dflike/server/src/systems/npcBrainSystem.ts

import {
  HUNGER_THRESHOLD, ENERGY_THRESHOLD, PRODUCTIVITY_THRESHOLD, Direction,
  type GoalType, type Needs, type Movement, type NPCBrain, type Position, type SocialState,
} from '@dflike/shared';
import type { World } from '../ecs/World.js';
import type { GameMap } from '../map/GameMap.js';
import { findPath } from '../map/pathfinding.js';
import type { EventMemoryService } from '../llm/eventMemoryService.js';

function findNearestResource(map: GameMap, from: Position): Position | null {
  const tiles = map.resourceTiles;
  if (tiles.length === 0) return null;
  let best = tiles[0];
  let bestDist = Math.abs(from.x - best.x) + Math.abs(from.y - best.y);
  for (let i = 1; i < tiles.length; i++) {
    const d = Math.abs(from.x - tiles[i].x) + Math.abs(from.y - tiles[i].y);
    if (d < bestDist) { best = tiles[i]; bestDist = d; }
  }
  return { x: best.x, y: best.y };
}

function closestPOI(map: GameMap, from: Position, type: 'food' | 'rest'): Position | null {
  const pois = map.getPointsOfInterest(type);
  if (pois.length === 0) return null;
  let best = pois[0].position;
  let bestDist = Math.abs(from.x - best.x) + Math.abs(from.y - best.y);
  for (let i = 1; i < pois.length; i++) {
    const d = Math.abs(from.x - pois[i].position.x) + Math.abs(from.y - pois[i].position.y);
    if (d < bestDist) { best = pois[i].position; bestDist = d; }
  }
  return best;
}

function directionTo(from: Position, to: Position): number {
  const dx = to.x - from.x;
  const dy = to.y - from.y;
  if (Math.abs(dx) > Math.abs(dy)) return dx > 0 ? Direction.RIGHT : Direction.LEFT;
  return dy > 0 ? Direction.DOWN : Direction.UP;
}

export function npcBrainSystem(world: World, map: GameMap, eventMemoryService?: EventMemoryService): void {
  for (const entity of world.query('npcBrain', 'needs', 'movement', 'position')) {
    const brain = world.getComponent<NPCBrain>(entity, 'npcBrain')!;
    const needs = world.getComponent<Needs>(entity, 'needs')!;
    const movement = world.getComponent<Movement>(entity, 'movement')!;
    const pos = world.getComponent<Position>(entity, 'position')!;

    const socialState = world.getComponent<SocialState>(entity, 'socialState');
    if (socialState && socialState.phase !== 'none') continue;

    // Skip if currently walking toward a goal
    if (movement.state === 'walking' && movement.path.length > 0) continue;

    // Check if at goal destination — recover needs
    if (brain.currentGoal === 'eat' && movement.state === 'idle') {
      const prevHunger = needs.hunger;
      needs.hunger = Math.min(100, needs.hunger + 20);
      if (eventMemoryService && prevHunger < HUNGER_THRESHOLD && needs.hunger >= HUNGER_THRESHOLD) {
        const name = world.getComponent<string>(entity, 'name') ?? 'Unknown';
        eventMemoryService.record(entity, {
          type: 'need_recovery',
          tick: 0,
          need: 'hunger',
          detail: `${name} satisfied their hunger`,
        });
      }
      brain.currentGoal = null;
    }
    if (brain.currentGoal === 'rest' && movement.state === 'idle') {
      const prevEnergy = needs.energy;
      needs.energy = Math.min(100, needs.energy + 20);
      if (eventMemoryService && prevEnergy < ENERGY_THRESHOLD && needs.energy >= ENERGY_THRESHOLD) {
        const name = world.getComponent<string>(entity, 'name') ?? 'Unknown';
        eventMemoryService.record(entity, {
          type: 'need_recovery',
          tick: 0,
          need: 'energy',
          detail: `${name} recovered their energy`,
        });
      }
      brain.currentGoal = null;
    }

    // Determine new goal based on needs priority
    const prevGoal = brain.currentGoal;
    let goal: GoalType = 'wander';
    if (needs.energy < ENERGY_THRESHOLD) goal = 'rest';
    else if (needs.hunger < HUNGER_THRESHOLD) goal = 'eat';
    else if (needs.productivity < PRODUCTIVITY_THRESHOLD) goal = 'gather';

    brain.currentGoal = goal;

    if (eventMemoryService && brain.currentGoal !== prevGoal && prevGoal !== null) {
      const name = world.getComponent<string>(entity, 'name') ?? 'Unknown';
      const goalLabels: Record<string, string> = { wander: 'wandering', eat: 'looking for food', rest: 'looking for rest', gather: 'looking for resources' };
      eventMemoryService.record(entity, {
        type: 'goal_change',
        tick: 0,
        oldGoal: prevGoal,
        newGoal: brain.currentGoal ?? 'idle',
        detail: `${name} started ${goalLabels[brain.currentGoal ?? ''] ?? brain.currentGoal}`,
      });
    }

    // Pick target based on goal
    let target: Position | null = null;
    if (goal === 'eat') {
      target = closestPOI(map, pos, 'food');
    } else if (goal === 'rest') {
      target = closestPOI(map, pos, 'rest');
    } else if (goal === 'gather') {
      target = findNearestResource(map, pos);
      if (!target) {
        goal = 'wander';
        brain.currentGoal = 'wander';
      }
    }
    if (!target) {
      target = map.getRandomWalkable();
    }

    // Pathfind to target
    const path = findPath(map, pos, target);
    if (path && path.length > 0) {
      movement.state = 'walking';
      movement.target = target;
      movement.path = path;
      movement.direction = directionTo(pos, path[0]);
    }
  }
}