// /components/professors/professorService.js

const Professor = require('./professorModel');
const User = require('../users/userModel');
const Role = require('../roles/roleModel');
const AppError = require('../../utils/AppError');
const eventEmitter = require('../../events/eventEmitter');
const EVENT_NAMES = require('../../constants/eventNames');
const { parsePaginationAndSort, buildFilterQuery, calculateMeta } = require('../../utils/pagination');
const { allocatePlaceholderNationalId } = require('../../utils/nationalId');

const createProfessor = async (data) => {
  let nationalIdCode = String(data.nationalIdCode || data.nationalId || '').trim();
  const phoneNumber = String(data.phoneNumber || data.phone || '').trim();

  if (!nationalIdCode) {
    nationalIdCode = await allocatePlaceholderNationalId(phoneNumber);
  }

  const payload = {
    ...data,
    name: String(data.name || '').trim(),
    surname: String(data.surname || '').trim(),
    nationalIdCode,
    phoneNumber,
    email: data.email ? String(data.email).trim().toLowerCase() : undefined,
    cardNumber: data.cardNumber ? String(data.cardNumber).trim() : undefined,
    shabaNumber: data.shabaNumber || data.iban ? String(data.shabaNumber || data.iban).trim() : undefined,
    bio: data.bio ? String(data.bio).trim() : undefined
  };

  const existing = await Professor.findOne({
    $or: [
      { nationalIdCode: payload.nationalIdCode },
      { phoneNumber: payload.phoneNumber },
      ...(payload.email ? [{ email: payload.email }] : [])
    ]
  });
  if (existing) {
    throw new AppError('PROFESSOR_ALREADY_EXISTS');
  }

  const professor = await Professor.create(payload);
  eventEmitter.emit(EVENT_NAMES.PROFESSOR_CREATED, { professorId: professor._id, name: `${professor.name} ${professor.surname}` });
  return professor;
};

const createProfessorFromUser = async (userId, additionalData = {}) => {
  if (!userId) {
    throw new AppError('VALIDATION_FAILED', null, 'User ID is required');
  }

  const user = await User.findById(userId);
  if (!user) {
    throw new AppError('USER_NOT_FOUND');
  }

  const professorRole = await Role.findOne({ name: 'Professor' });
  if (!professorRole) {
    throw new AppError('DEFAULT_ROLE_NOT_FOUND', null, 'Professor role not found');
  }

  // Update user role to Professor if not already
  if (String(user.role) !== String(professorRole._id)) {
    user.role = professorRole._id;
    await user.save();
  }

  // Determine name and surname
  let firstName = String(additionalData.name || '').trim();
  let lastName = String(additionalData.surname || '').trim();

  if (!firstName && !lastName) {
    const rawName = String(user.name || '').trim();
    const parts = rawName.split(/\s+/);
    if (parts.length > 1) {
      firstName = parts[0];
      lastName = parts.slice(1).join(' ');
    } else {
      firstName = rawName || 'استاد';
      lastName = rawName || 'استاد';
    }
  } else if (!lastName && firstName) {
    lastName = firstName;
  } else if (!firstName && lastName) {
    firstName = lastName;
  }

  let nationalIdCode = String(additionalData.nationalIdCode || additionalData.nationalId || user.nationalIdCode || '').trim();
  const phoneNumber = String(additionalData.phoneNumber || additionalData.phone || user.phoneNumber || '').trim();

  if (!nationalIdCode) {
    nationalIdCode = await allocatePlaceholderNationalId(phoneNumber);
  }

  const email = additionalData.email ? String(additionalData.email).trim().toLowerCase() : (user.email ? String(user.email).trim().toLowerCase() : undefined);
  const cardNumber = additionalData.cardNumber ? String(additionalData.cardNumber).trim() : (user.cardNumber ? String(user.cardNumber).trim() : undefined);
  const shabaNumber = additionalData.shabaNumber || additionalData.iban ? String(additionalData.shabaNumber || additionalData.iban).trim() : (user.shabaNumber ? String(user.shabaNumber).trim() : undefined);
  const bio = additionalData.bio ? String(additionalData.bio).trim() : undefined;
  
  let expertise = [];
  if (Array.isArray(additionalData.expertise)) {
    expertise = additionalData.expertise.map(String).map(s => s.trim()).filter(Boolean);
  } else if (typeof additionalData.expertise === 'string' && additionalData.expertise.trim()) {
    expertise = additionalData.expertise.split(',').map(s => s.trim()).filter(Boolean);
  }

  // Check if a Professor record already exists for this nationalIdCode or phoneNumber
  let professor = await Professor.findOne({
    $or: [
      { nationalIdCode },
      { phoneNumber }
    ]
  });

  if (professor) {
    professor.name = firstName;
    professor.surname = lastName;
    if (email) professor.email = email;
    if (cardNumber) professor.cardNumber = cardNumber;
    if (shabaNumber) professor.shabaNumber = shabaNumber;
    if (bio) professor.bio = bio;
    if (expertise.length > 0) professor.expertise = expertise;
    professor.isActive = true;
    await professor.save();
  } else {
    professor = await Professor.create({
      name: firstName,
      surname: lastName,
      nationalIdCode,
      phoneNumber,
      email,
      cardNumber,
      shabaNumber,
      bio,
      expertise,
      isActive: true
    });
  }

  eventEmitter.emit(EVENT_NAMES.PROFESSOR_CREATED, {
    professorId: professor._id,
    name: `${professor.name} ${professor.surname}`
  });

  const updatedUser = await User.findById(user._id)
    .select('-passwordHash -refreshTokens')
    .populate({ path: 'role', select: 'name permissions' })
    .lean();

  return { professor, user: updatedUser };
};

const getProfessorById = async (id) => {
  const professor = await Professor.findById(id).populate('courses', 'title type price');
  if (!professor) {
    throw new AppError('PROFESSOR_NOT_FOUND');
  }
  return professor;
};

const getAllProfessors = async (queryParams) => {
  const { page, limit, skip, sort } = parsePaginationAndSort(queryParams);
  const filter = buildFilterQuery(queryParams, ['name', 'surname', 'nationalIdCode', 'phoneNumber', 'email', 'expertise']);

  const [professors, totalCount] = await Promise.all([
    Professor.find(filter).populate('courses', 'title').sort(sort).skip(skip).limit(limit),
    Professor.countDocuments(filter)
  ]);

  const meta = calculateMeta(totalCount, page, limit);
  return { data: professors, meta };
};

const updateProfessor = async (id, updateData) => {
  const professor = await Professor.findById(id);
  if (!professor) {
    throw new AppError('PROFESSOR_NOT_FOUND');
  }

  const payload = { ...updateData };
  if (payload.nationalIdCode !== undefined || payload.nationalId !== undefined) {
    payload.nationalIdCode = String(payload.nationalIdCode || payload.nationalId || '').trim();
    delete payload.nationalId;
  }
  if (payload.phoneNumber !== undefined || payload.phone !== undefined) {
    payload.phoneNumber = String(payload.phoneNumber || payload.phone || '').trim();
    delete payload.phone;
  }
  if (payload.name !== undefined) payload.name = String(payload.name).trim();
  if (payload.surname !== undefined) payload.surname = String(payload.surname).trim();
  if (payload.email !== undefined) {
    payload.email = payload.email ? String(payload.email).trim().toLowerCase() : undefined;
  }
  if (payload.cardNumber !== undefined) {
    payload.cardNumber = payload.cardNumber ? String(payload.cardNumber).trim() : undefined;
  }
  if (payload.shabaNumber !== undefined || payload.iban !== undefined) {
    const val = payload.shabaNumber || payload.iban;
    payload.shabaNumber = val ? String(val).trim() : undefined;
    delete payload.iban;
  }
  if (payload.bio !== undefined) {
    payload.bio = payload.bio ? String(payload.bio).trim() : undefined;
  }

  Object.assign(professor, payload);
  await professor.save();
  return professor;
};

const deleteProfessor = async (id) => {
  const professor = await Professor.findById(id);
  if (!professor) {
    throw new AppError('PROFESSOR_NOT_FOUND');
  }

  await Professor.findByIdAndDelete(id);
  return null;
};

const searchProfessors = async (queryParams) => {
  return getAllProfessors(queryParams);
};

module.exports = {
  createProfessor,
  createProfessorFromUser,
  getProfessorById,
  getAllProfessors,
  updateProfessor,
  deleteProfessor,
  searchProfessors
};