import { expect, tap } from '@push.rocks/tapbundle';
import * as smartstate from '../ts/index.js';

type TTestStateParts = 'initTest' | 'persistTest' | 'forceTest';

interface ITestState {
  value: number;
  nested: {
    data: string;
  };
}

// ============================
// Init mode tests
// ============================

tap.test('should handle soft init mode (default)', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();

  const statePart1 = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  });
  expect(statePart1.getState()).toEqual({
    value: 1,
    nested: { data: 'initial' }
  });

  const statePart2 = await state.getStatePart<ITestState>('initTest');
  expect(statePart1 === statePart2).toBeTrue();
});

tap.test('should handle mandatory init mode', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();

  const statePart1 = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  }, 'mandatory');
  expect(statePart1).toBeInstanceOf(smartstate.StatePart);

  let error: Error | null = null;
  try {
    await state.getStatePart<ITestState>('initTest', {
      value: 2,
      nested: { data: 'second' }
    }, 'mandatory');
  } catch (e) {
    error = e as Error;
  }
  expect(error).not.toBeNull();
  expect(error?.message).toMatch(/already exists.*mandatory/);
});

tap.test('should handle force init mode', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();

  const statePart1 = await state.getStatePart<ITestState>('forceTest', {
    value: 1,
    nested: { data: 'initial' }
  });
  expect(statePart1.getState()?.value).toEqual(1);

  const statePart2 = await state.getStatePart<ITestState>('forceTest', {
    value: 2,
    nested: { data: 'forced' }
  }, 'force');
  expect(statePart2.getState()?.value).toEqual(2);
  expect(statePart1 === statePart2).toBeFalse();
});

tap.test('should handle missing initial state error', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();

  let error: Error | null = null;
  try {
    await state.getStatePart<ITestState>('initTest');
  } catch (e) {
    error = e as Error;
  }
  expect(error).not.toBeNull();
  expect(error?.message).toMatch(/does not exist.*no initial state/);
});

tap.test('should handle state validation', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();

  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  });

  let error: Error | null = null;
  try {
    await statePart.setState(null as any);
  } catch (e) {
    error = e as Error;
  }
  expect(error).not.toBeNull();
  expect(error?.message).toMatch(/Invalid state structure/);
});

tap.test('should handle undefined state in select', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = new smartstate.StatePart<TTestStateParts, ITestState>('initTest');

  const values: (ITestState | undefined)[] = [];
  statePart.select().subscribe(val => values.push(val));

  expect(values).toHaveLength(0);

  await statePart.setState({
    value: 1,
    nested: { data: 'test' }
  });

  expect(values).toHaveLength(1);
  expect(values[0]).toEqual({
    value: 1,
    nested: { data: 'test' }
  });
});

tap.test('should not notify on duplicate state', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  });

  let notificationCount = 0;
  statePart.select().subscribe(() => notificationCount++);

  expect(notificationCount).toEqual(1);

  await statePart.setState({ value: 1, nested: { data: 'initial' } });
  await statePart.setState({ value: 1, nested: { data: 'initial' } });
  await statePart.setState({ value: 1, nested: { data: 'initial' } });

  expect(notificationCount).toEqual(1);

  await statePart.setState({ value: 2, nested: { data: 'changed' } });
  expect(notificationCount).toEqual(2);
});

// ============================
// AbortSignal tests
// ============================

tap.test('select should complete when AbortSignal fires', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  });

  const controller = new AbortController();
  const values: any[] = [];
  let completed = false;

  statePart.select(undefined, { signal: controller.signal }).subscribe({
    next: (v) => values.push(v),
    complete: () => { completed = true; },
  });

  expect(values.length).toBeGreaterThanOrEqual(1);

  controller.abort();
  // Give microtask time
  await new Promise<void>((r) => setTimeout(r, 10));

  expect(completed).toBeTrue();
});

tap.test('select with pre-aborted signal should complete immediately', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  });

  const controller = new AbortController();
  controller.abort();

  let completed = false;
  statePart.select(undefined, { signal: controller.signal }).subscribe({
    complete: () => { completed = true; },
  });

  await new Promise<void>((r) => setTimeout(r, 10));
  expect(completed).toBeTrue();
});

tap.test('waitUntilPresent should reject when AbortSignal fires', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 0,
    nested: { data: '' }
  }, 'force');

  const controller = new AbortController();

  const promise = statePart.waitUntilPresent(
    (s) => s.value > 100 ? s : undefined as any,
    { signal: controller.signal }
  );

  // Abort before the condition can be met
  setTimeout(() => controller.abort(), 20);

  let error: Error | null = null;
  try {
    await promise;
  } catch (e) {
    error = e as Error;
  }
  expect(error).not.toBeNull();
  expect(error?.message).toEqual('Aborted');
});

tap.test('waitUntilPresent should still work with numeric timeout (backward compat)', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 42,
    nested: { data: 'present' }
  }, 'force');

  const result = await statePart.waitUntilPresent(undefined, 5000);
  expect(result.value).toEqual(42);
});

// ============================
// Middleware tests
// ============================

tap.test('middleware should transform state', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  }, 'force');

  statePart.addMiddleware((newState, oldState) => {
    return { ...newState, nested: { data: newState.nested.data.toUpperCase() } };
  });

  await statePart.setState({ value: 2, nested: { data: 'hello' } });
  expect(statePart.getState().nested.data).toEqual('HELLO');
});

tap.test('middleware should reject state changes on throw', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  }, 'force');

  statePart.addMiddleware((newState) => {
    if (newState.value < 0) {
      throw new Error('Value must be non-negative');
    }
    return newState;
  });

  let error: Error | null = null;
  try {
    await statePart.setState({ value: -1, nested: { data: 'bad' } });
  } catch (e) {
    error = e as Error;
  }

  expect(error).not.toBeNull();
  expect(error?.message).toEqual('Value must be non-negative');
  // State should be unchanged
  expect(statePart.getState().value).toEqual(1);
});

tap.test('multiple middlewares should run in order', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  }, 'force');

  const order: number[] = [];

  statePart.addMiddleware((newState) => {
    order.push(1);
    return { ...newState, value: newState.value + 10 };
  });

  statePart.addMiddleware((newState) => {
    order.push(2);
    return { ...newState, value: newState.value * 2 };
  });

  await statePart.setState({ value: 5, nested: { data: 'test' } });
  expect(order).toEqual([1, 2]);
  // (5 + 10) * 2 = 30
  expect(statePart.getState().value).toEqual(30);
});

tap.test('middleware removal should work', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  }, 'force');

  const remove = statePart.addMiddleware((newState) => {
    return { ...newState, value: newState.value * 100 };
  });

  await statePart.setState({ value: 2, nested: { data: 'test' } });
  expect(statePart.getState().value).toEqual(200);

  remove();

  await statePart.setState({ value: 3, nested: { data: 'test' } });
  expect(statePart.getState().value).toEqual(3);
});

// ============================
// Selector memoization tests
// ============================

tap.test('select with same selector fn should return cached observable', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  }, 'force');

  const selector = (s: ITestState) => s.value;
  const obs1 = statePart.select(selector);
  const obs2 = statePart.select(selector);
  expect(obs1).toEqual(obs2);
});

tap.test('select with no args should return cached observable', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  }, 'force');

  const obs1 = statePart.select();
  const obs2 = statePart.select();
  expect(obs1).toEqual(obs2);
});

tap.test('select with different selectors should return different observables', async () => {
  const state = new smartstate.Smartstate<TTestStateParts>();
  const statePart = await state.getStatePart<ITestState>('initTest', {
    value: 1,
    nested: { data: 'initial' }
  }, 'force');

  const obs1 = statePart.select((s) => s.value);
  const obs2 = statePart.select((s) => s.nested);
  expect(obs1).not.toEqual(obs2);
});

// ============================
// Batch update tests
// ============================

tap.test('batch should defer notifications until complete', async () => {
  type TBatchParts = 'partA' | 'partB';
  const state = new smartstate.Smartstate<TBatchParts>();
  const partA = await state.getStatePart<ITestState>('partA', {
    value: 1,
    nested: { data: 'a' }
  });
  const partB = await state.getStatePart<ITestState>('partB', {
    value: 2,
    nested: { data: 'b' }
  });

  const notificationsA: number[] = [];
  const notificationsB: number[] = [];

  partA.select((s) => s.value).subscribe((v) => notificationsA.push(v));
  partB.select((s) => s.value).subscribe((v) => notificationsB.push(v));

  // Reset after initial notifications
  notificationsA.length = 0;
  notificationsB.length = 0;

  await state.batch(async () => {
    await partA.setState({ value: 10, nested: { data: 'aa' } });
    await partB.setState({ value: 20, nested: { data: 'bb' } });

    // During batch, no notifications yet
    expect(notificationsA).toHaveLength(0);
    expect(notificationsB).toHaveLength(0);
  });

  // After batch, both should have notified
  expect(notificationsA).toContain(10);
  expect(notificationsB).toContain(20);
});

tap.test('nested batches should only flush at outermost level', async () => {
  type TBatchParts = 'nested';
  const state = new smartstate.Smartstate<TBatchParts>();
  const part = await state.getStatePart<ITestState>('nested', {
    value: 0,
    nested: { data: 'start' }
  });

  const values: number[] = [];
  part.select((s) => s.value).subscribe((v) => values.push(v));
  values.length = 0;

  await state.batch(async () => {
    await part.setState({ value: 1, nested: { data: 'a' } });

    await state.batch(async () => {
      await part.setState({ value: 2, nested: { data: 'b' } });
      // Still inside outer batch
      expect(values).toHaveLength(0);
    });

    // Inner batch ended but outer batch still active
    expect(values).toHaveLength(0);
  });

  // Now outer batch is done — should see final notification
  expect(values.length).toBeGreaterThanOrEqual(1);
  expect(values[values.length - 1]).toEqual(2);
});

// ============================
// Computed state tests
// ============================

tap.test('computed should derive from multiple state parts', async () => {
  type TComputedParts = 'first' | 'second';
  const state = new smartstate.Smartstate<TComputedParts>();
  const first = await state.getStatePart<{ count: number }>('first', { count: 5 });
  const second = await state.getStatePart<{ count: number }>('second', { count: 10 });

  const derived$ = state.computed(
    [first, second],
    (a, b) => a.count + b.count,
  );

  const values: number[] = [];
  derived$.subscribe((v) => values.push(v));

  expect(values).toContain(15);
});

tap.test('computed should update when a source changes', async () => {
  type TComputedParts = 'x' | 'y';
  const state = new smartstate.Smartstate<TComputedParts>();
  const x = await state.getStatePart<{ n: number }>('x', { n: 1 });
  const y = await state.getStatePart<{ n: number }>('y', { n: 2 });

  const derived$ = state.computed(
    [x, y],
    (xState, yState) => xState.n * yState.n,
  );

  const values: number[] = [];
  derived$.subscribe((v) => values.push(v));

  // Initial: 1 * 2 = 2
  expect(values[0]).toEqual(2);

  await x.setState({ n: 5 });

  // After update: 5 * 2 = 10
  expect(values[values.length - 1]).toEqual(10);
});

tap.test('standalone computed function should work', async () => {
  type TParts = 'a' | 'b';
  const state = new smartstate.Smartstate<TParts>();
  const a = await state.getStatePart<{ val: string }>('a', { val: 'hello' });
  const b = await state.getStatePart<{ val: string }>('b', { val: 'world' });

  const derived$ = smartstate.computed(
    [a, b],
    (aState, bState) => `${aState.val} ${bState.val}`,
  );

  const values: string[] = [];
  derived$.subscribe((v) => values.push(v));

  expect(values[0]).toEqual('hello world');

  await a.setState({ val: 'hi' });
  expect(values[values.length - 1]).toEqual('hi world');
});

// ============================
// Context Protocol tests
// ============================

tap.test('attachContextProvider should respond to context-request events', async () => {
  // EventTarget and CustomEvent are available in Node 18+
  if (typeof EventTarget === 'undefined') {
    console.log('Skipping context test — EventTarget not available');
    return;
  }

  type TParts = 'ctx';
  const state = new smartstate.Smartstate<TParts>();
  const statePart = await state.getStatePart<{ theme: string }>('ctx', { theme: 'dark' });

  const myContext = Symbol('test-context');

  // Use an EventTarget as a mock element
  const element = new EventTarget() as any as HTMLElement;

  const cleanup = smartstate.attachContextProvider(element, {
    context: myContext,
    statePart,
  });

  let receivedValue: any = null;

  // Dispatch a context-request event
  const event = new CustomEvent('context-request', {
    detail: {
      context: myContext,
      callback: (value: any) => { receivedValue = value; },
      subscribe: false,
    },
    bubbles: true,
    composed: true,
  });
  (element as any).dispatchEvent(event);

  expect(receivedValue).toEqual({ theme: 'dark' });

  cleanup();
});

tap.test('attachContextProvider should support subscriptions', async () => {
  if (typeof EventTarget === 'undefined') {
    console.log('Skipping context subscription test — EventTarget not available');
    return;
  }

  type TParts = 'ctxSub';
  const state = new smartstate.Smartstate<TParts>();
  const statePart = await state.getStatePart<{ count: number }>('ctxSub', { count: 0 });

  const myContext = Symbol('sub-context');
  const element = new EventTarget() as any as HTMLElement;

  const cleanup = smartstate.attachContextProvider(element, {
    context: myContext,
    statePart,
  });

  const receivedValues: any[] = [];
  let unsubFn: (() => void) | undefined;

  const event = new CustomEvent('context-request', {
    detail: {
      context: myContext,
      callback: (value: any, unsub?: () => void) => {
        receivedValues.push(value);
        if (unsub) unsubFn = unsub;
      },
      subscribe: true,
    },
    bubbles: true,
    composed: true,
  });
  (element as any).dispatchEvent(event);

  expect(receivedValues).toHaveLength(1);
  expect(receivedValues[0]).toEqual({ count: 0 });

  // Update state — should trigger subscription callback
  await statePart.setState({ count: 42 });

  // Give a tick for the subscription to fire
  await new Promise<void>((r) => setTimeout(r, 10));

  expect(receivedValues.length).toBeGreaterThanOrEqual(2);
  expect(receivedValues[receivedValues.length - 1]).toEqual({ count: 42 });

  // Unsubscribe
  expect(unsubFn).toBeDefined();
  unsubFn!();

  cleanup();
});

tap.test('attachContextProvider should ignore non-matching contexts', async () => {
  if (typeof EventTarget === 'undefined') {
    console.log('Skipping context mismatch test — EventTarget not available');
    return;
  }

  type TParts = 'ctxMismatch';
  const state = new smartstate.Smartstate<TParts>();
  const statePart = await state.getStatePart<{ v: number }>('ctxMismatch', { v: 1 });

  const myContext = Symbol('my-context');
  const otherContext = Symbol('other-context');
  const element = new EventTarget() as any as HTMLElement;

  const cleanup = smartstate.attachContextProvider(element, {
    context: myContext,
    statePart,
  });

  let called = false;
  const event = new CustomEvent('context-request', {
    detail: {
      context: otherContext,
      callback: () => { called = true; },
      subscribe: false,
    },
    bubbles: true,
    composed: true,
  });
  (element as any).dispatchEvent(event);

  expect(called).toBeFalse();

  cleanup();
});

// ============================
// Enterprise hardening tests
// ============================

tap.test('concurrent dispatchAction should serialize (counter reaches exactly 10)', async () => {
  type TParts = 'counter';
  const state = new smartstate.Smartstate<TParts>();
  const counter = await state.getStatePart<{ count: number }>('counter', { count: 0 });

  const increment = counter.createAction<void>(async (statePart) => {
    const current = statePart.getState();
    return { count: current.count + 1 };
  });

  // Fire 10 concurrent increments (no await)
  const promises: Promise<any>[] = [];
  for (let i = 0; i < 10; i++) {
    promises.push(counter.dispatchAction(increment, undefined));
  }
  await Promise.all(promises);

  expect(counter.getState().count).toEqual(10);
});

tap.test('concurrent setState should serialize (no lost updates)', async () => {
  type TParts = 'concurrent';
  const state = new smartstate.Smartstate<TParts>();
  const part = await state.getStatePart<{ values: number[] }>('concurrent', { values: [] });

  const promises: Promise<any>[] = [];
  for (let i = 0; i < 5; i++) {
    promises.push(
      part.setState({ values: [...(part.getState()?.values || []), i] })
    );
  }
  await Promise.all(promises);

  // At minimum, the final state should have been set 5 times without error
  // The exact values depend on serialization timing, but state should be valid
  expect(part.getState()).toBeTruthy();
  expect(part.getState().values).toBeInstanceOf(Array);
});

tap.test('dispose should complete the Subject and notify subscribers', async () => {
  type TParts = 'disposable';
  const state = new smartstate.Smartstate<TParts>();
  const part = await state.getStatePart<{ v: number }>('disposable', { v: 1 });

  let completed = false;
  part.select().subscribe({
    complete: () => { completed = true; },
  });

  part.dispose();

  expect(completed).toBeTrue();
});

tap.test('falsy state {count: 0} should trigger notification', async () => {
  type TParts = 'falsy';
  const state = new smartstate.Smartstate<TParts>();
  const part = await state.getStatePart<{ count: number }>('falsy', { count: 0 });

  const values: number[] = [];
  part.select((s) => s.count).subscribe((v) => values.push(v));

  // Initial value should include 0
  expect(values).toContain(0);

  await part.setState({ count: 0 });
  // Should not duplicate since hash is the same, but the initial notification should have fired
  expect(values.length).toBeGreaterThanOrEqual(1);
});

tap.test('waitUntilPresent should resolve for falsy non-null values like false', async () => {
  type TParts = 'falsyWait';
  const state = new smartstate.Smartstate<TParts>();
  const part = await state.getStatePart<{ flag: boolean }>('falsyWait', { flag: false });

  const result = await part.waitUntilPresent((s) => s.flag as any, 2000);
  // false is not null/undefined, so it should resolve
  // Actually false IS falsy for `value !== undefined && value !== null` — false passes that check
  expect(result).toBeFalse();
});

tap.test('batch re-entrancy: setState during flush should not deadlock', async () => {
  type TParts = 'reentrant';
  const state = new smartstate.Smartstate<TParts>();
  const part = await state.getStatePart<{ v: number }>('reentrant', { v: 0 });

  let flushSetStateDone = false;

  // Subscribe and trigger a setState during notification flush
  part.select((s) => s.v).subscribe((v) => {
    if (v === 1 && !flushSetStateDone) {
      flushSetStateDone = true;
      // Fire-and-forget setState during notification — should not deadlock
      part.setState({ v: 2 });
    }
  });

  await state.batch(async () => {
    await part.setState({ v: 1 });
  });

  // Wait for the fire-and-forget setState to complete
  await new Promise<void>((r) => setTimeout(r, 50));

  expect(part.getState().v).toEqual(2);
});

tap.test('force mode should dispose old StatePart (Subject completes)', async () => {
  type TParts = 'forceDispose';
  const state = new smartstate.Smartstate<TParts>();
  const old = await state.getStatePart<{ v: number }>('forceDispose', { v: 1 });

  let oldCompleted = false;
  old.select().subscribe({
    complete: () => { oldCompleted = true; },
  });

  await state.getStatePart<{ v: number }>('forceDispose', { v: 2 }, 'force');

  expect(oldCompleted).toBeTrue();
});

tap.test('getStatePart should accept 0 as initial value', async () => {
  type TParts = 'zeroInit';
  const state = new smartstate.Smartstate<TParts>();

  // 0 is falsy but should be accepted as a valid initial value
  const part = await state.getStatePart<number>('zeroInit', 0);
  expect(part.getState()).toEqual(0);
});

export default tap.start();