From f35815d62a9daf83f2aeac5beae9a13625b82eb6 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
Date: Thu, 15 Apr 2021 20:07:39 +0200
Subject: [PATCH] Simplest chat system

---
 schemas/chat-protocol.prs     |  5 +++
 src/chat-client-standalone.ts | 60 ++++++++++++++++++++++++++++++
 src/gen/chat-protocol.ts      | 69 +++++++++++++++++++++++++++++++++++
 3 files changed, 134 insertions(+)
 create mode 100644 schemas/chat-protocol.prs
 create mode 100644 src/chat-client-standalone.ts
 create mode 100644 src/gen/chat-protocol.ts

diff --git a/schemas/chat-protocol.prs b/schemas/chat-protocol.prs
new file mode 100644
index 0000000..b9a1d7d
--- /dev/null
+++ b/schemas/chat-protocol.prs
@@ -0,0 +1,5 @@
+version 1 .
+pointer Actor.Ref .
+
+Present = <Present @username string>.
+Says = <Says @who string @what string>.
diff --git a/src/chat-client-standalone.ts b/src/chat-client-standalone.ts
new file mode 100644
index 0000000..33dca3f
--- /dev/null
+++ b/src/chat-client-standalone.ts
@@ -0,0 +1,60 @@
+import { $Present, $Says, asPresent, asSays, fromPresent, fromSays, Present, Says } from "./gen/chat-protocol.js";
+import { fromObserve, Observe } from "./gen/dataspace.js";
+import { Assertion, Handle, Ref, Turn } from "./actor.js";
+import readline from 'readline';
+
+export default function (t: Turn, ds: Ref) {
+    let username = '';
+    let usernameHandle: Handle | undefined;
+
+    function updateUsername(t: Turn, u: string) {
+        username = u;
+        usernameHandle = t.replace(ds, usernameHandle, fromPresent(Present(username)));
+    }
+    updateUsername(t, 'user' + process.pid);
+
+    const usermap = new Map<Handle, Present>();
+    t.assert(ds, fromObserve(Observe({
+        label: $Present,
+        observer: t.ref({
+            assert(t: Turn, e0: Assertion, h: Handle): void {
+                const e = asPresent(e0);
+                console.log(`${e.username} arrived`);
+                usermap.set(h, e);
+            },
+            retract(t: Turn, h: Handle): void {
+                const e = usermap.get(h);
+                if (e) {
+                    usermap.delete(h);
+                    console.log(`${e.username} departed`);
+                }
+            },
+        }),
+    })));
+
+    t.assert(ds, fromObserve(Observe({
+        label: $Says,
+        observer: t.ref({
+            message(t: Turn, u0: Assertion): void {
+                const u = asSays(u0);
+                console.log(`${u.who}: ${u.what}`);
+            },
+        }),
+    })));
+
+    function sendUtterance(what: string) {
+        t.freshen(t => t.message(ds, fromSays(Says({ who: username, what }))));
+    }
+
+    const rl = readline.createInterface({ input: process.stdin, output: process.stdout });
+
+    rl.on('line', (line: string) => {
+        if (line.startsWith('/nick ')) {
+            t.freshen(t => updateUsername(t, line.slice(5).trimLeft()));
+        } else {
+            sendUtterance(line);
+        }
+    });
+
+    rl.on('close', () => t.freshen(t => t.quit()));
+}
diff --git a/src/gen/chat-protocol.ts b/src/gen/chat-protocol.ts
new file mode 100644
index 0000000..fce0b36
--- /dev/null
+++ b/src/gen/chat-protocol.ts
@@ -0,0 +1,69 @@
+import * as _ from "@preserves/core";
+import * as _i_Actor from "../actor";
+
+export const $Present = Symbol.for("Present");
+export const $Says = Symbol.for("Says");
+
+export type _ptr = _i_Actor.Ref;
+
+export type _val = _.Value<_ptr>;
+
+export type Present = {"username": string};
+
+export type Says = {"who": string, "what": string};
+
+
+export const _toPtr = (v: _val) => {let result: undefined | _ptr; result = _i_Actor.toRef(v); return result;};
+
+export function Present(username: string): Present {return {"username": username};}
+
+export function Says({who, what}: {who: string, what: string}): Says {return {"who": who, "what": what};}
+
+export function asPresent(v: _val): Present {
+    let result = toPresent(v);
+    if (result === void 0) throw new TypeError(`Invalid Present: ${_.stringify(v)}`);
+    return result;
+}
+
+export function toPresent(v: _val): undefined | Present {
+    let result: undefined | Present;
+    if (_.Record.isRecord<_val, _.Tuple<_val>, _ptr>(v)) {
+        let _tmp0: (null) | undefined;
+        _tmp0 = _.is(v.label, $Present) ? null : void 0;
+        if (_tmp0 !== void 0) {
+            let _tmp1: (string) | undefined;
+            _tmp1 = typeof v[0] === 'string' ? v[0] : void 0;
+            if (_tmp1 !== void 0) {result = {"username": _tmp1};};
+        };
+    };
+    return result;
+}
+
+export function fromPresent(_v: Present): _val {return _.Record($Present, [_v["username"]]);}
+
+export function asSays(v: _val): Says {
+    let result = toSays(v);
+    if (result === void 0) throw new TypeError(`Invalid Says: ${_.stringify(v)}`);
+    return result;
+}
+
+export function toSays(v: _val): undefined | Says {
+    let result: undefined | Says;
+    if (_.Record.isRecord<_val, _.Tuple<_val>, _ptr>(v)) {
+        let _tmp0: (null) | undefined;
+        _tmp0 = _.is(v.label, $Says) ? null : void 0;
+        if (_tmp0 !== void 0) {
+            let _tmp1: (string) | undefined;
+            _tmp1 = typeof v[0] === 'string' ? v[0] : void 0;
+            if (_tmp1 !== void 0) {
+                let _tmp2: (string) | undefined;
+                _tmp2 = typeof v[1] === 'string' ? v[1] : void 0;
+                if (_tmp2 !== void 0) {result = {"who": _tmp1, "what": _tmp2};};
+            };
+        };
+    };
+    return result;
+}
+
+export function fromSays(_v: Says): _val {return _.Record($Says, [_v["who"], _v["what"]]);}
+