feat(http): add response with headers and cookie writing

lib/prism/response.rb

@@ -0,0 +1,45 @@
+module Prism
+  class Response
+    attr_accessor :status
+    attr_reader :headers, :body
+
+    def initialize(status: 200, headers: nil, body: nil)
+      @status = status
+      @headers = headers || { 'Content-Type' => 'text/html;charset=utf-8' }
+      @body = body ? Array(body) : []
+    end
+
+    def write(chunk)
+      @body << chunk.to_s
+      self
+    end
+    alias_method :<<, :write
+
+    def [](name)
+      @headers[name]
+    end
+
+    def []=(name, value)
+      @headers[name] = value
+    end
+
+    def body=(value)
+      @body = Array(value)
+    end
+
+    def set_cookie(name, value, options = {})
+      cookie = +"#{name}=#{CGI.escape(value.to_s)}"
+      cookie << "; Path=#{options[:path] || '/'}"
+      cookie << "; Max-Age=#{options[:max_age]}" if options[:max_age]
+      cookie << '; HttpOnly' if options.fetch(:http_only, true)
+      cookie << '; Secure' if options[:secure]
+      cookie << "; SameSite=#{options[:same_site]}" if options[:same_site]
+      existing = @headers['Set-Cookie']
+      @headers['Set-Cookie'] = existing ? "#{existing}\n#{cookie}" : cookie
+    end
+
+    def finish
+      [@status, @headers, @body]
+    end
+  end
+end