[Ace] Game Localization - Core Engine

#==============================================================================
# Iavra Game Localization - Core Engine 1.00
# -----------------------------------------------------------------------------
# Description:
# Loads language files for the database and messages modules and manages the
# current language
# -----------------------------------------------------------------------------
# Prerequisites:
# (optional) Iavra Game.ini Access
# -----------------------------------------------------------------------------
# How to Use:
# To get an set the current language, call the follwoing methods:
#
# IAVRA::I18N.language
# IAVRA::I18N.language=
#
# Languages are stored in symbol form, like :en or :de. By default, the script
# stores the current language in its own file. If "Iavra Game.ini Access" is
# present, it will be stored in the Game.ini file, instead.
#
# Language files are basically Ruby hashes and built like this:
#
# {
#   :category =>
#   {
#     # module dependent
#   }
# }
#
# Localized text can be accessed by calling the following method:
#
# IAVRA::I18N[category]
#
# The language of a file is defined by its name and/or directory.
# -----------------------------------------------------------------------------
# Terms of Use:
# Free to use for both commercial and non-commercial games. Please give credit.
# -----------------------------------------------------------------------------
# Credits:
# Iavra
# -----------------------------------------------------------------------------
# Changelog:
# - 1.00: Release version.
#==============================================================================

($imported ||= {})[:iavra_i18n_core] = true

#==============================================================================
# ▼ IAVRA::I18N::CORE
#==============================================================================

module IAVRA
    module I18N
        module CORE

            #========================================================================
            # ■ ■ ■ ■ ■ CONFIGURATION ■ ■ ■ ■ ■
            #========================================================================

            #========================================================================
            # Lists all languages, that should be supported by the script.
            #========================================================================

            LANGUAGES = [:en, :de]

            #========================================================================
            # Defines the path, where language files will be loaded from. %s is
            # replaced by one of the entries of LANGUAGES and the whole string is
            # treated as a file glob.
            #========================================================================

            FILE_PATH = "I18N/%s{_*,}.rb"

            #========================================================================
            # This file is used to store the current language. If "Iavra Game.ini
            # Access" is present, the Game.ini file will be used, instead.
            #========================================================================

            PERSISTENCE = "I18N/current.txt"

            #========================================================================
            # Setting this to true will enable deep merging for loaded files, which
            # allows to split categories over multiple files.
            #========================================================================

            DEEP_MERGE = false

            #========================================================================
            # Setting this to true will cause language files to be loaded inside
            # their own thread, which acts as a sandbox. Since the files are read in
            # using eval, they could interact with the rest of your game if this is
            # set to false.
            #========================================================================

            SANDBOX = false

            #========================================================================
            # ■ ■ ■ ■ ■ CONFIGURATION ■ ■ ■ ■ ■
            #========================================================================

            class << self
                attr_accessor :language
                attr_reader :language_map
            end

            #========================================================================
            # Sandbox'ed eval, which runs inside its own thread with $SAFE = 4. This
            # is as close to a sandbox as i can get.
            #========================================================================

            def self.sandbox_eval(data)
                Thread.new{
                    $SAFE = 4
                    Thread.current[:result] = eval(data)
                }.join[:result]
            end

            #========================================================================
            # Methods for loading and saving the current language
            #========================================================================

            if(($imported ||= {})[:iavra_ini_access])

                def self.load_language
                    value = IAVRA::INI.load("i18n", "Language", "-").to_sym
                    value == :- ? nil : value
                end

                def self.save_language
                    IAVRA::INI.save("i18n", "Language", @language)
                end

            else

                def self.load_language
                    File.file?(PERSISTENCE) ? File.open(PERSISTENCE) {|file| file.read.to_sym} : nil
                end

                def self.save_language
                    File.open(PERSISTENCE, "w") {|file| file.write(@language.to_s)}
                end

            end

            #========================================================================
            # Loads the current language on game starts. Defaults to the first entry
            # in LANGUAGES, if no saved language can be found.
            #========================================================================

            def self.initialize_current_language
                @language = load_language || (flag = LANGUAGES[0])
                @language = nil if !LANGUAGES.include?(@language)
                save_language if flag
            end

            #========================================================================
            # Loads all language files, either directly or inside a sandbox'ed eval.
            # Afterwards, the files are merged to a hash.
            #========================================================================

            def self.initialize_language_map
                @language_map = Hash[LANGUAGES.map{|lang|
                    [lang, Dir[FILE_PATH.gsub("%s", lang.to_s)].map{|name|
                        File.open(name) {|f| d = f.read; (SANDBOX ? sandbox_eval(d) : eval(d)) || {}}
                    }.inject(DEEP_MERGE ? :iavra_i18n_deep_merge : :merge)]
                }]
            end

        end

        #==========================================================================
        # The initialize method is located outside the CORE module to make it
        # easier for the modules to hook themselves into it.
        #==========================================================================

        def self.initialize
            CORE.initialize_current_language
            CORE.initialize_language_map
        end

        #==========================================================================
        # This is called once at game start and whenever the current language is
        # changed and can be used by modules to perform actions.
        #==========================================================================

        def self.update
        end

        #==========================================================================
        # Getter and setter for the current language
        #==========================================================================

        def self.language
            CORE.language
        end

        def self.language=(lang)
            return if lang.nil?
            return if (sym = lang.to_sym) == language
            return unless CORE::LANGUAGES.include?(sym)
            CORE.language = sym
            CORE.save_language
            update
        end

        #==========================================================================
        # Shortcut method to access localized text
        #==========================================================================

        def self.[](sym)
            (CORE.language_map[language] || {})[sym] || {}
        end

    end
end

#==============================================================================
# ▼ Hash
#==============================================================================

class Hash

    #============================================================================
    # recursive deep merge
    #============================================================================

    def iavra_i18n_deep_merge(second)
        merger = proc{|key, v1, v2| Hash === v1 && Hash === v2 ? v1.merge(v2, &merger) : v2}
        self.merge(second, &merger)
    end

end

#==============================================================================
# ▼ DataManager
#==============================================================================

module DataManager

    class << self
        alias :iavra_i18n_core_load_database :load_database
    end

    def self.load_database
        iavra_i18n_core_load_database
        IAVRA::I18N.initialize
        IAVRA::I18N.update
    end

end