module PublicSuffix

Parses domain and returns the {PublicSuffix::Domain} instance.

@param [String, to_s] domain

The domain name or fully qualified domain name to parse.

@param [PublicSuffix::List] list

The rule list to search, defaults to the default {PublicSuffix::List}

@return [PublicSuffix::Domain]

@example Parse a valid domain

PublicSuffix.parse("google.com")
# => #<PublicSuffix::Domain ...>

@example Parse a valid subdomain

PublicSuffix.parse("www.google.com")
# => #<PublicSuffix::Domain ...>

@example Parse a fully qualified domain

PublicSuffix.parse("google.com.")
# => #<PublicSuffix::Domain ...>

@example Parse a fully qualified domain (subdomain)

PublicSuffix.parse("www.google.com.")
# => #<PublicSuffix::Domain ...>

@example Parse an invalid domain

PublicSuffix.parse("x.yz")
# => PublicSuffix::DomainInvalid

@example Parse an URL (not supported, only domains)

PublicSuffix.parse("http://www.google.com")
# => PublicSuffix::DomainInvalid

@raise [PublicSuffix::Error]

If domain is not a valid domain.

@raise [PublicSuffix::DomainNotAllowed]

If a rule for +domain+ is found, but the rule
doesn't allow +domain+.

# File lib/public_suffix.rb, line 57
def self.parse(domain, list = List.default)
  domain = domain.to_s.downcase
  rule   = list.find(domain)

  if rule.nil?
    raise DomainInvalid, "`#{domain}' is not a valid domain"
  end
  if !rule.allow?(domain)
    raise DomainNotAllowed, "`#{domain}' is not allowed according to Registry policy"
  end

  left, right = rule.decompose(domain)

  parts = left.split(".")
  # If we have 0 parts left, there is just a tld and no domain or subdomain
  # If we have 1 part  left, there is just a tld, domain and not subdomain
  # If we have 2 parts left, the last part is the domain, the other parts (combined) are the subdomain
  tld = right
  sld = parts.empty? ? nil : parts.pop
  trd = parts.empty? ? nil : parts.join(".")

  Domain.new(tld, sld, trd)
end

Checks whether +domain+ is assigned and allowed,

 without actually parsing it.

This method doesn't care whether domain is a domain or subdomain.
The validation is performed using the default {PublicSuffix::List}.

@param  [String, #to_s] domain
  The domain name or fully qualified domain name to validate.

@return [Boolean]

@example Validate a valid domain
  PublicSuffix.valid?("example.com")
  # => true

@example Validate a valid subdomain
  PublicSuffix.valid?("www.example.com")
  # => true

@example Validate a not-assigned domain
  PublicSuffix.valid?("example.qqq")
  # => false

@example Validate a not-allowed domain
  PublicSuffix.valid?("example.do")
  # => false
  PublicSuffix.valid?("www.example.do")
  # => true

@example Validate a fully qualified domain
  PublicSuffix.valid?("google.com.")
  # => true
  PublicSuffix.valid?("www.google.com.")
  # => true

@example Check an URL (which is not a valid domain)
  PublicSuffix.valid?("http://www.example.com")
  # => false

# File lib/public_suffix.rb, line 120
def self.valid?(domain)
  domain = domain.to_s.downcase
  rule   = List.default.find(domain)
  !rule.nil? && rule.allow?(domain)
end