/***********************************************************************************************************************************************************************
 * File Name: groups.ctrl.js (staff)
 * Type of Program: Controller
 * Description: Staff-scoped group endpoints.
 *              Returns only the groups the logged-in staff member belongs to,
 *              along with their members and associated task lists.
 ***********************************************************************************************************************************************************************/
const { Op } = require('sequelize');
const mdl_Users = require('../../models/users/users.mdl');
const { mdl_UserGroups, mdl_UserGroupMembers } = require('../../models/users/user_groups.mdl');
const { TaskList, Task, TaskRequirement, TaskListGroup } = require('../../models/task/task.mdl');
const { getFieldValues } = require("../../utils/fieldValues.util");
const { paginate } = require('../../utils/paginate.util');
const R = require('../../utils/response.util');
const { excludeAttributes: usersExclude, jsonbSchemas: usersSchemas, computedAttributes: userComputed } = require('../../models/users/users.attributes');

/**
 * GET /api/staff/groups
 * Returns all groups the staff member belongs to,
 * with member count and associated task lists.
 */
const getMyGroups = async (req, res) => {
  try {
    const staffUserId = req.user.user_id;

    const groups = await mdl_UserGroups.findAll({
      include: [
        {
          model: mdl_UserGroupMembers,
          required: true, // INNER JOIN — only groups the staff member is in
          where: { user_id: staffUserId },
          attributes: [],
        },
        {
          model: mdl_Users,
          as: 'members',
          attributes: ['user_id', 'email', 'personal_info', 'is_active'],
          through: { attributes: ['joined_at'] },
          required: false,
        },
        {
          model: TaskList,
          as: 'taskLists',
          attributes: ['task_list_id', 'name', 'description', 'createdAt'],
          through: { attributes: ['assignedAt'] },
          required: false,
          include: [
            {
              model: Task,
              as: 'tasks',
              attributes: ['task_id', 'name', 'deadline', 'status'],
              required: false,
            },
          ],
        },
      ],
      where: { is_active: true },
      order: [['name', 'ASC']],
    });

    // Add member_count computed field
    const data = groups.map(g => ({
      ...g.toJSON(),
      member_count: g.members?.length ?? 0,
    }));

    return res.status(200).json({ success: true, data });
  } catch (err) {
    console.error('[staff/groups] getMyGroups error:', err);
    return res.status(500).json({ success: false, message: 'Internal server error.' });
  }
};

/**
 * GET /api/staff/groups/:group_id
 * Returns a single group's full details — members + task lists.
 * Staff must be a member of this group.
 */
const getGroupById = async (req, res) => {
  try {
    const staffUserId = req.user.user_id;
    const groupId = parseInt(req.params.group_id);

    // Verify staff membership
    const membership = await mdl_UserGroupMembers.findOne({
      where: { user_id: staffUserId, group_id: groupId },
    });
    if (!membership) {
      return res.status(403).json({ success: false, message: 'You are not a member of this group.' });
    }

    const group = await mdl_UserGroups.findOne({
      where: { group_id: groupId, is_active: true },
      include: [
        {
          model: mdl_Users,
          as: 'members',
          attributes: ['user_id', 'email', 'personal_info', 'is_active', 'acc_type'],
          through: { attributes: ['joined_at'] },
        },
        {
          model: TaskList,
          as: 'taskLists',
          attributes: ['task_list_id', 'name', 'description', 'createdAt'],
          through: { attributes: ['assignedAt'] },
          include: [
            {
              model: Task,
              as: 'tasks',
              attributes: ['task_id', 'name', 'description', 'deadline', 'status'],
              include: [
                {
                  model: TaskRequirement,
                  as: 'requirements',
                  attributes: ['requirement_id', 'type', 'link_url', 'link_label', 'reference_id', 'reference_label', 'order'],
                },
              ],
            },
          ],
        },
      ],
    });

    if (!group) return res.status(404).json({ success: false, message: 'Group not found.' });

    return res.status(200).json({
      success: true,
      data: { ...group.toJSON(), member_count: group.members?.length ?? 0 },
    });
  } catch (err) {
    console.error('[staff/groups] getGroupById error:', err);
    return res.status(500).json({ success: false, message: 'Internal server error.' });
  }
};

// GET /staff/groups/:group_id/members
// Paginated, searchable, filterable — mirrors getUsers pattern
const getGroupMembers = async (req, res) => {
  try {
    const staffUserId = req.user.user_id;
    const groupId = parseInt(req.params.group_id);

    // Verify staff is a member of this group
    const membership = await mdl_UserGroupMembers.findOne({
      where: { user_id: staffUserId, group_id: groupId },
    });
    if (!membership) {
      return res.status(403).json({ success: false, message: 'You are not a member of this group.' });
    }

    // Confirm group exists
    const groupExists = await mdl_UserGroups.findOne({
      where: { group_id: groupId, is_active: true },
      attributes: ['group_id'],
    });
    if (!groupExists) {
      return res.status(404).json({ success: false, message: 'Group not found.' });
    }

    const result = await paginate(mdl_Users, req, {
      excludeAttributes: usersExclude,
      jsonbSchemas: usersSchemas,
      jsonbColumn: 'personal_info',
      computedAttributes: userComputed,
      context: "list",
      findOptions: {
        include: [
          {
            model: mdl_UserGroups,
            as: 'groups',
            through: { attributes: [] },
            attributes: ['group_id', 'name', 'group_code'],
            required: true,          // INNER JOIN — only users in this group
            where: { group_id: groupId },
          },
        ],
      },
    });

    return R.success(res, 'Group members retrieved.', result);
  } catch (err) {
    console.error('[staff/groups] getGroupMembers error:', err);
    return R.error(res, 'Could not retrieve group members.', 500);
  }
};

/**
 * GET /api/staff/groups/by-code/:group_code
 * Convenience endpoint — look up a group by its invite code.
 * Staff must still be a member.
 */
const getGroupByCode = async (req, res) => {
  try {
    const staffUserId = req.user.user_id;
    const groupCode = req.params.group_code.toUpperCase().trim();

    const group = await mdl_UserGroups.findOne({
      where: { group_code: groupCode, is_active: true },
    });

    if (!group) return res.status(404).json({ success: false, message: 'Group not found.' });

    // Verify staff membership
    const membership = await mdl_UserGroupMembers.findOne({
      where: { user_id: staffUserId, group_id: group.group_id },
    });
    if (!membership) {
      return res.status(403).json({ success: false, message: 'You are not a member of this group.' });
    }

    // Reuse getGroupById logic by patching req.params
    req.params.group_id = group.group_id;
    return getGroupById(req, res);
  } catch (err) {
    console.error('[staff/groups] getGroupByCode error:', err);
    return res.status(500).json({ success: false, message: 'Internal server error.' });
  }
};

// ─── GET /staff/groups/:group_id/members/field-values ────────────────────────
const getGroupMemberFieldValues = async (req, res) => {
  try {
    const staffUserId = req.user.user_id;
    const groupId     = parseInt(req.params.group_id);
 
    const membership = await mdl_UserGroupMembers.findOne({
      where: { user_id: staffUserId, group_id: groupId },
    });
    if (!membership) {
      return res.status(403).json({ success: false, message: "You are not a member of this group." });
    }
 
    const groupExists = await mdl_UserGroups.findOne({
      where: { group_id: groupId, is_active: true },
      attributes: ["group_id"],
    });
    if (!groupExists) {
      return res.status(404).json({ success: false, message: "Group not found." });
    }
 
    return getFieldValues(mdl_Users, "USER", {
      blockedFields:   ["password", "otp_code", "otp_expires_at", "personal_info"],
      extraDateFields: ["modifiedAt"],
      allowJsonb:      true,
      selfJoin:        true,
      // Scope distinct values to this group only
      baseWhere: {
        "$groups.group_id$": groupId,
      },
      associations: {
        groups: {
          model:      mdl_UserGroups,
          labelField: "name",
          valueField: "name",
          // INNER JOIN so values are scoped to group members only
          required:   true,
          where:      { group_id: groupId },
        },
      },
    })(req, res);
  } catch (err) {
    console.error("[staff/groups] getGroupMemberFieldValues error:", err);
    return R.error(res, "Could not retrieve field values.", 500);
  }
};

module.exports = { getMyGroups, getGroupById, getGroupByCode, getGroupMembers, getGroupMemberFieldValues };