--[[

--------------------------------------------------------------------------------

--                                                                            --

--                            NAMESPACE DETECT                                --

--                                                                            --

-- This module implements the {{namespace detect}} template in Lua, with a    --

-- few improvements: all namespaces and all namespace aliases are supported,  --

-- and namespace names are detected automatically for the local wiki. The     --

-- module can also use the corresponding subject namespace value if it is     --

-- used on a talk page. Parameter names can be configured for different wikis --

-- by altering the values in the "cfg" table in                               --

-- Module:Namespace detect/config.                                            --

--                                                                            --

--------------------------------------------------------------------------------

--]]



local data = mw.loadData('Module:Namespace detect/data')

local argKeys = data.argKeys

local cfg = data.cfg

local mappings = data.mappings



local yesno = require('Module:Yesno')

local mArguments -- Lazily initialise Module:Arguments

local mTableTools -- Lazily initilalise Module:TableTools

local ustringLower = mw.ustring.lower



local p = {}



local function fetchValue(t1, t2)

	-- Fetches a value from the table t1 for the first key in array t2 where

	-- a non-nil value of t1 exists.

	for i, key in ipairs(t2) do

		local value = t1key

		if value ~= nil then

			return value

		end

	end

	return nil

end



local function equalsArrayValue(t, value)

	-- Returns true if value equals a value in the array t. Otherwise

	-- returns false.

	for i, arrayValue in ipairs(t) do

		if value == arrayValue then

			return true

		end

	end

	return false

end



function p.getPageObject(page)

	-- Get the page object, passing the function through pcall in case of

	-- errors, e.g. being over the expensive function count limit.

	if page then

		local success, pageObject = pcall(mw.title.new, page)

		if success then

			return pageObject

		else

			return nil

		end

	else

		return mw.title.getCurrentTitle()

	end

end



-- Provided for backward compatibility with other modules

function p.getParamMappings()

	return mappings

end



local function getNamespace(args)

	-- This function gets the namespace name from the page object.

	local page = fetchValue(args, argKeys.demopage)

	if page == '' then

		page = nil

	end

	local demospace = fetchValue(args, argKeys.demospace)

	if demospace == '' then

		demospace = nil

	end

	local subjectns = fetchValue(args, argKeys.subjectns)

	local ret

	if demospace then

		-- Handle "demospace = main" properly.

		if equalsArrayValue(argKeys.main, ustringLower(demospace)) then

			ret = mw.site.namespaces0].name

		else

			ret = demospace

		end

	else

		local pageObject = p.getPageObject(page)

		if pageObject then

			if pageObject.isTalkPage then

				-- Get the subject namespace if the option is set,

				-- otherwise use "talk".

				if yesno(subjectns) then

					ret = mw.site.namespacespageObject.namespace].subject.name

				else

					ret = 'talk'

				end

			else

				ret = pageObject.nsText

			end

		else

			return nil -- return nil if the page object doesn't exist.

		end

	end

	ret = ret:gsub('_', ' ')

	return ustringLower(ret)

end



function p._main(args)

	-- Check the parameters stored in the mappings table for any matches.

	local namespace = getNamespace(args) or 'other' -- "other" avoids nil table keys

	local params = mappingsnamespace or {}

	local ret = fetchValue(args, params)

	--[[

	-- If there were no matches, return parameters for other namespaces.

	-- This happens if there was no text specified for the namespace that

	-- was detected or if the demospace parameter is not a valid

	-- namespace. Note that the parameter for the detected namespace must be

	-- completely absent for this to happen, not merely blank.

	--]]

	if ret == nil then

		ret = fetchValue(args, argKeys.other)

	end

	return ret

end



function p.main(frame)

	mArguments = require('Module:Arguments')

	local args = mArguments.getArgs(frame, {removeBlanks = false})

	local ret = p._main(args)

	return ret or ''

end



function p.table(frame)

	--[[

	-- Create a wikitable of all subject namespace parameters, for

	-- documentation purposes. The talk parameter is optional, in case it

	-- needs to be excluded in the documentation.

	--]]

	

	-- Load modules and initialise variables.

	mTableTools = require('Module:TableTools')

	local namespaces = mw.site.namespaces

	local cfg = data.cfg

	local useTalk = type(frame) == 'table' 

		and type(frame.args) == 'table' 

		and yesno(frame.args.talk) -- Whether to use the talk parameter.

	

	-- Get the header names.

	local function checkValue(value, default)

		if type(value) == 'string' then

			return value

		else

			return default

		end

	end

	local nsHeader = checkValue(cfg.wikitableNamespaceHeader, 'Namespace')

	local aliasesHeader = checkValue(cfg.wikitableAliasesHeader, 'Aliases')



	-- Put the namespaces in order.

	local mappingsOrdered = {}

	for nsname, params in pairs(mappings) do

		if useTalk or nsname ~= 'talk' then

			local nsid = namespacesnsname].id

			-- Add 1, as the array must start with 1; nsid 0 would be lost otherwise.

			nsid = nsid + 1 

			mappingsOrderednsid = params

		end

	end

	mappingsOrdered = mTableTools.compressSparseArray(mappingsOrdered)



	-- Build the table.

	local ret = '{| class="wikitable"'

		.. '\n|-'

		.. '\n! ' .. nsHeader

		.. '\n! ' .. aliasesHeader

	for i, params in ipairs(mappingsOrdered) do

		for j, param in ipairs(params) do

			if j == 1 then

				ret = ret .. '\n|-'

					.. '\n| <code>' .. param .. '</code>'

					.. '\n| '

			elseif j == 2 then

				ret = ret .. '<code>' .. param .. '</code>'

			else

				ret = ret .. ', <code>' .. param .. '</code>'

			end

		end

	end

	ret = ret .. '\n|-'

		.. '\n|}'

	return ret

end



return p