datacite/lupo

# frozen_string_literal: true

module Middleware
  class CompressedRequests
    def initialize(app)
      @app = app
    end

    def method_handled?(env)
      !!(env["REQUEST_METHOD"] =~ /(POST|PUT)/)
    end

    def encoding_handled?(env)
      ["gzip", "deflate"].include? env["HTTP_CONTENT_ENCODING"]
    end

    def call(env)
      request = Rack::Request.new(env)
      if method_handled?(env) && encoding_handled?(env)
        extracted = decode(env["rack.input"], env["HTTP_CONTENT_ENCODING"])
        hsh = JSON.parse(extracted)

        request.update_param("data",  hsh.fetch("data", {}))
        request.update_param("encoding", env["HTTP_CONTENT_ENCODING"])

        env.delete("HTTP_CONTENT_ENCODING")
        env["CONTENT_LENGTH"] = extracted.length
        env["rack.input"] = StringIO.new(extracted)
      end

      status, headers, response = @app.call(env)
      [status, headers, response]
    end

    def decode(input, content_encoding)
      case content_encoding
      # https://tickets.puppetlabs.com/browse/PUP-7251
      when "gzip" then Zlib::GzipReader.new(input, encoding: Encoding::BINARY).read
      when "deflate" then Zlib::Inflate.inflate(input.read)
      end
    end
  end
end