/**
 * StudentMS — script.js
 * Client-side validation, modals, and UI helpers.
 */

/* ═══════════════════════════════════════════
   1. AUTO-DISMISS FLASH MESSAGES
═══════════════════════════════════════════ */
document.addEventListener('DOMContentLoaded', () => {
  const alerts = document.querySelectorAll('.alert');
  alerts.forEach(alert => {
    setTimeout(() => {
      alert.style.transition = 'opacity .4s, transform .4s';
      alert.style.opacity = '0';
      alert.style.transform = 'translateX(40px)';
      setTimeout(() => alert.remove(), 420);
    }, 4500);
  });
});

/* ═══════════════════════════════════════════
   2. MOBILE NAVBAR TOGGLE
═══════════════════════════════════════════ */
const navToggle = document.getElementById('navToggle');
const navLinks  = document.getElementById('navLinks');
if (navToggle && navLinks) {
  navToggle.addEventListener('click', () => {
    navLinks.classList.toggle('open');
  });
  // Close when clicking outside
  document.addEventListener('click', (e) => {
    if (!navToggle.contains(e.target) && !navLinks.contains(e.target)) {
      navLinks.classList.remove('open');
    }
  });
}

/* ═══════════════════════════════════════════
   3. PASSWORD TOGGLE
═══════════════════════════════════════════ */
function togglePassword(inputId, btn) {
  const input = document.getElementById(inputId);
  const icon  = btn.querySelector('i');
  if (input.type === 'password') {
    input.type = 'text';
    icon.classList.replace('fa-eye', 'fa-eye-slash');
  } else {
    input.type = 'password';
    icon.classList.replace('fa-eye-slash', 'fa-eye');
  }
}

/* ═══════════════════════════════════════════
   4. LOGIN FORM VALIDATION
═══════════════════════════════════════════ */
const loginForm = document.getElementById('loginForm');
if (loginForm) {
  loginForm.addEventListener('submit', (e) => {
    let valid = true;

    const username = document.getElementById('username');
    const password = document.getElementById('password');
    const errUser  = document.getElementById('err-username');
    const errPass  = document.getElementById('err-password');

    // Reset
    [errUser, errPass].forEach(el => { if (el) el.textContent = ''; });
    [username, password].forEach(el => el.classList.remove('is-invalid'));

    if (!username.value.trim()) {
      errUser.textContent = 'Username is required.';
      username.classList.add('is-invalid');
      valid = false;
    }
    if (!password.value.trim()) {
      errPass.textContent = 'Password is required.';
      password.classList.add('is-invalid');
      valid = false;
    }

    if (!valid) e.preventDefault();
  });
}

/* ═══════════════════════════════════════════
   5. STUDENT FORM VALIDATION (add & edit)
═══════════════════════════════════════════ */
const studentForm = document.getElementById('studentForm');
if (studentForm) {
  studentForm.addEventListener('submit', (e) => {
    const errors = validateStudentForm();
    if (errors > 0) e.preventDefault();
  });
}

function validateStudentForm() {
  let errorCount = 0;

  // Helper: show error
  function showErr(fieldName, msg) {
    const errEl = document.getElementById(`err-${fieldName}`);
    const input = studentForm.querySelector(`[name="${fieldName}"]`);
    if (errEl) errEl.textContent = msg;
    if (input) input.classList.add('is-invalid');
    errorCount++;
  }

  // Helper: clear error
  function clearErr(fieldName) {
    const errEl = document.getElementById(`err-${fieldName}`);
    const input = studentForm.querySelector(`[name="${fieldName}"]`);
    if (errEl) errEl.textContent = '';
    if (input) input.classList.remove('is-invalid');
  }

  // Fields to validate
  const required = [
    'student_id', 'full_name', 'father_name', 'mother_name',
    'gender', 'dob', 'email', 'phone',
    'course', 'branch', 'year_sem',
    'address', 'city', 'state', 'pin_code'
  ];

  required.forEach(name => clearErr(name));

  // Required check
  required.forEach(name => {
    const el = studentForm.querySelector(`[name="${name}"]`);
    if (!el) return;
    if (!el.value.trim()) {
      const label = name.replace(/_/g, ' ').replace(/\b\w/g, c => c.toUpperCase());
      showErr(name, `${label} is required.`);
    }
  });

  // Email format
  const emailEl = studentForm.querySelector('[name="email"]');
  if (emailEl && emailEl.value.trim()) {
    const re = /^[\w.+-]+@[\w-]+\.[a-zA-Z]{2,}$/;
    if (!re.test(emailEl.value.trim())) {
      showErr('email', 'Enter a valid email address.');
    }
  }

  // Phone — 10 digits only
  const phoneEl = studentForm.querySelector('[name="phone"]');
  if (phoneEl && phoneEl.value.trim()) {
    if (!/^\d{10}$/.test(phoneEl.value.trim())) {
      showErr('phone', 'Phone must be exactly 10 digits.');
    }
  }

  // Pin code — 6 digits only
  const pinEl = studentForm.querySelector('[name="pin_code"]');
  if (pinEl && pinEl.value.trim()) {
    if (!/^\d{6}$/.test(pinEl.value.trim())) {
      showErr('pin_code', 'Pin Code must be exactly 6 digits.');
    }
  }

  // Date of birth — must not be in the future
  const dobEl = studentForm.querySelector('[name="dob"]');
  if (dobEl && dobEl.value) {
    const dob = new Date(dobEl.value);
    if (dob >= new Date()) {
      showErr('dob', 'Date of Birth cannot be in the future.');
    }
  }

  return errorCount;
}

// Live phone & pin – allow only digits
document.addEventListener('DOMContentLoaded', () => {
  const phoneInput = document.querySelector('[name="phone"]');
  const pinInput   = document.querySelector('[name="pin_code"]');

  if (phoneInput) {
    phoneInput.addEventListener('input', () => {
      phoneInput.value = phoneInput.value.replace(/\D/g, '').slice(0, 10);
    });
  }
  if (pinInput) {
    pinInput.addEventListener('input', () => {
      pinInput.value = pinInput.value.replace(/\D/g, '').slice(0, 6);
    });
  }
});

/* ═══════════════════════════════════════════
   6. DELETE MODAL
═══════════════════════════════════════════ */
let pendingDeleteId = null;

function confirmDelete(studentId, studentName) {
  pendingDeleteId = studentId;
  const modal = document.getElementById('deleteModal');
  const nameEl = document.getElementById('deleteStudentName');
  if (nameEl) nameEl.textContent = studentName;
  if (modal)  modal.style.display = 'flex';
}

function closeModal() {
  const modal = document.getElementById('deleteModal');
  if (modal) modal.style.display = 'none';
  pendingDeleteId = null;
}

function submitDelete() {
  if (!pendingDeleteId) return;
  const form = document.getElementById('deleteForm');
  if (form) {
    form.action = `/delete_student/${pendingDeleteId}`;
    form.submit();
  }
}

// Close modal when clicking backdrop
document.addEventListener('click', (e) => {
  const modal = document.getElementById('deleteModal');
  if (modal && e.target === modal) closeModal();
});

// Close modal on Escape key
document.addEventListener('keydown', (e) => {
  if (e.key === 'Escape') closeModal();
});

/* ═══════════════════════════════════════════
   7. SEARCH – CLEAR
═══════════════════════════════════════════ */
function clearSearch() {
  const input = document.getElementById('searchInput');
  if (input) {
    input.value = '';
    document.getElementById('searchForm').submit();
  }
}