class Async::HTTP::Headers

def == other
	if other.is_a? Hash
		to_h == other
	else
		@fields == other.fields
	end
end

def [] key
	@indexed ||= to_h
	
	@indexed[key]
end

def []= key, value
	@fields << [key, value]
	
	if @indexed
		key = key.downcase
		
		if current_value = @indexed[key]
			@indexed[key] = Array(current_value) << value
		else
			@indexed[key] = value
		end
	end
end

def delete(key)
	values, @fields = @fields.partition do |field|
		field.first.downcase == key
	end
	
	if @indexed
		@indexed.delete(key)
	end
	
	if field = values.last
		return field.last
	end
end

def each(&block)
	@fields.each(&block)
end

def freeze
	return if frozen?
	
	@indexed = to_h
	
	super
end

def include? key
	self[key] != nil
end

def initialize(fields = [])
	@fields = fields
	@indexed = to_h
end

def to_h
	@fields.inject({}) do |hash, (key, value)|
		key = key.downcase
		
		if current_value = hash[key]
			hash[key] = Array(current_value) << value
		else
			hash[key] = value
		end
		
		hash
	end
end