import {
  AsyncAdoptionScope,
  type AsyncCleanup,
  AsyncOwner,
  createSerializedAsyncWriter,
  mergeHydratedState,
  ownCompanionWindowCreation,
  registerSequentially,
} from "../src/lib/asyncOwnership.ts";

const assertEquals = <T>(actual: T, expected: T, message: string) => {
  if (actual !== expected) {
    throw new Error(`${message}: expected ${expected}, got ${actual}`);
  }
};

const assertArrayEquals = <T>(actual: T[], expected: T[], message: string) => {
  assertEquals(JSON.stringify(actual), JSON.stringify(expected), message);
};

const deferred = <T>() => {
  let resolve!: (value: T) => void;
  let reject!: (reason: unknown) => void;
  const promise = new Promise<T>((resolvePromise, rejectPromise) => {
    resolve = resolvePromise;
    reject = rejectPromise;
  });
  return { promise, resolve, reject };
};

Deno.test("unmount before listener resolution cleans the late listener and stops registration", async () => {
  const owner = new AsyncOwner();
  const first = deferred<AsyncCleanup>();
  let firstRegistrations = 0;
  let secondRegistrations = 0;
  let firstCleanups = 0;

  const registration = registerSequentially(owner, [
    () => {
      firstRegistrations += 1;
      return first.promise;
    },
    () => {
      secondRegistrations += 1;
      return Promise.resolve(() => {});
    },
  ]);

  assertEquals(
    firstRegistrations,
    1,
    "the first listener should start immediately",
  );
  const disposal = owner.dispose();
  first.resolve(() => {
    firstCleanups += 1;
  });

  assertEquals(
    await registration,
    false,
    "disposed registration should report cancellation",
  );
  assertEquals(
    firstCleanups,
    1,
    "the late listener should unlisten immediately",
  );
  assertEquals(
    secondRegistrations,
    0,
    "no later listener should start after disposal",
  );
  await disposal;
});

Deno.test("partial listener registration is fully cleaned across an in-flight listener", async () => {
  const owner = new AsyncOwner();
  const second = deferred<AsyncCleanup>();
  const secondStarted = deferred<void>();
  let firstCleanups = 0;
  let secondCleanups = 0;
  let thirdRegistrations = 0;

  const registration = registerSequentially(owner, [
    () =>
      Promise.resolve(() => {
        firstCleanups += 1;
      }),
    () => {
      secondStarted.resolve();
      return second.promise;
    },
    () => {
      thirdRegistrations += 1;
      return Promise.resolve(() => {});
    },
  ]);

  await secondStarted.promise;
  const disposal = owner.dispose();
  assertEquals(
    firstCleanups,
    1,
    "an owned listener should clean up during disposal",
  );

  second.resolve(() => {
    secondCleanups += 1;
  });
  assertEquals(
    await registration,
    false,
    "the in-flight registration should stop the sequence",
  );
  assertEquals(
    secondCleanups,
    1,
    "the in-flight listener should clean up when it resolves",
  );
  assertEquals(thirdRegistrations, 0, "the third listener should never start");
  await disposal;

  await owner.dispose();
  assertEquals(
    firstCleanups,
    1,
    "repeated disposal must not duplicate owned cleanup",
  );
  assertEquals(
    secondCleanups,
    1,
    "repeated disposal must not duplicate late cleanup",
  );
});

Deno.test("listener registration failure cleans the partial scope and skips later listeners", async () => {
  const owner = new AsyncOwner();
  const failure = new Error("registration failed");
  let firstCleanups = 0;
  let thirdRegistrations = 0;
  let reported: unknown;

  try {
    await registerSequentially(owner, [
      () =>
        Promise.resolve(() => {
          firstCleanups += 1;
        }),
      () => Promise.reject(failure),
      () => {
        thirdRegistrations += 1;
        return Promise.resolve(() => {});
      },
    ]);
  } catch (error) {
    reported = error;
  }

  assertEquals(reported, failure, "the registration error should be preserved");
  assertEquals(
    firstCleanups,
    1,
    "earlier listeners should clean up on setup failure",
  );
  assertEquals(
    thirdRegistrations,
    0,
    "later listeners should not start after setup failure",
  );
  assertEquals(
    owner.isActive(),
    false,
    "a failed registration scope should stay disposed",
  );
});

Deno.test("late refresh results and post-disposal refreshes cannot publish", async () => {
  const owner = new AsyncOwner();
  const refresh = deferred<string>();
  let refreshStarts = 0;
  const applied: string[] = [];

  const pending = owner.applyIfActive(
    () => {
      refreshStarts += 1;
      return refresh.promise;
    },
    (value) => applied.push(value),
  );

  const disposal = owner.dispose();
  refresh.resolve("stale");
  assertEquals(
    await pending,
    false,
    "a late refresh should report cancellation",
  );
  assertArrayEquals(applied, [], "a late refresh must not publish state");

  const afterDispose = await owner.applyIfActive(
    () => {
      refreshStarts += 1;
      return Promise.resolve("newer");
    },
    (value) => applied.push(value),
  );
  assertEquals(
    afterDispose,
    false,
    "a disposed owner should reject new refresh work",
  );
  assertEquals(refreshStarts, 1, "refresh work must not start after disposal");
  assertArrayEquals(
    applied,
    [],
    "post-disposal refreshes must not publish state",
  );
  await disposal;
});

Deno.test("disposal joins a late asynchronous listener cleanup", async () => {
  const owner = new AsyncOwner();
  const listener = deferred<AsyncCleanup>();
  const cleanupDone = deferred<void>();
  let cleanupStarts = 0;
  let disposalSettled = false;

  const registration = owner.register(() => listener.promise);
  const disposal = owner.dispose().then(() => {
    disposalSettled = true;
  });
  listener.resolve(async () => {
    cleanupStarts += 1;
    await cleanupDone.promise;
  });

  await Promise.resolve();
  assertEquals(
    cleanupStarts,
    1,
    "the late cleanup should start immediately on resolution",
  );
  assertEquals(
    disposalSettled,
    false,
    "disposal must wait for the asynchronous cleanup",
  );

  cleanupDone.resolve();
  assertEquals(
    await registration,
    false,
    "the disposed registration should remain cancelled",
  );
  await disposal;
  assertEquals(
    disposalSettled,
    true,
    "disposal should settle after cleanup completion",
  );
});

Deno.test("asynchronous cleanup rejection is reported and disposal still drains", async () => {
  const cleanupDone = deferred<void>();
  const failure = new Error("unlisten failed");
  const reported: unknown[] = [];
  const owner = new AsyncOwner((error) => reported.push(error));

  await owner.register(() =>
    Promise.resolve(async () => {
      await cleanupDone.promise;
      throw failure;
    })
  );
  const disposal = owner.dispose();
  cleanupDone.resolve();
  await disposal;

  assertEquals(
    reported.length,
    1,
    "the cleanup failure should be reported once",
  );
  assertEquals(
    reported[0],
    failure,
    "the original cleanup failure should be reported",
  );
});

Deno.test("a root adoption scope drains work and observes rejection", async () => {
  const first = deferred<void>();
  const failure = new Error("adopted cleanup failed");
  const reported: unknown[] = [];
  const scope = new AsyncAdoptionScope((error) => reported.push(error));
  let drained = false;

  scope.adopt(first.promise);
  scope.adopt(Promise.reject(failure));
  const drain = scope.drain().then(() => {
    drained = true;
  });
  await Promise.resolve();

  assertEquals(drained, false, "the adoption scope should retain pending work");
  assertEquals(
    reported.length,
    1,
    "an adopted rejection should be observed once",
  );
  assertEquals(
    reported[0],
    failure,
    "the adoption scope should report the original error",
  );

  first.resolve();
  await drain;
  assertEquals(
    drained,
    true,
    "the adoption scope should drain after all work settles",
  );
});

Deno.test("window close drains every admitted operation and rejects late owner registration", async () => {
  const scope = new AsyncAdoptionScope();
  const cleanupDone = deferred<void>();
  const unrelatedInvoke = deferred<string>();
  const owner = new AsyncOwner(() => {}, scope);
  let cleanupStarts = 0;

  await owner.register(() =>
    Promise.resolve(async () => {
      cleanupStarts += 1;
      await cleanupDone.promise;
    })
  );
  const unrelated = owner.applyIfActive(
    () => unrelatedInvoke.promise,
    () => {},
  );
  let closeDrained = false;
  const close = scope.disposeOwned().then(() => {
    closeDrained = true;
  });

  const lateOwner = new AsyncOwner(() => {}, scope);
  assertEquals(
    lateOwner.isActive(),
    false,
    "owner admission must close synchronously",
  );
  assertEquals(cleanupStarts, 1, "listener cleanup should start during close");
  assertEquals(closeDrained, false, "window close must await listener cleanup");

  cleanupDone.resolve();
  await Promise.resolve();
  assertEquals(
    closeDrained,
    false,
    "an admitted invoke must retain the webview after listener cleanup",
  );

  unrelatedInvoke.resolve("settled during close");
  assertEquals(
    await unrelated,
    false,
    "unrelated late invoke publication stays suppressed",
  );
  await close;
  assertEquals(
    closeDrained,
    true,
    "window close must join every admitted operation",
  );
});

Deno.test("closing during a dialog prevents its chained invoke from starting", async () => {
  const scope = new AsyncAdoptionScope();
  const owner = new AsyncOwner(() => {}, scope);
  const dialog = deferred<boolean>();
  let invokes = 0;

  const action = (async () => {
    let confirmed = false;
    if (
      !await owner.applyIfActive(
        () => dialog.promise,
        (answer) => {
          confirmed = answer;
        },
      ) || !confirmed
    ) {
      return;
    }
    await owner.applyIfActive(
      () => {
        invokes += 1;
        return Promise.resolve();
      },
      () => {},
    );
  })();

  const close = scope.disposeOwned();
  dialog.resolve(true);
  await action;
  await close;

  assertEquals(
    invokes,
    0,
    "a dialog result must not start work after close admission",
  );
});

Deno.test("closing during a helper import prevents later helper side effects", async () => {
  const scope = new AsyncAdoptionScope();
  const owner = new AsyncOwner(() => {}, scope);
  const imported = deferred<string>();
  let helperStarts = 0;

  const helper = (async () => {
    let moduleName: string | undefined;
    if (
      !await owner.applyIfActive(
        () => imported.promise,
        (value) => {
          moduleName = value;
        },
      ) || moduleName === undefined
    ) {
      return;
    }
    await owner.applyIfActive(
      () => {
        helperStarts += 1;
        return Promise.resolve();
      },
      () => {},
    );
  })();

  const close = scope.disposeOwned();
  imported.resolve("window helper");
  await helper;
  await close;

  assertEquals(
    helperStarts,
    0,
    "a late import must not focus or create a window",
  );
});

Deno.test("close after companion construction drains creation and both listeners before destroy", async () => {
  const scope = new AsyncAdoptionScope();
  const owner = new AsyncOwner(() => {}, scope);
  const createdCleanupDone = deferred<void>();
  const errorCleanupDone = deferred<void>();
  const bothCleanupsStarted = deferred<void>();
  const companionDestroyStarted = deferred<void>();
  const companionDestroyDone = deferred<void>();
  const order: string[] = [];
  let createdHandler: (() => void) | undefined;
  let errorHandler: ((payload: unknown) => void) | undefined;
  let cleanupStarts = 0;
  let latePublications = 0;
  let rootDestroyed = false;

  const noteCleanupStart = () => {
    cleanupStarts += 1;
    if (cleanupStarts === 2) bothCleanupsStarted.resolve();
  };
  const creation = ownCompanionWindowCreation(owner, {
    registerCreated: (handler) => {
      createdHandler = handler;
      return Promise.resolve(async () => {
        order.push("created-listener-cleanup");
        noteCleanupStart();
        await createdCleanupDone.promise;
      });
    },
    registerError: (handler) => {
      errorHandler = handler;
      return Promise.resolve(async () => {
        order.push("error-listener-cleanup");
        noteCleanupStart();
        await errorCleanupDone.promise;
      });
    },
    destroy: async () => {
      order.push("companion-destroy");
      companionDestroyStarted.resolve();
      await companionDestroyDone.promise;
    },
  }).then((result) => {
    if (owner.isActive()) latePublications += 1;
    return result;
  });
  scope.adopt(creation);

  if (createdHandler === undefined || errorHandler === undefined) {
    throw new Error(
      "construction must synchronously begin both creation listeners",
    );
  }
  const close = scope.disposeOwned().then(() => {
    order.push("root-destroy");
    rootDestroyed = true;
  });
  await Promise.resolve();
  assertEquals(
    rootDestroyed,
    false,
    "close must wait for the native creation outcome",
  );

  order.push("created-event");
  createdHandler();
  errorHandler(new Error("late losing outcome"));
  await bothCleanupsStarted.promise;
  assertEquals(
    rootDestroyed,
    false,
    "root destruction must wait for both native unlisten acknowledgements",
  );

  createdCleanupDone.resolve();
  errorCleanupDone.resolve();
  await companionDestroyStarted.promise;
  assertEquals(
    rootDestroyed,
    false,
    "a companion created after close must be destroyed before its parent realm",
  );
  companionDestroyDone.resolve();

  assertEquals(
    (await creation).kind,
    "created",
    "the first native outcome must win exactly once",
  );
  await close;
  assertEquals(
    latePublications,
    0,
    "late creation must not publish into disposed React state",
  );
  assertArrayEquals(
    order,
    [
      "created-event",
      "created-listener-cleanup",
      "error-listener-cleanup",
      "companion-destroy",
      "root-destroy",
    ],
    "creation, listener cleanup, companion destruction, and root destruction stay ordered",
  );
});

Deno.test("listener-first bootstrap keeps an update that arrives during the initial refresh", async () => {
  const owner = new AsyncOwner();
  const initial = deferred<string>();
  const update = deferred<string>();
  const published: string[] = [];
  let emitUpdate: (() => Promise<boolean>) | undefined;
  const order: string[] = [];

  await owner.register(() => {
    order.push("listener");
    emitUpdate = () =>
      owner.applyLatestIfActive(
        () => update.promise,
        (value) => published.push(value),
      );
    return Promise.resolve(() => {});
  });
  order.push("snapshot");
  const initialRefresh = owner.applyLatestIfActive(
    () => initial.promise,
    (value) => published.push(value),
  );
  const eventRefresh = emitUpdate?.();
  if (eventRefresh === undefined) throw new Error("listener was not installed");

  initial.resolve("stale-initial");
  assertEquals(
    await initialRefresh,
    false,
    "the event should supersede the bootstrap snapshot",
  );
  update.resolve("event-update");
  assertEquals(await eventRefresh, true, "the event refresh should publish");

  assertArrayEquals(
    order,
    ["listener", "snapshot"],
    "the listener must precede the snapshot",
  );
  assertArrayEquals(
    published,
    ["event-update"],
    "the bootstrap interval must not lose updates",
  );
  await owner.dispose();
});

Deno.test("out-of-order refresh completion publishes only the latest request", async () => {
  const owner = new AsyncOwner();
  const older = deferred<string>();
  const newer = deferred<string>();
  const published: string[] = [];

  const olderRefresh = owner.applyLatestIfActive(
    () => older.promise,
    (value) => published.push(value),
  );
  const newerRefresh = owner.applyLatestIfActive(
    () => newer.promise,
    (value) => published.push(value),
  );

  newer.resolve("newer");
  assertEquals(await newerRefresh, true, "the newest refresh should publish");
  older.resolve("older");
  assertEquals(
    await olderRefresh,
    false,
    "the older refresh should be suppressed",
  );
  assertArrayEquals(
    published,
    ["newer"],
    "older completion must not overwrite newer state",
  );
  await owner.dispose();
});

Deno.test("settings hydration keeps saved fields while applying newer user edits", () => {
  const restored = {
    accent: "saved-accent",
    density: "saved-density",
    username: "saved-user",
  };
  const pendingEdits = { accent: "user-edit" };

  const merged = mergeHydratedState(restored, pendingEdits);

  assertEquals(
    merged.accent,
    "user-edit",
    "the newer edit should win its field",
  );
  assertEquals(
    merged.density,
    "saved-density",
    "unrelated saved fields must survive",
  );
  assertEquals(
    merged.username,
    "saved-user",
    "the full saved baseline must be retained",
  );
});

Deno.test("serialized writes do not start a newer value before the older value settles", async () => {
  const firstDone = deferred<void>();
  const firstStarted = deferred<void>();
  const secondDone = deferred<void>();
  const secondStarted = deferred<void>();
  const starts: number[] = [];
  const writer = createSerializedAsyncWriter<number>((value) => {
    starts.push(value);
    if (value === 1) {
      firstStarted.resolve();
      return firstDone.promise;
    }
    secondStarted.resolve();
    return secondDone.promise;
  }, () => {});

  const firstWrite = writer.enqueue(1);
  const secondWrite = writer.enqueue(2);
  await firstStarted.promise;
  assertArrayEquals(
    starts,
    [1],
    "only the oldest write should start initially",
  );

  firstDone.resolve();
  await firstWrite;
  await secondStarted.promise;
  assertArrayEquals(
    starts,
    [1, 2],
    "the newer write should start after the older write",
  );

  secondDone.resolve();
  await secondWrite;
  await writer.waitForIdle();
});

Deno.test("a failed serialized write is reported and does not block the newer value", async () => {
  const firstDone = deferred<void>();
  const firstStarted = deferred<void>();
  const secondStarted = deferred<void>();
  const failure = new Error("first write failed");
  const errors: unknown[] = [];
  const starts: number[] = [];
  const writer = createSerializedAsyncWriter<number>(async (value) => {
    starts.push(value);
    if (value === 1) {
      firstStarted.resolve();
      await firstDone.promise;
      throw failure;
    }
    secondStarted.resolve();
  }, (error) => errors.push(error));

  const firstWrite = writer.enqueue(1);
  const secondWrite = writer.enqueue(2);
  await firstStarted.promise;
  assertArrayEquals(
    starts,
    [1],
    "the failed write should still own the queue first",
  );

  firstDone.resolve();
  await firstWrite;
  await secondStarted.promise;
  await secondWrite;

  assertArrayEquals(
    starts,
    [1, 2],
    "a newer write should run after the failure is handled",
  );
  assertEquals(errors.length, 1, "the failed write should be reported once");
  assertEquals(
    errors[0],
    failure,
    "the original write failure should be reported",
  );
});

Deno.test("closing a writer stops admission and drains the pending write", async () => {
  const pending = deferred<void>();
  const started = deferred<void>();
  const writes: number[] = [];
  const writer = createSerializedAsyncWriter<number>(async (value) => {
    writes.push(value);
    started.resolve();
    await pending.promise;
  }, () => {});

  void writer.enqueue(1);
  await started.promise;
  let drained = false;
  const drain = writer.closeAndWait().then(() => {
    drained = true;
  });
  await writer.enqueue(2);

  assertEquals(drained, false, "close must wait for the admitted write");
  assertArrayEquals(writes, [1], "close must reject newer writes");
  pending.resolve();
  await drain;
  assertEquals(drained, true, "close should settle after the pending write");
});