# frozen_string_literal: true

# Verify the email is a valid email format based on RFC8222
class EmailFormatValidator < ActiveModel::EachValidator
  #
  # RFC822, obsolete and more lax in most cases
  #
  # CTL         =  <any ASCII control           ; (  0- 37,  0.- 31.)
  # SPACE       =  <ASCII SP, space>            ; (     40,      32.)
  # specials    =  "(" / ")" / "<" / ">" / "@"  ; Must be in quoted-
  #             /  "," / ";" / ":" / "\" / <">  ;  string, to use
  #             /  "." / "[" / "]"              ;  within a word.
  # atom        =  1*<any CHAR except specials, SPACE and CTLs>
  #
  # qtext       =  <any CHAR excepting <">,     ; => may be folded "\" & CR, and including linear-white-space>
  # quoted-pair =  "\" CHAR                     ; may quote any char
  # quoted-string = <"> *(qtext/quoted-pair) <">; Regular qtext or quoted chars.
  # word        =  atom / quoted-string
  #
  # local-part  =  word *("." word)             ; uninterpreted
  #
  # domain-ref  =  atom                         ; symbolic reference
  # sub-domain  =  domain-ref / domain-literal
  # domain      =  sub-domain *("." sub-domain)
  #
  # addr-spec   =  local-part "@" domain        ; global address
  #

  ctl = '\x00-\x1f'
  space = ' '
  specials = '\(\)\<\>\@\,\;\:\\\"\.\[\]'
  atom = "[^#{ctl}#{space}#{specials}]+?"
  dot_atom = "#{atom}(?:\.#{atom})*" # in common use, allowed by RFC2822

  qtext = '[^\"\`]+'
  quoted_pair = '\\.'
  quoted_string = "\"(?:#{qtext}|#{quoted_pair})+?\""
  word = "(?:#{dot_atom}|#{quoted_string})"

  local_part = word # ignore word[.word]

  domain_ref = dot_atom
  domain_literal = "\[#{atom}(?:[\.\:]#{atom})*\]" # only used for IPv4/IPv6 addresses
  sub_domain = "(?:#{domain_ref}|#{domain_literal})"
  domain = sub_domain

  addr_spec = "#{local_part}\@#{domain}"

  addr_ws = "\s*(#{addr_spec})\s*"
  addr_list = "^#{addr_ws}(?:,#{addr_ws})*$"

  EMAIL_ADDRESS_REGEX = /#{addr_list}/

  def validate_each(record, attribute, value)
    return if valid_email?(value, options[:strict])
    record.errors.add(attribute, message: options[:message] || 'is invalid')
  end

  def valid_email?(email, strict = false)
    if strict
      !!(email =~ EMAIL_ADDRESS_REGEX)
    else
      !!(email =~ /^[\S&&[^@]]+@[\S&&[^@]]+$/)
    end
  end
end