openfoodnetwork/app/services/fdc_backorderer.rb

# frozen_string_literal: true

# Place and update orders based on missing stock.
class FdcBackorderer
  attr_reader :user, :urls

  def initialize(user, urls)
    @user = user
    @urls = urls
  end

  def find_or_build_order(ofn_order)
    find_open_order(ofn_order) || build_new_order(ofn_order)
  end

  def build_new_order(ofn_order)
    OrderBuilder.new_order(ofn_order, urls.orders_url).tap do |order|
      order.saleSession = build_sale_session(ofn_order)
    end
  end

  # Try the new method and fall back to old method.
  def find_open_order(ofn_order)
    lookup_open_order(ofn_order)
  end

  def lookup_open_order(ofn_order)
    # There should be only one link at the moment but we may support
    # ordering from multiple suppliers one day.
    semantic_ids = ofn_order.semantic_links.pluck(:semantic_id)

    semantic_ids.lazy
      # Make sure we select an order from the right supplier:
      .select { |id| id.starts_with?(urls.orders_url) }
      # Fetch the order from the remote DFC server, lazily:
      .map { |id| find_order(id) }
      .compact
      # Just in case someone completed the order without updating our database:
      .select { |o| o.orderStatus == order_status.HELD }
      .first
      # The DFC Connector doesn't recognise status values properly yet.
      # So we are overriding the value with something that can be exported.
      &.tap { |o| o.orderStatus = "dfc-v:Held" }
  end

  def find_order(semantic_id)
    find_subject(import(semantic_id), "dfc-b:Order")
  end

  def find_or_build_order_line(order, offer)
    find_order_line(order, offer) || build_order_line(order, offer)
  end

  def build_order_line(order, offer)
    # Order lines are enumerated in the FDC API and we must assign a unique
    # semantic id. We need to look at current ids to avoid collisions.
    # existing_ids = order.lines.map do |line|
    #   line.semanticId.match(/[0-9]+$/).to_s.to_i
    # end
    # next_id = existing_ids.max.to_i + 1

    # Suggested by FDC team:
    next_id = order.lines.count + 1

    OrderLineBuilder.build(offer, 0).tap do |line|
      line.semanticId = "#{order.semanticId}/OrderLines/#{next_id}"
      order.lines << line
    end
  end

  def find_order_line(order, offer)
    order.lines.find do |line|
      line.offer.offeredItem.semanticId == offer.offeredItem.semanticId
    end
  end

  def find_subject(object_or_graph, type)
    if object_or_graph.is_a?(Array)
      object_or_graph.find { |i| i.semanticType == type }
    else
      object_or_graph
    end
  end

  def import(url)
    api = DfcRequest.new(user)
    json = api.call(url)
    DfcIo.import(json)
  end

  def send_order(backorder)
    lines = backorder.lines
    offers = lines.map(&:offer)
    products = offers.map(&:offeredItem)
    sessions = [backorder.saleSession].compact
    json = DfcIo.export(backorder, *lines, *offers, *products, *sessions)

    api = DfcRequest.new(user)

    method = if new?(backorder)
               :post # -> create
             else
               :put  # -> update
             end

    result = api.call(backorder.semanticId, json, method:)
    find_subject(DfcIo.import(result), "dfc-b:Order")
  end

  def complete_order(backorder)
    backorder.orderStatus = "dfc-v:Complete"
    send_order(backorder)
  end

  def new?(order)
    order.semanticId == urls&.orders_url
  end

  def build_sale_session(order)
    SaleSessionBuilder.build(order.order_cycle).tap do |session|
      session.semanticId = urls.sale_session_url
    end
  end

  private

  def order_status
    DfcLoader.vocabulary("vocabulary").STATES.ORDERSTATE
  end
end