From 4564f9e434f3e0cb95d72d11b2de972997729426 Mon Sep 17 00:00:00 2001
From: scamiv <6170744+scamiv@users.noreply.github.com>
Date: Fri, 26 Dec 2025 23:54:56 +0100
Subject: [PATCH] Refactor TransportShipExecution for improved pathfinding and
 routing

- Replace targetTransportTile with MultiSourceAnyTargetBFS bestTransportShipRoute for enhanced route determination
- Update pathfinding logic to handle retreat paths
---
 src/core/execution/TransportShipExecution.ts  | 199 ++++++------
 src/core/game/TransportShipUtils.ts           | 285 ++++++++++++++++--
 .../pathfinding/MultiSourceAnyTargetBFS.ts    |  48 +--
 3 files changed, 398 insertions(+), 134 deletions(-)

diff --git a/src/core/execution/TransportShipExecution.ts b/src/core/execution/TransportShipExecution.ts
index 6e37e066d..56e5533d1 100644
--- a/src/core/execution/TransportShipExecution.ts
+++ b/src/core/execution/TransportShipExecution.ts
@@ -10,9 +10,10 @@ import {
   UnitType,
 } from "../game/Game";
 import { TileRef } from "../game/GameMap";
-import { targetTransportTile } from "../game/TransportShipUtils";
-import { PathFindResultType } from "../pathfinding/AStar";
-import { PathFinder } from "../pathfinding/PathFinding";
+import {
+  bestTransportShipRoute,
+  boatPathFromTileToShore,
+} from "../game/TransportShipUtils";
 import { AttackExecution } from "./AttackExecution";
 
 const malusForRetreat = 25;
@@ -28,12 +29,13 @@ export class TransportShipExecution implements Execution {
   private target: Player | TerraNullius;
 
   // TODO make private
-  public path: TileRef[];
+  public path: TileRef[] = [];
   private dst: TileRef | null;
 
   private boat: Unit;
-
-  private pathFinder: PathFinder;
+  private forwardPath: TileRef[] = [];
+  private pathIndex = 0;
+  private usingReverseRetreatPath = false;
 
   private originalOwner: Player;
 
@@ -70,7 +72,6 @@ export class TransportShipExecution implements Execution {
 
     this.lastMove = ticks;
     this.mg = mg;
-    this.pathFinder = PathFinder.Mini(mg, 10_000, true, 100);
 
     if (
       this.attacker.unitCount(UnitType.TransportShip) >=
@@ -100,40 +101,33 @@ export class TransportShipExecution implements Execution {
 
     this.startTroops = Math.min(this.startTroops, this.attacker.troops());
 
-    this.dst = targetTransportTile(this.mg, this.ref);
-    if (this.dst === null) {
+    const route = bestTransportShipRoute(
+      this.mg,
+      this.attacker,
+      this.ref,
+      this.src,
+    );
+    if (route === false) {
       console.warn(
-        `${this.attacker} cannot send ship to ${this.target}, cannot find attack tile`,
+        `${this.attacker} cannot send ship to ${this.target}, no route found`,
       );
       this.active = false;
       return;
     }
 
-    const closestTileSrc = this.attacker.canBuild(
-      UnitType.TransportShip,
-      this.dst,
-    );
-    if (closestTileSrc === false) {
-      console.warn(`can't build transport ship`);
+    // Basic affordability/availability checks (avoid relying on transport-ship spawn heuristics).
+    const boatCost = this.mg.unitInfo(UnitType.TransportShip).cost(this.mg, this.attacker);
+    if (!this.attacker.isAlive() || this.attacker.gold() < boatCost) {
       this.active = false;
       return;
     }
 
-    if (this.src === null) {
-      // Only update the src if it's not already set
-      // because we assume that the src is set to the best spawn tile
-      this.src = closestTileSrc;
-    } else {
-      if (
-        this.mg.owner(this.src) !== this.attacker ||
-        !this.mg.isShore(this.src)
-      ) {
-        console.warn(
-          `src is not a shore tile or not owned by: ${this.attacker.name()}`,
-        );
-        this.src = closestTileSrc;
-      }
-    }
+    this.src = route.src;
+    this.dst = route.dst;
+    this.forwardPath = route.path;
+    this.path = route.path;
+    this.pathIndex = 0;
+    this.usingReverseRetreatPath = false;
 
     this.boat = this.attacker.buildUnit(UnitType.TransportShip, this.src, {
       troops: this.startTroops,
@@ -217,67 +211,96 @@ export class TransportShipExecution implements Execution {
         if (this.boat.targetTile() !== this.dst) {
           this.boat.setTargetTile(this.dst);
         }
-      }
-    }
 
-    const result = this.pathFinder.nextTile(this.boat.tile(), this.dst);
-    switch (result.type) {
-      case PathFindResultType.Completed:
-        if (this.mg.owner(this.dst) === this.attacker) {
-          const deaths = this.boat.troops() * (malusForRetreat / 100);
-          const survivors = this.boat.troops() - deaths;
-          this.attacker.addTroops(survivors);
-          this.boat.delete(false);
-          this.active = false;
-
-          // Record stats
-          this.mg
-            .stats()
-            .boatArriveTroops(this.attacker, this.target, survivors);
-          if (deaths) {
-            this.mg.displayMessage(
-              `Attack cancelled, ${renderTroops(deaths)} soldiers killed during retreat.`,
-              MessageType.ATTACK_CANCELLED,
-              this.attacker.id(),
-            );
-          }
-          return;
-        }
-        this.attacker.conquer(this.dst);
-        if (this.target.isPlayer() && this.attacker.isFriendly(this.target)) {
-          this.attacker.addTroops(this.boat.troops());
-        } else {
-          this.mg.addExecution(
-            new AttackExecution(
-              this.boat.troops(),
-              this.attacker,
-              this.targetID,
+        // Retreat is just the existing forward path in reverse (hot-path friendly).
+        // Fallback to a recompute only if we can't safely reverse (e.g. path invalidated).
+        if (!this.usingReverseRetreatPath) {
+          const curr = this.boat.tile();
+          const idx = curr === null ? -1 : this.forwardPath.indexOf(curr);
+          if (idx >= 0) {
+            this.path = this.forwardPath.slice(0, idx + 1).reverse();
+            this.pathIndex = 0;
+            this.usingReverseRetreatPath = true;
+          } else {
+            const retreatPath = boatPathFromTileToShore(
+              this.mg,
+              curr!,
               this.dst,
-              false,
-            ),
-          );
+            );
+            if (retreatPath !== null) {
+              this.path = retreatPath;
+              this.pathIndex = 0;
+              this.usingReverseRetreatPath = true;
+            }
+          }
         }
-        this.boat.delete(false);
-        this.active = false;
-
-        // Record stats
-        this.mg
-          .stats()
-          .boatArriveTroops(this.attacker, this.target, this.boat.troops());
-        return;
-      case PathFindResultType.NextTile:
-        this.boat.move(result.node);
-        break;
-      case PathFindResultType.Pending:
-        break;
-      case PathFindResultType.PathNotFound:
-        // TODO: add to poisoned port list
-        console.warn(`path not found to dst`);
-        this.attacker.addTroops(this.boat.troops());
-        this.boat.delete(false);
-        this.active = false;
-        return;
+      }
+    } else {
+      this.usingReverseRetreatPath = false;
     }
+
+    if (this.path.length === 0 || this.pathIndex >= this.path.length - 1) {
+      // Treat as arrived; should be rare (e.g. src==dst edge).
+      this.finish();
+      return;
+    }
+
+    const next = this.path[this.pathIndex + 1];
+    if (next === undefined) {
+      this.finish();
+      return;
+    }
+    this.boat.move(next);
+    this.pathIndex++;
+
+    if (this.dst !== null && next === this.dst) {
+      this.finish();
+      return;
+    }
+  }
+
+  private finish() {
+    if (this.dst === null) {
+      this.active = false;
+      return;
+    }
+
+    if (this.mg.owner(this.dst) === this.attacker) {
+      const deaths = this.boat.troops() * (malusForRetreat / 100);
+      const survivors = this.boat.troops() - deaths;
+      this.attacker.addTroops(survivors);
+      this.boat.delete(false);
+      this.active = false;
+
+      this.mg.stats().boatArriveTroops(this.attacker, this.target, survivors);
+      if (deaths) {
+        this.mg.displayMessage(
+          `Attack cancelled, ${renderTroops(deaths)} soldiers killed during retreat.`,
+          MessageType.ATTACK_CANCELLED,
+          this.attacker.id(),
+        );
+      }
+      return;
+    }
+
+    this.attacker.conquer(this.dst);
+    if (this.target.isPlayer() && this.attacker.isFriendly(this.target)) {
+      this.attacker.addTroops(this.boat.troops());
+    } else {
+      this.mg.addExecution(
+        new AttackExecution(
+          this.boat.troops(),
+          this.attacker,
+          this.targetID,
+          this.dst,
+          false,
+        ),
+      );
+    }
+    this.boat.delete(false);
+    this.active = false;
+
+    this.mg.stats().boatArriveTroops(this.attacker, this.target, this.boat.troops());
   }
 
   owner(): Player {
diff --git a/src/core/game/TransportShipUtils.ts b/src/core/game/TransportShipUtils.ts
index a0af53526..d7b190e49 100644
--- a/src/core/game/TransportShipUtils.ts
+++ b/src/core/game/TransportShipUtils.ts
@@ -1,8 +1,260 @@
-import { PathFindResultType } from "../pathfinding/AStar";
-import { MiniAStar } from "../pathfinding/MiniAStar";
+import { MultiSourceAnyTargetBFS } from "../pathfinding/MultiSourceAnyTargetBFS";
 import { Game, Player, UnitType } from "./Game";
 import { andFN, GameMap, manhattanDistFN, TileRef } from "./GameMap";
 
+type BoatRoute = {
+  src: TileRef;
+  dst: TileRef;
+  path: TileRef[];
+};
+
+let boatBfs: MultiSourceAnyTargetBFS | null = null;
+let boatBfsNumTiles = 0;
+function getBoatBfs(gm: GameMap): MultiSourceAnyTargetBFS {
+  const numTiles = gm.width() * gm.height();
+  if (boatBfs === null || boatBfsNumTiles !== numTiles) {
+    boatBfs = new MultiSourceAnyTargetBFS(numTiles);
+    boatBfsNumTiles = numTiles;
+  }
+  return boatBfs;
+}
+
+function insertTopK(
+  items: { tile: TileRef; dist: number }[],
+  tile: TileRef,
+  dist: number,
+  k: number,
+) {
+  if (items.length === 0) {
+    items.push({ tile, dist });
+    return;
+  }
+  if (items.length === k && dist >= items[items.length - 1]!.dist) {
+    return;
+  }
+  let i = items.length;
+  items.push({ tile, dist });
+  while (i > 0 && items[i - 1]!.dist > dist) {
+    items[i] = items[i - 1]!;
+    i--;
+  }
+  items[i] = { tile, dist };
+  if (items.length > k) items.pop();
+}
+
+function shoreTargetsNearClick(
+  gm: Game,
+  attacker: Player,
+  click: TileRef,
+  targetOwner: Player | ReturnType<Game["terraNullius"]>,
+  maxTargets: number,
+  scanRadiusTN: number,
+): TileRef[] {
+  // Explicit target: if user clicks a shore tile, use that exact shore.
+  if (gm.isShore(click) && gm.owner(click) !== attacker) {
+    const owner = gm.owner(click);
+    if (!owner.isPlayer() || !attacker.isFriendly(owner)) {
+      return [click];
+    }
+    return [];
+  }
+
+  // Water click: search a larger area but return only the closest shore tile.
+  // This prevents "snapping" to far-away shores while still being usable on open water.
+  if (gm.isWater(click)) {
+    const cx = gm.x(click);
+    const cy = gm.y(click);
+    const r = 50;
+    let best: TileRef | null = null;
+    let bestDist = Infinity;
+    for (let y = cy - r; y <= cy + r; y++) {
+      for (let x = cx - r; x <= cx + r; x++) {
+        if (!gm.isValidCoord(x, y)) continue;
+        const tile = gm.ref(x, y);
+        if (!gm.isShore(tile)) continue;
+        const owner = gm.owner(tile);
+        if (owner === attacker) continue;
+        if (owner.isPlayer() && attacker.isFriendly(owner)) continue;
+        const dist = Math.abs(x - cx) + Math.abs(y - cy);
+        if (dist < bestDist) {
+          bestDist = dist;
+          best = tile;
+        }
+      }
+    }
+    return best === null ? [] : [best];
+  }
+
+  // Default behavior: scan a bounding box near the click for candidate shore tiles.
+  // (Previously, player targets used all border tiles, which could pick very distant shores.)
+  const top: { tile: TileRef; dist: number }[] = [];
+  const cx = gm.x(click);
+  const cy = gm.y(click);
+  const r = scanRadiusTN;
+  for (let y = cy - r; y <= cy + r; y++) {
+    for (let x = cx - r; x <= cx + r; x++) {
+      if (!gm.isValidCoord(x, y)) continue;
+      const tile = gm.ref(x, y);
+      if (!gm.isShore(tile)) continue;
+
+      if (targetOwner.isPlayer()) {
+        if (gm.owner(tile) !== targetOwner) continue;
+      } else {
+        if (gm.hasOwner(tile)) continue;
+      }
+
+      if (gm.owner(tile) === attacker) continue;
+      const dist = Math.abs(x - cx) + Math.abs(y - cy);
+      insertTopK(top, tile, dist, maxTargets);
+    }
+  }
+  return top.map((x) => x.tile);
+}
+
+function adjacentWaterTiles(gm: GameMap, shore: TileRef): TileRef[] {
+  const out: TileRef[] = [];
+  for (const n of gm.neighbors(shore)) {
+    if (gm.isWater(n)) out.push(n);
+  }
+  return out;
+}
+
+function pickLandingForTargetWater(
+  gm: GameMap,
+  click: TileRef,
+  targetWater: TileRef,
+  targetShores: readonly TileRef[],
+): TileRef | null {
+  // targetShores are already sorted by closeness to click; first adjacency wins.
+  for (const shore of targetShores) {
+    for (const n of gm.neighbors(shore)) {
+      if (n === targetWater) return shore;
+    }
+  }
+  // Fallback: should not happen if targetWater was built from these shores.
+  let best: TileRef | null = null;
+  let bestDist = Infinity;
+  for (const shore of targetShores) {
+    if (!gm.neighbors(shore).some((n) => gm.isWater(n))) continue;
+    const d = gm.manhattanDist(click, shore);
+    if (d < bestDist) {
+      bestDist = d;
+      best = shore;
+    }
+  }
+  return best;
+}
+
+export function boatPathFromTileToShore(
+  gm: GameMap,
+  startTile: TileRef,
+  dstShore: TileRef,
+): TileRef[] | null {
+  if (!gm.isValidRef(startTile) || !gm.isValidRef(dstShore)) return null;
+  if (!gm.isShore(dstShore)) return null;
+
+  const targetWater = adjacentWaterTiles(gm, dstShore);
+  if (targetWater.length === 0) return null;
+
+  const bfs = getBoatBfs(gm);
+
+  let seedNodes: TileRef[] = [];
+  let seedOrigins: TileRef[] = [];
+  if (gm.isWater(startTile)) {
+    seedNodes = [startTile];
+    seedOrigins = [startTile];
+  } else if (gm.isShore(startTile)) {
+    const adj = adjacentWaterTiles(gm, startTile);
+    if (adj.length === 0) return null;
+    seedNodes = adj;
+    seedOrigins = adj.map(() => startTile);
+  } else {
+    return null;
+  }
+
+  const result = bfs.findWaterPathFromSeeds(gm, seedNodes, seedOrigins, targetWater, {
+    kingMoves: true,
+    noCornerCutting: true,
+    maxVisited: 300_000,
+  });
+  if (result === null) return null;
+
+  if (gm.isWater(startTile)) {
+    return [...result.path, dstShore];
+  }
+  return [startTile, ...result.path, dstShore];
+}
+
+export function bestTransportShipRoute(
+  gm: Game,
+  attacker: Player,
+  clickTile: TileRef,
+  preferredSrc: TileRef | null = null,
+  maxTargetShores = 96,
+): BoatRoute | false {
+  const other = gm.owner(clickTile);
+  if (other === attacker) return false;
+  if (other.isPlayer() && attacker.isFriendly(other)) return false;
+
+  const targetShores = shoreTargetsNearClick(
+    gm,
+    attacker,
+    clickTile,
+    other,
+    maxTargetShores,
+    10,
+  );
+  if (targetShores.length === 0) return false;
+
+  const targetWater: TileRef[] = [];
+  for (const shore of targetShores) {
+    targetWater.push(...adjacentWaterTiles(gm, shore));
+  }
+  if (targetWater.length === 0) return false;
+
+  const sourceShores: TileRef[] =
+    preferredSrc !== null && gm.isValidRef(preferredSrc)
+      ? [preferredSrc]
+      : candidateShoreTiles(gm, attacker, clickTile);
+
+  const seedNodeToOrigin = new Map<TileRef, TileRef>();
+  for (const shore of sourceShores) {
+    if (!gm.isValidRef(shore)) continue;
+    if (gm.owner(shore) !== attacker) continue;
+    if (!gm.isShore(shore)) continue;
+    for (const w of adjacentWaterTiles(gm, shore)) {
+      if (!seedNodeToOrigin.has(w)) {
+        seedNodeToOrigin.set(w, shore);
+      }
+    }
+  }
+  if (seedNodeToOrigin.size === 0) return false;
+
+  const seedNodes: TileRef[] = [];
+  const seedOrigins: TileRef[] = [];
+  for (const [node, origin] of seedNodeToOrigin.entries()) {
+    seedNodes.push(node);
+    seedOrigins.push(origin);
+  }
+
+  const bfs = getBoatBfs(gm);
+  const result = bfs.findWaterPathFromSeeds(gm, seedNodes, seedOrigins, targetWater, {
+    kingMoves: true,
+    noCornerCutting: true,
+    // Hard budget to avoid pathological cases; tweak as needed.
+    maxVisited: 300_000,
+  });
+  if (result === null) return false;
+
+  const dst = pickLandingForTargetWater(gm, clickTile, result.target, targetShores);
+  if (dst === null) return false;
+
+  const src = result.source;
+  // Full route includes the shore endpoints to drive unit movement.
+  const path = [src, ...result.path, dst];
+  return { src, dst, path };
+}
+
 export function canBuildTransportShip(
   game: Game,
   player: Player,
@@ -144,32 +396,9 @@ export function bestShoreDeploymentSource(
   player: Player,
   target: TileRef,
 ): TileRef | false {
-  const t = targetTransportTile(gm, target);
-  if (t === null) return false;
-
-  const candidates = candidateShoreTiles(gm, player, t);
-  if (candidates.length === 0) return false;
-
-  const aStar = new MiniAStar(gm, gm.miniMap(), candidates, t, 1_000_000, 1);
-  const result = aStar.compute();
-  if (result !== PathFindResultType.Completed) {
-    console.warn(`bestShoreDeploymentSource: path not found: ${result}`);
-    return false;
-  }
-  const path = aStar.reconstructPath();
-  if (path.length === 0) {
-    return false;
-  }
-  const potential = path[0];
-  // Since mini a* downscales the map, we need to check the neighbors
-  // of the potential tile to find a valid deployment point
-  const neighbors = gm
-    .neighbors(potential)
-    .filter((n) => gm.isShore(n) && gm.owner(n) === player);
-  if (neighbors.length === 0) {
-    return false;
-  }
-  return neighbors[0];
+  const route = bestTransportShipRoute(gm, player, target, null);
+  if (route === false) return false;
+  return route.src;
 }
 
 export function candidateShoreTiles(
diff --git a/src/core/pathfinding/MultiSourceAnyTargetBFS.ts b/src/core/pathfinding/MultiSourceAnyTargetBFS.ts
index 70f1778e4..144381972 100644
--- a/src/core/pathfinding/MultiSourceAnyTargetBFS.ts
+++ b/src/core/pathfinding/MultiSourceAnyTargetBFS.ts
@@ -41,7 +41,17 @@ export class MultiSourceAnyTargetBFS {
     targets: readonly TileRef[],
     opts: MultiSourceAnyTargetBFSOptions = {},
   ): MultiSourceAnyTargetBFSResult | null {
-    if (sources.length === 0 || targets.length === 0) return null;
+    return this.findWaterPathFromSeeds(gm, sources, sources, targets, opts);
+  }
+
+  findWaterPathFromSeeds(
+    gm: GameMap,
+    seedNodes: readonly TileRef[],
+    seedOrigins: readonly TileRef[],
+    targets: readonly TileRef[],
+    opts: MultiSourceAnyTargetBFSOptions = {},
+  ): MultiSourceAnyTargetBFSResult | null {
+    if (seedNodes.length === 0 || targets.length === 0) return null;
 
     const stamp = this.nextStamp();
 
@@ -58,14 +68,17 @@ export class MultiSourceAnyTargetBFS {
     let head = 0;
     let tail = 0;
 
-    for (const s of sources) {
-      if (s < 0 || s >= this.visitedStamp.length) continue;
-      if (!gm.isWater(s)) continue;
-      if (this.visitedStamp[s] === stamp) continue;
-      this.visitedStamp[s] = stamp;
-      this.prev[s] = -1;
-      this.startOf[s] = s;
-      this.queue[tail++] = s;
+    const count = Math.min(seedNodes.length, seedOrigins.length);
+    for (let i = 0; i < count; i++) {
+      const node = seedNodes[i]!;
+      const origin = seedOrigins[i]!;
+      if (node < 0 || node >= this.visitedStamp.length) continue;
+      if (!gm.isWater(node)) continue;
+      if (this.visitedStamp[node] === stamp) continue;
+      this.visitedStamp[node] = stamp;
+      this.prev[node] = -1;
+      this.startOf[node] = origin;
+      this.queue[tail++] = node;
     }
 
     if (tail === 0) return null;
@@ -94,7 +107,7 @@ export class MultiSourceAnyTargetBFS {
         if (gm.isWater(n) && this.visitedStamp[n] !== stamp) {
           this.visit(n, node, stamp);
           this.queue[tail++] = n;
-          if (++visitedCount >= maxVisited) return null;
+          if (++visitedCount > maxVisited) return null;
         }
       }
       if (node < lastRowStart) {
@@ -102,7 +115,7 @@ export class MultiSourceAnyTargetBFS {
         if (gm.isWater(s) && this.visitedStamp[s] !== stamp) {
           this.visit(s, node, stamp);
           this.queue[tail++] = s;
-          if (++visitedCount >= maxVisited) return null;
+          if (++visitedCount > maxVisited) return null;
         }
       }
       if (x !== 0) {
@@ -110,7 +123,7 @@ export class MultiSourceAnyTargetBFS {
         if (gm.isWater(wv) && this.visitedStamp[wv] !== stamp) {
           this.visit(wv, node, stamp);
           this.queue[tail++] = wv;
-          if (++visitedCount >= maxVisited) return null;
+          if (++visitedCount > maxVisited) return null;
         }
       }
       if (x !== w - 1) {
@@ -118,7 +131,7 @@ export class MultiSourceAnyTargetBFS {
         if (gm.isWater(ev) && this.visitedStamp[ev] !== stamp) {
           this.visit(ev, node, stamp);
           this.queue[tail++] = ev;
-          if (++visitedCount >= maxVisited) return null;
+          if (++visitedCount > maxVisited) return null;
         }
       }
 
@@ -134,7 +147,7 @@ export class MultiSourceAnyTargetBFS {
         ) {
           this.visit(nw, node, stamp);
           this.queue[tail++] = nw;
-          if (++visitedCount >= maxVisited) return null;
+          if (++visitedCount > maxVisited) return null;
         }
       }
       if (node >= w && x !== w - 1) {
@@ -146,7 +159,7 @@ export class MultiSourceAnyTargetBFS {
         ) {
           this.visit(ne, node, stamp);
           this.queue[tail++] = ne;
-          if (++visitedCount >= maxVisited) return null;
+          if (++visitedCount > maxVisited) return null;
         }
       }
       if (node < lastRowStart && x !== 0) {
@@ -158,7 +171,7 @@ export class MultiSourceAnyTargetBFS {
         ) {
           this.visit(sw, node, stamp);
           this.queue[tail++] = sw;
-          if (++visitedCount >= maxVisited) return null;
+          if (++visitedCount > maxVisited) return null;
         }
       }
       if (node < lastRowStart && x !== w - 1) {
@@ -170,7 +183,7 @@ export class MultiSourceAnyTargetBFS {
         ) {
           this.visit(se, node, stamp);
           this.queue[tail++] = se;
-          if (++visitedCount >= maxVisited) return null;
+          if (++visitedCount > maxVisited) return null;
         }
       }
     }
@@ -201,4 +214,3 @@ export class MultiSourceAnyTargetBFS {
     return this.stamp;
   }
 }
-