From abf984bd5d97f749671a3710e02f94f7801a8669 Mon Sep 17 00:00:00 2001
From: Brian Sakal <brian@sakal.us>
Date: Mon, 8 May 2023 21:07:03 -0400
Subject: [PATCH] TypeScript, send()

---
 src/index.ts | 55 +++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 48 insertions(+), 7 deletions(-)

diff --git a/src/index.ts b/src/index.ts
index 97e079e..d764f93 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,12 +1,13 @@
-export interface Machine_T<S,E> {
+type EventShape = [name:string, payload:any];
+export interface Machine_T<S,E extends EventShape> {
   states: Array<State_T<S,E>>
 }
-export interface State_T<S,E> {
+export interface State_T<S,E extends EventShape> {
   name: S;
   ons: Array<On_T<S,E>>;
 }
-export interface On_T<S,E> {
-  eventName: E;
+export interface On_T<S,E extends EventShape> {
+  eventName: E[0];
   reactions: Array<Do_T | Goto_T<S>>;
 };
 export interface Do_T {
@@ -19,10 +20,50 @@ export interface Goto_T<S> {
   targetStateName: S;
 };
 
-export const Machine = function<S,E>(...states:Array<State_T<S,E>>) : Machine_T<S,E> { return {states}; };
-export const State = function<S,E>(name:S, ...ons:Array<On_T<S,E>>) : State_T<S,E>{ return {name, ons}; };
-export const On = function<S,E>(eventName:E, ...reactions:Array<Do_T | Goto_T<S>>) : On_T<S,E>{ return {eventName, reactions}; };
+export const Machine = function<S,E extends EventShape>(...states:Array<State_T<S,E>>) : Machine_T<S,E> { return {states}; };
+export const State = function<S,E extends EventShape>(name:S, ...ons:Array<On_T<S,E>>) : State_T<S,E>{ return {name, ons}; };
+export const On = function<S,E extends EventShape>(eventName:E[0], ...reactions:Array<Do_T | Goto_T<S>>) : On_T<S,E>{ return {eventName, reactions}; };
 export const Do = function(fn:DoFn_T) : Do_T{ return {type:'Do', fn}; };
 export const Goto = function<S>(targetStateName:S) : Goto_T<S> { return {type:'Goto', targetStateName} };
+
+
+export interface Interpreter_T<S,E extends EventShape,C> {
+  machine: Machine_T<S,E>;
+  state: S;
+  context: C | {};
+}
+export function interpret<S,E extends EventShape,C>(machine:Machine_T<S,E>, options?:{state?:S, context?:C | {}}) : Interpreter_T<S,E,C>{
+  let {state, context} = options || {};
+  if(typeof state === 'undefined'){ state = machine.states[0].name; }
+  if(typeof context === 'undefined'){ context = {}; }
+  return {machine, state, context};
+}
+
+/**  Helper function for `send()`
+ */
+function getState<S,E extends EventShape,C>(interpreter : Interpreter_T<S,E,C>) : State_T<S,E>{
+  return interpreter.machine.states.find((state)=>state.name===interpreter.state) as unknown as State_T<S,E>;
+}
+/**  Helper function for `send()`
+ */
+function getOns<S,E extends EventShape>(state : State_T<S,E>, event:E) : Array<On_T<S,E>>{
+  return state.ons.filter((on)=>on.eventName===event[0]);
+}
+/**  Inject an Event into the Interpreter's "tick queue".
+ * 
+ * An event can be signify something "new" happening, such that its reactions should run on the next Tick;
+ * or it can signify a milestone "within" the current Tick, such that a Tick can be thought of as having 
+ * "sub-Ticks".
+ * 
+ * This distinction is significant for proper ordering of reaction execution, and also for determining
+ * whether to run a reaction at all. If an Event is received, and is specified to be applied on a past 
+ * Tick, it is discarded.
+ */
+export function send<S,E extends EventShape,C>(interpreter : Interpreter_T<S,E,C>, event:E){
+  const state = getState(interpreter);
+  const ons = getOns(state, event);
+  ons.forEach
+}
+
 export const Spawn = function(){};
 export const Unspawn = function(){};
\ No newline at end of file