Automation with Daml Triggers full code

module Market where

import DA.Date

template User
with
party : Party
where
signatory party
key party : Party
maintainer key

nonconsuming choice NewSellOffer : ()
  with
    observers : [Party]
    title : Text
    description : Text
    price : Int
  controller party
    do
      now <- getTime
      create $ SellOffer {seller = party, date = toDateUTC now, ..}
      pure ()

nonconsuming choice TakeSellOffer : ()
  with
    offer : ContractId SellOffer
  controller party
    do
      exercise offer DoTrade with tradePartner = party
      pure ()

nonconsuming choice ConfirmPayment : ()
  with
    invoice : ContractId Invoice
  controller party
    do
      Invoice{..} <- fetch invoice
      assert $ owner == party
      create $ PaymentConfirmation
                  with
                    invoice = invoice
                    party = party
                    obligor = obligor
      pure ()

template SellOffer
with
observers : [Party]
title : Text
description : Text
price : Int
seller : Party
date : Date
where
signatory seller
observer observers

nonconsuming choice DoTrade : ()
  with
    tradePartner : Party
  controller tradePartner
    do
      assert $ tradePartner `elem` observers
      archive self
      create $ Invoice {owner = seller, obligor = tradePartner, amount = price, description = title}
      pure ()

template Invoice
with
owner : Party
obligor : Party
amount : Int
description : Text
where
signatory obligor
observer owner

template PaymentConfirmation
with
invoice : ContractId Invoice
party : Party
obligor : Party
where
signatory party
observer obligor

nonconsuming choice ArchiveInvoice : ()
  controller obligor
  do
    archive invoice
    archive self