import { describe, it, expect } from '@jest/globals';

/**
 * Unit tests for exchange-rate-providers routes
 * Focus: DELETE endpoint and test-connection endpoint
 *
 * Note: These are logic tests, not full integration tests with database
 */

describe('Exchange Rate Providers Routes', () => {
  describe('DELETE endpoint logic', () => {
    /**
     * TC-D03: Cannot delete in-use provider
     */
    it('should prevent deletion of in-use provider', () => {
      // Mock scenario
      const targetProviderId = 'provider-1';
      const activeProviderId = 'provider-1'; // Same as target

      // Logic from DELETE endpoint
      const isInUse = targetProviderId === activeProviderId;

      expect(isInUse).toBe(true);
      // In actual endpoint: return 400 with error message
    });

    /**
     * TC-D02: Allow deletion of non-active provider
     */
    it('should allow deletion of non-active provider', () => {
      const targetProviderId: string = 'provider-2';
      const activeProviderId: string = 'provider-1'; // Different

      const isInUse = targetProviderId === activeProviderId;

      expect(isInUse).toBe(false);
      // In actual endpoint: proceed with deletion
    });

    /**
     * TC-D04: Cannot delete last enabled provider
     */
    it('should prevent deletion of last enabled provider', () => {
      // Mock scenario: target is enabled, no other enabled providers
      const otherEnabledCount = 0;
      const providerEnabled = true;
      const providerStatus: string = 'active';

      const isLastEnabled = otherEnabledCount === 0 && providerEnabled && providerStatus !== 'paused';

      expect(isLastEnabled).toBe(true);
      // In actual endpoint: return 400 with error message
    });

    /**
     * TC-D05: Allow deletion when multiple enabled providers exist
     */
    it('should allow deletion when other enabled providers exist', () => {
      const otherEnabledCount: number = 2; // Other enabled providers available
      const providerEnabled = true;
      const providerStatus: string = 'active';

      const isLastEnabled = otherEnabledCount === 0 && providerEnabled && providerStatus !== 'paused';

      expect(isLastEnabled).toBe(false);
      // In actual endpoint: proceed with deletion
    });

    /**
     * TC-D09: Allow deletion of paused provider
     */
    it('should allow deletion of paused provider even if no other enabled', () => {
      const otherEnabledCount = 0;
      const providerEnabled = true;
      const providerStatus = 'paused';

      const isLastEnabled = otherEnabledCount === 0 && providerEnabled && providerStatus !== 'paused';

      expect(isLastEnabled).toBe(false);
      // Paused providers don't count as "active", safe to delete
    });
  });

  describe('Active provider selection logic', () => {
    /**
     * Verify the logic for determining active provider matches frontend
     */
    it('should select lowest priority enabled provider', () => {
      const allProviders = [
        { id: 'p1', priority: 2, enabled: true, status: 'active' },
        { id: 'p2', priority: 1, enabled: true, status: 'active' },
        { id: 'p3', priority: 3, enabled: false, status: 'active' },
      ];

      // Logic from DELETE endpoint
      const activeProviders = allProviders
        .filter((p) => p.enabled && p.status !== 'paused')
        .sort((a, b) => a.priority - b.priority);

      const activeProviderId = activeProviders[0]?.id || null;

      expect(activeProviderId).toBe('p2'); // Lowest priority among enabled
    });

    it('should exclude paused providers from active selection', () => {
      const allProviders = [
        { id: 'p1', priority: 1, enabled: true, status: 'paused' },
        { id: 'p2', priority: 2, enabled: true, status: 'active' },
      ];

      const activeProviders = allProviders
        .filter((p) => p.enabled && p.status !== 'paused')
        .sort((a, b) => a.priority - b.priority);

      const activeProviderId = activeProviders[0]?.id || null;

      expect(activeProviderId).toBe('p2'); // p1 is paused, so p2 is active
    });

    it('should return null when no active providers', () => {
      const allProviders = [
        { id: 'p1', priority: 1, enabled: false, status: 'active' },
        { id: 'p2', priority: 2, enabled: true, status: 'paused' },
      ];

      const activeProviders = allProviders
        .filter((p) => p.enabled && p.status !== 'paused')
        .sort((a, b) => a.priority - b.priority);

      const activeProviderId = activeProviders[0]?.id || null;

      expect(activeProviderId).toBeNull();
    });
  });

  describe('Test connection endpoint validation', () => {
    /**
     * TC-T07: Invalid provider type
     */
    it('should reject invalid provider types', () => {
      const allowedTypes = ['token-data', 'coingecko', 'coinmarketcap'];
      const testType = 'invalid-type';

      const isValid = allowedTypes.includes(testType);

      expect(isValid).toBe(false);
      // In actual endpoint: return 400
    });

    /**
     * TC-T01: Valid provider types
     */
    it('should accept valid provider types', () => {
      const allowedTypes = ['token-data', 'coingecko', 'coinmarketcap'];

      expect(allowedTypes.includes('token-data')).toBe(true);
      expect(allowedTypes.includes('coingecko')).toBe(true);
      expect(allowedTypes.includes('coinmarketcap')).toBe(true);
    });

    /**
     * Test symbol selection
     */
    it('should use ETH as test symbol', () => {
      const testSymbol = 'ETH';

      expect(testSymbol).toBe('ETH');
      // ETH is most common and stable token for testing
    });
  });

  describe('Safety constraint scenarios', () => {
    /**
     * INT-02: Full delete protection workflow
     */
    it('should handle delete protection workflow correctly', () => {
      // Scenario: 2 providers, A (priority 1), B (priority 2)
      const providers = [
        { id: 'A', priority: 1, enabled: true, status: 'active' },
        { id: 'B', priority: 2, enabled: true, status: 'active' },
      ];

      // Provider A is in-use
      const activeProviders = providers
        .filter((p) => p.enabled && p.status !== 'paused')
        .sort((a, b) => a.priority - b.priority);
      let activeProviderId = activeProviders[0]?.id;

      expect(activeProviderId).toBe('A');

      // Try to delete A - should be blocked
      const canDeleteA = activeProviderId !== 'A';
      expect(canDeleteA).toBe(false);

      // Disable A
      providers[0]!.enabled = false;

      // Now B should become active
      const updatedActiveProviders = providers
        .filter((p) => p.enabled && p.status !== 'paused')
        .sort((a, b) => a.priority - b.priority);
      activeProviderId = updatedActiveProviders[0]?.id;

      expect(activeProviderId).toBe('B');

      // Now A can be deleted (not in-use, not last enabled since B exists)
      const canDeleteANow = activeProviderId !== 'A';
      const otherEnabledCount: number = 1; // B is enabled
      const aIsLastEnabled = otherEnabledCount === 0 && !providers[0]!.enabled;

      expect(canDeleteANow).toBe(true);
      expect(aIsLastEnabled).toBe(false);
    });
  });
});
