require 'json'
require 'net/http'
require 'uri'

USER = "pdp8"
WWW_DOMAIN = "pdp8.info"
WWW_URL = "https://#{WWW_DOMAIN}"
SOCIAL_DOMAIN = "social.#{WWW_DOMAIN}"

ACCOUNT = "#{USER}@#{SOCIAL_DOMAIN}"
SOCIAL_URL = "https://#{SOCIAL_DOMAIN}"
ACTOR = URI.join(SOCIAL_URL, USER)

MATRIX = "@#{USER}:matrix.#{WWW_DOMAIN}"

class Application
  def call(env)
    code = 404
    type = "application/activity+json"

    case env['REQUEST_METHOD']

    when 'POST'
      case env["REQUEST_URI"]

      when "/inbox"
        type = "text/plain"
        signature_header = {}
        env["HTTP_SIGNATURE"].split(',').each do |pair|
          k, v = pair.split('=')
          signature_header[k] = v.gsub('"', '')
        end
        key_id    = signature_header['keyId']
        headers   = signature_header['headers']
        signature = Base64.decode64(signature_header['signature'])
        uri = URI(key_id)
        res = Net::HTTP.get_response(uri)
        actor = JSON.parse(res.body)
        key = OpenSSL::PKey::RSA.new(actor['publicKey']['publicKeyPem'])

        comparison_string = headers.split(' ').map do |signed_header_name|
          if signed_header_name == '(request-target)'
            '(request-target): post /inbox'
          else
            "#{signed_header_name}: #{env["HTTP_" + signed_header_name.upcase]}"
          end
        end.join("\n")
        if key.verify(OpenSSL::Digest::SHA256.new, signature, comparison_string)
          input = JSON.parse(env["rack.input"].gets)
          code = 200
          response = "OK"
        else
          code = 401
          response = 'Request signature could not be verified'
        end

      end

    when 'GET'

      case env["REQUEST_URI"]

      when "/.well-known/webfinger?resource=acct:#{ACCOUNT}"
        code = 200
        type = "application/jrd+json"
        response = {
          "subject" => "acct:#{ACCOUNT}",
          "links" => [
            {
              "rel" => "self",
              "type" => "application/activity+json",
              "href" => ACTOR
            }
          ]
        }

      when "/#{USER}"
        code = 200
        response = {
          "@context" => ["https://www.w3.org/ns/activitystreams"],
          "id" => ACTOR,
          "type" => "Person",
          "preferredUsername" => USER,
          "name" => USER,
          "inbox" => URI.join(SOCIAL_URL, "inbox"),
          "outbox" => URI.join(SOCIAL_URL, "outbox"),
          "following" => URI.join(SOCIAL_URL, "following"),
          "followers" => URI.join(SOCIAL_URL, "followers"),
          "liked" => URI.join(SOCIAL_URL, "liked"),
          "icon" => {
            "type" => "Image",
            "url" => "https://pdp8.info/pdp8.png"
          },
          "attachment": [
            {
              "type": "PropertyValue",
              "name": "Web",
              "value": "<a href=\"#{WWW_URL}\">#{WWW_DOMAIN}</a>"
            },
            {
              "type": "PropertyValue",
              "name": "Fediverse",
              "value": "<a rel=\"me\" href=\"#{ACTOR}\">@#{ACCOUNT}</a>"
            },
            {
              "type": "PropertyValue",
              "name": "Matrix",
              "value": "<a rel=\"me\" href=\"https://matrix.to/#/#{MATRIX}\">MATRIX</a>"
            }
          ],
          "publicKey" => {
            "@context" => "https://w3id.org/security/v1",
            "@type" => "Key",
            "id" => "#{ACTOR}#main-key",
            "owner" => ACTOR,
            "publicKeyPem" => File.read("public.pem")
          }
        }

      when "/outbox"
        code = 200
        type = "application/activity+json"
        response = {
          "@context" => "https://www.w3.org/ns/activitystreams",
          "summary" => "",
          "type" => "OrderedCollection",
          "totalItems" => 2,
          # TODO generate items from src/www
          "orderedItems" => [
            {
              "type" => "Note",
              "name" => "A Simple Note",
              "tag" => [
                {
                  "type" => "Hashtag",
                  "name" => "#activitypub",
                  "href" => "https://s3lph.me/activitypub/tags/activitypub"
                },
              ]
            },
            {
              "type" => "Note",
              "name" => "Another Simple Note"
            }
          ]
        }
      when "/following"
      when "/followers"
      when "/liked"
      end

    end
    [code, { "Content-Type" => type }, [response.to_json]]
  end
end