--- **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 1035 2011-07-09 03:20:13Z kaelten $
local MAJOR,MINOR = "AceLocale-3.0", 6

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 getmetatable, setmetatable, rawset, rawget = getmetatable, 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. Must be set on the first locale registered. If set to "raw", nils will be returned for unknown keys (no metatable used).
-- @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)

    -- GAME_LOCALE allows translators to test translations of addons without having that wow client installed
    local gameLocale = GAME_LOCALE or gameLocale

    local app = AceLocale.apps[application]

    if silent and app and getmetatable(app) ~= readmetasilent then
        geterrorhandler()("Usage: NewLocale(application, locale[, isDefault[, silent]]): 'silent' must be specified for the first locale registered")
    end

    if not app then
        if silent=="raw" then
            app = {}
        else
            app = setmetatable({}, silent and readmetasilent or readmeta)
        end
        AceLocale.apps[application] = app
        AceLocale.appnames[app] = application
    end

    if locale ~= gameLocale and not isDefault then
        return -- nop, we don't need these translations
    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
