Start using reducer to track tile locations

ui/src/elements.tsx

@@ -1,5 +1,7 @@
 import * as React from "react";
-import {Letter as LetterData} from "word_grid";
+import {GameWasm, Letter as LetterData, Tray} from "word_grid";
+import {createRoot} from "react-dom/client";
+import {useReducer, useState} from "react";
 
 export enum LocationType {
     GRID,
@@ -13,6 +15,75 @@ export interface CoordinateData {
 
 export type PlayableLetterData = LetterData & CoordinateData;
 
+function matchCoordinate(playerLetters: PlayableLetterData[], coords: CoordinateData): number {
+
+    for (let i=0; i<playerLetters.length; i++){
+        let letter = playerLetters[i];
+
+        if (letter.location === coords.location && letter.index === coords.index) {
+            return i;
+        }
+    }
+
+    return null; // no match
+
+}
+
+function movePlayableLetters(playerLetters: PlayableLetterData[], update: {start: CoordinateData, end: CoordinateData}) {
+
+    let startIndex = matchCoordinate(playerLetters, update.start);
+    let endIndex = matchCoordinate(playerLetters, update.end);
+
+    if(startIndex != null) {
+        let startLetter = playerLetters[startIndex];
+        startLetter.location = update.end.location;
+        startLetter.index = update.end.index;
+    }
+
+    if(endIndex != null) {
+        let endLetter = playerLetters[endIndex];
+        endLetter.location = update.start.location;
+        endLetter.index = update.start.index;
+    }
+
+    return playerLetters.slice();
+}
+
+export function Game(props: {wasm: GameWasm}) {
+
+    const [playerLetters, dispatch] = useReducer(movePlayableLetters, null, (_) => {
+            let tray: Tray = props.wasm.get_tray();
+
+            // initial state
+            let letters: PlayableLetterData[] = tray.letters.map((ld, i) => {
+                ld["location"] = LocationType.TRAY;
+                ld["index"] = i;
+                return ld as PlayableLetterData;
+            })
+
+            return letters;
+    })
+
+
+    return <>
+        <TileTray letters={playerLetters} trayLength={7}/>
+        <button onClick={(e) => {
+          dispatch({
+              "start": {
+                "location": LocationType.TRAY,
+                  "index": 0
+              },
+              "end": {
+                  "location": LocationType.TRAY,
+                  "index": 3
+              },
+          })
+        }}>Swap two</button>
+    </>;
+
+
+}
+
 export function Letter(props: { data: LetterData }): React.JSX.Element {
     return <div className="letter">
         <div className="text">{props.data.text}</div>

ui/src/index.tsx

@@ -1,7 +1,8 @@
 import init, {greet, GameWasm} from '../node_modules/word_grid/word_grid.js';
-import {LocationType, PlayableLetterData, TileTray} from "./elements";
+import {Game, LocationType, PlayableLetterData, TileTray} from "./elements";
 import {createRoot} from "react-dom/client";
 import {Tray} from "word_grid";
+import * as React from "react";
 
 async function run() {
     // First up we need to actually load the wasm file, so we use the
@@ -32,22 +33,10 @@ async function run() {
     // modes
     await init();
 
-    greet("Heyo!");
-
     let game = new GameWasm(BigInt(1234));
-    let tray: Tray = game.get_tray();
-
-    // initial state
-    let letters: PlayableLetterData[] = tray.letters.map((ld, i) => {
-        ld["location"] = LocationType.TRAY;
-        ld["index"] = i;
-        return ld as PlayableLetterData;
-    })
-
-    console.log({tray});
 
     const root = createRoot(document.getElementById("root"));
-    root.render(<TileTray letters={letters} trayLength={7}/>);
+    root.render(<Game wasm={game} />);
 
 }