// public/dashboard/js/realtime.js
// Realtime dashboard (SSE + fallback snapshot)

import { apiGetRealtimeSnapshot } from './api.js';
import { API_CONFIG } from './config.js';

const REALTIME_STREAM_URL = `${API_CONFIG.BASE_URL}/retribusi/v1/realtime/stream`;

class RealtimeManager {
  constructor() {
    this.eventSource = null;
    this.snapshotTimer = null;
    this.isConnected = false;
  }

  init() {
    // Mulai SSE, kalau gagal pakai fallback polling snapshot
    this.startSSE();
    this.startSnapshotFallback();
  }

  startSSE() {
    try {
      const token = localStorage.getItem('token') || '';
      // SSE tidak support custom headers, jadi token harus di query string
      // TAPI sesuai spec, parameter yang benar adalah 'last_id', bukan 'token'
      // Token tetap dikirim via Authorization header jika backend support
      // Untuk SSE, kita pakai query string karena EventSource tidak support custom headers
      const params = new URLSearchParams();
      // Jika ada last_id dari state, tambahkan
      // params.append('last_id', this.lastEventId || '');
      // Token tetap di query string untuk SSE (limitation EventSource)
      if (token) {
        // Backend harus handle token dari query string atau implement custom SSE handler
        // Untuk sekarang, kita tetap pakai query string karena EventSource limitation
        params.append('token', token);
      }
      const url = `${REALTIME_STREAM_URL}?${params.toString()}`;

      console.log('[Realtime] Connect SSE:', url);

      // EventSource tidak support custom headers, jadi token harus di query string
      // Backend harus handle ini atau implement custom SSE handler dengan fetch + stream
      this.eventSource = new EventSource(url);

      this.eventSource.onopen = () => {
        console.log('[Realtime] SSE opened');
        this.isConnected = true;
      };

      this.eventSource.onmessage = (event) => {
        try {
          const data = JSON.parse(event.data);
          console.log('[Realtime] SSE event:', data);
          
          // Backend kirim realtime_events, bisa berupa:
          // - event baru (entry baru)
          // - snapshot agregat (total_count_today, by_category, dll)
          // Sesuaikan dengan struktur yang backend kirim via SSE
          
          // Jika backend kirim snapshot via SSE, parse sama seperti fetchSnapshot()
          if (data.total_count_today !== undefined || data.by_category) {
            const personCat = (data.by_category || []).find(c => c.category === 'person_walk') || { total_count: 0 };
            const motorCat = (data.by_category || []).find(c => c.category === 'motor') || { total_count: 0 };
            const carCat = (data.by_category || []).find(c => c.category === 'car') || { total_count: 0 };
            
            const kpiData = {
              totalPeople: personCat.total_count || 0,
              totalVehicles: (motorCat.total_count || 0) + (carCat.total_count || 0),
              totalCount: data.total_count_today || 0,
              totalAmount: data.total_amount_today || 0
            };
            
            window.dispatchEvent(new CustomEvent('realtime:snapshot', { detail: kpiData }));
          }
        } catch (e) {
          console.warn('[Realtime] gagal parse event data', e, event.data);
        }
      };

      this.eventSource.onerror = (err) => {
        console.error('[Realtime] SSE error', err);
        this.isConnected = false;
        // Biarkan browser auto-reconnect, kalau tetap gagal nanti fallback snapshot yang jalan
      };
    } catch (e) {
      console.error('[Realtime] tidak bisa inisialisasi SSE', e);
      this.isConnected = false;
    }
  }

  async fetchSnapshot() {
    try {
      // Struktur response setelah di-unwrap: { total_count_today, total_amount_today, by_gate, by_category }
      // Gunakan timezone Indonesia UTC+7 untuk mendapatkan tanggal lokal yang benar
      const now = new Date();
      // Format tanggal dalam timezone Asia/Jakarta (UTC+7)
      const formatter = new Intl.DateTimeFormat('en-CA', {
        timeZone: 'Asia/Jakarta',
        year: 'numeric',
        month: '2-digit',
        day: '2-digit'
      });
      const today = formatter.format(now);
      const snapshot = await apiGetRealtimeSnapshot({
        date: today,
        location_code: '' // bisa diambil dari state dashboard jika perlu
      });
      
      console.log('[Realtime] snapshot:', snapshot);
      
      // Parse data snapshot sesuai struktur resmi
      const parsed = {
        totalCount: snapshot.total_count_today || 0,
        totalAmount: snapshot.total_amount_today || 0,
        byGate: Array.isArray(snapshot.by_gate) ? snapshot.by_gate : [],
        byCategory: Array.isArray(snapshot.by_category) ? snapshot.by_category : []
      };
      
      // Hitung total orang & kendaraan dari by_category
      const personCat = parsed.byCategory.find(c => c.category === 'person_walk') || { total_count: 0 };
      const motorCat = parsed.byCategory.find(c => c.category === 'motor') || { total_count: 0 };
      const carCat = parsed.byCategory.find(c => c.category === 'car') || { total_count: 0 };
      
      const kpiData = {
        totalPeople: personCat.total_count || 0,
        totalVehicles: (motorCat.total_count || 0) + (carCat.total_count || 0),
        totalCount: parsed.totalCount,
        totalAmount: parsed.totalAmount
      };
      
      // Dispatch event untuk update dashboard real-time
      window.dispatchEvent(new CustomEvent('realtime:snapshot', { detail: kpiData }));
      
    } catch (e) {
      console.error('[Realtime] gagal ambil snapshot', e);
    }
  }

  startSnapshotFallback() {
    // Polling ringan tiap 5 detik, hanya kalau SSE belum stable
    if (this.snapshotTimer) clearInterval(this.snapshotTimer);
    this.snapshotTimer = setInterval(() => {
      if (!this.isConnected) {
        this.fetchSnapshot();
      }
    }, 5000);
  }

  stop() {
    if (this.eventSource) {
      this.eventSource.close();
      this.eventSource = null;
    }
    if (this.snapshotTimer) {
      clearInterval(this.snapshotTimer);
      this.snapshotTimer = null;
    }
    this.isConnected = false;
  }
}

export const Realtime = new RealtimeManager();

// Auto-init saat dashboard dibuka
document.addEventListener('DOMContentLoaded', () => {
  Realtime.init();
});