/**
 * Property-Based Tests for Degree model
 * Feature: degree-management-refactor
 * Uses: fast-check + mongodb-memory-server + jest
 */

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');

let mongod;

// Increase global timeout for slow MongoDB startup and PBT runs
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({});
});

// ─── Seed Helpers ────────────────────────────────────────────────────────────

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

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

async function createLevel() {
  const id = 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'),
    ...overrides,
  };
}

// ─── Property 2: Validation các trường bắt buộc của Degree ──────────────────

// Feature: degree-management-refactor, Property 2: Validation các trường bắt buộc của Degree
test('Property 2: saving Degree without each required field throws ValidationError', async () => {
  // Validates: Requirements 2.1
  const requiredFields = [
    'qualification_number',
    'student_name',
    'program_name',
    'type',
    'department',
    'level',
    'issued_date',
  ];

  await fc.assert(
    fc.asyncProperty(
      fc.constantFrom(...requiredFields),
      async (missingField) => {
        const dept = await createDept();
        const lvl = await createLevel();
        const data = makeDegreeData(dept, lvl);
        delete data[missingField];

        let threw = false;
        try {
          const doc = new Degree(data);
          await doc.save();
        } catch (err) {
          threw = true;
          // Should be a ValidationError (or pre-save Error for type-related)
          const isValidation =
            err.name === 'ValidationError' ||
            (err.message && err.message.includes('required'));
          expect(isValidation).toBe(true);
        }
        expect(threw).toBe(true);
      }
    ),
    { numRuns: 100 }
  );
}, 60000);

// ─── Property 3: Conditional validation type-number ─────────────────────────

// Feature: degree-management-refactor, Property 3: Conditional validation type-number
test('Property 3: certification type without certification_number throws; qualification saves ok', async () => {
  // Validates: Requirements 2.3, 2.4
  await fc.assert(
    fc.asyncProperty(
      fc.boolean(), // true = certification (should fail), false = qualification (should pass)
      async (isCertification) => {
        const dept = await createDept();
        const lvl = await createLevel();

        if (isCertification) {
          // certification without certification_number → must throw
          const data = makeDegreeData(dept, lvl, { type: 'certification' });
          // no certification_number
          let threw = false;
          try {
            const doc = new Degree(data);
            await doc.save();
          } catch (err) {
            threw = true;
            expect(err.message).toMatch(/certification_number/i);
          }
          expect(threw).toBe(true);
        } else {
          // qualification without certification_number → must succeed
          const data = makeDegreeData(dept, lvl, { type: 'qualification' });
          const doc = new Degree(data);
          const saved = await doc.save();
          expect(saved._id).toBeDefined();
          await Degree.deleteOne({ _id: saved._id });
        }
      }
    ),
    { numRuns: 100 }
  );
}, 60000);

// ─── Property 4: Uniqueness của qualification_number ────────────────────────

// Feature: degree-management-refactor, Property 4: Uniqueness của qualification_number
test('Property 4: two Degrees with same qualification_number → second save throws duplicate key error', async () => {
  // Validates: Requirements 2.5, 2.7
  await fc.assert(
    fc.asyncProperty(
      fc.string({ minLength: 1, maxLength: 30 }).filter(s => s.trim().length > 0),
      async (qn) => {
        const dept = await createDept();
        const lvl = await createLevel();

        const data1 = makeDegreeData(dept, lvl, { qualification_number: `QN-${qn}` });
        const data2 = makeDegreeData(dept, lvl, { qualification_number: `QN-${qn}` });

        await Degree.create(data1);

        let threw = false;
        try {
          await Degree.create(data2);
        } catch (err) {
          threw = true;
          // MongoServerError code 11000 = duplicate key
          expect(err.code === 11000 || err.name === 'MongoServerError').toBe(true);
        }
        expect(threw).toBe(true);

        // cleanup
        await Degree.deleteMany({ qualification_number: `QN-${qn}` });
      }
    ),
    { numRuns: 100 }
  );
}, 120000);

// ─── Property 5: Sparse uniqueness của certification_number ─────────────────

// Feature: degree-management-refactor, Property 5: Sparse uniqueness của certification_number
test('Property 5: same non-null certification_number → duplicate error; both null → both save ok', async () => {
  // Validates: Requirements 2.6, 2.7
  await fc.assert(
    fc.asyncProperty(
      fc.boolean(), // true = test duplicate, false = test sparse (both null)
      async (testDuplicate) => {
        const dept = await createDept();
        const lvl = await createLevel();

        if (testDuplicate) {
          const cn = `CN-${uid()}`;
          const data1 = makeDegreeData(dept, lvl, {
            type: 'certification',
            certification_number: cn,
          });
          const data2 = makeDegreeData(dept, lvl, {
            type: 'certification',
            certification_number: cn,
          });

          await Degree.create(data1);

          let threw = false;
          try {
            await Degree.create(data2);
          } catch (err) {
            threw = true;
            expect(err.code === 11000 || err.name === 'MongoServerError').toBe(true);
          }
          expect(threw).toBe(true);

          await Degree.deleteMany({ certification_number: cn });
        } else {
          // Both without certification_number (sparse index allows multiple nulls)
          const data1 = makeDegreeData(dept, lvl, { type: 'qualification' });
          const data2 = makeDegreeData(dept, lvl, { type: 'qualification' });

          const saved1 = await Degree.create(data1);
          const saved2 = await Degree.create(data2);

          expect(saved1._id).toBeDefined();
          expect(saved2._id).toBeDefined();

          await Degree.deleteMany({ _id: { $in: [saved1._id, saved2._id] } });
        }
      }
    ),
    { numRuns: 100 }
  );
}, 120000);

// ─── Property 6: Round-trip tạo Degree ──────────────────────────────────────

// Feature: degree-management-refactor, Property 6: Round-trip tạo Degree
test('Property 6: save Degree then findById returns matching fields', async () => {
  // Validates: Requirements 3.5
  await fc.assert(
    fc.asyncProperty(
      fc.record({
        student_name: fc.string({ minLength: 1, maxLength: 50 }).filter(s => s.trim() === s && s.trim().length > 0),
        program_name: fc.string({ minLength: 1, maxLength: 50 }).filter(s => s.trim() === s && s.trim().length > 0),
      }),
      async ({ student_name, program_name }) => {
        const dept = await createDept();
        const lvl = await createLevel();
        const data = makeDegreeData(dept, lvl, { student_name, program_name });

        const saved = await Degree.create(data);
        const found = await Degree.findById(saved._id);

        expect(found).not.toBeNull();
        expect(found.qualification_number).toBe(data.qualification_number);
        expect(found.student_name).toBe(student_name);
        expect(found.program_name).toBe(program_name);
        expect(found.type).toBe(data.type);
        expect(found.department.toString()).toBe(dept._id.toString());
        expect(found.level.toString()).toBe(lvl._id.toString());

        await Degree.deleteOne({ _id: saved._id });
      }
    ),
    { numRuns: 100 }
  );
}, 120000);

// ─── Property 7: Round-trip cập nhật Degree ─────────────────────────────────

// Feature: degree-management-refactor, Property 7: Round-trip cập nhật Degree
test('Property 7: update student_name then findById returns updated value', async () => {
  // Validates: Requirements 3.8
  await fc.assert(
    fc.asyncProperty(
      fc.string({ minLength: 1, maxLength: 50 }).filter(s => s.trim() === s && s.trim().length > 0),
      async (newName) => {
        const dept = await createDept();
        const lvl = await createLevel();
        const data = makeDegreeData(dept, lvl);

        const saved = await Degree.create(data);
        await Degree.findByIdAndUpdate(saved._id, { student_name: newName });
        const found = await Degree.findById(saved._id);

        expect(found).not.toBeNull();
        expect(found.student_name).toBe(newName);

        await Degree.deleteOne({ _id: saved._id });
      }
    ),
    { numRuns: 100 }
  );
}, 120000);

// ─── Property 8: Round-trip xóa Degree ──────────────────────────────────────

// Feature: degree-management-refactor, Property 8: Round-trip xóa Degree
test('Property 8: delete Degree then findById returns null', async () => {
  // Validates: Requirements 3.9
  await fc.assert(
    fc.asyncProperty(
      fc.constant(null), // no extra input needed
      async () => {
        const dept = await createDept();
        const lvl = await createLevel();
        const data = makeDegreeData(dept, lvl);

        const saved = await Degree.create(data);
        await Degree.findByIdAndDelete(saved._id);
        const found = await Degree.findById(saved._id);

        expect(found).toBeNull();
      }
    ),
    { numRuns: 100 }
  );
}, 120000);