'use strict';
const mdl_Product    = require('../../models/courses/products.mdl');
const mdl_Category   = require('../../models/courses/categories.mdl');
const { Course, CourseProductCategory: mdl_CourseProductCategory } = require('../../models/courses/courses.mdl');
const R                        = require('../../utils/response.util');
const logActivity              = require('../../utils/logActivity.util');

// ─── PRODUCT (generic, keyed by purchasable_type + purchasable_id) ───────────
// Course/Unit/Lesson each get their own thin route + exported handler below,
// all delegating to these so the CRUD logic isn't tripled across the three
// content types — see routes/admin/products.routes.js.

async function getProductFor(purchasable_type, purchasable_id) {
  return mdl_Product.findOne({ where: { purchasable_type, purchasable_id }, paranoid: false });
}

async function upsertProductFor(purchasable_type, purchasable_id, body, adminUserId) {
  const { name, description, price, currency, access_days, is_active } = body;
  if (!name || price == null) {
    const err = new Error('name and price are required.');
    err.status = 400;
    throw err;
  }

  const existing = await mdl_Product.findOne({ where: { purchasable_type, purchasable_id }, paranoid: false });

  if (existing) {
    if (existing.deletedAt) await existing.restore();
    await existing.update({ name, description: description ?? null, price, currency: currency ?? 'USD', access_days: access_days ?? null, is_active: is_active ?? true });
    logActivity(adminUserId, `upsert_${purchasable_type}_product`, { entityType: 'product', entityId: existing.id, details: { purchasable_type, purchasable_id, name } });
    return { product: existing, created: false };
  }

  const product = await mdl_Product.create({ purchasable_type, purchasable_id, name, description: description ?? null, price, currency: currency ?? 'USD', access_days: access_days ?? null, is_active: is_active ?? true });
  logActivity(adminUserId, `upsert_${purchasable_type}_product`, { entityType: 'product', entityId: product.id, details: { purchasable_type, purchasable_id, name } });
  return { product, created: true };
}

async function removeProductFor(purchasable_type, purchasable_id, adminUserId) {
  const product = await mdl_Product.findOne({ where: { purchasable_type, purchasable_id } });
  if (!product) return false;
  await product.destroy();
  logActivity(adminUserId, `remove_${purchasable_type}_product`, { entityType: 'product', details: { purchasable_type, purchasable_id } });
  return true;
}

function makeProductHandlers(purchasable_type, paramName) {
  return {
    get: async (req, res) => {
      try {
        const product = await getProductFor(purchasable_type, req.params[paramName]);
        return R.success(res, 'Product retrieved.', product ?? null);
      } catch (err) {
        console.error(`[ADMIN][PRODUCTS][GET][${purchasable_type}]`, err);
        return R.error(res, 'Could not retrieve product.', 500);
      }
    },
    upsert: async (req, res) => {
      try {
        const { product, created } = await upsertProductFor(purchasable_type, req.params[paramName], req.body, req.user?.user_id);
        return R.success(res, created ? 'Product created.' : 'Product updated.', product, created ? 201 : 200);
      } catch (err) {
        if (err.status === 400) return R.error(res, err.message, 400);
        console.error(`[ADMIN][PRODUCTS][UPSERT][${purchasable_type}]`, err);
        return R.error(res, 'Could not save product.', 500);
      }
    },
    remove: async (req, res) => {
      try {
        const removed = await removeProductFor(purchasable_type, req.params[paramName], req.user?.user_id);
        if (!removed) return R.error(res, 'Product not found.', 404);
        return R.success(res, 'Product removed.');
      } catch (err) {
        console.error(`[ADMIN][PRODUCTS][REMOVE][${purchasable_type}]`, err);
        return R.error(res, 'Could not remove product.', 500);
      }
    },
  };
}

const courseProductHandlers = makeProductHandlers('course', 'courseId');

exports.getCourseProduct    = courseProductHandlers.get;
exports.upsertCourseProduct = courseProductHandlers.upsert;
exports.removeCourseProduct = courseProductHandlers.remove;

// ─── CATEGORIES (per course) ──────────────────────────────────────────────────

exports.getCourseCategories = async (req, res) => {
  try {
    const course = await Course.findByPk(req.params.courseId, {
      include: [{ model: mdl_Category, as: 'categories', through: { attributes: [] } }],
    });
    if (!course) return R.error(res, 'Course not found.', 404);
    return R.success(res, 'Course categories retrieved.', course.categories ?? []);
  } catch (err) {
    console.error('[ADMIN][PRODUCTS][GET CATEGORIES]', err);
    return R.error(res, 'Could not retrieve course categories.', 500);
  }
};

exports.syncCourseCategories = async (req, res) => {
  try {
    const { courseId } = req.params;
    const { category_ids = [] } = req.body;

    await mdl_CourseProductCategory.destroy({ where: { course_id: courseId } });

    if (category_ids.length > 0) {
      await mdl_CourseProductCategory.bulkCreate(
        category_ids.map((id) => ({ course_id: courseId, category_id: id }))
      );
    }

    logActivity(req.user?.user_id, 'sync_course_categories', { entityType: 'product', details: { course_id: courseId, category_ids, count: category_ids.length } });
    return R.success(res, 'Course categories updated.');
  } catch (err) {
    console.error('[ADMIN][PRODUCTS][SYNC CATEGORIES]', err);
    return R.error(res, 'Could not sync course categories.', 500);
  }
};