/**
 * Property-Based Test: Password Change Round-Trip
 *
 * Feature: user-profile, Property 3: Password change round-trip
 *
 * For any valid current password and any new password of 8+ characters,
 * after a successful change, bcrypt.compare(newPassword, storedHash) returns true.
 *
 * Validates: Requirements 2.2, 2.7
 */

const fc = require('fast-check');
const bcrypt = require('bcryptjs');

// bcrypt cost factor — production uses 10, but we use 4 (the minimum) here
// to keep 100 iterations feasible within test timeouts. The round-trip property
// holds regardless of cost factor.
const BCRYPT_COST = 4;

describe('Feature: user-profile, Property 3: Password change round-trip', () => {
  it('after a password change, bcrypt.compare(newPassword, newHash) returns true', async () => {
    await fc.assert(
      fc.asyncProperty(
        // Current password: any non-empty string (length >= 1)
        fc.string({ minLength: 1, maxLength: 72 }),
        // New password: any string of length >= 8 (bcrypt max input is 72 bytes)
        fc.string({ minLength: 8, maxLength: 72 }),
        async (currentPassword, newPassword) => {
          // Step 1: Hash the current password (simulates existing stored hash)
          const currentHash = await bcrypt.hash(currentPassword, BCRYPT_COST);

          // Step 2: Verify the current password against the stored hash
          // (simulates the bcrypt.compare check in the change-password route)
          const currentPasswordValid = await bcrypt.compare(currentPassword, currentHash);
          expect(currentPasswordValid).toBe(true);

          // Step 3: Hash the new password (simulates bcrypt.hash(newPassword, 10) in the route)
          const newHash = await bcrypt.hash(newPassword, BCRYPT_COST);

          // Step 4: Verify the new password matches the new hash (round-trip property)
          const newPasswordValid = await bcrypt.compare(newPassword, newHash);
          expect(newPasswordValid).toBe(true);
        }
      ),
      { numRuns: 100 }
    );
  }, 120000); // 2-minute timeout for 100 bcrypt iterations
});
