'use strict';

const mdl_AchievementDefinitions = require('../../models/users/achievement_definitions.mdl');
const CourseAchievement          = require('../../models/courses/course_achievement.mdl');
const R                          = require('../../utils/response.util');
const logActivity                = require('../../utils/logActivity.util');

const VALID_TYPES = ['badge', 'milestone'];

// ─── GET /admin/achievements ──────────────────────────────────────────────────

exports.getAchievements = async (req, res) => {
  try {
    const achievements = await mdl_AchievementDefinitions.findAll({
      order: [['createdAt', 'ASC']],
    });
    return R.success(res, 'Achievements retrieved.', achievements);
  } catch (err) {
    console.error('[ADMIN][GET ACHIEVEMENTS]', err);
    return R.error(res, 'Could not retrieve achievements.', 500);
  }
};

// ─── GET /admin/achievements/:id ──────────────────────────────────────────────

exports.getAchievement = async (req, res) => {
  try {
    const achievement = await mdl_AchievementDefinitions.findByPk(req.params.id);
    if (!achievement) return R.error(res, 'Achievement not found.', 404);
    return R.success(res, 'Achievement retrieved.', achievement);
  } catch (err) {
    console.error('[ADMIN][GET ACHIEVEMENT]', err);
    return R.error(res, 'Could not retrieve achievement.', 500);
  }
};

// ─── POST /admin/achievements ─────────────────────────────────────────────────

exports.createAchievement = async (req, res) => {
  try {
    const { key, type, label, description, icon, trigger, is_active } = req.body;
    if (!key || !label) return R.error(res, 'key and label are required.', 400);
    if (type && !VALID_TYPES.includes(type)) return R.error(res, `type must be one of: ${VALID_TYPES.join(', ')}.`, 400);

    const exists = await mdl_AchievementDefinitions.findOne({ where: { key } });
    if (exists) return R.error(res, `An achievement with key "${key}" already exists.`, 409);

    const achievement = await mdl_AchievementDefinitions.create({
      key,
      type:        type || 'badge',
      label,
      description: description ?? null,
      icon:        icon        || null,
      trigger:     trigger     || null,
      is_active:   is_active !== undefined ? !!is_active : true,
      is_system:   false, // only seed data may be system-protected
    });

    logActivity(req.user?.user_id, 'create_achievement', { entityType: 'achievement', details: { key, label } });

    return R.success(res, 'Achievement created.', achievement, 201);
  } catch (err) {
    console.error('[ADMIN][CREATE ACHIEVEMENT]', err);
    return R.error(res, 'Could not create achievement.', 500);
  }
};

// ─── PUT /admin/achievements/:id ──────────────────────────────────────────────

exports.updateAchievement = async (req, res) => {
  try {
    const achievement = await mdl_AchievementDefinitions.findByPk(req.params.id);
    if (!achievement) return R.error(res, 'Achievement not found.', 404);

    const { key, type, label, description, icon, trigger, is_active } = req.body;

    if (achievement.is_system && key !== undefined && key !== achievement.key)
      return R.error(res, 'The key of a system achievement cannot be changed.', 400);
    if (achievement.is_system && type !== undefined && type !== achievement.type)
      return R.error(res, 'The type of a system achievement cannot be changed.', 400);
    if (type && !VALID_TYPES.includes(type)) return R.error(res, `type must be one of: ${VALID_TYPES.join(', ')}.`, 400);

    if (!achievement.is_system && key !== undefined && key !== achievement.key) {
      const exists = await mdl_AchievementDefinitions.findOne({ where: { key } });
      if (exists) return R.error(res, `An achievement with key "${key}" already exists.`, 409);
    }

    await achievement.update({
      key:         (!achievement.is_system && key !== undefined) ? key : achievement.key,
      type:        (!achievement.is_system && type !== undefined) ? type : achievement.type,
      label:       label       ?? achievement.label,
      description: description !== undefined ? (description || null) : achievement.description,
      icon:        icon        !== undefined ? (icon        || null) : achievement.icon,
      trigger:     trigger     !== undefined ? (trigger     || null) : achievement.trigger,
      is_active:   is_active   !== undefined ? !!is_active           : achievement.is_active,
    });

    logActivity(req.user?.user_id, 'update_achievement', { entityType: 'achievement', details: { id: achievement.achievement_definition_id, key: achievement.key } });

    return R.success(res, 'Achievement updated.', achievement);
  } catch (err) {
    console.error('[ADMIN][UPDATE ACHIEVEMENT]', err);
    return R.error(res, 'Could not update achievement.', 500);
  }
};

// ─── DELETE /admin/achievements/:id ───────────────────────────────────────────

exports.deleteAchievement = async (req, res) => {
  try {
    const achievement = await mdl_AchievementDefinitions.findByPk(req.params.id);
    if (!achievement) return R.error(res, 'Achievement not found.', 404);
    if (achievement.is_system) return R.error(res, 'Built-in system achievements cannot be deleted.', 400);

    const assignedCourses = await CourseAchievement.count({ where: { achievement_key: achievement.key } });
    if (assignedCourses > 0)
      return R.error(res, `Cannot delete — ${assignedCourses} course(s) still reference this achievement. Unassign it first.`, 409);

    await achievement.destroy();
    logActivity(req.user?.user_id, 'delete_achievement', { entityType: 'achievement', details: { key: achievement.key } });
    return R.success(res, 'Achievement deleted.');
  } catch (err) {
    console.error('[ADMIN][DELETE ACHIEVEMENT]', err);
    return R.error(res, 'Could not delete achievement.', 500);
  }
};