import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
import { Knex } from 'knex';
// Mock Knex and dependencies
// vi.mock('knex'); // More sophisticated mocking might be needed

// Import functions to test
import {
  findOrCreateCurrentBucketUsageRecord,
  updateBucketUsageMinutes,
  reconcileBucketUsageRecord,
  // Assuming calculatePeriod is exported if direct testing is needed, otherwise test via findOrCreate
} from '@alga-psa/billing/services/bucketUsageService';

// Mock data and setup
const mockTenant = 'test-tenant';
const mockClientId = 'client-uuid-123';
const mockServiceId = 'service-uuid-456';
const mockPlanId = 'plan-uuid-789';
const mockUsageId = 'usage-uuid-abc';

// Mock Knex transaction object
const mockTrx = {
  // Mock necessary Knex methods used by the service functions
  // e.g., select, where, join, insert, update, first, transaction, raw, fn.now()
  // This needs to be comprehensive based on actual usage within the functions.
  // Example:
  select: vi.fn().mockReturnThis(),
  where: vi.fn().mockReturnThis(),
  andWhere: vi.fn().mockReturnThis(),
  orWhereNull: vi.fn().mockReturnThis(),
  join: vi.fn().mockReturnThis(),
  leftJoin: vi.fn().mockReturnThis(),
  on: vi.fn().mockReturnThis(),
  andOn: vi.fn().mockReturnThis(),
  andOnVal: vi.fn().mockReturnThis(),
  first: vi.fn().mockResolvedValue(undefined), // Default mock
  insert: vi.fn().mockReturnThis(),
  returning: vi.fn().mockResolvedValue([]), // Default mock
  update: vi.fn().mockResolvedValue(0), // Default mock
  sum: vi.fn().mockReturnThis(),
  raw: vi.fn((sql, bindings) => ({ sql, bindings })), // Simple mock for raw
  fn: {
    now: vi.fn(() => new Date().toISOString()), // Mock now()
  },
  client: { // Mock client config for tenant context
    config: {
      tenant: mockTenant,
    },
  },
  // Mock transaction commit/rollback if needed, though often handled by test runner setup/teardown
  commit: vi.fn().mockResolvedValue(undefined),
  rollback: vi.fn().mockResolvedValue(undefined),
} as unknown as Knex.Transaction; // Cast to Transaction type

describe('BucketUsageService Unit Tests', () => {

  beforeEach(() => {
    // Reset mocks before each test
    vi.clearAllMocks();
    // Reset mock implementations to defaults if necessary
    (mockTrx.first as any).mockResolvedValue(undefined);
    (mockTrx.returning as any).mockResolvedValue([]);
    (mockTrx.update as any).mockResolvedValue(0);
    (mockTrx.sum as any).mockReturnThis(); // Reset sum chaining
  });

  describe('findOrCreateCurrentBucketUsageRecord', () => {
    it.skip('should find an existing bucket usage record for the correct period', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - calculatePeriod returns a valid period
      // - trx('bucket_usage').where(...).first() returns a mock existing record
      // Assert:
      // - The function returns the mocked existing record.
      // - No insert call is made.
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should create a new bucket usage record if none exists for the period (no rollover)', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - calculatePeriod returns a valid period
      // - trx('bucket_usage').where(...).first() returns undefined (for current period)
      // - trx('contract_line_service_bucket_config').where(...).first() returns config with allow_rollover = false
      // - trx('bucket_usage').insert(...).returning('*') returns the new mock record
      // Assert:
      // - The function returns the new mock record.
      // - The new record has minutes_used = 0, overage_minutes = 0, rolled_over_minutes = 0.
      // - Correct period_start, period_end, contract_line_id, etc. are used in insert.
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should create a new record and calculate rollover hours correctly when rollover is enabled and previous period exists', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - calculatePeriod returns a valid period
      // - trx('bucket_usage').where(...).first() returns undefined (for current period)
      // - trx('contract_line_service_bucket_config').where(...).first() returns config with allow_rollover = true, total_minutes = 6000
      // - trx('bucket_usage').where(...) for *previous* period returns a record with minutes_used = 4800
      // - trx('bucket_usage').insert(...).returning('*') returns the new mock record
      // Assert:
      // - The function returns the new mock record.
      // - The new record has rolled_over_minutes = 1200 (6000 - 4800).
      expect(true).toBe(false); // Placeholder
    });

     it.skip('should create a new record with zero rollover hours if rollover is enabled but previous period does not exist', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - calculatePeriod returns a valid period
      // - trx('bucket_usage').where(...).first() returns undefined (for current period)
      // - trx('contract_line_service_bucket_config').where(...).first() returns config with allow_rollover = true
      // - trx('bucket_usage').where(...) for *previous* period returns undefined
      // - trx('bucket_usage').insert(...).returning('*') returns the new mock record
      // Assert:
      // - The function returns the new mock record.
      // - The new record has rolled_over_hours = 0.
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should throw an error if the billing period cannot be calculated', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - calculatePeriod returns null
      // Assert:
      // - The function throws an appropriate error.
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should throw an error if the bucket configuration is missing', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - calculatePeriod returns a valid period
      // - trx('bucket_usage').where(...).first() returns undefined
      // - trx('contract_line_service_bucket_config').where(...).first() returns undefined
      // Assert:
      // - The function throws an appropriate error.
      expect(true).toBe(false); // Placeholder
    });

    // TODO: Add tests for different billing frequencies (monthly, quarterly, annually) in calculatePeriod if testing directly
  });

  describe('updateBucketUsageMinutes', () => {
    it.skip('should correctly increment minutes_used and calculate overage_minutes', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - trx('bucket_usage').join(...).where(...).first() returns { minutes_used: 50, rolled_over_minutes: 10, total_minutes: 100 }
      // - trx('bucket_usage').where(...).update(...) returns 1 (update successful)
      // Input: minutesDelta = 60
      // Assert:
      // - The update call receives { minutes_used: 110, overage_minutes: 0 } (110 - 110 = 0)
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should correctly decrement minutes_used and calculate overage_minutes (should become 0)', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - trx('bucket_usage').join(...).where(...).first() returns { minutes_used: 7200, rolled_over_minutes: 0, total_minutes: 6000 } (currently in overage)
      // - trx('bucket_usage').where(...).update(...) returns 1
      // Input: minutesDelta = -1800
      // Assert:
      // - The update call receives { minutes_used: 5400, overage_minutes: 0 } (5400 - 6000 is negative, so 0)
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should not change hours if hoursDelta is 0', async () => {
      // TODO: Implement test
      // Input: hoursDelta = 0
      // Assert:
      // - No database update call is made.
      // - The function returns void/Promise<void> successfully.
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should throw an error if the bucket usage record or config is not found', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - trx('bucket_usage').join(...).where(...).first() returns undefined
      // Assert:
      // - The function throws an appropriate error.
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should throw an error if the update fails (returns 0 rows updated)', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - trx('bucket_usage').join(...).where(...).first() returns valid data
      // - trx('bucket_usage').where(...).update(...) returns 0
      // Assert:
      // - The function throws an appropriate error.
      expect(true).toBe(false); // Placeholder
    });
  });

  describe('reconcileBucketUsageRecord', () => {
    it.skip('should correctly calculate total minutes from time entries and usage tracking and update the record', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - trx('bucket_usage').join(...).where(...).first() returns a record with period, client, service, total_minutes=6000
      // - trx('time_entries').where(...).sum(...) returns { total_duration_minutes: 7200 } (120 hours)
      // - trx('usage_tracking').where(...).sum(...) returns { total_quantity: 1800 } (30 hours)
      // - trx('bucket_usage').where(...).update(...) returns 1
      // Assert:
      // - Calculated totalMinutesUsed = 9000 (7200 + 1800)
      // - Calculated newOverageMinutes = 3000 (9000 - 6000)
      // - The update call receives { minutes_used: 9000, overage_minutes: 3000 }
      expect(true).toBe(false); // Placeholder
    });

     it.skip('should handle cases with no time entries or no usage tracking records', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - trx('bucket_usage').join(...).where(...).first() returns a record, total_hours=50
      // - trx('time_entries').where(...).sum(...) returns { total_duration_minutes: null } or { total_duration_minutes: 0 }
      // - trx('usage_tracking').where(...).sum(...) returns { total_quantity: 10 }
      // - trx('bucket_usage').where(...).update(...) returns 1
      // Assert:
      // - Calculated totalHoursUsed = 10
      // - Calculated newOverageMinutes = 0
      // - The update call receives { minutes_used: 600, overage_minutes: 0 }
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should throw an error if the bucket usage record or config is not found', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - trx('bucket_usage').join(...).where(...).first() returns undefined
      // Assert:
      // - The function throws an appropriate error.
      // - No sum or update calls are made.
      expect(true).toBe(false); // Placeholder
    });

    it.skip('should throw an error if the update fails', async () => {
      // TODO: Implement test
      // Mock DB calls:
      // - trx('bucket_usage').join(...).where(...).first() returns valid data
      // - Sum calls return valid data
      // - trx('bucket_usage').where(...).update(...) returns 0
      // Assert:
      // - The function throws an appropriate error.
      expect(true).toBe(false); // Placeholder
    });

    // TODO: Add tests considering different data types for sum results (e.g., string vs number) if necessary
  });

});