import { mkdtemp, readFile, rm } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";

import { afterEach, describe, expect, it, vi } from "vitest";

import { createClientRuleRegistry, ClientRuleRegistryError } from "../plugin/core/rules.js";
import {
  createInitialClientState,
  createYonexusClientStateStore,
  ensureClientKeyPair,
  hasClientKeyPair,
  hasClientSecret,
  loadYonexusClientState,
  saveYonexusClientState,
  type YonexusClientState
} from "../plugin/core/state.js";
import { signMessage, verifySignature } from "../plugin/crypto/keypair.js";

// Inline protocol helpers (to avoid submodule dependency in tests)
function createAuthRequestSigningInput(input: {
  secret: string;
  nonce: string;
  proofTimestamp: number;
}): string {
  return JSON.stringify({
    secret: input.secret,
    nonce: input.nonce,
    timestamp: input.proofTimestamp
  });
}

function isValidAuthNonce(nonce: string): boolean {
  return /^[A-Za-z0-9_-]{24}$/.test(nonce);
}

function isTimestampFresh(
  proofTimestamp: number,
  now: number,
  maxDriftSeconds: number = 10
): { ok: true } | { ok: false; reason: "stale_timestamp" | "future_timestamp" } {
  const drift = proofTimestamp - now;
  if (Math.abs(drift) < maxDriftSeconds) {
    return { ok: true };
  }

  return {
    ok: false,
    reason: drift < 0 ? "stale_timestamp" : "future_timestamp"
  };
}

const tempDirs: string[] = [];

afterEach(async () => {
  await Promise.all(tempDirs.splice(0).map((dir) => rm(dir, { recursive: true, force: true })));
});

async function createTempStatePath(): Promise<string> {
  const dir = await mkdtemp(join(tmpdir(), "yonexus-client-test-"));
  tempDirs.push(dir);
  return join(dir, "state.json");
}

describe("Yonexus.Client state store", () => {
  it("creates minimal initial state when the file does not exist", async () => {
    const filePath = await createTempStatePath();

    const state = await loadYonexusClientState(filePath, "client-a");

    expect(state.identifier).toBe("client-a");
    expect(hasClientSecret(state)).toBe(false);
    expect(hasClientKeyPair(state)).toBe(false);
  });

  it("persists and reloads local trust material", async () => {
    const filePath = await createTempStatePath();
    const state: YonexusClientState = {
      ...createInitialClientState("client-a"),
      publicKey: "pubkey",
      privateKey: "privkey",
      secret: "secret-value",
      pairedAt: 1_710_000_000,
      authenticatedAt: 1_710_000_100,
      updatedAt: 1_710_000_101
    };

    await saveYonexusClientState(filePath, state);
    const reloaded = await loadYonexusClientState(filePath, "client-a");

    expect(reloaded).toEqual(state);
    const raw = JSON.parse(await readFile(filePath, "utf8")) as { version: number };
    expect(raw.version).toBe(1);
  });

  it("generates and persists an Ed25519 keypair only once", async () => {
    const filePath = await createTempStatePath();
    const store = createYonexusClientStateStore(filePath);
    const initial = createInitialClientState("client-a");

    const first = await ensureClientKeyPair(initial, store);
    expect(first.generated).toBe(true);
    expect(hasClientKeyPair(first.state)).toBe(true);

    const signature = await signMessage(first.state.privateKey!, "hello yonexus");
    await expect(verifySignature(first.state.publicKey!, "hello yonexus", signature)).resolves.toBe(
      true
    );

    const second = await ensureClientKeyPair(first.state, store);
    expect(second.generated).toBe(false);
    expect(second.state.privateKey).toBe(first.state.privateKey);
    expect(second.state.publicKey).toBe(first.state.publicKey);
  });
});

describe("Yonexus.Client rule registry", () => {
  it("dispatches exact-match rule messages to the registered processor", () => {
    const registry = createClientRuleRegistry();
    const processor = vi.fn();
    registry.registerRule("chat_sync", processor);

    const handled = registry.dispatch("chat_sync::{\"body\":\"hello\"}");

    expect(handled).toBe(true);
    expect(processor).toHaveBeenCalledWith("chat_sync::{\"body\":\"hello\"}");
    expect(registry.getRules()).toEqual(["chat_sync"]);
  });

  it("rejects reserved and duplicate registrations", () => {
    const registry = createClientRuleRegistry();
    registry.registerRule("chat_sync", () => undefined);

    expect(() => registry.registerRule("builtin", () => undefined)).toThrow(ClientRuleRegistryError);
    expect(() => registry.registerRule("chat_sync", () => undefined)).toThrow(
      "Rule 'chat_sync' is already registered"
    );
  });

  it("returns false when no processor matches a message", () => {
    const registry = createClientRuleRegistry();

    expect(registry.dispatch("chat_sync::{\"body\":\"hello\"}")).toBe(false);
  });
});

describe("Yonexus.Client auth flow", () => {
  it("constructs valid auth request signing input", () => {
    const input = createAuthRequestSigningInput({
      secret: "my-secret",
      nonce: "RANDOM24CHARSTRINGX001",
      proofTimestamp: 1_710_000_000
    });

    expect(input).toBe(
      '{"secret":"my-secret","nonce":"RANDOM24CHARSTRINGX001","timestamp":1710000000}'
    );
  });

  it("validates nonce format correctly", () => {
    expect(isValidAuthNonce("RANDOM24CHARSTRINGX00001")).toBe(true);
    expect(isValidAuthNonce("RANDOM24CHARSTRINGX00")).toBe(false);
    expect(isValidAuthNonce("RANDOM24CHARSTRINGX0001")).toBe(false);
    expect(isValidAuthNonce("invalid_nonce_with_!@#")).toBe(false);
    expect(isValidAuthNonce("")).toBe(false);
  });

  it("validates timestamp freshness", () => {
    const now = 1_710_000_000;

    expect(isTimestampFresh(now, now)).toEqual({ ok: true });
    expect(isTimestampFresh(now - 5, now)).toEqual({ ok: true });
    expect(isTimestampFresh(now + 5, now)).toEqual({ ok: true });

    expect(isTimestampFresh(now - 15, now)).toEqual({ ok: false, reason: "stale_timestamp" });
    expect(isTimestampFresh(now + 15, now)).toEqual({ ok: false, reason: "future_timestamp" });
  });
});

describe("Yonexus.Client phase state machine", () => {
  it("transitions from idle to connecting to connected", () => {
    const sm = createClientStateMachine();

    expect(sm.getState()).toBe("idle");

    sm.transition("connect");
    expect(sm.getState()).toBe("connecting");

    sm.transition("connected");
    expect(sm.getState()).toBe("connected");
  });

  it("handles pairing required flow", () => {
    const sm = createClientStateMachine();

    sm.transition("connect");
    sm.transition("connected");
    sm.transition("pair_required");
    expect(sm.getState()).toBe("pairing_required");

    sm.transition("pairing_started");
    expect(sm.getState()).toBe("pairing_pending");

    sm.transition("pair_success");
    expect(sm.getState()).toBe("authenticating");

    sm.transition("auth_success");
    expect(sm.getState()).toBe("authenticated");
  });

  it("handles re-pair required from authenticated", () => {
    const sm = createClientStateMachine();

    sm.transition("connect");
    sm.transition("connected");
    sm.transition("pair_required");
    sm.transition("pairing_started");
    sm.transition("pair_success");
    sm.transition("auth_success");
    expect(sm.getState()).toBe("authenticated");

    sm.transition("re_pair_required");
    expect(sm.getState()).toBe("pairing_required");
  });

  it("handles disconnect and reconnect", () => {
    const sm = createClientStateMachine();

    sm.transition("connect");
    sm.transition("connected");
    sm.transition("auth_required");
    sm.transition("auth_success");
    expect(sm.getState()).toBe("authenticated");

    sm.transition("disconnect");
    expect(sm.getState()).toBe("reconnecting");

    sm.transition("connect");
    expect(sm.getState()).toBe("connecting");
  });

  it("emits state change events", () => {
    const sm = createClientStateMachine();
    const listener = vi.fn();

    sm.on("stateChange", listener);
    sm.transition("connect");

    expect(listener).toHaveBeenCalledWith({ from: "idle", to: "connecting" });
  });
});

describe("Yonexus.Client heartbeat scheduling", () => {
  it("schedules heartbeat only when authenticated", () => {
    const heartbeat = createHeartbeatScheduler({ intervalMs: 300_000 });

    expect(heartbeat.isRunning()).toBe(false);

    heartbeat.start();
    expect(heartbeat.isRunning()).toBe(true);

    heartbeat.stop();
    expect(heartbeat.isRunning()).toBe(false);
  });

  it("emits heartbeat tick at configured interval", () => {
    vi.useFakeTimers();
    const onTick = vi.fn();
    const heartbeat = createHeartbeatScheduler({ intervalMs: 300_000, onTick });

    heartbeat.start();
    expect(onTick).not.toHaveBeenCalled();

    vi.advanceTimersByTime(300_000);
    expect(onTick).toHaveBeenCalledTimes(1);

    vi.advanceTimersByTime(300_000);
    expect(onTick).toHaveBeenCalledTimes(2);

    heartbeat.stop();
    vi.useRealTimers();
  });

  it("resets interval on restart", () => {
    vi.useFakeTimers();
    const onTick = vi.fn();
    const heartbeat = createHeartbeatScheduler({ intervalMs: 300_000, onTick });

    heartbeat.start();
    vi.advanceTimersByTime(150_000);

    heartbeat.stop();
    heartbeat.start();

    vi.advanceTimersByTime(150_000);
    expect(onTick).not.toHaveBeenCalled();

    vi.advanceTimersByTime(150_000);
    expect(onTick).toHaveBeenCalledTimes(1);

    heartbeat.stop();
    vi.useRealTimers();
  });
});

type ClientState =
  | "idle"
  | "connecting"
  | "connected"
  | "pairing_required"
  | "pairing_pending"
  | "authenticating"
  | "authenticated"
  | "reconnecting"
  | "error";

type ClientEvent =
  | "connect"
  | "connected"
  | "disconnected"
  | "disconnect"
  | "pair_required"
  | "pairing_started"
  | "pair_success"
  | "pair_failed"
  | "auth_required"
  | "auth_success"
  | "auth_failed"
  | "re_pair_required"
  | "error";

interface StateMachine {
  getState(): ClientState;
  transition(event: ClientEvent): void;
  on(event: "stateChange", handler: (change: { from: ClientState; to: ClientState }) => void): void;
}

function createClientStateMachine(): StateMachine {
  let state: ClientState = "idle";
  const listeners: Array<(change: { from: ClientState; to: ClientState }) => void> = [];

  const transitions: Record<ClientState, Partial<Record<ClientEvent, ClientState>>> = {
    idle: { connect: "connecting" },
    connecting: { connected: "connected", error: "error", disconnect: "reconnecting" },
    connected: {
      pair_required: "pairing_required",
      auth_required: "authenticating",
      disconnect: "reconnecting"
    },
    pairing_required: { pairing_started: "pairing_pending", disconnect: "reconnecting" },
    pairing_pending: {
      pair_success: "authenticating",
      pair_failed: "pairing_required",
      disconnect: "reconnecting"
    },
    authenticating: {
      auth_success: "authenticated",
      auth_failed: "pairing_required",
      re_pair_required: "pairing_required",
      disconnect: "reconnecting"
    },
    authenticated: { re_pair_required: "pairing_required", disconnect: "reconnecting" },
    reconnecting: { connect: "connecting" },
    error: { connect: "connecting" }
  };

  return {
    getState: () => state,
    transition: (event: ClientEvent) => {
      const nextState = transitions[state]?.[event];
      if (nextState) {
        const from = state;
        state = nextState;
        listeners.forEach((l) => l({ from, to: nextState }));
      }
    },
    on: (event, handler) => {
      if (event === "stateChange") {
        listeners.push(handler);
      }
    }
  };
}

interface HeartbeatScheduler {
  start(): void;
  stop(): void;
  isRunning(): boolean;
}

function createHeartbeatScheduler(options: {
  intervalMs: number;
  onTick?: () => void;
}): HeartbeatScheduler {
  let timer: ReturnType<typeof setInterval> | null = null;

  return {
    start: () => {
      if (timer) clearInterval(timer);
      timer = setInterval(() => {
        options.onTick?.();
      }, options.intervalMs);
    },
    stop: () => {
      if (timer) {
        clearInterval(timer);
        timer = null;
      }
    },
    isRunning: () => timer !== null
  };
}