nEngine/examples/sample-game/mods/sample-game-mod/index.mjs

const FISH_STATS_ID = "mod:fish-stats";
const FISH_STAMINA_COST = 5;
const FISH_MIN_STAMINA = 5;

export default {
  manifest: { id: "sample-game-mod", version: "0.1.0" },
  hooks: {
    onDayStart(ctx) {
      const { world, time, emit } = ctx;
      const { day, season } = time.get();

      let stats = world.get("mod:sample-stats");
      if (!stats) {
        stats = world.create({ id: "mod:sample-stats", type: "mod-state", greetings: 0 });
      }
      stats.greetings += 1;

      let mayor = world.get("npc:mayor");
      if (!mayor) {
        mayor = world.create({
          id: "npc:mayor",
          type: "npc",
          x: 6,
          y: 3,
          name: "Mayor",
          label: "Mayor",
          dialogue: "mayor",
        });
      }

      const routineState = world.get("sm:mayor-routine")?.state ?? "sleeping";
      const walkX = routineState === "market-day" ? 12 : 6;
      const walkY = 3 + (day % 4);
      mayor.x = walkX;
      mayor.y = walkY;

      // Mia the merchant arrives once the mayor-talk-quest is complete — the
      // restoration arc's second NPC (content/dialogues/mia.yaml). Gated so she
      // never appears before the starter arc's day-2 npc.list assertion.
      const player = world.get("player");
      const miaUnlocked = player?.questProgress?.["mayor-talk-quest"] === "complete";
      let mia = world.get("npc:mia");
      if (miaUnlocked) {
        const miaX = 14 + (day % 3);
        const miaY = 11;
        if (!mia) {
          mia = world.create({
            id: "npc:mia",
            type: "npc",
            x: miaX,
            y: miaY,
            name: "Mia",
            label: "Mia",
            dialogue: "mia",
          });
        } else {
          mia.x = miaX;
          mia.y = miaY;
        }
      }

      const weather = world.get("weather")?.weatherId ?? "unknown";

      emit("mod:sample-day-start", {
        modId: "sample-game-mod",
        day,
        season,
        weather,
        greetings: stats.greetings,
        mayor: { x: walkX, y: walkY },
      });
    },

    onPlayerIntent(ctx) {
      const intent = ctx.payload;
      if (!intent || typeof intent !== "object") return;
      if (intent.action !== "interact" || intent.ok !== true) return;
      const tile = intent.tile;
      if (!tile || typeof tile.x !== "number" || typeof tile.y !== "number") return;
      if (!isWaterTile(ctx, tile.x, tile.y)) return;

      const player = ctx.world.get("player");
      if (!player) return;
      const stamina = typeof player.stamina === "number" ? player.stamina : 100;
      const day = ctx.time.get().day;

      if (stamina < FISH_MIN_STAMINA) {
        ctx.emit("mod:fish-too-tired", { x: tile.x, y: tile.y, stamina, day });
        return;
      }

      const inventory = isRecord(player.inventory) ? player.inventory : {};
      player.inventory = inventory;
      const total = (inventory.fish ?? 0) + 1;
      inventory.fish = total;

      player.stamina = stamina - FISH_STAMINA_COST;
      const skills = isRecord(player.skills) ? player.skills : {};
      player.skills = skills;
      skills.fishing = (skills.fishing ?? 0) + 1;

      const stats = fishStats(ctx);
      stats.catches += 1;

      ctx.emit("item-acquire", { itemId: "fish", qty: 1, total });
      ctx.emit("mod:fish-caught", {
        fish: "fish",
        size: 1 + ((stats.catches - 1) % 3),
        x: tile.x,
        y: tile.y,
        stamina: player.stamina,
        catches: stats.catches,
        day,
      });

      ctx.world.remove(`plot:${tile.x}:${tile.y}`);
    },
  },
};

function isWaterTile(ctx, x, y) {
  const map = ctx.world.query({ type: "map" })[0];
  if (!map) return false;
  const layers = Array.isArray(map.layers) ? map.layers : [];
  const layer = layers.find((candidate) => candidate.name === "ground") ?? layers[0];
  if (!layer || !Array.isArray(layer.data)) return false;
  return layer.data[y]?.[x] === "water";
}

function fishStats(ctx) {
  let stats = ctx.world.get(FISH_STATS_ID);
  if (!stats) {
    stats = ctx.world.create({ id: FISH_STATS_ID, type: "mod-state", catches: 0 });
  }
  return stats;
}

function isRecord(value) {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}