/**
 * Property-Based Tests: Dashboard, Department, Level, AuditLog
 * Feature: degree-management-refactor
 * Uses: fast-check + mongodb-memory-server + jest
 * Properties: 19, 20, 21, 22, 23, 24
 */

const mongoose = require('mongoose');
const { MongoMemoryServer } = require('mongodb-memory-server');
const fc = require('fast-check');

// Models
const Degree = require('../models/degree');
const Department = require('../models/department');
const Level = require('../models/level');
const AuditLog = require('../models/auditLog');

// Audit
const writeAuditLog = require('../audit/writeAuditLog');
const AUDIT_ACTIONS = require('../constants/auditAction');

let mongod;

jest.setTimeout(120000);

// ─── Setup / Teardown ────────────────────────────────────────────────────────

beforeAll(async () => {
  mongod = await MongoMemoryServer.create();
  const uri = mongod.getUri();
  await mongoose.connect(uri);
});

afterAll(async () => {
  await mongoose.disconnect();
  await mongod.stop();
});

afterEach(async () => {
  await Degree.deleteMany({});
  await Department.deleteMany({});
  await Level.deleteMany({});
  await AuditLog.deleteMany({});
});

// ─── Helpers ─────────────────────────────────────────────────────────────────

let _counter = 0;
function uid() {
  return `${Date.now()}_${++_counter}_${Math.random().toString(36).slice(2)}`;
}

async function createDept(nameSuffix) {
  const id = nameSuffix || uid();
  return Department.create({ name: `dept_${id}`, slug: `dept-${id}` });
}

async function createLevel(typeSuffix) {
  const id = typeSuffix || uid();
  return Level.create({ type: `level_${id}` });
}

function makeDegreeData(dept, level, overrides = {}) {
  const id = uid();
  return {
    qualification_number: `QN-${id}`,
    student_name: `Student ${id}`,
    program_name: `Program ${id}`,
    type: 'qualification',
    department: dept._id,
    level: level._id,
    issued_date: new Date('2024-01-01'),
    status: 'active',
    ...overrides,
  };
}

// Minimal mock req for writeAuditLog
function mockReq() {
  return {
    session: { user: { id: null } },
    headers: { 'x-forwarded-for': '127.0.0.1' },
    ip: '127.0.0.1',
  };
}

// ─── Property 19: Dashboard thống kê chính xác ───────────────────────────────

// Feature: degree-management-refactor, Property 19: Dashboard thống kê chính xác
test('Property 19: dashboard counts match seeded degree data', async () => {
  // Validates: Requirements 7.1, 7.2, 7.3
  await fc.assert(
    fc.asyncProperty(
      fc.integer({ min: 1, max: 10 }),
      fc.integer({ min: 0, max: 10 }),
      async (qualCount, certCount) => {
        await Degree.deleteMany({});
        await Department.deleteMany({});
        await Level.deleteMany({});

        const dept = await createDept();
        const lvl = await createLevel();

        // Seed qualification degrees (all active)
        for (let i = 0; i < qualCount; i++) {
          await Degree.create(makeDegreeData(dept, lvl, { type: 'qualification', status: 'active' }));
        }

        // Seed certification degrees (half active, half revoked)
        const certActive = Math.floor(certCount / 2);
        const certRevoked = certCount - certActive;
        for (let i = 0; i < certActive; i++) {
          const id = uid();
          await Degree.create(makeDegreeData(dept, lvl, {
            type: 'certification',
            certification_number: `CN-${id}`,
            status: 'active',
          }));
        }
        for (let i = 0; i < certRevoked; i++) {
          const id = uid();
          await Degree.create(makeDegreeData(dept, lvl, {
            type: 'certification',
            certification_number: `CN-${id}`,
            status: 'revoked',
          }));
        }

        const expectedTotal = qualCount + certCount;
        const expectedQual = qualCount;
        const expectedCert = certCount;
        const expectedActive = qualCount + certActive;
        const expectedRevoked = certRevoked;

        // Run same queries as dashboardController.getDashboard
        const thirtyDaysAgo = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
        const [total, qualificationCount, certificationCount, activeCount, revokedCount, recentCount] =
          await Promise.all([
            Degree.countDocuments(),
            Degree.countDocuments({ type: 'qualification' }),
            Degree.countDocuments({ type: 'certification' }),
            Degree.countDocuments({ status: 'active' }),
            Degree.countDocuments({ status: 'revoked' }),
            Degree.countDocuments({ createdAt: { $gte: thirtyDaysAgo } }),
          ]);

        expect(total).toBe(expectedTotal);
        expect(qualificationCount).toBe(expectedQual);
        expect(certificationCount).toBe(expectedCert);
        expect(activeCount).toBe(expectedActive);
        expect(revokedCount).toBe(expectedRevoked);
        // All seeded degrees are recent (just created)
        expect(recentCount).toBe(expectedTotal);
      }
    ),
    { numRuns: 100 }
  );
}, 120000);

// ─── Property 20: Tự động sinh slug cho Department ───────────────────────────

// Feature: degree-management-refactor, Property 20: Tự động sinh slug cho Department
test('Property 20: slug generated from department name is lowercase, spaces replaced with hyphens, no special chars', async () => {
  // Validates: Requirements 8.2
  await fc.assert(
    fc.asyncProperty(
      // Generate names with letters, spaces, digits — avoid empty after trim
      fc.stringMatching(/^[a-zA-Z][a-zA-Z0-9 ]{0,28}[a-zA-Z0-9]$/).filter(s => s.trim().length > 0),
      async (name) => {
        // Apply same slug logic as departmentController.create
        const slug = name.toLowerCase().trim().replace(/\s+/g, '-').replace(/[^a-z0-9-]/g, '');

        // Verify slug properties
        expect(slug).toBe(slug.toLowerCase());
        expect(slug).not.toMatch(/\s/);
        expect(slug).not.toMatch(/[^a-z0-9-]/);
        if (name.trim().includes(' ')) {
          expect(slug).toContain('-');
        }
      }
    ),
    { numRuns: 100 }
  );
}, 60000);

// ─── Property 21: Level yêu cầu trường type ──────────────────────────────────

// Feature: degree-management-refactor, Property 21: Level yêu cầu trường type
test('Property 21: creating Level without type field throws ValidationError', async () => {
  // Validates: Requirements 8.5
  await fc.assert(
    fc.asyncProperty(
      fc.constant(null),
      async () => {
        let threw = false;
        try {
          const doc = new Level({});
          await doc.save();
        } catch (err) {
          threw = true;
          expect(
            err.name === 'ValidationError' ||
            (err.message && err.message.toLowerCase().includes('type'))
          ).toBe(true);
        }
        expect(threw).toBe(true);
      }
    ),
    { numRuns: 100 }
  );
}, 60000);

// ─── Property 22: Referential integrity khi xóa Department/Level ─────────────

// Feature: degree-management-refactor, Property 22: Referential integrity khi xóa Department/Level
test('Property 22: deleting Department or Level referenced by a Degree is blocked', async () => {
  // Validates: Requirements 8.6
  await fc.assert(
    fc.asyncProperty(
      fc.boolean(), // true = test Department, false = test Level
      async (testDepartment) => {
        const dept = await createDept();
        const lvl = await createLevel();

        // Create a degree referencing both
        await Degree.create(makeDegreeData(dept, lvl));

        if (testDepartment) {
          // Simulate departmentController.destroy logic
          const count = await Degree.countDocuments({ department: dept._id });
          expect(count).toBeGreaterThan(0);
          // Deletion should be blocked (count > 0 means we would not delete)
          const wouldDelete = count === 0;
          expect(wouldDelete).toBe(false);
        } else {
          // Simulate levelController.destroy logic
          const count = await Degree.countDocuments({ level: lvl._id });
          expect(count).toBeGreaterThan(0);
          const wouldDelete = count === 0;
          expect(wouldDelete).toBe(false);
        }
      }
    ),
    { numRuns: 100 }
  );
}, 120000);

// ─── Property 23: Audit log được ghi sau mỗi CRUD operation ──────────────────

// Feature: degree-management-refactor, Property 23: Audit log được ghi sau mỗi CRUD operation
test('Property 23: writeAuditLog creates AuditLog with correct action, model, documentId', async () => {
  // Validates: Requirements 9.1
  await fc.assert(
    fc.asyncProperty(
      fc.constantFrom(
        AUDIT_ACTIONS.CREATE_DEGREE,
        AUDIT_ACTIONS.UPDATE_DEGREE,
        AUDIT_ACTIONS.DELETE_DEGREE
      ),
      async (action) => {
        const dept = await createDept();
        const lvl = await createLevel();
        const degree = await Degree.create(makeDegreeData(dept, lvl));

        await writeAuditLog({
          model: 'Degree',
          documentId: degree._id,
          action,
          before: null,
          after: degree.toObject(),
          changes: [],
          req: mockReq(),
        });

        const log = await AuditLog.findOne({ documentId: degree._id, action });
        expect(log).not.toBeNull();
        expect(log.model).toBe('Degree');
        expect(log.action).toBe(action);
        expect(log.documentId.toString()).toBe(degree._id.toString());

        // cleanup
        await AuditLog.deleteMany({ documentId: degree._id });
        await Degree.deleteOne({ _id: degree._id });
      }
    ),
    { numRuns: 100 }
  );
}, 120000);

// ─── Property 24: Audit log hiển thị theo thứ tự thời gian giảm dần ──────────

// Feature: degree-management-refactor, Property 24: Audit log hiển thị theo thứ tự thời gian giảm dần
test('Property 24: AuditLog.find().sort({ createdAt: -1 }) returns logs in descending order', async () => {
  // Validates: Requirements 9.2
  await fc.assert(
    fc.asyncProperty(
      fc.integer({ min: 2, max: 8 }),
      async (n) => {
        await AuditLog.deleteMany({});

        const dept = await createDept();
        const lvl = await createLevel();
        const degree = await Degree.create(makeDegreeData(dept, lvl));

        // Create n audit logs with distinct timestamps (1 second apart)
        const base = Date.now() - n * 1000;
        for (let i = 0; i < n; i++) {
          await AuditLog.create({
            model: 'Degree',
            documentId: degree._id,
            action: AUDIT_ACTIONS.CREATE_DEGREE,
            before: null,
            after: null,
            changes: [],
            ipAddress: '127.0.0.1',
            userAgent: '',
            performedBy: null,
            createdAt: new Date(base + i * 1000),
          });
        }

        const logs = await AuditLog.find().sort({ createdAt: -1 });

        expect(logs.length).toBe(n);
        for (let i = 0; i < logs.length - 1; i++) {
          expect(logs[i].createdAt.getTime()).toBeGreaterThanOrEqual(
            logs[i + 1].createdAt.getTime()
          );
        }

        // cleanup
        await AuditLog.deleteMany({});
        await Degree.deleteOne({ _id: degree._id });
      }
    ),
    { numRuns: 100 }
  );
}, 120000);