nEngine/packages/mcp/test/placement-namespace.test.ts

import { mkdtemp, mkdir, readFile, rm, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { describe, expect, it } from "vitest";
import { createEngine, type BuildingDef } from "@nengine/core";
import { createEngineNamespaces, McpGateway } from "../src/index.js";

const TIME_YAML = [
  "id: default",
  "dayLengthTicks: 480",
  "seasons:",
  "  - { name: spring, dayCount: 28 }",
  "start: { day: 1, season: spring }",
  "",
].join("\n");

const FARM_YAML = [
  "id: farm",
  "width: 5",
  "height: 5",
  'tilesetRef: "tiles"',
  "spawn: { x: 0, y: 0 }",
  "layers:",
  "  - name: ground",
  "    data:",
  "      - [grass, grass, water, water, water]",
  "      - [grass, grass, water, water, water]",
  "      - [grass, grass, grass, grass, grass]",
  "      - [tilled, tilled, grass, grass, grass]",
  "      - [tilled, tilled, grass, grass, grass]",
  "",
].join("\n");

const SHED_YAML = [
  "id: shed",
  "name: Shed",
  "footprint: { w: 2, h: 2 }",
  "buildable: map",
  "blocksMovement: true",
  'description: "Stores tools and harvests."',
  "",
].join("\n");

const FENCE_YAML = [
  "id: fence",
  "name: Fence",
  "footprint: { w: 1, h: 1 }",
  "buildable: { tiles: [grass] }",
  "blocksMovement: true",
  "",
].join("\n");

const BARN_DEF = {
  id: "barn",
  name: "Barn",
  footprint: { w: 3, h: 2 },
  buildable: { tiles: ["grass"] },
  blocksMovement: true,
  description: "Houses animals.",
};

interface Setup {
  engine: ReturnType<typeof createEngine>;
  gateway: McpGateway;
  tmp: string;
  close: () => Promise<void>;
}

async function setup(): Promise<Setup> {
  const tmp = await mkdtemp(join(tmpdir(), "farm-placement-ns-"));
  await mkdir(join(tmp, "maps"), { recursive: true });
  await mkdir(join(tmp, "buildings"), { recursive: true });
  await writeFile(join(tmp, "time.yaml"), TIME_YAML);
  await writeFile(join(tmp, "maps", "farm.yaml"), FARM_YAML);
  await writeFile(join(tmp, "buildings", "shed.yaml"), SHED_YAML);
  await writeFile(join(tmp, "buildings", "fence.yaml"), FENCE_YAML);

  const engine = createEngine({ contentDir: tmp });
  const gateway = new McpGateway();
  for (const namespace of createEngineNamespaces(engine, { gateway })) {
    gateway.register(namespace);
  }
  await engine.start();
  return {
    engine,
    gateway,
    tmp,
    close: async () => {
      await engine.stop();
      await rm(tmp, { recursive: true, force: true });
    },
  };
}

async function callText(gateway: McpGateway, name: string, args: Record<string, unknown> = {}): Promise<{
  ok: boolean;
  text: string;
}> {
  const result = await gateway.callTool(name, args);
  return { ok: result.isError !== true, text: result.content[0]?.text ?? "" };
}

describe("placement namespace", () => {
  it("building.create writes content/buildings/<id>.yaml, registers live, and persists across restart", async () => {
    const { engine, gateway, tmp, close } = await setup();
    try {
      const created = await callText(gateway, "placement.building.create", { def: BARN_DEF });
      expect(created.ok).toBe(true);
      expect(JSON.parse(created.text) as BuildingDef).toEqual(BARN_DEF);

      expect(engine.registry.get<BuildingDef>("building", "barn")).toEqual(BARN_DEF);

      const file = await readFile(join(tmp, "buildings", "barn.yaml"), "utf8");
      expect(file).toContain("id: barn");
      expect(file).toContain("blocksMovement: true");

      await engine.stop();
      const reloaded = createEngine({ contentDir: tmp });
      await reloaded.start();
      try {
        expect(reloaded.registry.get<BuildingDef>("building", "barn")).toEqual(BARN_DEF);
      } finally {
        await reloaded.stop();
      }
    } finally {
      await close();
    }
  });

  it("building.validate accepts a valid def and rejects an invalid one", async () => {
    const { gateway, close } = await setup();
    try {
      const valid = await callText(gateway, "placement.building.validate", { def: BARN_DEF });
      expect(valid.ok).toBe(true);
      expect(JSON.parse(valid.text)).toEqual(BARN_DEF);

      const invalid = await callText(gateway, "placement.building.validate", {
        def: { id: "nope", footprint: { w: 0, h: 1 }, buildable: "map", blocksMovement: true },
      });
      expect(invalid.ok).toBe(false);
      expect(invalid.text).toMatch(/footprint/);
    } finally {
      await close();
    }
  });

  it("placement.building.create rejects an invalid def and does not write or register", async () => {
    const { engine, gateway, tmp, close } = await setup();
    try {
      const bad = await callText(gateway, "placement.building.create", {
        def: { id: "broken", footprint: { w: 1, h: 1 }, buildable: { tiles: [] }, blocksMovement: true },
      });
      expect(bad.ok).toBe(false);
      expect(engine.registry.get("building", "broken")).toBeUndefined();
      await expect(readFile(join(tmp, "buildings", "broken.yaml"))).rejects.toThrow();
    } finally {
      await close();
    }
  });

  it("building.update merges a patch, validates, rewrites the file, and re-registers", async () => {
    const { engine, gateway, tmp, close } = await setup();
    try {
      const updated = await callText(gateway, "placement.building.update", {
        id: "fence",
        patch: { description: "A sturdy fence post." },
      });
      expect(updated.ok).toBe(true);
      const def = JSON.parse(updated.text) as BuildingDef;
      expect(def.description).toBe("A sturdy fence post.");
      expect(def.blocksMovement).toBe(true);

      const file = await readFile(join(tmp, "buildings", "fence.yaml"), "utf8");
      expect(file).toContain("A sturdy fence post.");

      const missing = await callText(gateway, "placement.building.update", {
        id: "nope",
        patch: { blocksMovement: false },
      });
      expect(missing.ok).toBe(false);
      expect(missing.text).toMatch(/building not found: nope/);

      const badPatch = await callText(gateway, "placement.building.update", {
        id: "fence",
        patch: { footprint: { w: 0, h: 1 } },
      });
      expect(badPatch.ok).toBe(false);
      expect(badPatch.text).toMatch(/footprint/);
      expect(engine.registry.get<BuildingDef>("building", "fence")?.description).toBe("A sturdy fence post.");
    } finally {
      await close();
    }
  });

  it("building.list returns one-line summaries and building.get the full def", async () => {
    const { gateway, close } = await setup();
    try {
      const listed = await callText(gateway, "placement.building.list");
      expect(listed.ok).toBe(true);
      expect(JSON.parse(listed.text)).toEqual({
        buildings: [
          { id: "fence", name: "Fence", w: 1, h: 1, blocksMovement: true },
          { id: "shed", name: "Shed", w: 2, h: 2, blocksMovement: true },
        ],
      });

      const got = await callText(gateway, "placement.building.get", { buildingId: "shed" });
      expect(got.ok).toBe(true);
      expect(JSON.parse(got.text)).toMatchObject({ id: "shed", footprint: { w: 2, h: 2 } });

      const missing = await callText(gateway, "placement.building.get", { buildingId: "nope" });
      expect(missing.ok).toBe(false);
      expect(missing.text).toMatch(/building not found: nope/);
    } finally {
      await close();
    }
  });

  it("placement.place creates a placed entity and placement.list/occupies/remove roundtrip", async () => {
    const { gateway, close } = await setup();
    try {
      const placed = await callText(gateway, "placement.place", { buildingId: "shed", x: 3, y: 3 });
      expect(placed.ok).toBe(true);
      expect(JSON.parse(placed.text)).toEqual({
        id: "building:shed:3:3",
        type: "building",
        buildingId: "shed",
        x: 3,
        y: 3,
        w: 2,
        h: 2,
        blocksMovement: true,
      });

      const listed = await callText(gateway, "placement.list");
      expect(JSON.parse(listed.text)).toEqual({
        buildings: [{ id: "building:shed:3:3", type: "building", buildingId: "shed", x: 3, y: 3, w: 2, h: 2, blocksMovement: true }],
      });

      const inside = await callText(gateway, "placement.occupies", { x: 4, y: 4 });
      expect(JSON.parse(inside.text)).toMatchObject({ id: "building:shed:3:3" });
      const outside = await callText(gateway, "placement.occupies", { x: 0, y: 0 });
      expect(JSON.parse(outside.text)).toBeNull();

      const removed = await callText(gateway, "placement.remove", { x: 3, y: 3 });
      expect(JSON.parse(removed.text)).toMatchObject({ id: "building:shed:3:3" });
      const empty = await callText(gateway, "placement.list");
      expect(JSON.parse(empty.text)).toEqual({ buildings: [] });
    } finally {
      await close();
    }
  });

  it("placement.place error paths: unknown building, out of bounds, unbuildable tile, overlap", async () => {
    const { gateway, close } = await setup();
    try {
      const unknown = await callText(gateway, "placement.place", { buildingId: "barn", x: 0, y: 0 });
      expect(unknown.ok).toBe(false);
      expect(unknown.text).toMatch(/unknown building: barn/);

      const bounds = await callText(gateway, "placement.place", { buildingId: "shed", x: 4, y: 4 });
      expect(bounds.ok).toBe(false);
      expect(bounds.text).toMatch(/footprint out of bounds/);

      const tile = await callText(gateway, "placement.place", { buildingId: "fence", x: 2, y: 0 });
      expect(tile.ok).toBe(false);
      expect(tile.text).toMatch(/tile \(2,0\) is not buildable for fence/);

      await callText(gateway, "placement.place", { buildingId: "fence", x: 0, y: 0 });
      const overlap = await callText(gateway, "placement.place", { buildingId: "fence", x: 0, y: 0 });
      expect(overlap.ok).toBe(false);
      expect(overlap.text).toMatch(/overlaps existing building/);

      const badCoord = await callText(gateway, "placement.place", { buildingId: "fence", x: -1, y: 0 });
      expect(badCoord.ok).toBe(false);
      expect(badCoord.text).toMatch(/non-negative integers/);
    } finally {
      await close();
    }
  });

  it("resources: placement://buildings, placement://{id}, placement://placed", async () => {
    const { gateway, close } = await setup();
    try {
      const catalog = await gateway.readResource("placement://buildings");
      const defs = JSON.parse(catalog.contents[0]?.text ?? "{}");
      expect(defs.buildings.map((building: { id: string }) => building.id)).toEqual(["fence", "shed"]);

      const single = await gateway.readResource("placement://shed");
      expect(JSON.parse(single.contents[0]?.text ?? "{}")).toMatchObject({ id: "shed" });

      await callText(gateway, "placement.place", { buildingId: "fence", x: 0, y: 0 });
      const placed = await gateway.readResource("placement://placed");
      expect(JSON.parse(placed.contents[0]?.text ?? "{}")).toEqual({
        buildings: [{ id: "building:fence:0:0", type: "building", buildingId: "fence", x: 0, y: 0, w: 1, h: 1, blocksMovement: true }],
      });

      await expect(gateway.readResource("placement://missing")).rejects.toThrow(/building not found: missing/);
    } finally {
      await close();
    }
  });

  it("serves the placement.create-prompt prompt", async () => {
    const { gateway, close } = await setup();
    try {
      const prompt = await gateway.getPrompt("placement.create-prompt", {});
      const text = prompt.messages[0]?.content.text ?? "";
      expect(text).toContain("footprint");
      expect(text).toContain("buildable");
      expect(text).toContain("blocksMovement");
      expect(text).toContain("placement.building.validate");
      expect(text).toContain("content/buildings/<id>.yaml");
    } finally {
      await close();
    }
  });
});