import { resolve } from "node:path";
import { describe, expect, it } from "vitest";
import {
  ACTIVE_DIALOGUE_ENTITY_ID,
  createEngine,
  dialogueSchema,
  type DialogueDef,
  type DialogueSystem,
  type InventorySystem,
  type SaveSystem,
  type System,
  type TimeSystem,
} 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 dialogueOf(engine: ReturnType<typeof createEngine>): DialogueSystem {
  const dialogue = engine.systems.get<DialogueSystem>("dialogue");
  if (!dialogue) throw new Error("dialogue system not booted");
  return dialogue;
}

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 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 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 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 };
}

const SIMPLE_DEF: DialogueDef = {
  id: "test-welcome",
  startNode: "hello",
  nodes: [
    {
      id: "hello",
      text: "Hello!",
      choices: [
        { text: "Give me a seed", to: "thanks", actions: [{ action: "give-item", itemId: "parsnip-seed", qty: 1 }] },
        { text: "No thanks", to: "bye" },
      ],
    },
    { id: "thanks", text: "Here you go." },
    { id: "bye", text: "Bye!" },
  ],
};

describe("dialogueSchema", () => {
  it("accepts a valid def and rejects unknown startNode / bad targets / mixed choices+to / empty choices / duplicate ids", () => {
    expect(dialogueSchema.safeParse(SIMPLE_DEF).success).toBe(true);

    const badStart = dialogueSchema.safeParse({ ...SIMPLE_DEF, startNode: "nope" });
    expect(badStart.success).toBe(false);

    const badChoiceTo = dialogueSchema.safeParse({
      ...SIMPLE_DEF,
      nodes: [
        {
          id: "hello",
          text: "Hello!",
          choices: [{ text: "Go", to: "ghost" }],
        },
      ],
    });
    expect(badChoiceTo.success).toBe(false);

    const badNodeTo = dialogueSchema.safeParse({
      ...SIMPLE_DEF,
      nodes: [
        { id: "hello", text: "Hello!", to: "ghost" },
        { id: "bye", text: "Bye" },
      ],
    });
    expect(badNodeTo.success).toBe(false);

    const mixed = dialogueSchema.safeParse({
      ...SIMPLE_DEF,
      nodes: [{ id: "hello", text: "Hello!", to: "bye", choices: [{ text: "Go", to: "bye" }] }],
    });
    expect(mixed.success).toBe(false);

    const emptyChoices = dialogueSchema.safeParse({
      ...SIMPLE_DEF,
      nodes: [{ id: "hello", text: "Hello!", choices: [] }],
    });
    expect(emptyChoices.success).toBe(false);

    const duplicateIds = dialogueSchema.safeParse({
      ...SIMPLE_DEF,
      nodes: [
        { id: "hello", text: "a" },
        { id: "hello", text: "b" },
      ],
    });
    expect(duplicateIds.success).toBe(false);

    const emptyNodes = dialogueSchema.safeParse({ ...SIMPLE_DEF, nodes: [] });
    expect(emptyNodes.success).toBe(false);
  });

  it("accepts a terminal node and a linear node chain", () => {
    const def = dialogueSchema.safeParse({
      id: "linear",
      startNode: "a",
      nodes: [
        { id: "a", text: "start", to: "b" },
        { id: "b", text: "end" },
      ],
    });
    expect(def.success).toBe(true);
  });
});

describe("DialogueSystem.start", () => {
  it("returns the start node state, creates the active entity, emits dialogue-start, and fires onDialogueStart", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      engine.registry.register("dialogue", SIMPLE_DEF);
      const hookFired: unknown[] = [];
      engine.hooks.on("onDialogueStart", (ctx) => {
        hookFired.push(ctx.world.get(ACTIVE_DIALOGUE_ENTITY_ID)?.nodeId);
      });

      const state = dialogueOf(engine).start("test-welcome");
      expect(state).toEqual({
        dialogueId: "test-welcome",
        nodeId: "hello",
        text: "Hello!",
        choices: [
          { text: "Give me a seed", to: "thanks" },
          { text: "No thanks", to: "bye" },
        ],
      });
      expect(engine.world.get(ACTIVE_DIALOGUE_ENTITY_ID)).toMatchObject({
        type: "dialogue",
        dialogueId: "test-welcome",
        nodeId: "hello",
      });
      expect(seen.some((s) => s.event === "dialogue-start")).toBe(true);
      expect(seen.find((s) => s.event === "dialogue-start")?.payload).toEqual({
        dialogueId: "test-welcome",
        nodeId: "hello",
      });
      expect(hookFired).toEqual(["hello"]);
    } finally {
      await engine.stop();
    }
  });

  it("runs the start node's actions on enter", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("dialogue", {
        id: "test-action",
        startNode: "gift",
        nodes: [
          { id: "gift", text: "Have a seed.", actions: [{ action: "give-item", itemId: "parsnip-seed", qty: 1 }] },
        ],
      });
      dialogueOf(engine).start("test-action");
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(1);
    } finally {
      await engine.stop();
    }
  });

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

  it("starting a second dialogue replaces the first without emitting dialogue-end", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      engine.registry.register("dialogue", SIMPLE_DEF);
      engine.registry.register("dialogue", {
        id: "other",
        startNode: "a",
        nodes: [
          { id: "a", text: "other", to: "b" },
          { id: "b", text: "end" },
        ],
      });
      const dialogue = dialogueOf(engine);
      dialogue.start("test-welcome");
      const replaced = dialogue.start("other");
      expect(replaced.dialogueId).toBe("other");
      expect(engine.world.get(ACTIVE_DIALOGUE_ENTITY_ID)).toMatchObject({ dialogueId: "other" });
      expect(seen.some((s) => s.event === "dialogue-end")).toBe(false);
    } finally {
      await engine.stop();
    }
  });
});

describe("DialogueSystem.choose", () => {
  it("advances through a choice, runs its actions, and updates the entity", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      engine.registry.register("dialogue", {
        ...SIMPLE_DEF,
        nodes: [
          {
            id: "hello",
            text: "Hello!",
            choices: [
              { text: "Give me a seed", to: "thanks", actions: [{ action: "give-item", itemId: "parsnip-seed", qty: 1 }] },
              { text: "No thanks", to: "bye" },
            ],
          },
          { id: "thanks", text: "Here you go.", to: "another" },
          { id: "another", text: "Anything else?" },
          { id: "bye", text: "Bye!" },
        ],
      });
      const dialogue = dialogueOf(engine);
      dialogue.start("test-welcome");

      const next = dialogue.choose(0);
      expect(next).toEqual({
        dialogueId: "test-welcome",
        nodeId: "thanks",
        text: "Here you go.",
        choices: [{ text: "Continue", to: "another" }],
      });
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(1);
      expect(engine.world.get(ACTIVE_DIALOGUE_ENTITY_ID)?.nodeId).toBe("thanks");
      expect(seen.some((s) => s.event === "item-acquire")).toBe(true);
    } finally {
      await engine.stop();
    }
  });

  it("a choice with no actions advances without side effects", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("dialogue", SIMPLE_DEF);
      const dialogue = dialogueOf(engine);
      dialogue.start("test-welcome");
      const next = dialogue.choose(1);
      expect(next.nodeId).toBe("bye");
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(0);
    } finally {
      await engine.stop();
    }
  });

  it("throws on an out-of-range index or when no dialogue is active", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("dialogue", SIMPLE_DEF);
      const dialogue = dialogueOf(engine);
      dialogue.start("test-welcome");
      expect(() => dialogue.choose(2)).toThrow(/choice index out of range: 2/);
      expect(() => dialogue.choose(-1)).toThrow(/choice index out of range: -1/);
      dialogue.end();
      expect(() => dialogue.choose(0)).toThrow(/no active dialogue/);
    } finally {
      await engine.stop();
    }
  });

  it("a linear to-node presents a synthesized Continue choice", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("dialogue", {
        id: "test-linear",
        startNode: "a",
        nodes: [
          { id: "a", text: "first", to: "b" },
          { id: "b", text: "last" },
        ],
      });
      const dialogue = dialogueOf(engine);
      const start = dialogue.start("test-linear");
      expect(start).toEqual({
        dialogueId: "test-linear",
        nodeId: "a",
        text: "first",
        choices: [{ text: "Continue", to: "b" }],
      });
      const next = dialogue.choose(0);
      expect(next.nodeId).toBe("b");
    } finally {
      await engine.stop();
    }
  });
});

describe("DialogueSystem lifecycle (terminal nodes)", () => {
  it("entering a terminal node ends the dialogue, emits dialogue-end, and fires onDialogueEnd", async () => {
    const { system: spy, seen } = eventSpy();
    const engine = engineSetup(spy);
    await engine.start();
    try {
      engine.registry.register("dialogue", SIMPLE_DEF);
      const hookFired: unknown[] = [];
      engine.hooks.on("onDialogueEnd", (ctx) => {
        hookFired.push(ctx.world.get(ACTIVE_DIALOGUE_ENTITY_ID) === undefined);
      });

      const dialogue = dialogueOf(engine);
      dialogue.start("test-welcome");
      const final = dialogue.choose(0);
      expect(final).toEqual({
        dialogueId: "test-welcome",
        nodeId: "thanks",
        text: "Here you go.",
        choices: [],
      });
      expect(engine.world.get(ACTIVE_DIALOGUE_ENTITY_ID)).toBeUndefined();
      expect(dialogue.current()).toBeNull();
      expect(seen.some((s) => s.event === "dialogue-end")).toBe(true);
      expect(seen.find((s) => s.event === "dialogue-end")?.payload).toEqual({ dialogueId: "test-welcome" });
      expect(hookFired).toEqual([true]);
    } finally {
      await engine.stop();
    }
  });

  it("a choices node whose conditions all fail is treated as terminal", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("dialogue", {
        id: "test-gated",
        startNode: "door",
        nodes: [
          {
            id: "door",
            text: "Knock knock.",
            choices: [
              { text: "Come in", to: "inside", when: { op: "exists", path: "player.flag" } },
            ],
          },
          { id: "inside", text: "Welcome." },
        ],
      });
      const dialogue = dialogueOf(engine);
      const state = dialogue.start("test-gated");
      expect(state.choices).toEqual([]);
      expect(engine.world.get(ACTIVE_DIALOGUE_ENTITY_ID)).toBeUndefined();
      expect(dialogue.current()).toBeNull();
    } finally {
      await engine.stop();
    }
  });
});

describe("DialogueSystem conditions", () => {
  it("gated choices are hidden from current() and choose indexes into the available list", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("dialogue", {
        id: "test-gate",
        startNode: "ask",
        nodes: [
          {
            id: "ask",
            text: "Ask me.",
            choices: [
              { text: "Always here", to: "open" },
              { text: "Only with the flag", to: "secret", when: { op: "exists", path: "player.flag" } },
            ],
          },
          { id: "open", text: "Open." },
          { id: "secret", text: "Secret." },
        ],
      });
      const dialogue = dialogueOf(engine);
      dialogue.start("test-gate");
      expect(dialogue.current()?.choices).toEqual([{ text: "Always here", to: "open" }]);

      const player = engine.world.get("player");
      if (!player) throw new Error("player entity not seeded");
      player.flag = "set";
      expect(dialogue.current()?.choices).toEqual([
        { text: "Always here", to: "open" },
        { text: "Only with the flag", to: "secret" },
      ]);
      expect(dialogue.choose(1).nodeId).toBe("secret");
    } finally {
      await engine.stop();
    }
  });

  it("when conditions resolve payload.* from the start ctx", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("dialogue", {
        id: "test-payload",
        startNode: "greet",
        nodes: [
          {
            id: "greet",
            text: "Hi.",
            choices: [
              { text: "Morning", to: "day", when: { op: "eq", path: "payload.partOfDay", value: "morning" } },
              { text: "Evening", to: "night" },
            ],
          },
          { id: "day", text: "Good morning." },
          { id: "night", text: "Good evening." },
        ],
      });
      const dialogue = dialogueOf(engine);
      dialogue.start("test-payload", { payload: { partOfDay: "morning" } });
      expect(dialogue.choose(0).nodeId).toBe("day");
    } finally {
      await engine.stop();
    }
  });
});

describe("DialogueSystem persistence", () => {
  it("the active dialogue entity survives save snapshot/restore", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("dialogue", SIMPLE_DEF);
      const dialogue = dialogueOf(engine);
      dialogue.start("test-welcome");

      const snapshot = saveOf(engine).snapshot();
      expect(snapshot.world.some((e) => e.id === ACTIVE_DIALOGUE_ENTITY_ID && e.nodeId === "hello")).toBe(true);

      saveOf(engine).restore(snapshot);
      expect(dialogue.current()).toEqual({
        dialogueId: "test-welcome",
        nodeId: "hello",
        text: "Hello!",
        choices: [
          { text: "Give me a seed", to: "thanks" },
          { text: "No thanks", to: "bye" },
        ],
      });
    } finally {
      await engine.stop();
    }
  });
});

describe("real content dialogue (welcome)", () => {
  it("drives the seeded welcome dialogue: branches, linear to, terminal end, and the flag-gated returning choice", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      const dialogue = dialogueOf(engine);
      const start = dialogue.start("welcome");
      expect(start.nodeId).toBe("hello");
      expect(start.choices).toEqual([
        { text: "Thanks! What should I plant first?", to: "seed-tip" },
        { text: "I am just exploring today.", to: "farewell" },
      ]);

      const planted = dialogue.choose(0);
      expect(planted).toMatchObject({ nodeId: "seed-tip", text: expect.stringContaining("Parsnip") });
      expect(planted.choices).toEqual([{ text: "Continue", to: "farewell" }]);
      expect(inventoryOf(engine).count("parsnip-seed")).toBe(1);

      const farewell = dialogue.choose(0);
      expect(farewell).toEqual({ dialogueId: "welcome", nodeId: "farewell", text: "See you around!", choices: [] });
      expect(dialogue.current()).toBeNull();

      const player = engine.world.get("player");
      if (!player) throw new Error("player entity not seeded");
      player.flag = "welcomed";
      const returning = dialogue.start("welcome");
      expect(returning.choices).toEqual([
        { text: "Thanks! What should I plant first?", to: "seed-tip" },
        { text: "You remember me from last season?", to: "returning" },
        { text: "I am just exploring today.", to: "farewell" },
      ]);
      expect(dialogue.choose(1).nodeId).toBe("returning");
    } finally {
      await engine.stop();
    }
  });

  it("a condition-gated welcome choice can gate on the time system (time.day path)", async () => {
    const engine = engineSetup();
    await engine.start();
    try {
      engine.registry.register("dialogue", {
        id: "test-time-gate",
        startNode: "ask",
        nodes: [
          {
            id: "ask",
            text: "What day is it?",
            choices: [
              { text: "Late spring", to: "late", when: { op: "gte", path: "time.day", value: 20 } },
              { text: "Early", to: "early" },
            ],
          },
          { id: "late", text: "The season is ending soon." },
          { id: "early", text: "Plenty of time." },
        ],
      });
      const dialogue = dialogueOf(engine);
      timeOf(engine).set(5, "spring");
      dialogue.start("test-time-gate");
      expect(dialogue.current()?.choices).toEqual([{ text: "Early", to: "early" }]);

      timeOf(engine).set(25, "spring");
      expect(dialogue.current()?.choices).toEqual([
        { text: "Late spring", to: "late" },
        { text: "Early", to: "early" },
      ]);
    } finally {
      await engine.stop();
    }
  });
});