const path = require('path');
const Qualification = require('../models/qualification');
const Department = require('../models/department');
const Level = require('../models/level');
const writeAuditLog = require('../audit/writeAuditLog');
const AUDIT_ACTIONS = require('../constants/auditAction');
const { generateSignedUrl } = require('../utils/signedUrl');

function normalizePath(filePath) {
  if (!filePath) return undefined;
  return path.basename(filePath.replace(/\\/g, '/'));
}

// GET /admin/qualification
exports.index = async (req, res) => {
  try {
    const { search, status } = req.query;
    const filter = {};
    if (search) {
      filter.$or = [
        { qualification_number: { $regex: search, $options: 'i' } },
        { student_name: { $regex: search, $options: 'i' } }
      ];
    }
    if (status) filter.status = status;

    const [qualifications, departments, levels] = await Promise.all([
      Qualification.find(filter).populate('department level').sort({ createdAt: -1 }),
      Department.find(), Level.find()
    ]);

    res.render('admin/qualification/index', {
      qualifications, departments, levels, query: req.query,
      user: req.session.user, layout: 'layouts/admin', title: 'Qualifications'
    });
  } catch (err) {
    console.error(err);
    req.flash('error', 'Error loading qualifications');
    res.redirect('/admin/dashboard');
  }
};

// GET /admin/qualification/create
exports.createForm = async (req, res) => {
  try {
    const [departments, levels] = await Promise.all([Department.find(), Level.find()]);
    res.render('admin/qualification/create', {
      departments, levels, user: req.session.user,
      layout: 'layouts/admin', title: 'Create Qualification'
    });
  } catch (err) {
    req.flash('error', 'Error'); res.redirect('/admin/qualification');
  }
};

// POST /admin/qualification/create
exports.create = async (req, res) => {
  try {
    const data = { ...req.body };
    const imgFiles = req.files?.degree_image;
    if (imgFiles?.length) data.degree_image = imgFiles.map(f => normalizePath(f.path));

    const qual = new Qualification(data);
    await qual.save();
    await writeAuditLog({ model: 'Qualification', documentId: qual._id, action: AUDIT_ACTIONS.CREATE_QUALIFICATION, before: null, after: qual.toObject(), req });

    req.flash('success', 'Qualification created');
    res.redirect('/admin/qualification');
  } catch (err) {
    console.error(err);
    try {
      const [departments, levels] = await Promise.all([Department.find(), Level.find()]);
      res.render('admin/qualification/create', {
        error: err.message, formData: req.body, departments, levels,
        user: req.session.user, layout: 'layouts/admin', title: 'Create Qualification'
      });
    } catch { req.flash('error', err.message); res.redirect('/admin/qualification'); }
  }
};

// GET /admin/qualification/:id/edit
exports.editForm = async (req, res) => {
  try {
    const qual = await Qualification.findById(req.params.id).populate('department level');
    if (!qual) { req.flash('error', 'Not found'); return res.redirect('/admin/qualification'); }
    const [departments, levels] = await Promise.all([Department.find(), Level.find()]);
    res.render('admin/qualification/edit', {
      qual, departments, levels, user: req.session.user,
      layout: 'layouts/admin', title: 'Edit Qualification'
    });
  } catch (err) {
    req.flash('error', 'Error'); res.redirect('/admin/qualification');
  }
};

// POST /admin/qualification/:id/edit
exports.update = async (req, res) => {
  try {
    const qual = await Qualification.findById(req.params.id);
    if (!qual) { req.flash('error', 'Not found'); return res.redirect('/admin/qualification'); }
    const before = qual.toObject();

    const fields = ['qualification_number','student_name','program_name','department','level',
      'issued_date','status','passport_number','address','topic_name','topic_short_desc'];
    fields.forEach(f => { if (req.body[f] !== undefined) qual[f] = req.body[f]; });

    const imgFiles = req.files?.degree_image;
    if (imgFiles?.length) qual.degree_image = imgFiles.map(f => normalizePath(f.path));

    await qual.save();
    await writeAuditLog({ model: 'Qualification', documentId: qual._id, action: AUDIT_ACTIONS.UPDATE_QUALIFICATION, before, after: qual.toObject(), req });

    req.flash('success', 'Qualification updated');
    res.redirect('/admin/qualification');
  } catch (err) {
    req.flash('error', err.message); res.redirect('back');
  }
};

// POST /admin/qualification/:id/delete
exports.destroy = async (req, res) => {
  try {
    const qual = await Qualification.findById(req.params.id);
    if (!qual) { req.flash('error', 'Not found'); return res.redirect('/admin/qualification'); }
    await writeAuditLog({ model: 'Qualification', documentId: qual._id, action: AUDIT_ACTIONS.DELETE_QUALIFICATION, before: qual.toObject(), after: null, req });
    await qual.deleteOne();
    req.flash('success', 'Qualification deleted');
    res.redirect('/admin/qualification');
  } catch (err) {
    req.flash('error', 'Error deleting'); res.redirect('/admin/qualification');
  }
};

// GET /api/verify-degree/:degree_id?api_key=xxx
exports.apiVerify = async (req, res) => {
  try {
    const qual = await Qualification.findOne({
      qualification_number: { $regex: new RegExp('^' + req.params.degree_id + '$', 'i') }
    }).populate('department level');

    if (!qual) return res.status(404).json({ error: 'Degree not found' });
    if (qual.status === 'revoked') return res.status(404).json({ error: 'Degree has been revoked' });

    const baseUrl = process.env.BACKEND_URL ?? `${req.protocol}://${req.get('host')}`;
    const buildUrl = (files) => {
      if (!files?.length) return undefined;
      return files.map(f => generateSignedUrl(baseUrl, path.basename(f)));
    };

    const response = {
      full_name: qual.student_name,
      program_name: qual.program_name,
      degree_id: qual.qualification_number,
    };
    if (qual.passport_number) response.passport_number = qual.passport_number;
    if (qual.address) response.address = qual.address;
    const imgs = buildUrl(qual.degree_image);
    if (imgs) response.degree_image = imgs;
    if (qual.topic_name) {
      response.topic_name = qual.topic_name;
      if (qual.topic_short_desc) response.topic_short_desc = qual.topic_short_desc;
    }

    return res.json(response);
  } catch (err) {
    console.error(err);
    return res.status(500).json({ error: 'Internal server error' });
  }
};