import { mkdtemp, mkdir, 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 AnimalDef,
  type AnimalEntity,
  type AnimalProduceEvent,
  type GrowthSystem,
  type SaveSystem,
  type System,
} 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: 2",
  "height: 2",
  'tilesetRef: "tiles"',
  "spawn: { x: 0, y: 0 }",
  "layers:",
  "  - name: ground",
  "    data:",
  "      - [a, b]",
  "      - [b, a]",
  "",
].join("\n");

const CHICKEN_DEF: AnimalDef = {
  id: "chicken",
  stages: [
    { name: "chick", days: 2, feedRequired: false },
    { name: "grown", days: 2, feedRequired: true },
    { name: "laying", days: 1, feedRequired: true },
  ],
  produces: [{ itemId: "egg", qty: 1 }],
};

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

async function setup(spy?: System): Promise<Setup> {
  const tmp = await mkdtemp(join(tmpdir(), "farm-animal-"));
  await mkdir(join(tmp, "maps"), { recursive: true });
  await writeFile(join(tmp, "time.yaml"), TIME_YAML);
  await writeFile(join(tmp, "maps", "farm.yaml"), FARM_YAML);

  const systems: System[] = [];
  if (spy) systems.push(spy);
  const engine = createEngine({ contentDir: tmp, systems });
  await engine.start();
  engine.registry.register("animal", CHICKEN_DEF);
  return {
    engine,
    close: async () => {
      await engine.stop();
      await rm(tmp, { recursive: true, force: true });
    },
  };
}

function growthOf(engine: ReturnType<typeof createEngine>): GrowthSystem {
  const growth = engine.systems.get<GrowthSystem>("growth");
  if (!growth) throw new Error("growth system not booted");
  return growth;
}

function saveOf(engine: ReturnType<typeof createEngine>): SaveSystem {
  const save = engine.systems.get<SaveSystem>("save");
  if (!save) throw new Error("save system not booted");
  return save;
}

function eventSpy(): { system: System; seen: { event: string; payload: unknown }[] } {
  const seen: { event: string; payload: unknown }[] = [];
  const system: System = {
    id: "spy",
    init() {},
    on(event, payload) {
      seen.push({ event, payload });
    },
  };
  return { system, seen };
}

function eventsOf(seen: { event: string; payload: unknown }[], event: string): AnimalProduceEvent[] {
  return seen.filter((entry) => entry.event === event).map((entry) => entry.payload as AnimalProduceEvent);
}

describe("GrowthSystem animals", () => {
  it("spawnAnimal creates an entity at stage 0 with the next available number", async () => {
    const { engine, close } = await setup();
    try {
      const first = growthOf(engine).spawnAnimal("chicken", 3, 3);
      expect(first).toEqual({
        id: "animal:chicken:1",
        type: "animal",
        animalId: "chicken",
        x: 3,
        y: 3,
        stageIndex: 0,
        daysInStage: 0,
        fed: false,
      });
      expect(engine.world.get("animal:chicken:1")).toBeDefined();

      const second = growthOf(engine).spawnAnimal("chicken", 4, 4);
      expect(second.id).toBe("animal:chicken:2");
      expect(engine.world.query({ type: "animal" })).toHaveLength(2);
    } finally {
      await close();
    }
  });

  it("spawnAnimal rejects unknown animal defs and bad coords", async () => {
    const { engine, close } = await setup();
    try {
      const growth = growthOf(engine);
      expect(() => growth.spawnAnimal("cow", 1, 1)).toThrow(/unknown animal def: cow/);
      expect(() => growth.spawnAnimal("chicken", -1, 1)).toThrow(/non-negative integers/);
      expect(() => growth.spawnAnimal("chicken", 1.5, 1)).toThrow(/non-negative integers/);
      expect(engine.world.query({ type: "animal" })).toHaveLength(0);
    } finally {
      await close();
    }
  });

  it("a fed animal advances through stages on day boundaries and emits animal-grow", async () => {
    const { system: spy, seen } = eventSpy();
    const { engine, close } = await setup(spy);
    try {
      const growth = growthOf(engine);
      growth.spawnAnimal("chicken", 3, 3);

      growth.step(480);
      let animal = engine.world.get("animal:chicken:1") as AnimalEntity;
      expect(animal.stageIndex).toBe(0);
      expect(animal.daysInStage).toBe(1);
      expect(eventsOf(seen, "animal-grow")).toHaveLength(0);

      growth.step(480);
      animal = engine.world.get("animal:chicken:1") as AnimalEntity;
      expect(animal.stageIndex).toBe(1);
      expect(animal.daysInStage).toBe(0);
      expect(animal.fed).toBe(false);
      expect(eventsOf(seen, "animal-grow")).toEqual([
        { animalId: "animal:chicken:1", x: 3, y: 3, animalDefId: "chicken", stageIndex: 1, stage: "grown" },
      ]);

      growth.feed("animal:chicken:1");
      growth.step(480);
      growth.feed("animal:chicken:1");
      growth.step(480);
      animal = engine.world.get("animal:chicken:1") as AnimalEntity;
      expect(animal.stageIndex).toBe(2);
      expect(animal.daysInStage).toBe(0);
      expect(eventsOf(seen, "animal-grow").map((e) => e.stageIndex)).toEqual([1, 2]);
    } finally {
      await close();
    }
  });

  it("an un-fed animal on a feedRequired stage does not advance", async () => {
    const { engine, close } = await setup();
    try {
      const growth = growthOf(engine);
      growth.spawnAnimal("chicken", 3, 3);
      growth.step(480);
      growth.step(480);
      expect((engine.world.get("animal:chicken:1") as AnimalEntity).stageIndex).toBe(1);

      for (let day = 0; day < 3; day++) {
        growth.step(480);
      }
      const animal = engine.world.get("animal:chicken:1") as AnimalEntity;
      expect(animal.stageIndex).toBe(1);
      expect(animal.daysInStage).toBe(0);
    } finally {
      await close();
    }
  });

  it("a mature animal produces per eligible day, resets fed, and skips without feeding", async () => {
    const { system: spy, seen } = eventSpy();
    const { engine, close } = await setup(spy);
    try {
      const growth = growthOf(engine);
      growth.spawnAnimal("chicken", 3, 3);
      growth.step(480);
      growth.step(480);
      growth.feed("animal:chicken:1");
      growth.step(480);
      growth.feed("animal:chicken:1");
      growth.step(480);
      expect((engine.world.get("animal:chicken:1") as AnimalEntity).stageIndex).toBe(2);

      growth.feed("animal:chicken:1");
      growth.step(480);
      const produces = eventsOf(seen, "animal-produce");
      expect(produces).toEqual([
        { animalId: "animal:chicken:1", x: 3, y: 3, animalDefId: "chicken", stageIndex: 2, stage: "laying" },
      ]);
      let animal = engine.world.get("animal:chicken:1") as AnimalEntity;
      expect(animal.fed).toBe(false);

      growth.step(480);
      expect(eventsOf(seen, "animal-produce")).toHaveLength(1);
      animal = engine.world.get("animal:chicken:1") as AnimalEntity;
      expect(animal.fed).toBe(false);

      growth.feed("animal:chicken:1");
      growth.step(480);
      expect(eventsOf(seen, "animal-produce")).toHaveLength(2);
    } finally {
      await close();
    }
  });

  it("feed sets fed true and emits animal-fed; unknown entity throws", async () => {
    const { system: spy, seen } = eventSpy();
    const { engine, close } = await setup(spy);
    try {
      const growth = growthOf(engine);
      growth.spawnAnimal("chicken", 3, 3);
      const fed = growth.feed("animal:chicken:1");
      expect(fed.fed).toBe(true);
      expect(eventsOf(seen, "animal-fed")).toEqual([{ animalId: "animal:chicken:1", animalDefId: "chicken" }]);

      expect(() => growth.feed("ghost")).toThrow(/unknown animal: ghost/);
      engine.world.create({ id: "plot:1:1", type: "plot", x: 1, y: 1, tilled: false, watered: false });
      expect(() => growth.feed("plot:1:1")).toThrow(/unknown animal: plot:1:1/);
    } finally {
      await close();
    }
  });

  it("forceAnimalStage jumps an animal and emits animal-grow; rejects bad indices and entities", async () => {
    const { system: spy, seen } = eventSpy();
    const { engine, close } = await setup(spy);
    try {
      const growth = growthOf(engine);
      growth.spawnAnimal("chicken", 3, 3);
      const animal = growth.forceAnimalStage("animal:chicken:1", 2);
      expect(animal.stageIndex).toBe(2);
      expect(animal.daysInStage).toBe(0);
      expect(eventsOf(seen, "animal-grow")).toEqual([
        { animalId: "animal:chicken:1", x: 3, y: 3, animalDefId: "chicken", stageIndex: 2, stage: "laying" },
      ]);

      expect(() => growth.forceAnimalStage("animal:chicken:1", 5)).toThrow(/out of range/);
      expect(() => growth.forceAnimalStage("ghost", 0)).toThrow(/unknown animal: ghost/);
    } finally {
      await close();
    }
  });

  it("onAnimalGrow and onAnimalProduce hooks fire", async () => {
    const { engine, close } = await setup();
    try {
      const grew: string[] = [];
      const produced: string[] = [];
      engine.hooks.on("onAnimalGrow", (ctx) => {
        const animal = ctx.world.query({ type: "animal" })[0] as AnimalEntity | undefined;
        grew.push(`${animal?.animalId}:${animal?.stageIndex ?? -1}`);
      });
      engine.hooks.on("onAnimalProduce", (ctx) => {
        const animal = ctx.world.query({ type: "animal" })[0] as AnimalEntity | undefined;
        produced.push(`${animal?.animalId}:${animal?.stageIndex ?? -1}`);
      });

      const growth = growthOf(engine);
      growth.spawnAnimal("chicken", 3, 3);
      growth.step(480);
      growth.step(480);
      growth.feed("animal:chicken:1");
      growth.step(480);
      growth.feed("animal:chicken:1");
      growth.step(480);
      growth.feed("animal:chicken:1");
      growth.step(480);
      expect(grew).toEqual(["chicken:1", "chicken:2"]);
      expect(produced).toEqual(["chicken:2"]);
    } finally {
      await close();
    }
  });

  it("animal entities survive save snapshot/restore", async () => {
    const { engine, close } = await setup();
    try {
      const growth = growthOf(engine);
      growth.spawnAnimal("chicken", 3, 3);
      growth.feed("animal:chicken:1");
      growth.forceAnimalStage("animal:chicken:1", 1);

      const snapshot = saveOf(engine).snapshot();
      expect(
        snapshot.world.some(
          (e) => e.id === "animal:chicken:1" && e.type === "animal" && e.animalId === "chicken" && e.stageIndex === 1 && e.fed === true,
        ),
      ).toBe(true);

      saveOf(engine).restore(snapshot);
      const animal = engine.world.get("animal:chicken:1") as AnimalEntity;
      expect(animal).toMatchObject({ type: "animal", animalId: "chicken", stageIndex: 1, fed: true });
    } finally {
      await close();
    }
  });
});