require 'digest'
require "image_processing/vips"

class XmppSetAvatarJob < ApplicationJob
  queue_as :default

  def perform(user:, overwrite: false)
    return if Rails.env.development?
    @user = user

    unless overwrite
      current_avatar = get_current_avatar
      Rails.logger.info { "User #{user.cn} already has an avatar set" }
      return if current_avatar.present?
    end

    Rails.logger.debug { "Setting XMPP avatar for user #{user.cn}" }

    stanzas = build_xep0084_stanzas

    stanzas.each do |stanza|
      payload = { from: @user.address, to: @user.address, stanza: stanza }
      res = ejabberd.send_stanza payload
      raise res.inspect if res.status != 200
    end
  end

  private

    def ejabberd
      @ejabberd ||= EjabberdApiClient.new
    end

    def get_current_avatar
      res = ejabberd.get_vcard2 @user, "PHOTO", "BINVAL"

      if res.status == 200
        # VCARD PHOTO/BINVAL prop exists
        res.body
      elsif res.status == 400
        # VCARD or PHOTO/BINVAL prop does not exist
        nil
      else
        # Unexpected error, let job fail
        raise res.inspect
      end
    end

    def process_avatar
      @user.avatar.blob.open do |file|
        processed = ImageProcessing::Vips
          .source(file)
          .resize_to_fill(256, 256)
          .convert("png")
          .call
        processed.read
      end
    end

    # See https://xmpp.org/extensions/xep-0084.html
    def build_xep0084_stanzas
      img_data    = process_avatar
      sha1_hash   = Digest::SHA1.hexdigest(img_data)
      base64_data = Base64.strict_encode64(img_data)

      [
        """
<iq type='set' from='#{@user.address}' id='avatar-data-#{rand(101)}'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='urn:xmpp:avatar:data'>
      <item id='#{sha1_hash}'>
        <data xmlns='urn:xmpp:avatar:data'>#{base64_data}</data>
      </item>
    </publish>
  </pubsub>
</iq>
        """.strip,
        """
<iq type='set' from='#{@user.address}' id='avatar-metadata-#{rand(101)}'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='urn:xmpp:avatar:metadata'>
      <item id='#{sha1_hash}'>
        <metadata xmlns='urn:xmpp:avatar:metadata'>
          <info bytes='#{img_data.size}'
                id='#{sha1_hash}'
                height='256'
                type='image/png'
                width='256'/>
        </metadata>
      </item>
    </publish>
  </pubsub>
</iq>
        """.strip,
      ]
    end
end