daml/templates/gsg-trigger.patch

diff -Naur create-daml-app/daml/ChatBot.daml gsg-trigger/daml/ChatBot.daml
--- create-daml-app/daml/ChatBot.daml	1970-01-01 01:00:00.000000000 +0100
+++ gsg-trigger/daml/ChatBot.daml	2021-08-18 13:15:25.000000000 +0200
@@ -0,0 +1,29 @@
+module ChatBot where
+
+import qualified Daml.Trigger as T
+import qualified User
+import qualified DA.List.Total as List
+import DA.Action (when)
+import DA.Optional (whenSome)
+
+autoReply : T.Trigger ()
+autoReply = T.Trigger
+  { initialize = pure ()
+  , updateState = \_ -> pure ()
+  , rule = \p -> do
+      message_contracts <- T.query @User.Message
+      let messages = map snd message_contracts
+      debug $ "Messages so far: " <> show (length messages)
+      let lastMessage = List.maximumOn (.receivedAt) messages
+      debug $ "Last message: " <> show lastMessage
+      whenSome lastMessage $ \m ->
+        when (m.receiver == p) $ do
+          users <- T.query @User.User
+          debug users
+          let isSender = (\user -> user.username == m.sender)
+          let replyTo = List.head $ filter (\(_, user) -> isSender user) users
+          whenSome replyTo $ \(sender, _) ->
+            T.dedupExercise sender (User.SendMessage p "Please, tell me more about that.")
+  , registeredTemplates = T.AllInDar
+  , heartbeat = None
+  }
diff -Naur create-daml-app/daml/NoOp.daml gsg-trigger/daml/NoOp.daml
--- create-daml-app/daml/NoOp.daml	1970-01-01 01:00:00.000000000 +0100
+++ gsg-trigger/daml/NoOp.daml	2021-08-18 13:15:25.000000000 +0200
@@ -0,0 +1,13 @@
+module NoOp where
+
+import qualified Daml.Trigger as T
+
+noOp : T.Trigger ()
+noOp = T.Trigger with
+  initialize = pure ()
+  updateState = \_ -> pure ()
+  rule = \_ -> do
+    debug "triggered"
+    pure ()
+  registeredTemplates = T.AllInDar
+  heartbeat = None
diff -Naur create-daml-app/daml/User.daml gsg-trigger/daml/User.daml
--- create-daml-app/daml/User.daml	2021-08-12 14:36:31.000000000 +0200
+++ gsg-trigger/daml/User.daml	2021-08-18 13:15:25.000000000 +0200
@@ -25,3 +25,24 @@
         archive self
         create this with following = userToFollow :: following
     -- FOLLOW_END
+    -- SEND_BEGIN
+    -- New definition for SendMessage
+    nonconsuming choice SendMessage: ContractId Message with
+        sender: Party
+        content: Text
+      controller sender
+      do
+        assertMsg "Designated user must follow you back to send a message" (elem sender following)
+        now <- getTime
+        create Message with sender, receiver = username, content, receivedAt = now
+    -- SEND_END
+
+-- MESSAGE_BEGIN
+template Message with
+    sender: Party
+    receiver: Party
+    content: Text
+    receivedAt: Time
+  where
+    signatory sender, receiver
+-- MESSAGE_END
diff -Naur create-daml-app/daml.yaml.template gsg-trigger/daml.yaml.template
--- create-daml-app/daml.yaml.template	2021-05-12 10:23:33.000000000 +0200
+++ gsg-trigger/daml.yaml.template	2021-08-18 13:15:25.000000000 +0200
@@ -6,10 +6,12 @@
 - Alice
 - Bob
 - Charlie
+# trigger-dependencies-begin
 dependencies:
 - daml-prim
 - daml-stdlib
 - daml-trigger
+# trigger-dependencies-end
 sandbox-options:
 - --wall-clock-time
 - --ledgerid=__PROJECT_NAME__-sandbox
diff -Naur create-daml-app/ui/src/components/MainView.tsx.template gsg-trigger/ui/src/components/MainView.tsx.template
--- create-daml-app/ui/src/components/MainView.tsx.template	2021-05-12 10:23:33.000000000 +0200
+++ gsg-trigger/ui/src/components/MainView.tsx.template	2021-08-18 13:18:18.000000000 +0200
@@ -8,6 +8,8 @@
 import { useParty, useLedger, useStreamFetchByKeys, useStreamQueries } from '@daml/react';
 import UserList from './UserList';
 import PartyListEdit from './PartyListEdit';
+import MessageEdit from './MessageEdit';
+import MessageList from './MessageList';
 
 // USERS_BEGIN
 const MainView: React.FC = () => {
@@ -78,6 +80,20 @@
               />
               {/* USERLIST_END */}
             </Segment>
+            <Segment>
+              <Header as='h2'>
+                <Icon name='pencil square' />
+                <Header.Content>
+                  Messages
+                  <Header.Subheader>Send a message to a follower</Header.Subheader>
+                </Header.Content>
+              </Header>
+              <MessageEdit
+                followers={followers.map(follower => follower.username)}
+              />
+              <Divider />
+              <MessageList />
+            </Segment>
           </Grid.Column>
         </Grid.Row>
       </Grid>
diff -Naur create-daml-app/ui/src/components/MessageEdit.tsx.template gsg-trigger/ui/src/components/MessageEdit.tsx.template
--- create-daml-app/ui/src/components/MessageEdit.tsx.template	1970-01-01 01:00:00.000000000 +0100
+++ gsg-trigger/ui/src/components/MessageEdit.tsx.template	2021-08-18 13:20:33.000000000 +0200
@@ -0,0 +1,65 @@
+import React from 'react'
+import { Form, Button } from 'semantic-ui-react';
+import { Party } from '@daml/types';
+import { User } from '@daml.js/__PROJECT_NAME__';
+import { useParty, useLedger } from '@daml/react';
+
+type Props = {
+  followers: Party[];
+}
+
+/**
+ * React component to edit a message to send to a follower.
+ */
+const MessageEdit: React.FC<Props> = ({followers}) => {
+  const sender = useParty();
+  const [receiver, setReceiver] = React.useState<string | undefined>();
+  const [content, setContent] = React.useState("");
+  const [isSubmitting, setIsSubmitting] = React.useState(false);
+  const ledger = useLedger();
+
+  const submitMessage = async (event: React.FormEvent) => {
+    try {
+      event.preventDefault();
+      if (receiver === undefined) {
+        return;
+      }
+      setIsSubmitting(true);
+      await ledger.exerciseByKey(User.User.SendMessage, receiver, {sender, content});
+      setContent("");
+    } catch (error) {
+      alert(`Error sending message:\n${JSON.stringify(error)}`);
+    } finally {
+      setIsSubmitting(false);
+    }
+  };
+
+  return (
+    <Form onSubmit={submitMessage}>
+      <Form.Dropdown
+        selection
+        className='test-select-message-receiver'
+        placeholder="Select a follower"
+        options={followers.map(follower => ({ key: follower, text: follower, value: follower }))}
+        value={receiver}
+        onChange={event => setReceiver(event.currentTarget.textContent ?? undefined)}
+      />
+      <Form.Input
+        className='test-select-message-content'
+        placeholder="Write a message"
+        value={content}
+        onChange={event => setContent(event.currentTarget.value)}
+      />
+      <Button
+        fluid
+        className='test-select-message-send-button'
+        type="submit"
+        disabled={isSubmitting || receiver === undefined || content === ""}
+        loading={isSubmitting}
+        content="Send"
+      />
+    </Form>
+  );
+};
+
+export default MessageEdit;
diff -Naur create-daml-app/ui/src/components/MessageList.tsx.template gsg-trigger/ui/src/components/MessageList.tsx.template
--- create-daml-app/ui/src/components/MessageList.tsx.template	1970-01-01 01:00:00.000000000 +0100
+++ gsg-trigger/ui/src/components/MessageList.tsx.template	2021-08-18 13:20:45.000000000 +0200
@@ -0,0 +1,28 @@
+import React from 'react'
+import { List, ListItem } from 'semantic-ui-react';
+import { User } from '@daml.js/__PROJECT_NAME__';
+import { useStreamQueries } from '@daml/react';
+
+/**
+ * React component displaying the list of messages for the current user.
+ */
+const MessageList: React.FC = () => {
+  const messagesResult = useStreamQueries(User.Message);
+
+  return (
+    <List relaxed>
+      {messagesResult.contracts.map(message => {
+        const {sender, receiver, content} = message.payload;
+        return (
+          <ListItem
+            className='test-select-message-item'
+            key={message.contractId}>
+            <strong>{sender} &rarr; {receiver}:</strong> {content}
+          </ListItem>
+        );
+      })}
+    </List>
+  );
+};
+
+export default MessageList;