:tada: Add selected mech in collection

dev-front/src/mech/squad/Squad.tsx

@@ -3,6 +3,7 @@ import Member from './Member';
 import logo from '../../logo.svg';
 import Mech from '../../Mech';
 import MechObserver from '../../MechObserver';
+import { isEmptySlot } from '../../MechUtils';
 
 function instead<T>(array: T[], index: number, newItem: T): T[] {
     return array.map((item, i) => {
@@ -14,6 +15,14 @@ function instead<T>(array: T[], index: number, newItem: T): T[] {
     });
 }
 
+function hasFreeSlot(squad: Mech[]) {
+    return squad.some(isEmptySlot)
+}
+
+function isSquadFull(squad: Mech[]) {
+    return !hasFreeSlot(squad);
+}
+
 
 function Squad({pickObservers} : {pickObservers: {[key: string] : MechObserver}}) {
 
@@ -23,8 +32,21 @@ function Squad({pickObservers} : {pickObservers: {[key: string] : MechObserver}}
     const placeHolder: Mech = {id: -1, name: 'Empty slot', kind: '_', health: 0};
     const [squadMechs, setSquadMechs] = useState([it1, it2, it3]);
 
+    function putInFreeSlot(mech: Mech, squad: Mech[]): Mech[] {
+        const freeSlotIndex = squad.findIndex(isEmptySlot);
+        console.log('Next free slot : ', freeSlotIndex);
+        return instead(squad, freeSlotIndex, mech);
+    }
+
+
     function addToSquad(mech: Mech) {
-        console.log("New mech added :", mech)
+        console.log("New mech to add :", mech)
+        if (isSquadFull(squadMechs)) {
+            console.log("Squad is full, sorry");
+            return;
+        }
+
+        setSquadMechs(putInFreeSlot(mech, squadMechs));
     }
 
     function removeFromSquad(index: number) {