[Beta][QoL] Improved cursor memory for target selection in Doubles (#4849)

* Added more intelligent cursor memory for target selection in Doubles

* Added documentation

* Fixed variable name.

* Apply suggestions from code review

Co-authored-by: Moka <54149968+MokaStitcher@users.noreply.github.com>

---------

Co-authored-by: frutescens <info@laptop>
Co-authored-by: Moka <54149968+MokaStitcher@users.noreply.github.com>

src/ui/target-select-ui-handler.ts

@@ -13,9 +13,11 @@ import { SubstituteTag } from "#app/data/battler-tags";
 export type TargetSelectCallback = (targets: BattlerIndex[]) => void;
 
 export default class TargetSelectUiHandler extends UiHandler {
-  private fieldIndex: integer;
+  private fieldIndex: number;
   private move: Moves;
   private targetSelectCallback: TargetSelectCallback;
+  private cursor0: number; // associated with BattlerIndex.PLAYER
+  private cursor1: number; // associated with BattlerIndex.PLAYER_2
 
   private isMultipleTargets: boolean = false;
   private targets: BattlerIndex[];
@@ -42,8 +44,9 @@ export default class TargetSelectUiHandler extends UiHandler {
     this.fieldIndex = args[0] as integer;
     this.move = args[1] as Moves;
     this.targetSelectCallback = args[2] as TargetSelectCallback;
+    const user = this.scene.getPlayerField()[this.fieldIndex];
 
-    const moveTargets = getMoveTargets(this.scene.getPlayerField()[this.fieldIndex], this.move);
+    const moveTargets = getMoveTargets(user, this.move);
     this.targets = moveTargets.targets;
     this.isMultipleTargets = moveTargets.multiple ?? false;
 
@@ -53,11 +56,29 @@ export default class TargetSelectUiHandler extends UiHandler {
 
     this.enemyModifiers = this.scene.getModifierBar(true);
 
-    this.setCursor(this.targets.includes(this.cursor) ? this.cursor : this.targets[0]);
+    if (this.fieldIndex === BattlerIndex.PLAYER) {
-
+      this.resetCursor(this.cursor0, user);
+    } else if (this.fieldIndex === BattlerIndex.PLAYER_2) {
+      this.resetCursor(this.cursor1, user);
+    }
     return true;
   }
 
+  /**
+   * Determines what value to assign the main cursor based on the previous turn's target or the user's status
+   * @param cursorN the cursor associated with the user's field index
+   * @param user the Pokemon using the move
+   */
+  resetCursor(cursorN: number, user: Pokemon): void {
+    if (!Utils.isNullOrUndefined(cursorN)) {
+      if ([ BattlerIndex.PLAYER, BattlerIndex.PLAYER_2 ].includes(cursorN) || user.battleSummonData.waveTurnCount === 1) {
+        // Reset cursor on the first turn of a fight or if an ally was targeted last turn
+        cursorN = -1;
+      }
+    }
+    this.setCursor(this.targets.includes(cursorN) ? cursorN : this.targets[0]);
+  }
+
   processInput(button: Button): boolean {
     const ui = this.getUi();
 
@@ -67,6 +88,15 @@ export default class TargetSelectUiHandler extends UiHandler {
       const targetIndexes: BattlerIndex[] = this.isMultipleTargets ? this.targets : [ this.cursor ];
       this.targetSelectCallback(button === Button.ACTION ? targetIndexes : []);
       success = true;
+      if (this.fieldIndex === BattlerIndex.PLAYER) {
+        if (Utils.isNullOrUndefined(this.cursor0) || this.cursor0 !== this.cursor) {
+          this.cursor0 = this.cursor;
+        }
+      } else if (this.fieldIndex === BattlerIndex.PLAYER_2) {
+        if (Utils.isNullOrUndefined(this.cursor1) || this.cursor1 !== this.cursor) {
+          this.cursor1 = this.cursor;
+        }
+      }
     } else if (this.isMultipleTargets) {
       success = false;
     } else {
@@ -152,7 +182,6 @@ export default class TargetSelectUiHandler extends UiHandler {
         yoyo: true
       }));
     });
-
     return ret;
   }
 
@@ -184,7 +213,6 @@ export default class TargetSelectUiHandler extends UiHandler {
   }
 
   clear() {
-    this.cursor = -1;
     super.clear();
     this.eraseCursor();
   }