# frozen_string_literal: true

require 'active_support/all'
require 'cfita/codici_catastali'

module Cfita
  # Controllo codice fiscale italiano
  class CodiceFiscale
    attr_reader :fiscal_code,
                :sex,
                :birth_place,
                :birth_date,
                :data,
                :errors

    def self.ccat
      @ccat ||= JSON.parse(open('ccat.json'))
    end

    def initialize(fiscal_code, birth_place: nil)
      @fiscal_code = fiscal_code.upcase.strip
      @birth_place = birth_place
      @data = {}
      @errors = []
      parse
    end

    def to_s
      fiscal_code
    end

    def valid?(birth_place: nil)
      result = errors.empty?
      result = birth_place?(birth_place) if result && birth_place
      result
    end

    private

    def parse
      check_size
      check_chars
      return if errors.any?

      check_checksum
      return if errors.any?

      check_birth_date
      check_birth_place
    end

    def check_size
      size = @fiscal_code.size
      errors << "Lunghezza errata (#{size})" unless size == 16
    end

    def check_chars
      test = @fiscal_code == @fiscal_code[/^[A-Z0-9]*$/]
      errors << 'Caratteri non ammessi' unless test
    end

    def check_checksum
      errors << 'Checksum errato' if checksum != @fiscal_code.last
    end

    def check_sex
      case @fiscal_code[9]
      when /[0-3LMNP]/
        @data[:sex] = 'M'
      when /[4-7QRST]/
        @data[:sex] = 'F'
      else
        @errors << 'Cifra decina giorno di nascita errata'
      end
    end

    def check_birth_place
      # debugger
      letter = @fiscal_code[11]
      numbers =
        @fiscal_code[12..14]
        .split(//)
        .map do |c|
          i = OMOCODICI.index(c)
          i ? i.to_s : c
        end
        .join
      codice_catastale = letter + numbers

      birth_places = CODICI_CATASTALI[codice_catastale]
      @errors << "Codice istat #{codice_catastale} non trovato" unless birth_places
      if @birth_place
        unless birth_places&.include?(@birth_place)
          @errors << "Luogo di nascita #{@birth_place} non coerente, al codice catastale #{codice_catastale} corrisponde a #{birth_places.join(' o a ')}"
        end
      end
    end

    MESI = 'ABCDEHLMPRST'.freeze

    def check_birth_date
      yy = cifre(6..7)
      return if @errors.any?

      day = cifre(9..10)
      return if @errors.any?

      @errors << 'Cifra decina giorno di nascita errata' if day > 71
      return if @errors.any?

      @data[:sex] = day > 40 ? 'F' : 'M'

      month = MESI.index(@fiscal_code[8])
      @errors << 'Mese errato' unless month
      return if @errors.any?

      @birth_date =
        Date.new(yy2yyyy(yy), month + 1, day % 40) rescue nil

      @errors << 'Data di nascita errata' unless @birth_date
      return if @errors.any?

      @data[:birth_date] = @birth_date
    end

    def yy2yyyy(yy)
      Date.today.year -
        (Date.today.year % 100 + 100 - yy ) % 100
    end

    def cifre(range)
      result = 0
      range.each do |position|
        char = @fiscal_code[position]
        value = CIFRE.index(char)
        @errors << "Carattere '#{char}' errato in posizione #{position}" unless value
        return nil unless value

        result *= 10
        result += value % 10
      end
      result
    end

    DISPARI = [
      1, 0, 5, 7, 9,
      13, 15, 17, 19, 21,
      2, 4, 18, 20, 11,
      3, 6, 8, 12, 14,
      16, 10, 22, 25, 24, 23
    ].freeze

    OMOCODICI = 'LMNPQRSTUV'
    CIFRE = ('0123456789' + OMOCODICI).freeze

    def checksum
      tot = 0
      @fiscal_code[0..14].bytes.first(15).each.with_index do |byte, i|
        next unless byte

        byte -= byte < 65 ? 48 : 65
        sign = (i % 2).zero?
        tot += sign ? DISPARI[byte] : byte
      end
      (tot % 26 + 65).chr
    end
  end
end