# frozen_string_literal: true

require "set"
require "dry/inflector/rules"

module Dry
  class Inflector
    # Inflections
    #
    # @since 0.1.0
    class Inflections
      require "dry/inflector/inflections/defaults"

      # Instantiate a set of inflection rules.
      # It adds the default rules and the optional customizations, passed as a block.
      #
      # @param blk [Proc] the optional, custom rules
      #
      # @since 0.1.0
      # @api private
      def self.build(&blk)
        new do |inflect|
          Defaults.call(inflect)
          blk.call(inflect) if block_given?
        end
      end

      # Pluralization rules
      #
      # @return [Dry::Inflector::Rules]
      #
      # @since 0.1.0
      # @api private
      attr_reader :plurals

      # Singularization rules
      #
      # @return [Dry::Inflector::Rules]
      #
      # @since 0.1.0
      # @api private
      attr_reader :singulars

      # Uncountable rules
      #
      # @return [Set]
      #
      # @since 0.1.0
      # @api private
      attr_reader :uncountables

      # Human rules
      #
      # @return [Dry::Inflector::Rules]
      #
      # @since 0.1.0
      # @api private
      attr_reader :humans

      # Instantiate the rules
      #
      # @return [Dry::Inflector::Inflections]
      # @yieldparam [self]
      #
      # @since 0.1.0
      # @api private
      def initialize
        @plurals      = Rules.new
        @singulars    = Rules.new
        @humans       = Rules.new
        @uncountables = Set[]

        yield(self) if block_given?
      end

      # Add a custom pluralization rule
      #
      # Specifies a new pluralization rule and its replacement.
      # The rule can either be a string or a regular expression.
      # The replacement should always be a string that may include references to the matched data from the rule.
      #
      # @param rule [String, Regexp] the rule
      # @param replacement [String] the replacement
      #
      # @since 0.1.0
      #
      # @example
      #   require "dry/inflector"
      #
      #   inflector = Dry::Inflector.new do |inflections|
      #     inflections.plural "virus", "viruses"
      #   end
      def plural(rule, replacement)
        rule(rule, replacement, plurals)
      end

      # Add a custom singularization rule
      #
      # Specifies a new singularization rule and its replacement.
      # The rule can either be a string or a regular expression.
      # The replacement should always be a string that may include references to the matched data from the rule.
      #
      # @param rule [String, Regexp] the rule
      # @param replacement [String] the replacement
      #
      # @since 0.1.0
      #
      # @example
      #   require "dry/inflector"
      #
      #   inflector = Dry::Inflector.new do |inflections|
      #     inflections.singular "thieves", "thief"
      #   end
      def singular(rule, replacement)
        rule(rule, replacement, singulars)
      end

      # Add a custom pluralization rule
      #
      # Specifies a new irregular that applies to both pluralization and singularization at the same time.
      # This can only be used for strings, not regular expressions.
      # You simply pass the irregular in singular and plural form.
      #
      # @param singular [String] the singular
      # @param plural [String] the plural
      #
      # @since 0.1.0
      #
      # @example
      #   require "dry/inflector"
      #
      #   inflector = Dry::Inflector.new do |inflections|
      #     inflections.singular "octopus", "octopi"
      #   end
      def irregular(singular, plural)
        uncountables.delete(singular)
        uncountables.delete(plural)

        add_irregular(singular, plural, plurals)
        add_irregular(plural, singular, singulars)
      end

      # Add a custom rule for uncountable words
      #
      # Uncountable will not be inflected
      #
      # @param [Enumerable<String>] words
      #
      # @since 0.1.0
      #
      # @example
      #   require "dry/inflector"
      #
      #   inflector = Dry::Inflector.new do |inflections|
      #     inflections.uncountable "money"
      #     inflections.uncountable "money", "information"
      #     inflections.uncountable %w(money information rice)
      #   end
      def uncountable(*words)
        uncountables.merge(words.flatten)
      end

      # Add a custom humanize rule
      #
      # Specifies a humanized form of a string by a regular expression rule or by a string mapping.
      # When using a regular expression based replacement, the normal humanize formatting is called after the replacement.
      # When a string is used, the human form should be specified as desired (example: `"The name"`, not `"the_name"`)
      #
      # @param rule [String, Regexp] the rule
      # @param replacement [String] the replacement
      #
      # @since 0.1.0
      #
      # @example
      #   require "dry/inflector"
      #
      #   inflector = Dry::Inflector.new do |inflections|
      #     inflections.human(/_cnt$/i, '\1_count')
      #     inflections.human("legacy_col_person_name", "Name")
      #   end
      def human(rule, replacement)
        humans.insert(0, [rule, replacement])
      end

      private

      # Add irregular inflection
      #
      # @param rule [String] the rule
      # @param replacement [String] the replacement
      #
      # @return [undefined]
      #
      # @since 0.1.0
      # @api private
      def add_irregular(rule, replacement, target)
        head, *tail = rule.chars.to_a
        rule(/(#{head})#{tail.join}\z/i, '\1' + replacement[1..-1], target)
      end

      # Add a new rule
      #
      # @param rule [String, Regexp] the rule
      # @param replacement [String, Regexp] the replacement
      # @param target [Dry::Inflector::Rules] the target
      #
      # @since 0.1.0
      # @api private
      def rule(rule, replacement, target)
        uncountables.delete(rule)
        uncountables.delete(replacement)

        target.insert(0, [rule, replacement])
      end
    end
  end
end