import { ActivityLevelFormatter } from "@/lib/formatters/ActivityLevelFormatter";
import type { DashboardStatsViewData } from '@/lib/view-data/DashboardStatsViewData';
import { ViewModel } from "../contracts/view-models/ViewModel";

/**
 * DashboardStatsViewModel
 *
 * View Model for admin dashboard statistics.
 * Provides formatted statistics and derived metrics for UI.
 */
export class DashboardStatsViewModel extends ViewModel {
  totalUsers: number;
  activeUsers: number;
  suspendedUsers: number;
  deletedUsers: number;
  systemAdmins: number;
  recentLogins: number;
  newUsersToday: number;
  userGrowth: {
    label: string;
    value: number;
    color: string;
  }[];
  roleDistribution: {
    label: string;
    value: number;
    color: string;
  }[];
  statusDistribution: {
    active: number;
    suspended: number;
    deleted: number;
  };
  activityTimeline: {
    date: string;
    newUsers: number;
    logins: number;
  }[];

  // UI-specific derived fields (primitive outputs only)
  readonly activeRate: number;
  readonly activeRateFormatted: string;
  readonly adminRatio: string;
  readonly activityLevelLabel: string;
  readonly activityLevelValue: 'low' | 'medium' | 'high';

  constructor(viewData: DashboardStatsViewData) {
    super();
    this.totalUsers = viewData.totalUsers;
    this.activeUsers = viewData.activeUsers;
    this.suspendedUsers = viewData.suspendedUsers;
    this.deletedUsers = viewData.deletedUsers;
    this.systemAdmins = viewData.systemAdmins;
    this.recentLogins = viewData.recentLogins;
    this.newUsersToday = viewData.newUsersToday;
    this.userGrowth = viewData.userGrowth;
    this.roleDistribution = viewData.roleDistribution;
    this.statusDistribution = viewData.statusDistribution;
    this.activityTimeline = viewData.activityTimeline;

    // Derive active rate
    this.activeRate = this.totalUsers > 0 ? (this.activeUsers / this.totalUsers) * 100 : 0;
    this.activeRateFormatted = `${Math.round(this.activeRate)}%`;

    // Derive admin ratio
    const nonAdmins = Math.max(1, this.totalUsers - this.systemAdmins);
    this.adminRatio = `1:${Math.floor(nonAdmins / Math.max(1, this.systemAdmins))}`;

    // Derive activity level using Display Object
    const engagementRate = this.totalUsers > 0 ? (this.recentLogins / this.totalUsers) * 100 : 0;
    this.activityLevelLabel = ActivityLevelFormatter.levelLabel(engagementRate);
    this.activityLevelValue = ActivityLevelFormatter.levelValue(engagementRate);
  }
}