/**
 * Watermark CAS race condition tests
 */

import { compareJwtIds } from '../validation';

describe('Watermark CAS Race Conditions', () => {
  const testJwtIds = [
    '1704067200_abc123_12345678', // 2024-01-01 00:00:00
    '1704153600_mno345_87654321', // 2024-01-02 00:00:00
    '1704240000_new123_abcdef01', // 2024-01-03 00:00:00
    '1704326400_xyz789_23456789', // 2024-01-04 00:00:00
    '1704412800_stu901_34567890'  // 2024-01-05 00:00:00
  ];

  describe('Concurrent Bootstrap Race', () => {
    it('should handle two clients bootstrapping concurrently', async () => {
      // Simulate two clients fetching the same data concurrently
      const client1Bootstrap = testJwtIds[2]; // 2024-01-03
      const client2Bootstrap = testJwtIds[3]; // 2024-01-04 (newer)
      
      // Client 1 attempts to set watermark
      const client1Result = await simulateWatermarkUpdate(null, client1Bootstrap);
      expect(client1Result.success).toBe(true);
      expect(client1Result.watermark).toBe(client1Bootstrap);
      
      // Client 2 attempts to set watermark (should succeed due to CAS)
      const client2Result = await simulateWatermarkUpdate(client1Bootstrap, client2Bootstrap);
      expect(client2Result.success).toBe(true);
      expect(client2Result.watermark).toBe(client2Bootstrap);
      
      // Final watermark should be the maximum JWT ID
      const finalWatermark = await getCurrentWatermark();
      expect(finalWatermark).toBe(client2Bootstrap);
      if (finalWatermark && client1Bootstrap) {
        expect(compareJwtIds(finalWatermark, client1Bootstrap)).toBeGreaterThan(0);
      }
    });

    it('should reject older watermark updates', async () => {
      // Set initial watermark
      await simulateWatermarkUpdate(null, testJwtIds[3]); // 2024-01-04
      
      // Attempt to set older watermark (should fail)
      const result = await simulateWatermarkUpdate(testJwtIds[3], testJwtIds[1]); // 2024-01-02
      expect(result.success).toBe(false);
      expect(result.watermark).toBe(testJwtIds[3]); // Unchanged
    });

    it('should handle null watermark bootstrap', async () => {
      // First client sets watermark from null
      const result1 = await simulateWatermarkUpdate(null, testJwtIds[2]);
      expect(result1.success).toBe(true);
      
      // Second client attempts to set watermark from null (should fail)
      const result2 = await simulateWatermarkUpdate(null, testJwtIds[1]);
      expect(result2.success).toBe(false);
      expect(result2.watermark).toBe(testJwtIds[2]); // First client's watermark
    });
  });

  describe('Overlapping Polls Race', () => {
    it('should handle overlapping polls with different results', async () => {
      // Set initial watermark
      await simulateWatermarkUpdate(null, testJwtIds[1]); // 2024-01-02
      
      // Client 1 polls and finds changes up to 2024-01-03
      const client1Changes = [testJwtIds[2]]; // 2024-01-03
      const client1Result = await simulatePollAndUpdate(testJwtIds[1], client1Changes);
      expect(client1Result.success).toBe(true);
      expect(client1Result.newWatermark).toBe(testJwtIds[2]);
      
      // Client 2 polls concurrently and finds changes up to 2024-01-04
      const client2Changes = [testJwtIds[2], testJwtIds[3]]; // 2024-01-03, 2024-01-04
      const client2Result = await simulatePollAndUpdate(testJwtIds[2], client2Changes);
      expect(client2Result.success).toBe(true);
      expect(client2Result.newWatermark).toBe(testJwtIds[3]);
      
      // Final watermark should be the maximum
      const finalWatermark = await getCurrentWatermark();
      expect(finalWatermark).toBe(testJwtIds[3]);
    });

    it('should prevent duplicate notifications from overlapping polls', async () => {
      // Set initial watermark
      await simulateWatermarkUpdate(null, testJwtIds[1]);
      
      // Both clients find the same change
      const sharedChange = testJwtIds[2];
      
      // Client 1 processes change
      const client1Result = await simulatePollAndUpdate(testJwtIds[1], [sharedChange]);
      expect(client1Result.success).toBe(true);
      expect(client1Result.notificationsGenerated).toBe(1);
      
      // Client 2 attempts to process same change (should be no-op)
      const client2Result = await simulatePollAndUpdate(testJwtIds[1], [sharedChange]);
      expect(client2Result.success).toBe(false); // No new changes
      expect(client2Result.notificationsGenerated).toBe(0);
    });
  });

  describe('Watermark Monotonicity', () => {
    it('should maintain monotonic watermark advancement', async () => {
      let currentWatermark = null;
      
      // Process changes in order
      for (let i = 0; i < testJwtIds.length; i++) {
        const newWatermark = testJwtIds[i];
        const result = await simulateWatermarkUpdate(currentWatermark, newWatermark);
        
        expect(result.success).toBe(true);
        expect(result.watermark).toBe(newWatermark);
        
        // Verify monotonicity
        if (currentWatermark) {
          expect(compareJwtIds(newWatermark, currentWatermark)).toBeGreaterThan(0);
        }
        
        currentWatermark = newWatermark;
      }
    });

    it('should reject non-monotonic watermark updates', async () => {
      // Set watermark to middle value
      await simulateWatermarkUpdate(null, testJwtIds[2]);
      
      // Attempt to set older watermark
      const result = await simulateWatermarkUpdate(testJwtIds[2], testJwtIds[0]);
      expect(result.success).toBe(false);
      
      // Attempt to set same watermark
      const result2 = await simulateWatermarkUpdate(testJwtIds[2], testJwtIds[2]);
      expect(result2.success).toBe(false);
    });
  });

  describe('Platform-Specific CAS Implementation', () => {
    it('should verify SQL CAS returns row update count', async () => {
      // Simulate SQL UPDATE ... WHERE condition
      const sqlResult = await simulateSqlWatermarkUpdate(null, testJwtIds[0]);
      expect(sqlResult.rowsAffected).toBe(1);
      
      // Attempt to update with same condition (should affect 0 rows)
      const sqlResult2 = await simulateSqlWatermarkUpdate(null, testJwtIds[0]);
      expect(sqlResult2.rowsAffected).toBe(0);
    });

    it('should verify Room CAS returns update count', async () => {
      // Simulate Room @Query with return type Int
      const roomResult = await simulateRoomWatermarkUpdate(null, testJwtIds[0]);
      expect(roomResult).toBe(1);
      
      // Attempt to update with same condition
      const roomResult2 = await simulateRoomWatermarkUpdate(null, testJwtIds[0]);
      expect(roomResult2).toBe(0);
    });

    it('should verify Core Data CAS returns success boolean', async () => {
      // Simulate Core Data compare-and-swap
      const coreDataResult = await simulateCoreDataWatermarkUpdate(null, testJwtIds[0]);
      expect(coreDataResult).toBe(true);
      
      // Attempt to update with same condition
      const coreDataResult2 = await simulateCoreDataWatermarkUpdate(null, testJwtIds[0]);
      expect(coreDataResult2).toBe(false);
    });

    it('should verify storage CAS returns success boolean', async () => {
      // Simulate storage transaction
      const storageResult = await simulateStorageWatermarkUpdate(null, testJwtIds[0]);
      expect(storageResult).toBe(true);
      
      // Attempt to update with same condition
      const storageResult2 = await simulateStorageWatermarkUpdate(null, testJwtIds[0]);
      expect(storageResult2).toBe(false);
    });
  });
});

// Mock implementations for testing
let mockWatermark: string | null = null;

async function simulateWatermarkUpdate(
  expectedWatermark: string | null, 
  newWatermark: string
): Promise<{ success: boolean; watermark: string | null }> {
  // Simulate CAS logic with proper comparison
  if (mockWatermark === expectedWatermark) {
    // If current watermark is null or new watermark is greater, update
    if (mockWatermark === null || compareJwtIds(newWatermark, mockWatermark) > 0) {
      mockWatermark = newWatermark;
      return { success: true, watermark: newWatermark };
    }
  }
  return { success: false, watermark: mockWatermark };
}

async function simulatePollAndUpdate(
  currentWatermark: string | null,
  changes: string[]
): Promise<{ success: boolean; newWatermark: string | null; notificationsGenerated: number }> {
  if (changes.length === 0) {
    return { success: false, newWatermark: currentWatermark, notificationsGenerated: 0 };
  }
  
  const latestChange = changes[changes.length - 1];
  const result = await simulateWatermarkUpdate(currentWatermark, latestChange);
  
  return {
    success: result.success,
    newWatermark: result.watermark,
    notificationsGenerated: result.success ? changes.length : 0
  };
}

async function getCurrentWatermark(): Promise<string | null> {
  return mockWatermark;
}

async function simulateSqlWatermarkUpdate(
  expectedWatermark: string | null,
  newWatermark: string
): Promise<{ rowsAffected: number }> {
  if (mockWatermark === expectedWatermark) {
    mockWatermark = newWatermark;
    return { rowsAffected: 1 };
  }
  return { rowsAffected: 0 };
}

async function simulateRoomWatermarkUpdate(
  expectedWatermark: string | null,
  newWatermark: string
): Promise<number> {
  if (mockWatermark === expectedWatermark) {
    mockWatermark = newWatermark;
    return 1;
  }
  return 0;
}

async function simulateCoreDataWatermarkUpdate(
  expectedWatermark: string | null,
  newWatermark: string
): Promise<boolean> {
  if (mockWatermark === expectedWatermark) {
    mockWatermark = newWatermark;
    return true;
  }
  return false;
}

async function simulateStorageWatermarkUpdate(
  expectedWatermark: string | null,
  newWatermark: string
): Promise<boolean> {
  if (mockWatermark === expectedWatermark) {
    mockWatermark = newWatermark;
    return true;
  }
  return false;
}

// Reset mock state before each test
beforeEach(() => {
  mockWatermark = null;
});
