--- **AceLocale-3.0** manages localization in addons, allowing for multiple locale to be registered with fallback to the base locale for untranslated strings.
-- @class file
-- @name AceLocale-3.0
-- @release $Id: AceLocale-3.0.lua 895 2009-12-06 16:28:55Z nevcairiel $
local MAJOR,MINOR = "AceLocale-3.0", 2

local AceLocale, oldminor = LibStub:NewLibrary(MAJOR, MINOR)

if not AceLocale then return end -- no upgrade needed

-- Lua APIs
local assert, tostring, error = assert, tostring, error
local setmetatable, rawset, rawget = setmetatable, rawset, rawget

-- Global vars/functions that we don't upvalue since they might get hooked, or upgraded
-- List them here for Mikk's FindGlobals script
-- GLOBALS: GAME_LOCALE, geterrorhandler

local gameLocale = GetLocale()
if gameLocale == "enGB" then
	gameLocale = "enUS"
end

AceLocale.apps = AceLocale.apps or {}          -- array of ["AppName"]=localetableref
AceLocale.appnames = AceLocale.appnames or {}  -- array of [localetableref]="AppName"

-- This metatable is used on all tables returned from GetLocale
local readmeta = {
	__index = function(self, key) -- requesting totally unknown entries: fire off a nonbreaking error and return key
		rawset(self, key, key)      -- only need to see the warning once, really
		geterrorhandler()(MAJOR..": "..tostring(AceLocale.appnames[self])..": Missing entry for '"..tostring(key).."'")
		return key
	end
}

-- This metatable is used on all tables returned from GetLocale if the silent flag is true, it does not issue a warning on unknown keys
local readmetasilent = {
	__index = function(self, key) -- requesting totally unknown entries: return key
		rawset(self, key, key)      -- only need to invoke this function once
		return key
	end
}

-- Remember the locale table being registered right now (it gets set by :NewLocale())
-- NOTE: Do never try to register 2 locale tables at once and mix their definition.
local registering

-- local assert false function
local assertfalse = function() assert(false) end

-- This metatable proxy is used when registering nondefault locales
local writeproxy = setmetatable({}, {
	__newindex = function(self, key, value)
		rawset(registering, key, value == true and key or value) -- assigning values: replace 'true' with key string
	end,
	__index = assertfalse
})

-- This metatable proxy is used when registering the default locale. 
-- It refuses to overwrite existing values
-- Reason 1: Allows loading locales in any order
-- Reason 2: If 2 modules have the same string, but only the first one to be 
--           loaded has a translation for the current locale, the translation
--           doesn't get overwritten.
--
local writedefaultproxy = setmetatable({}, {
	__newindex = function(self, key, value)
		if not rawget(registering, key) then
			rawset(registering, key, value == true and key or value)
		end
	end,
	__index = assertfalse
})

--- Register a new locale (or extend an existing one) for the specified application.
-- :NewLocale will return a table you can fill your locale into, or nil if the locale isn't needed for the players
-- game locale.
-- @paramsig application, locale[, isDefault[, silent]]
-- @param application Unique name of addon / module
-- @param locale Name of the locale to register, e.g. "enUS", "deDE", etc.
-- @param isDefault If this is the default locale being registered (your addon is written in this language, generally enUS)
-- @param silent If true, the locale will not issue warnings for missing keys. Can only be set on the default locale.
-- @usage
-- -- enUS.lua
-- local L = LibStub("AceLocale-3.0"):NewLocale("TestLocale", "enUS", true)
-- L["string1"] = true
--
-- -- deDE.lua
-- local L = LibStub("AceLocale-3.0"):NewLocale("TestLocale", "deDE")
-- if not L then return end
-- L["string1"] = "Zeichenkette1"
-- @return Locale Table to add localizations to, or nil if the current locale is not required.
function AceLocale:NewLocale(application, locale, isDefault, silent)
	
	if silent and not isDefault then
		error("Usage: NewLocale(application, locale[, isDefault[, silent]]): 'silent' can only be specified for the default locale", 2)
	end
	
	-- GAME_LOCALE allows translators to test translations of addons without having that wow client installed
	-- Ammo: I still think this is a bad idea, for instance an addon that checks for some ingame string will fail, just because some other addon
	-- gives the user the illusion that they can run in a different locale? Ditch this whole thing or allow a setting per 'application'. I'm of the
	-- opinion to remove this.
	local gameLocale = GAME_LOCALE or gameLocale

	if locale ~= gameLocale and not isDefault then
		return -- nop, we don't need these translations
	end
	
	local app = AceLocale.apps[application]
	
	if not app then
		app = setmetatable({}, silent and readmetasilent or readmeta)
		AceLocale.apps[application] = app
		AceLocale.appnames[app] = application
	end

	registering = app -- remember globally for writeproxy and writedefaultproxy
	
	if isDefault then
		return writedefaultproxy
	end

	return writeproxy
end

--- Returns localizations for the current locale (or default locale if translations are missing).
-- Errors if nothing is registered (spank developer, not just a missing translation)
-- @param application Unique name of addon / module
-- @param silent If true, the locale is optional, silently return nil if it's not found (defaults to false, optional)
-- @return The locale table for the current language.
function AceLocale:GetLocale(application, silent)
	if not silent and not AceLocale.apps[application] then
		error("Usage: GetLocale(application[, silent]): 'application' - No locales registered for '"..tostring(application).."'", 2)
	end
	return AceLocale.apps[application]
end
