/***********************************************************************************************************************************************************************
 * File Name: users.controller.js  (admin)
 * Type of Program: Controller
 * Description: Admin-level user management — full CRUD on any user.
 *
 * Author: rgrgogu
 * Date Created: Oct. 6, 2025
 ***********************************************************************************************************************************************************************/
const sequelize = require('../../config/db.config');
const { Op, Sequelize } = require('sequelize');
const bcrypt = require('bcryptjs');
const crypto = require('crypto');

const mdl_Users = require('../../models/users/users.mdl');
const mdl_UserSessions = require('../../models/users/user_sessions.mdl');
const mdl_Achievements = require('../../models/users/achievements.mdl');
const mdl_UserBans = require('../../models/users/user_bans.mdl');
const { mdl_UserGroups, mdl_UserGroupMembers } = require('../../models/users/user_groups.mdl');
const mdl_UserTiers = require('../../models/tiers/user_tiers.mdl');
const mdl_Payments = require('../../models/tiers/payments.mdl');
const mdl_QuizAttempt = require('../../models/courses/quiz_attempt.mdl');

const { sendEmail }  = require('../../services/email.service');
const trustedDevice  = require('../../services/trustedDevice.service');
const { fmtDate }    = require('../../utils/datetime.util');
const logActivity    = require('../../utils/logActivity.util');
const R = require('../../utils/response.util');
const { paginate } = require('../../utils/paginate.util');
const { enrichPersonalInfo } = require('../../utils/personalInfo.util');
const { getFieldValues } = require("../../utils/fieldValues.util");
const { resolveUserAvatar } = require('../../utils/resolveAvatar.util');

const { excludeAttributes: usersExclude, jsonbSchemas: usersSchemas, computedAttributes: userComputed } = require('../../models/users/users.attributes');

const EXCLUDED = ['password', 'otp_code', 'otp_expires_at', 'must_change_password', 'password_expires_at'];
const auditByFields = ['createdBy', 'updatedBy', 'deletedBy'];

// ─── GROUPS FILTER ────────────────────────────────────────────────────────────
//
// "groups" is a M2M association, not a real column on `users` — buildQuery's
// generic Sequelize.col()-based filtering can't touch it. Pull any `groups`
// filter out of the request's filter list (so paginate() never sees a field
// it can't resolve) and turn it into an EXISTS subquery instead. EXISTS keeps
// the LEFT JOIN group data on each row intact (all of a user's groups still
// show up), while only matching users who belong to at least one of the
// selected groups.
function extractGroupsFilter(req) {
  let filters = [];
  try { filters = JSON.parse(req.query.filters || '[]'); } catch { filters = []; }

  const groupsFilter = filters.find((f) => f.id === 'groups');
  const remaining = filters.filter((f) => f.id !== 'groups');
  req.query.filters = JSON.stringify(remaining);

  if (!groupsFilter?.value) return null;

  const groupIds = (Array.isArray(groupsFilter.value) ? groupsFilter.value : [groupsFilter.value])
    .map((v) => parseInt(v, 10))
    .filter((v) => !Number.isNaN(v));

  return groupIds.length ? groupIds : null;
}

function groupsExistsWhere(groupIds) {
  if (!groupIds) return undefined;
  return Sequelize.literal(`EXISTS (
    SELECT 1 FROM "user_group_members" ugm
    WHERE ugm.user_id = "User"."user_id"
      AND ugm."deletedAt" IS NULL
      AND ugm.group_id IN (${groupIds.join(',')})
  )`);
}

// ─── GET ALL ──────────────────────────────────────────────────────────────────

exports.getUsers = async (req, res) => {
  try {
    const groupIds = extractGroupsFilter(req);

    const result = await paginate(mdl_Users, req, {
      excludeAttributes: usersExclude,
      jsonbSchemas: usersSchemas,
      jsonbColumn: 'personal_info',
      computedAttributes: userComputed,
      context: "list",
      auditOptions: { mdl_Users, parentAlias: 'User' },
      findOptions: {
        where: groupsExistsWhere(groupIds),
        include: [{
          model:      mdl_UserGroups,
          as:         'groups',
          through:    { attributes: [] },          // hide junction columns
          attributes: ['group_id', 'name', 'group_code'],
          required:   false,                       // LEFT JOIN — users with no group still appear
        }],
      },
    });

    return R.success(res, 'Users retrieved.', result);
  } catch (err) {
    console.error('[ADMIN][GET ALL USERS]', err);
    return R.error(res, 'Could not retrieve users.', 500);
  }
};

// ─── GET ONE ──────────────────────────────────────────────────────────────────

exports.getUser = async (req, res) => {
  try {
    const { id } = req.params;
    if (!id || id === 'undefined') return R.error(res, 'Invalid User ID.', 400);

    const user = await mdl_Users.findByPk(id, {
      attributes: { exclude: EXCLUDED },
      include: [{
        model: mdl_UserGroups,
        as: 'groups',
        through: { attributes: [] },
      }],
    });

    if (!user) return R.error(res, 'User not found.', 404);
    return R.success(res, 'User retrieved.', await resolveUserAvatar(user));
  } catch (err) {
    console.error('[ADMIN][GET USER]', err);
    return R.error(res, 'Could not retrieve user.', 500);
  }
};

// ─── ADD STAFF ────────────────────────────────────────────────────────────────

exports.addStaffUser = async (req, res) => {
  try {
    const { email, personal_info = {} } = req.body;

    if (!email)
      return R.error(res, 'Email is required.', 400);

    if (!personal_info?.name?.given_name || !personal_info?.name?.last_name)
      return R.error(res, 'First name and last name are required.', 400);

    const existing = await mdl_Users.findOne({ where: { email } });
    if (existing) return R.error(res, 'Email is already in use.', 409);

    const plainPassword = crypto.randomBytes(8).toString('base64url').slice(0, 12);
    const hashed = await bcrypt.hash(plainPassword, 12);
    const passwordExpiresAt = new Date(Date.now() + 24 * 60 * 60 * 1000);
    const enriched = enrichPersonalInfo(personal_info);
    const fullName = enriched?.name?.full_name ?? email;

    const user = await mdl_Users.create({
      email,
      password: hashed,
      password_expires_at: passwordExpiresAt,
      must_change_password: true,
      acc_type: 'staff',
      reg_type: 'system',
      is_active: true,
      is_verified: true,
      createdBy: req.user.user_id,
      personal_info: enriched,
    });

    await sendEmail({
      to: email, type: 'ADD_STAFF', data: {
        name: fullName, email, password: plainPassword, expiryHours: 24,
      },
    });

    logActivity(req.user.user_id, 'create_staff', { entityType: 'user', entityId: user.user_id, details: { email } });

    return R.success(res, 'Staff user created successfully.', {
      user_id: user.user_id,
      email: user.email,
      acc_type: user.acc_type,
    }, 201);
  } catch (err) {
    console.error('[ADMIN][ADD STAFF USER]', err);
    return R.error(res, 'Could not create staff user.', 500);
  }
};

// ─── UPDATE ───────────────────────────────────────────────────────────────────

exports.updateUser = async (req, res) => {
  try {
    const user = await mdl_Users.findByPk(req.params.id);
    if (!user) return R.error(res, 'User not found.', 404);

    const allowed = ['acc_type', 'is_active', 'personal_info'];
    const updates = {};
    allowed.forEach((k) => { if (req.body[k] !== undefined) updates[k] = req.body[k]; });

    if (Number(req.params.id) === req.user.user_id && updates.acc_type !== undefined)
      return R.error(res, 'Admins cannot change their own role.', 400);

    if (updates.personal_info)
      updates.personal_info = enrichPersonalInfo(updates.personal_info);

    updates.updatedBy = req.user.user_id;

    await user.update(updates);

    logActivity(req.user.user_id, 'update_user', { entityType: 'user', entityId: Number(req.params.id) });

    const updated = await mdl_Users.findByPk(req.params.id, { attributes: { exclude: EXCLUDED } });
    return R.success(res, 'User updated.', updated);
  } catch (err) {
    console.error('[ADMIN][UPDATE USER]', err);
    return R.error(res, 'Could not update user.', 500);
  }
};

// ─── DEACTIVATE (soft delete) ─────────────────────────────────────────────────

exports.deactivateUser = async (req, res) => {
  try {
    if (Number(req.params.id) === req.user.user_id)
      return R.error(res, 'You cannot deactivate your own account.', 400);

    const user = await mdl_Users.findByPk(req.params.id);
    if (!user) return R.error(res, 'User not found.', 404);
    if (!user.is_active && user.deletedAt)
      return R.error(res, 'User is already deactivated.', 400);

    await user.update({ is_active: false, deletedBy: req.user.user_id });
    await user.destroy();

    await mdl_UserGroupMembers.update(
      { deletedBy: req.user.user_id },
      { where: { user_id: req.params.id } }
    );
    await mdl_UserGroupMembers.destroy({ where: { user_id: req.params.id } });

    await mdl_UserSessions.update(
      { is_active: false, logout_info: { date: new Date().toISOString(), forced_by: req.user.user_id } },
      { where: { user_id: req.params.id } }
    );
    await trustedDevice.revokeAllForUser(req.params.id);

    logActivity(req.user.user_id, 'deactivate_user', { entityType: 'user', entityId: Number(req.params.id) });

    return R.success(res, 'User deactivated successfully.');
  } catch (err) {
    console.error('[ADMIN][DEACTIVATE USER]', err);
    return R.error(res, 'Could not deactivate user.', 500);
  }
};

// ─── BULK DEACTIVATE ──────────────────────────────────────────────────────────

exports.bulkDeactivateUsers = async (req, res) => {
  try {
    const { ids } = req.body;
    if (!Array.isArray(ids) || !ids.length)
      return R.error(res, 'No user IDs provided.', 400);

    if (ids.includes(req.user.user_id))
      return R.error(res, 'You cannot deactivate your own account.', 400);

    const users = await mdl_Users.findAll({ where: { user_id: ids } });
    if (!users.length) return R.error(res, 'No users found.', 404);

    const activeUsers = users.filter((u) => u.is_active && !u.deletedAt);
    if (!activeUsers.length)
      return R.error(res, 'All selected users are already deactivated.', 400);

    const activeIds = activeUsers.map((u) => u.user_id);

    await mdl_Users.update(
      { is_active: false, deletedBy: req.user.user_id },
      { where: { user_id: activeIds } }
    );
    await mdl_Users.destroy({ where: { user_id: activeIds } });

    await mdl_UserGroupMembers.update(
      { deletedBy: req.user.user_id },
      { where: { user_id: activeIds } }
    );
    await mdl_UserGroupMembers.destroy({ where: { user_id: activeIds } });

    await mdl_UserSessions.update(
      { is_active: false, logout_info: { date: new Date().toISOString(), forced_by: req.user.user_id } },
      { where: { user_id: activeIds } }
    );
    await trustedDevice.revokeAllForUser(activeIds);

    return R.success(res, `${activeIds.length} user(s) deactivated successfully.`, {
      deactivated_ids: activeIds,
      skipped_ids: ids.filter((id) => !activeIds.includes(id)),
    });
  } catch (err) {
    console.error('[ADMIN][BULK DEACTIVATE USERS]', err);
    return R.error(res, 'Could not deactivate users.', 500);
  }
};

// ─── RESTORE ──────────────────────────────────────────────────────────────────

exports.restoreUser = async (req, res) => {
  try {
    const user = await mdl_Users.findOne({
      where: { user_id: req.params.id }, paranoid: false,
    });
    if (!user) return R.error(res, 'User not found.', 404);
    if (!user.deletedAt) return R.error(res, 'User is not deactivated.', 400);

    await user.restore();
    await user.update({ is_active: true, updatedBy: req.user.user_id, deletedBy: null });

    logActivity(req.user.user_id, 'restore_user', { entityType: 'user', entityId: Number(req.params.id) });

    return R.success(res, 'User restored successfully.');
  } catch (err) {
    console.error('[ADMIN][RESTORE USER]', err);
    return R.error(res, 'Could not restore user.', 500);
  }
};

// ─── BULK RESTORE ─────────────────────────────────────────────────────────────

exports.bulkRestoreUsers = async (req, res) => {
  try {
    const { ids } = req.body;
    if (!Array.isArray(ids) || !ids.length)
      return R.error(res, 'No user IDs provided.', 400);

    const users = await mdl_Users.findAll({ where: { user_id: ids }, paranoid: false });
    if (!users.length) return R.error(res, 'No users found.', 404);

    const deletedUsers = users.filter((u) => u.deletedAt);
    if (!deletedUsers.length)
      return R.error(res, 'All selected users are already active.', 400);

    const deletedIds = deletedUsers.map((u) => u.user_id);

    await mdl_Users.restore({ where: { user_id: deletedIds } });
    await mdl_Users.update(
      { is_active: true, updatedBy: req.user.user_id, deletedBy: null },
      { where: { user_id: deletedIds }, paranoid: false }
    );

    return R.success(res, `${deletedIds.length} user(s) restored successfully.`, {
      restored_ids: deletedIds,
      skipped_ids: ids.filter((id) => !deletedIds.includes(id)),
    });
  } catch (err) {
    console.error('[ADMIN][BULK RESTORE USERS]', err);
    return R.error(res, 'Could not restore users.', 500);
  }
};

// ─── PERMANENT DELETE ─────────────────────────────────────────────────────────
//
// The live DB has several FKs on users.user_id that are NO ACTION rather than
// the CASCADE the migration source claims (schema drift) — achievements,
// quiz_attempts, user_tiers, and payments all block a hard delete unless their
// rows for this user are removed first. Also null out the "who did this"
// actor columns (granted_by/revoked_by/lifted_by) on OTHER users' records,
// since those aren't this user's own data and shouldn't be deleted.
//
// UserBan.banned_by is NOT NULL (a ban record must always keep its banner),
// so a user who has ever banned someone can't be nulled out or hard-deleted —
// getBannerBlockedIds() below identifies those and callers must exclude them.
async function purgeUserDependents(userIds, t) {
  await mdl_UserGroupMembers.destroy({ where: { user_id: userIds }, force: true, transaction: t });
  await mdl_Achievements.destroy({ where: { user_id: userIds }, transaction: t });
  await mdl_QuizAttempt.destroy({ where: { user_id: userIds }, transaction: t });
  await mdl_UserTiers.destroy({ where: { user_id: userIds }, transaction: t });
  await mdl_Payments.destroy({ where: { user_id: userIds }, transaction: t });

  await mdl_Achievements.update({ granted_by: null }, { where: { granted_by: userIds }, transaction: t });
  await mdl_UserTiers.update({ granted_by: null }, { where: { granted_by: userIds }, transaction: t });
  await mdl_UserTiers.update({ revoked_by: null }, { where: { revoked_by: userIds }, transaction: t });
  await mdl_UserBans.update({ lifted_by: null }, { where: { lifted_by: userIds }, transaction: t });
}

async function getBannerBlockedIds(userIds, t) {
  const bans = await mdl_UserBans.findAll({
    where: { banned_by: userIds }, attributes: ['banned_by'], group: ['banned_by'], transaction: t,
  });
  return bans.map((b) => b.banned_by);
}

exports.permanentlyDeleteUser = async (req, res) => {
  const t = await sequelize.transaction();
  try {
    if (Number(req.params.id) === req.user.user_id) {
      await t.rollback();
      return R.error(res, 'You cannot permanently delete your own account.', 400);
    }

    const user = await mdl_Users.findOne({
      where: { user_id: req.params.id }, paranoid: false, transaction: t,
    });
    if (!user) { await t.rollback(); return R.error(res, 'User not found.', 404); }
    if (!user.deletedAt) { await t.rollback(); return R.error(res, 'User must be deactivated before it can be permanently deleted.', 400); }

    const bannerBlockedIds = await getBannerBlockedIds([user.user_id], t);
    if (bannerBlockedIds.length) {
      await t.rollback();
      return R.error(res, 'Cannot delete: this user has banned other users, and ban records must keep their banner on file.', 400);
    }

    await purgeUserDependents([user.user_id], t);
    await user.destroy({ force: true, transaction: t });

    await t.commit();

    logActivity(req.user.user_id, 'permanently_delete_user', { entityType: 'user', entityId: Number(req.params.id) });

    return R.success(res, 'User permanently deleted.');
  } catch (err) {
    await t.rollback();
    console.error('[ADMIN][PERMANENT DELETE USER]', err);
    return R.error(res, 'Could not permanently delete user.', 500);
  }
};

// ─── BULK PERMANENT DELETE ────────────────────────────────────────────────────

exports.bulkPermanentlyDeleteUsers = async (req, res) => {
  const t = await sequelize.transaction();
  try {
    const { ids } = req.body;
    if (!Array.isArray(ids) || !ids.length) {
      await t.rollback();
      return R.error(res, 'No user IDs provided.', 400);
    }

    if (ids.includes(req.user.user_id)) {
      await t.rollback();
      return R.error(res, 'You cannot permanently delete your own account.', 400);
    }

    const users = await mdl_Users.findAll({ where: { user_id: ids }, paranoid: false, transaction: t });
    if (!users.length) { await t.rollback(); return R.error(res, 'No users found.', 404); }

    const deletedUsers = users.filter((u) => u.deletedAt);
    if (!deletedUsers.length) {
      await t.rollback();
      return R.error(res, 'All selected users must be deactivated before they can be permanently deleted.', 400);
    }

    const archivedIds = deletedUsers.map((u) => u.user_id);
    const bannerBlockedIds = await getBannerBlockedIds(archivedIds, t);
    const deletedIds = archivedIds.filter((id) => !bannerBlockedIds.includes(id));

    if (!deletedIds.length) {
      await t.rollback();
      return R.error(res, 'Cannot delete: all selected users have banned other users, and ban records must keep their banner on file.', 400);
    }

    await purgeUserDependents(deletedIds, t);
    await mdl_Users.destroy({ where: { user_id: deletedIds }, force: true, transaction: t });

    await t.commit();

    logActivity(req.user.user_id, 'bulk_permanently_delete_users', {
      entityType: 'user',
      details:    { ids: deletedIds, count: deletedIds.length },
    });

    return R.success(res, `${deletedIds.length} user(s) permanently deleted.`, {
      deleted_ids: deletedIds,
      skipped_ids: ids.filter((id) => !deletedIds.includes(id)),
    });
  } catch (err) {
    await t.rollback();
    console.error('[ADMIN][BULK PERMANENT DELETE USERS]', err);
    return R.error(res, 'Could not permanently delete users.', 500);
  }
};

// ─── SESSIONS ─────────────────────────────────────────────────────────────────

exports.getUserSessions = async (req, res) => {
  try {
    const sessions = await mdl_UserSessions.findAll({
      where: { user_id: req.params.id },
      attributes: { exclude: ['refresh_token_hash'] },
      order: [['createdAt', 'DESC']],
    });
    return R.success(res, 'Sessions retrieved.', sessions);
  } catch (err) {
    console.error('[ADMIN][GET USER SESSIONS]', err);
    return R.error(res, 'Could not retrieve sessions.', 500);
  }
};

exports.terminateSession = async (req, res) => {
  try {
    const session = await mdl_UserSessions.findByPk(req.params.sid);
    if (!session) return R.error(res, 'Session not found.', 404);

    await session.update({
      is_active: false,
      logout_info: { date: new Date().toISOString(), forced_by: req.user.user_id },
    });
    await trustedDevice.revokeBySessionId(session.session_id);

    logActivity(req.user.user_id, 'terminate_session', { entityType: 'session', entityId: session.session_id });

    return R.success(res, 'Session terminated.');
  } catch (err) {
    console.error('[ADMIN][TERMINATE SESSION]', err);
    return R.error(res, 'Could not terminate session.', 500);
  }
};

// ─── FIELD VALUES ─────────────────────────────────────────────────────────────

const getUserFieldValuesBase = getFieldValues(mdl_Users, "USER", {
  blockedFields:   ["password", "otp_code", "otp_expires_at", "personal_info"],
  extraDateFields: ["modifiedAt", "ban_expires_at"],
  allowJsonb:      true,
  selfJoin:        true,
});

// "groups" isn't a Users model attribute, so the generic getFieldValues()
// helper can't resolve it — special-case it here, delegate everything else.
exports.getUserFieldValues = async (req, res) => {
  if (req.query.field === 'groups') {
    const groups = await mdl_UserGroups.findAll({
      attributes: [['group_id', 'value'], ['name', 'label']],
      order: [['name', 'ASC']],
      raw: true,
    });
    return R.success(res, 'Field values retrieved.', groups);
  }

  return getUserFieldValuesBase(req, res);
};

// ─── ARCHIVED ─────────────────────────────────────────────────────────────────

// ─── GET ARCHIVED USERS ───────────────────────────────────────────────────────
exports.getArchivedUsers = async (req, res) => {
  try {
    const groupIds = extractGroupsFilter(req);
    const archivedWhere = { deletedAt: { [Op.ne]: null }, is_active: false };
    const groupsWhere = groupsExistsWhere(groupIds);

    const result = await paginate(mdl_Users, req, {
      excludeAttributes: usersExclude,
      jsonbSchemas:      usersSchemas,
      jsonbColumn:       'personal_info',
      computedAttributes: userComputed,
      context:           'archived',
      auditOptions:      { mdl_Users, parentAlias: 'User' },
      findOptions: {
        paranoid: false,
        where:    groupsWhere ? { [Op.and]: [archivedWhere, groupsWhere] } : archivedWhere,
        include: [{
          model:      mdl_UserGroups,
          as:         'groups',
          through:    { attributes: [] },
          attributes: ['group_id', 'name', 'group_code'],
          required:   false,
        }],
      },
    });

    return R.success(res, 'Archived users retrieved.', result);
  } catch (err) {
    console.error('[ADMIN][GET ARCHIVED USERS]', err);
    return R.error(res, 'Could not retrieve archived users.', 500);
  }
};

// ─── GET USER ACHIEVEMENTS ────────────────────────────────────────────────────

exports.getUserAchievements = async (req, res) => {
  try {
    const { id } = req.params;
    const user = await mdl_Users.findByPk(id, { attributes: ['user_id'] });
    if (!user) return R.error(res, 'User not found.', 404);

    const achievements = await mdl_Achievements.findAll({
      where: { user_id: id },
      order: [['granted_at', 'DESC']],
    });

    return R.success(res, 'Achievements retrieved.', achievements);
  } catch (err) {
    console.error('[ADMIN][GET USER ACHIEVEMENTS]', err);
    return R.error(res, 'Could not retrieve achievements.', 500);
  }
};

// ─── BAN USER ─────────────────────────────────────────────────────────────────

exports.banUser = async (req, res) => {
  try {
    const { id } = req.params;

    if (Number(id) === req.user.user_id)
      return R.error(res, 'You cannot ban your own account.', 400);

    const user = await mdl_Users.findByPk(id);
    if (!user) return R.error(res, 'User not found.', 404);
    if (user.is_banned) return R.error(res, 'User is already banned.', 400);

    const { reason, ban_type, expires_at } = req.body;

    if (!reason?.trim()) return R.error(res, 'Ban reason is required.', 400);
    if (!['temporary', 'permanent'].includes(ban_type))
      return R.error(res, 'Invalid ban type. Must be "temporary" or "permanent".', 400);
    if (ban_type === 'temporary' && !expires_at)
      return R.error(res, 'Expiry date is required for temporary bans.', 400);
    if (ban_type === 'temporary' && new Date(expires_at) <= new Date())
      return R.error(res, 'Expiry date must be in the future.', 400);

    const banExpiresAt = ban_type === 'temporary' ? new Date(expires_at) : null;

    await sequelize.transaction(async (t) => {
      await mdl_UserBans.create({
        user_id:    id,
        banned_by:  req.user.user_id,
        reason:     reason.trim(),
        ban_type,
        banned_at:  new Date(),
        expires_at: banExpiresAt,
      }, { transaction: t });

      await user.update({ is_banned: true, ban_expires_at: banExpiresAt }, { transaction: t });

      await mdl_UserSessions.update(
        { is_active: false, logout_info: { date: new Date().toISOString(), forced_by: req.user.user_id } },
        { where: { user_id: id }, transaction: t }
      );
      await trustedDevice.revokeAllForUser(id);
    });

    logActivity(req.user.user_id, 'ban_user', {
      entityType: 'user',
      entityId:   Number(id),
      details:    { reason: reason.trim(), ban_type, expires_at: banExpiresAt },
    });

    sendEmail({
      to:   user.email,
      type: 'BANNED',
      data: {
        name:     user.personal_info?.name?.full_name ?? 'User',
        email:    user.email,
        date:     fmtDate(new Date()),
        reason:   reason.trim(),
        ban_type,
      },
    }).catch((err) => console.error('[ADMIN][BAN USER] Email failed:', err));

    return R.success(res, 'User banned successfully.');
  } catch (err) {
    console.error('[ADMIN][BAN USER]', err);
    return R.error(res, 'Could not ban user.', 500);
  }
};

// ─── UNBAN USER ───────────────────────────────────────────────────────────────

exports.unbanUser = async (req, res) => {
  try {
    const { id } = req.params;

    const user = await mdl_Users.findByPk(id);
    if (!user) return R.error(res, 'User not found.', 404);
    if (!user.is_banned) return R.error(res, 'User is not currently banned.', 400);

    const { lift_reason } = req.body;

    const activeBan = await mdl_UserBans.findOne({
      where: { user_id: id, is_lifted: false },
      order: [['banned_at', 'DESC']],
    });

    await sequelize.transaction(async (t) => {
      if (activeBan) {
        await activeBan.update({
          is_lifted:   true,
          lifted_at:   new Date(),
          lifted_by:   req.user.user_id,
          lift_reason: lift_reason?.trim() || null,
        }, { transaction: t });
      }

      await user.update({ is_banned: false, ban_expires_at: null }, { transaction: t });
    });

    logActivity(req.user.user_id, 'unban_user', { entityType: 'user', entityId: Number(id) });

    sendEmail({
      to:   user.email,
      type: 'BAN_LIFTED',
      data: {
        name:  user.personal_info?.name?.full_name ?? 'User',
        email: user.email,
        date:  fmtDate(new Date()),
      },
    }).catch((err) => console.error('[ADMIN][UNBAN USER] Email failed:', err));

    return R.success(res, 'User unbanned successfully.');
  } catch (err) {
    console.error('[ADMIN][UNBAN USER]', err);
    return R.error(res, 'Could not unban user.', 500);
  }
};

// ─── MAKE ADMIN ───────────────────────────────────────────────────────────────

exports.makeAdmin = async (req, res) => {
  try {
    const { id } = req.params;

    if (Number(id) === req.user.user_id)
      return R.error(res, 'You cannot change your own role.', 400);

    const user = await mdl_Users.findByPk(id);
    if (!user) return R.error(res, 'User not found.', 404);
    if (user.acc_type === 'admin')
      return R.error(res, 'User is already an administrator.', 400);

    await user.update({ acc_type: 'admin', updatedBy: req.user.user_id });

    logActivity(req.user.user_id, 'make_admin', { entityType: 'user', entityId: Number(id) });

    const fullName = user.personal_info?.name?.full_name ?? 'User';
    sendEmail({
      to:   user.email,
      type: 'MADE_ADMIN',
      data: { name: fullName.split(' ')[0], email: user.email },
    }).catch((err) => console.error('[ADMIN][MAKE ADMIN] Email failed:', err));

    return R.success(res, 'User promoted to Administrator.');
  } catch (err) {
    console.error('[ADMIN][MAKE ADMIN]', err);
    return R.error(res, 'Could not update user role.', 500);
  }
};

// ─── DEMOTE ADMIN ─────────────────────────────────────────────────────────────

exports.demoteAdmin = async (req, res) => {
  try {
    const { id } = req.params;

    if (Number(id) === req.user.user_id)
      return R.error(res, 'You cannot change your own role.', 400);

    const user = await mdl_Users.findByPk(id);
    if (!user) return R.error(res, 'User not found.', 404);
    if (user.acc_type !== 'admin')
      return R.error(res, 'User is not an administrator.', 400);

    await user.update({ acc_type: 'user', updatedBy: req.user.user_id });

    logActivity(req.user.user_id, 'demote_admin', { entityType: 'user', entityId: Number(id) });

    const fullName = user.personal_info?.name?.full_name ?? 'User';
    sendEmail({
      to:   user.email,
      type: 'DEMOTED_ADMIN',
      data: { name: fullName.split(' ')[0], email: user.email },
    }).catch((err) => console.error('[ADMIN][DEMOTE ADMIN] Email failed:', err));

    return R.success(res, 'Administrator access removed.');
  } catch (err) {
    console.error('[ADMIN][DEMOTE ADMIN]', err);
    return R.error(res, 'Could not update user role.', 500);
  }
};

// ─── BULK BAN ─────────────────────────────────────────────────────────────────

exports.bulkBanUsers = async (req, res) => {
  try {
    const { ids, reason, ban_type, expires_at } = req.body;

    if (!Array.isArray(ids) || !ids.length)
      return R.error(res, 'No user IDs provided.', 400);
    if (ids.includes(req.user.user_id))
      return R.error(res, 'You cannot ban your own account.', 400);
    if (!reason?.trim()) return R.error(res, 'Ban reason is required.', 400);
    if (!['temporary', 'permanent'].includes(ban_type))
      return R.error(res, 'Invalid ban type.', 400);
    if (ban_type === 'temporary' && !expires_at)
      return R.error(res, 'Expiry date is required for temporary bans.', 400);
    if (ban_type === 'temporary' && new Date(expires_at) <= new Date())
      return R.error(res, 'Expiry date must be in the future.', 400);

    const users = await mdl_Users.findAll({ where: { user_id: ids } });
    if (!users.length) return R.error(res, 'No users found.', 404);

    const unbannedUsers = users.filter((u) => !u.is_banned);
    if (!unbannedUsers.length)
      return R.error(res, 'All selected users are already banned.', 400);

    const targetIds  = unbannedUsers.map((u) => u.user_id);
    const banExpiresAt = ban_type === 'temporary' ? new Date(expires_at) : null;
    const now = new Date();

    await sequelize.transaction(async (t) => {
      await mdl_UserBans.bulkCreate(
        targetIds.map((uid) => ({
          user_id:    uid,
          banned_by:  req.user.user_id,
          reason:     reason.trim(),
          ban_type,
          banned_at:  now,
          expires_at: banExpiresAt,
        })),
        { transaction: t }
      );

      await mdl_Users.update(
        { is_banned: true, ban_expires_at: banExpiresAt },
        { where: { user_id: targetIds }, transaction: t }
      );

      await mdl_UserSessions.update(
        { is_active: false, logout_info: { date: now.toISOString(), forced_by: req.user.user_id } },
        { where: { user_id: targetIds }, transaction: t }
      );
      await trustedDevice.revokeAllForUser(targetIds);
    });

    const dateStr = fmtDate(new Date());
    unbannedUsers.forEach((u) => {
      sendEmail({
        to:   u.email,
        type: 'BANNED',
        data: {
          name:     u.personal_info?.name?.full_name ?? 'User',
          email:    u.email,
          date:     dateStr,
          reason:   reason.trim(),
          ban_type,
        },
      }).catch((err) => console.error('[ADMIN][BULK BAN] Email failed:', u.email, err));
    });

    return R.success(res, `${targetIds.length} user(s) banned successfully.`, {
      banned_ids:  targetIds,
      skipped_ids: ids.filter((id) => !targetIds.includes(Number(id))),
    });
  } catch (err) {
    console.error('[ADMIN][BULK BAN USERS]', err);
    return R.error(res, 'Could not ban users.', 500);
  }
};

// ─── GET USER BAN HISTORY ─────────────────────────────────────────────────────

exports.getUserBans = async (req, res) => {
  try {
    const { id } = req.params;

    const user = await mdl_Users.findByPk(id, { attributes: ['user_id'] });
    if (!user) return R.error(res, 'User not found.', 404);

    const bans = await mdl_UserBans.findAll({
      where: { user_id: id },
      include: [
        { model: mdl_Users, as: 'banner', attributes: ['user_id', 'email', 'personal_info'] },
        { model: mdl_Users, as: 'lifter', attributes: ['user_id', 'email', 'personal_info'] },
      ],
      order: [['banned_at', 'DESC']],
    });

    return R.success(res, 'Ban history retrieved.', bans);
  } catch (err) {
    console.error('[ADMIN][GET USER BANS]', err);
    return R.error(res, 'Could not retrieve ban history.', 500);
  }
};

// ─── BULK UNBAN ───────────────────────────────────────────────────────────────

exports.bulkUnbanUsers = async (req, res) => {
  try {
    const { ids, lift_reason } = req.body;

    if (!Array.isArray(ids) || !ids.length)
      return R.error(res, 'No user IDs provided.', 400);

    const users = await mdl_Users.findAll({ where: { user_id: ids } });
    if (!users.length) return R.error(res, 'No users found.', 404);

    const bannedUsers = users.filter((u) => u.is_banned);
    if (!bannedUsers.length)
      return R.error(res, 'None of the selected users are currently banned.', 400);

    const targetIds = bannedUsers.map((u) => u.user_id);
    const now = new Date();

    await sequelize.transaction(async (t) => {
      await mdl_UserBans.update(
        {
          is_lifted:   true,
          lifted_at:   now,
          lifted_by:   req.user.user_id,
          lift_reason: lift_reason?.trim() || null,
        },
        { where: { user_id: targetIds, is_lifted: false }, transaction: t }
      );

      await mdl_Users.update(
        { is_banned: false, ban_expires_at: null },
        { where: { user_id: targetIds }, transaction: t }
      );
    });

    logActivity(req.user.user_id, 'bulk_unban_users', {
      entityType: 'user',
      details:    { unban_ids: targetIds },
    });

    const dateStr = fmtDate(now);
    bannedUsers.forEach((u) => {
      sendEmail({
        to:   u.email,
        type: 'BAN_LIFTED',
        data: {
          name:  u.personal_info?.name?.full_name ?? 'User',
          email: u.email,
          date:  dateStr,
        },
      }).catch((err) => console.error('[ADMIN][BULK UNBAN] Email failed:', u.email, err));
    });

    return R.success(res, `${targetIds.length} user(s) unbanned successfully.`, {
      unbanned_ids: targetIds,
      skipped_ids:  ids.filter((id) => !targetIds.includes(Number(id))),
    });
  } catch (err) {
    console.error('[ADMIN][BULK UNBAN USERS]', err);
    return R.error(res, 'Could not unban users.', 500);
  }
};