import { resolve } from "node:path";
import { describe, expect, it } from "vitest";
import {
  createEngine,
  TriggerSystem,
  type ConditionExpr,
  type InventorySystem,
  type System,
  type TimeSystem,
  type TriggerDef,
  type TriggerEvalCtx,
} from "../src/index.js";

const repoRoot = resolve(process.cwd(), "../..");
const contentDir = resolve(repoRoot, "content");
const modsDir = resolve(repoRoot, "mods");

function engineSetup(spy?: System) {
  return createEngine({ contentDir, modsDir, systems: spy ? [spy] : [] });
}

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

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

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

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 ctxOf(values: Record<string, unknown>): TriggerEvalCtx {
  return { get: (path) => values[path] };
}

describe("TriggerSystem.evaluate", () => {
  it("evaluates eq/gte/lte/exists comparisons", () => {
    const system = new TriggerSystem();
    const ctx = ctxOf({ "time.day": 5, "time.season": "summer", "player.flag": undefined });

    const eq: ConditionExpr = { op: "eq", path: "time.season", value: "summer" };
    expect(system.evaluate(eq, ctx)).toBe(true);
    expect(system.evaluate({ ...eq, value: "winter" }, ctx)).toBe(false);

    const gte: ConditionExpr = { op: "gte", path: "time.day", value: 5 };
    expect(system.evaluate(gte, ctx)).toBe(true);
    expect(system.evaluate({ op: "gte", path: "time.day", value: 6 }, ctx)).toBe(false);

    const lte: ConditionExpr = { op: "lte", path: "time.day", value: 5 };
    expect(system.evaluate(lte, ctx)).toBe(true);
    expect(system.evaluate({ op: "lte", path: "time.day", value: 4 }, ctx)).toBe(false);

    const exists: ConditionExpr = { op: "exists", path: "player.flag" };
    expect(system.evaluate(exists, ctx)).toBe(false);
    expect(system.evaluate({ op: "exists", path: "time.day" }, ctx)).toBe(true);
  });

  it("gte/lte are false when either operand is not a number", () => {
    const system = new TriggerSystem();
    expect(system.evaluate({ op: "gte", path: "time.season", value: "summer" }, ctxOf({ "time.season": "summer" }))).toBe(false);
    expect(system.evaluate({ op: "gte", path: "time.day", value: "5" }, ctxOf({ "time.day": 5 }))).toBe(false);
    expect(system.evaluate({ op: "lte", path: "time.day", value: 5 }, ctxOf({ "time.day": undefined }))).toBe(false);
  });

  it("evaluates and/or/not composition", () => {
    const system = new TriggerSystem();
    const ctx = ctxOf({ "time.day": 1, "time.season": "summer", "player.flag": "welcomed" });

    const andTrue: ConditionExpr = {
      and: [
        { op: "eq", path: "time.day", value: 1 },
        { op: "eq", path: "time.season", value: "summer" },
      ],
    };
    expect(system.evaluate(andTrue, ctx)).toBe(true);
    expect(system.evaluate({ and: [...andTrue.and, { op: "eq", path: "time.day", value: 2 }] }, ctx)).toBe(false);

    const orTrue: ConditionExpr = {
      or: [
        { op: "eq", path: "time.day", value: 99 },
        { op: "eq", path: "time.season", value: "summer" },
      ],
    };
    expect(system.evaluate(orTrue, ctx)).toBe(true);
    expect(system.evaluate({ or: [{ op: "eq", path: "time.day", value: 99 }, { op: "eq", path: "time.season", value: "winter" }] }, ctx)).toBe(false);

    const notTrue: ConditionExpr = { not: { op: "eq", path: "time.season", value: "winter" } };
    expect(system.evaluate(notTrue, ctx)).toBe(true);
    expect(system.evaluate({ not: { op: "eq", path: "time.season", value: "summer" } }, ctx)).toBe(false);
  });
});

describe("TriggerSystem.fire", () => {
  it("condition true runs actions, emits trigger-fire, and fires the onTriggerFire hook", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      const hookFired: unknown[] = [];
      engine.hooks.on("onTriggerFire", (ctx) => {
        hookFired.push({ world: ctx.world.get("player")?.id, time: ctx.time.get().day });
      });

      timeOf(engine).set(5, "spring");
      const result = triggerOf(engine).fire("spring-gift");
      expect(result).toEqual({ triggerId: "spring-gift", fired: true });
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(1);
      expect(hookFired).toEqual([{ world: "player", time: 5 }]);
      expect(seen.some((s) => s.event === "trigger-fire")).toBe(true);
      const firedEvent = seen.find((s) => s.event === "trigger-fire")?.payload as { triggerId: string };
      expect(firedEvent).toEqual({ triggerId: "spring-gift" });
    } finally {
      await engine.stop();
    }
  });

  it("condition false runs no actions and emits no trigger-fire", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      timeOf(engine).set(1, "spring");
      const result = triggerOf(engine).fire("spring-gift");
      expect(result).toEqual({ triggerId: "spring-gift", fired: false });
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(0);
      expect(seen.some((s) => s.event === "trigger-fire")).toBe(false);
    } finally {
      await engine.stop();
    }
  });

  it("unknown trigger id throws", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      expect(() => triggerOf(engine).fire("nope")).toThrow(/unknown trigger: nope/);
    } finally {
      await engine.stop();
    }
  });

  it("set-state action mutates an entity field", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "mark-player",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "set-state", path: "player.flag", value: "welcomed" }],
      });
      const player = engine.world.get("player");
      if (!player) throw new Error("player entity not seeded");
      expect(player.flag).toBeUndefined();

      const result = triggerOf(engine).fire("mark-player");
      expect(result).toEqual({ triggerId: "mark-player", fired: true });
      expect(player.flag).toBe("welcomed");
    } finally {
      await engine.stop();
    }
  });

  it("set-state on a missing entity throws", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "bad-state",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "set-state", path: "world.ghost.state", value: 1 }],
      });
      expect(() => triggerOf(engine).fire("bad-state")).toThrow(/no entity: ghost/);
    } finally {
      await engine.stop();
    }
  });

  it("emit-event action emits the event with payload", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "hello",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "emit-event", event: "behavior:hello", payload: { greeting: "hi" } }],
      });
      const result = triggerOf(engine).fire("hello");
      expect(result).toEqual({ triggerId: "hello", fired: true });
      const emitted = seen.find((s) => s.event === "behavior:hello")?.payload as { greeting: string };
      expect(emitted).toEqual({ greeting: "hi" });
    } finally {
      await engine.stop();
    }
  });

  it("play-sound emits a sound-play event and dialogue actions are accepted no-ops in headless v1", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "flavor",
        when: { op: "exists", path: "time.day" },
        fire: [
          { action: "play-sound", sound: "chime" },
          { action: "dialogue", text: "hello" },
        ],
      });
      const result = triggerOf(engine).fire("flavor");
      expect(result).toEqual({ triggerId: "flavor", fired: true });
      expect(seen).toEqual([
        { event: "sound-play", payload: { soundId: "chime" } },
        { event: "trigger-fire", payload: { triggerId: "flavor" } },
      ]);
    } finally {
      await engine.stop();
    }
  });
});

describe("TriggerSystem add action (D33)", () => {
  it("add accumulates across multiple fires on a numeric field", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "gain-gold",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "add", path: "player.gold", value: 5 }],
      });
      const player = engine.world.get("player");
      if (!player) throw new Error("player entity not seeded");
      player.gold = 10;
      expect(triggerOf(engine).fire("gain-gold").fired).toBe(true);
      expect(triggerOf(engine).fire("gain-gold").fired).toBe(true);
      expect(player.gold).toBe(20);
    } finally {
      await engine.stop();
    }
  });

  it("negative add decrements a numeric field", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "spend-gold",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "add", path: "player.gold", value: -3 }],
      });
      const player = engine.world.get("player");
      if (!player) throw new Error("player entity not seeded");
      player.gold = 10;
      triggerOf(engine).fire("spend-gold");
      expect(player.gold).toBe(7);
    } finally {
      await engine.stop();
    }
  });

  it("a missing field starts from 0 then adds", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "first-gold",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "add", path: "player.gold", value: 100 }],
      });
      const player = engine.world.get("player");
      if (!player) throw new Error("player entity not seeded");
      delete player.gold;
      triggerOf(engine).fire("first-gold");
      expect(player.gold).toBe(100);
      triggerOf(engine).fire("first-gold");
      expect(player.gold).toBe(200);
    } finally {
      await engine.stop();
    }
  });

  it("add on a non-numeric field throws", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "bad-add",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "add", path: "player.gold", value: 1 }],
      });
      const player = engine.world.get("player");
      if (!player) throw new Error("player entity not seeded");
      player.gold = "rich";
      expect(() => triggerOf(engine).fire("bad-add")).toThrow(/action add: field player\.gold is not a number/);
    } finally {
      await engine.stop();
    }
  });

  it("add on a missing entity throws like set-state", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "bad-add-entity",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "add", path: "world.ghost.score", value: 1 }],
      });
      expect(() => triggerOf(engine).fire("bad-add-entity")).toThrow(/no entity: ghost/);
    } finally {
      await engine.stop();
    }
  });

  it("add works in state machine onEnter actions", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("statemachine", {
        id: "gold-machine",
        initial: "start",
        states: [
          { id: "start" },
          { id: "done", onEnter: [{ action: "add", path: "player.gold", value: 100 }] },
        ],
        transitions: [{ from: "start", to: "done", when: { op: "exists", path: "time.day" } }],
      });
      triggerOf(engine).machineTransition("gold-machine", "done");
      expect(engine.world.get("player")?.gold).toBe(100);
    } finally {
      await engine.stop();
    }
  });

  it("set-state remains absolute after adds", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "reset-gold",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "set-state", path: "player.gold", value: 42 }],
      });
      const player = engine.world.get("player");
      if (!player) throw new Error("player entity not seeded");
      player.gold = 100;
      triggerOf(engine).fire("reset-gold");
      expect(player.gold).toBe(42);
    } finally {
      await engine.stop();
    }
  });
});

describe("TriggerSystem.match", () => {
  it("runs triggers whose condition matches the event payload (time.day style ctx)", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "gift-on-parsnip",
        when: { op: "eq", path: "payload.itemId", value: "parsnip" },
        fire: [{ action: "give-item", itemId: "parsnip-seed", qty: 1 }],
      });

      timeOf(engine).set(1, "spring");
      inventoryOf(engine).give("parsnip", 1);
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(1);
      expect(seen.some((s) => s.event === "trigger-fire")).toBe(true);

      inventoryOf(engine).give("hoe", 1);
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(1);
    } finally {
      await engine.stop();
    }
  });

  it("spring-gift fires on any bus event once time.day >= 5", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      timeOf(engine).set(1, "spring");
      inventoryOf(engine).give("parsnip", 1);
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(0);

      timeOf(engine).set(5, "spring");
      inventoryOf(engine).give("parsnip", 1);
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(1);
      inventoryOf(engine).give("parsnip", 1);
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(2);
    } finally {
      await engine.stop();
    }
  });

  it("trigger-fire events are never re-matched (v1 loop guard)", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "echo",
        when: { op: "exists", path: "time.day" },
        fire: [{ action: "emit-event", event: "trigger-fire", payload: { triggerId: "echo" } }],
      });

      expect(triggerOf(engine).match("trigger-fire", {})).toEqual({ fired: 0 });

      timeOf(engine).set(1, "spring");
      const result = triggerOf(engine).match("behavior:seed", {});
      expect(result).toEqual({ fired: 1 });
      const triggerFireCount = seen.filter((s) => s.event === "trigger-fire").length;
      expect(triggerFireCount).toBe(2);
    } finally {
      await engine.stop();
    }
  });

  it("engine forwards bus events to the trigger system via on()", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      engine.registry.register("behavior", {
        id: "summer-day",
        when: {
          and: [
            { op: "eq", path: "time.day", value: 1 },
            { op: "eq", path: "time.season", value: "summer" },
          ],
        },
        fire: [{ action: "emit-event", event: "behavior:summer", payload: { day: 1 } }],
      });

      timeOf(engine).set(1, "spring");
      inventoryOf(engine).give("parsnip", 1);
      expect(seen.some((s) => s.event === "behavior:summer")).toBe(false);

      timeOf(engine).set(1, "summer");
      inventoryOf(engine).give("parsnip", 1);
      expect(seen.some((s) => s.event === "behavior:summer")).toBe(true);
    } finally {
      await engine.stop();
    }
  });
});