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# frozen_string_literal: true
# Released under the MIT License.
# Copyright, 2025, by Samuel Williams.
require_relative "split"
require_relative "../quoted_string"
require_relative "../error"
module Protocol
module HTTP
module Header
# The `accept-language` header represents a list of languages that the client can accept.
class AcceptLanguage < Split
ParseError = Class.new(Error)
# https://tools.ietf.org/html/rfc3066#section-2.1
NAME = /\*|[A-Z]{1,8}(-[A-Z0-9]{1,8})*/i
# https://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.9
QVALUE = /0(\.[0-9]{0,6})?|1(\.[0]{0,6})?/
# https://greenbytes.de/tech/webdav/rfc7231.html#quality.values
LANGUAGE = /\A(?<name>#{NAME})(\s*;\s*q=(?<q>#{QVALUE}))?\z/
Language = Struct.new(:name, :q) do
def quality_factor
(q || 1.0).to_f
end
def <=> other
other.quality_factor <=> self.quality_factor
end
end
# Parse the `accept-language` header value into a list of languages.
#
# @returns [Array(Charset)] the list of character sets and their associated quality factors.
def languages
self.map do |value|
if match = value.match(LANGUAGE)
Language.new(match[:name], match[:q])
else
raise ParseError.new("Could not parse language: #{value.inspect}")
end
end
end
end
end
end
end
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