# encoding: UTF-8

# Copyright 2012 Twitter, Inc
# http://www.apache.org/licenses/LICENSE-2.0

module TwitterCldr
  module Shared
    module LanguageCodes

      LANGUAGE_CODES_DUMP_PATH = File.join(TwitterCldr::RESOURCES_DIR, 'shared', 'language_codes_table.dump')

      NAME_STANDARD = :name # fake standard, mostly for internal use

      VALID_STANDARDS = {
        bcp_47:    [:bcp_47, :bcp_47_alt],
        iso_639_1: [:iso_639_1],
        iso_639_2: [:iso_639_2, :iso_639_2_term],
        iso_639_3: [:iso_639_3]
      }

      VALID_STANDARDS[NAME_STANDARD] = [NAME_STANDARD]
      VALID_STANDARDS.freeze

      class << self

        def languages
          resource[NAME_STANDARD].keys
        end

        def valid_standard?(standard)
          VALID_STANDARDS.include?(standard.to_sym)
        end

        def valid_code?(code, standard)
          standards = validate_standard(standard)
          standards.any? { |std| (resource[std] || {}).has_key?(code.to_sym) }
        end

        def convert(code, from_and_to = {})
          from, to = extract_from_and_to_options(from_and_to)

          from.each do |from_std|
            to.each do |to_std|
              if result = (resource[from_std] || {}).fetch(code.to_sym, {})[to_std]
                return result
              end
            end
          end

          nil
        end

        def from_language(language, standard)
          convert(language, from: NAME_STANDARD, to: standard)
        end

        def to_language(code, standard)
          convert(code, from: standard, to: NAME_STANDARD).to_s
        end

        def standards_for(code, standard)
          standards = validate_standard(standard)

          standards.each do |std|
            if found = resource[std][code.to_sym]
              # exclude fake NAME_STANDARD standard
              return (found.keys & VALID_STANDARDS.keys) - [NAME_STANDARD]
            end
          end

          []
        end

        def standards_for_language(language)
          standards_for(language, NAME_STANDARD)
        end

        private

        def resource
          @resource ||= File.open(LANGUAGE_CODES_DUMP_PATH) { |file| Marshal.load(file.read) }
        end

        def extract_from_and_to_options(from_and_to)
          TwitterCldr::Utils.deep_symbolize_keys(from_and_to).values_at(:from, :to).map do |standard|
            raise ArgumentError, 'options :from and :to are required' if standard.nil?
            validate_standard(standard)
          end
        end

        def validate_standard(standard)
          raise ArgumentError, "standard can't be nil" if standard.nil?
          raise ArgumentError, "#{standard.inspect} is not a valid standard name" unless valid_standard?(standard)

          VALID_STANDARDS[standard.to_sym]
        end

      end

    end
  end
end