require 'i18n'
require 'request_store'
require 'mobility/version'

=begin

Mobility is a gem for storing and retrieving localized data through attributes
on a class. The {Mobility} module includes all necessary methods and modules to
support defining backend accessors on a class.

To enable Mobility on a class, simply include or extend the {Mobility} module,
and define any attribute accessors using {Translates#mobility_accessor} (aliased to the
value of {Mobility.accessor_method}, which defaults to +translates+).

  class MyClass
    extend Mobility
    translates :title, backend: :key_value
  end

When defining this module, Mobility attempts to +require+ various gems (for
example, +active_record+ and +sequel+) to evaluate which are loaded. Loaded
gems are tracked with dynamic subclasses of the {Loaded} module and referenced
in backends to define gem-dependent behavior.

=end
module Mobility
  require "mobility/attributes"
  require "mobility/backend"
  require "mobility/backends"
  require "mobility/backend_resetter"
  require "mobility/configuration"
  require "mobility/loaded"
  require "mobility/plugins"
  require "mobility/translates"
  require "mobility/wrapper"

  # General error for version compatibility conflicts
  class VersionNotSupportedError < ArgumentError; end

  begin
    require "rails"
    Loaded::Rails = true
  rescue LoadError => e
    raise unless e.message =~ /rails/
    Loaded::Rails = false
  end

  begin
    require "active_record"
    raise VersionNotSupportedError, "Mobility is only compatible with ActiveRecord 4.2 and greater" if ::ActiveRecord::VERSION::STRING < "4.2"
    Loaded::ActiveRecord = true
  rescue LoadError => e
    raise unless e.message =~ /active_record/
    Loaded::ActiveRecord = false
  end

  if Loaded::ActiveRecord
    require "mobility/active_model"
    require "mobility/active_record"
    if Loaded::Rails
      require "rails/generators/mobility/generators"
    end
  end

  begin
    require "sequel"
    raise VersionNotSupportedError, "Mobility is only compatible with Sequel 4.0 and greater" if ::Sequel::MAJOR < 4
    require "sequel/plugins/mobility"
    #TODO avoid automatically including the inflector extension
    require "sequel/extensions/inflector"
    require "sequel/plugins/dirty"
    require "mobility/sequel"
    Loaded::Sequel = true
  rescue LoadError => e
    raise unless e.message =~ /sequel/
    Loaded::Sequel = false
  end

  class << self
    def extended(model_class)
      return if model_class.respond_to? :mobility_accessor

      model_class.include(InstanceMethods)
      model_class.extend(ClassMethods)

      if translates = Mobility.config.accessor_method
        model_class.singleton_class.send(:alias_method, translates, :mobility_accessor)
      end

      if Loaded::ActiveRecord
        model_class.include(ActiveRecord)                   if model_class < ::ActiveRecord::Base
        model_class.include(ActiveRecord::AttributeMethods) if model_class.ancestors.include?(::ActiveRecord::AttributeMethods)
      end

      if Loaded::Sequel
        model_class.include(Sequel) if model_class < ::Sequel::Model
      end
    end

    # Extends model with this class so that +include Mobility+ is equivalent to
    # +extend Mobility+ (but +extend+ is preferred).
    # @param model_class
    def included(model_class)
      model_class.extend self
    end

    # @!group Locale Accessors
    # @return [Symbol] Mobility locale
    def locale
      read_locale || I18n.locale
    end

    # Sets Mobility locale
    # @param [Symbol] locale Locale to set
    # @raise [InvalidLocale] if locale is nil or not in
    #   +I18n.available_locales+ (if +I18n.enforce_available_locales+ is +true+)
    # @return [Symbol] Locale
    def locale=(locale)
      set_locale(locale)
    end

    # Sets Mobility locale around block
    # @param [Symbol] locale Locale to set in block
    # @yield [Symbol] Locale
    def with_locale(locale)
      previous_locale = read_locale
      begin
        set_locale(locale)
        yield(locale)
      ensure
        set_locale(previous_locale)
      end
    end
    # @!endgroup

    # @return [RequestStore] Request store
    def storage
      RequestStore.store
    end

    # @!group Configuration Methods
    # @return [Mobility::Configuration] Mobility configuration
    def config
      @configuration ||= Mobility::Configuration.new
    end

    # (see Mobility::Configuration#accessor_method)
    # @!method accessor_method
    #
    # (see Mobility::Configuration#query_method)
    # @!method query_method

    # (see Mobility::Configuration#default_fallbacks)
    # @!method default_fallbacks

    # (see Mobility::Configuration#default_backend)
    # @!method default_backend

    # (see Mobility::Configuration#default_options)
    # @!method default_options
    #
    # (see Mobility::Configuration#plugins)
    # @!method plugins
    #
    # (see Mobility::Configuration#default_accessor_locales)
    # @!method default_accessor_locales
    %w[accessor_method query_method default_backend default_options plugins default_accessor_locales].each do |method_name|
      define_method method_name do
        config.public_send(method_name)
      end
    end

    define_method :default_fallbacks do |*args|
      config.public_send(:default_fallbacks, *args)
    end

    # Configure Mobility
    # @yield [Mobility::Configuration] Mobility configuration
    def configure
      yield config
    end
    # @!endgroup

    # Return normalized locale
    # @param [String,Symbol] locale
    # @return [String] Normalized locale
    # @example
    #   Mobility.normalize_locale(:ja)
    #   #=> "ja"
    #   Mobility.normalize_locale("pt-BR")
    #   #=> "pt_br"
    def normalize_locale(locale = Mobility.locale)
      "#{locale.to_s.downcase.sub("-", "_")}".freeze
    end
    alias_method :normalized_locale, :normalize_locale

    # Return normalized locale accessor name
    # @param [String,Symbol] attribute
    # @param [String,Symbol] locale
    # @return [String] Normalized locale accessor name
    # @example
    #   Mobility.normalize_locale_accessor(:foo, :ja)
    #   #=> "foo_ja"
    #   Mobility.normalize_locale_accessor(:bar, "pt-BR")
    #   #=> "bar_pt_br"
    def normalize_locale_accessor(attribute, locale = Mobility.locale)
      "#{attribute}_#{normalize_locale(locale)}".freeze
    end

    # Raises InvalidLocale exception if the locale passed in is present but not available.
    # @param [String,Symbol] locale
    # @raise [InvalidLocale] if locale is present but not available
    def enforce_available_locales!(locale)
      if I18n.enforce_available_locales
        raise Mobility::InvalidLocale.new(locale) unless (I18n.locale_available?(locale) || locale.nil?)
      end
    end

    protected

    def read_locale
      storage[:mobility_locale]
    end

    def set_locale(locale)
      locale = locale.to_sym if locale
      enforce_available_locales!(locale)
      storage[:mobility_locale] = locale
    end
  end

  module InstanceMethods
    # Fetch backend for an attribute
    # @param [String] attribute Attribute
    def mobility_backend_for(attribute)
      send(Backend.method_name(attribute))
    end

    def initialize_dup(other)
      @mobility_backends = nil
      super
    end
  end

  module ClassMethods
    include Translates

    def mobility
      @mobility ||= Mobility::Wrapper.new(self)
    end

    def translated_attribute_names
      mobility.translated_attribute_names
    end

    def inherited(subclass)
      subclass.instance_variable_set(:@mobility, mobility.dup)
      super
    end
  end

  class BackendRequired < ArgumentError; end
  class InvalidLocale < I18n::InvalidLocale; end
end