' then
			return arg
		else
			return cfg.naDefault
		end
	else
		return nil
	end
end

-- Get page type specified by an explicit namespace argument.
local function getNamespaceArgPageType(title, args)
	local namespaceArg = getNamespaceArg(title, args)
	if namespaceArg == true then
		-- Namespace has been explicitly enabled, so return the default for
		-- this namespace
		return getExplicitPageType(title)
	elseif namespaceArg == false then
		-- Namespace has been explicitly disabled
		return getDefaultPageType(args)
	elseif namespaceArg then
		-- This namespaces uses custom text
		return namespaceArg
	else
		return nil
	end
end


-- Get page type not specified or detected by other means
local function getOtherPageType(title, args)
-- Whether the title is in the set of default active namespaces which are looked up in cfg.pagetypes.
	local isInDefaultActiveNamespace = false
	local defaultNamespacesKey = args[cfg.defaultns]
	if defaultNamespacesKey == cfg.defaultnsAll then
		isInDefaultActiveNamespace = true
	else
		local defaultNamespaces
		if defaultNamespacesKey == cfg.defaultnsExtended then
			defaultNamespaces = cfg.extendedNamespaces
		elseif defaultNamespacesKey == cfg.defaultnsNone then
			defaultNamespaces = {}
		else
			defaultNamespaces = cfg.defaultNamespaces
		end
		isInDefaultActiveNamespace = defaultNamespaces[title.namespace]
	end
	if isInDefaultActiveNamespace then
		return getExplicitPageType(title)
	else
		return getDefaultPageType(args)
	end
end

function p._main(args)
	local title
	if args.page then
		title = mw.title.new(args.page)
	else
		title = mw.title.getCurrentTitle()
	end
	if title and not yesno(args.talk, true) and args[cfg.defaultns] ~= cfg.defaultnsAll then
		title = title.subjectPageTitle
	end
	local pageType = detectRedirects(title, args)
		or nonExistent(title, args)
		or parseContent(title, args, {
			{'softredirect', cfg.softRedirect, cfg.softRedirectDefault},
			{'setindex', cfg.sia, cfg.siaDefault, true},
			{'disambiguation', cfg.dab, cfg.dabDefault, true},
			{'rfd', cfg.rfd, cfg.rfdDefault},
		})
		or (title.namespace == 0 and getMainNamespaceClassPageType(title, args))
		or getNamespaceArgPageType(title, args)
		or getOtherPageType(title, args)
	if yesno(args.plural, false) then
		pageType = pluralize(pageType)
	end
	if yesno(args.caps, false) then
		pageType = capitalize(pageType)
	end
	return pageType
end

function p.main(frame)
	local args = require('Module:Arguments').getArgs(frame)
	return p._main(args)
end

return p