require "hashid/rails/version"
require "hashid/rails/configuration"
require "hashids"
require "active_record"

module Hashid
  module Rails
    # Arbitrary value to verify hashid
    # https://en.wikipedia.org/wiki/Phrases_from_The_Hitchhiker%27s_Guide_to_the_Galaxy#On_the_Internet_and_in_software
    HASHID_TOKEN = 42

    def self.included(base)
      base.extend ClassMethods
    end

    # Get configuration or load defaults
    def self.configuration
      @configuration ||= Configuration.new
    end

    # Set configuration settings with a block
    def self.configure
      yield(configuration)
    end

    # Reset gem configuration to defaults
    def self.reset
      @configuration = Configuration.new
    end

    def hashid
      self.class.encode_id(id)
    end
    alias to_param hashid

    module ClassMethods
      def relation
        super.tap { |r| r.extend ClassMethods }
      end

      def has_many(*args, &block) # rubocop:disable Style/PredicateName
        options = args.extract_options!
        options[:extend] = Array(options[:extend]).push(ClassMethods)
        super(*args, options, &block)
      end

      def encode_id(ids)
        if ids.is_a?(Array)
          ids.map { |id| hashid_encode(id) }
        else
          hashid_encode(ids)
        end
      end

      # @param ids [String, Integer, Array<Integer, String>] id(s) to decode.
      # @param fallback [Boolean] indicates whether to return the passed in
      #   id(s) if unable to decode or if already decoded.
      def decode_id(ids, fallback: false)
        if ids.is_a?(Array)
          ids.map { |id| hashid_decode(id, fallback: fallback) }
        else
          hashid_decode(ids, fallback: fallback)
        end
      end

      def find(*ids)
        expects_array = ids.first.is_a?(Array)

        uniq_ids = ids.flatten.compact.uniq
        uniq_ids = uniq_ids.first unless expects_array || uniq_ids.size > 1

        if Hashid::Rails.configuration.override_find
          super(decode_id(uniq_ids, fallback: true))
        else
          super
        end
      end

      def find_by_hashid(hashid)
        find_by(id: decode_id(hashid, fallback: false))
      end

      def find_by_hashid!(hashid)
        find_by!(id: decode_id(hashid, fallback: false))
      end

      private

      def hashids
        Hashids.new(*Hashid::Rails.configuration.for_table(table_name))
      end

      def hashid_encode(id)
        if Hashid::Rails.configuration.sign_hashids
          hashids.encode(HASHID_TOKEN, id)
        else
          hashids.encode(id)
        end
      end

      def hashid_decode(id, fallback:)
        decoded_hashid = hashids.decode(id.to_s)
        fallback_value = fallback ? id : nil

        if Hashid::Rails.configuration.sign_hashids
          valid_hashid?(decoded_hashid) ? decoded_hashid.last : fallback_value
        else
          decoded_hashid.first
        end
      end

      def valid_hashid?(decoded_hashid)
        decoded_hashid.size == 2 && decoded_hashid.first == HASHID_TOKEN
      end
    end
  end
end