import { useEffect } from 'react';
import { AppState, Platform } from 'react-native';
import { useNavigation } from '@react-navigation/native';
import type { NativeStackNavigationProp } from '@react-navigation/native-stack';
import * as Notifications from 'expo-notifications';
import type { Zone } from 'parksmarter-client';
import { ps } from '@/api/client';
import { parseApiTime } from '@/api/parseTime';
import type { LabelKind } from '@/api/zoneLabels';
import type { RootStackParamList } from '@/navigation/RootNavigator';
import {
  ensureNotificationPermission,
  REMINDER_CHANNEL_ID,
} from '@/notifications/localReminders';
import {
  getCountdownEnabled,
  getReminderLeadMinutes,
  getRemindersEnabled,
} from '@/features/notifications/reminderPrefs';
import { logLine } from '@/features/diagnostics/fileLogger';
import type { ParkingArea } from '@/api/parkingAreas';
import {
  clearActiveParking,
  getActiveParking,
  setActiveParking,
  setParkedPin,
  type ActiveParking,
  type ParkedSpot,
} from './activeParkingStore';
import {
  clearSession,
  consumePendingAction,
  hasNativeCountdown,
  showSession,
} from '../../../modules/bbp-notify';

/**
 * Everything that happens while a car is parked, paid or free, lives here.
 *
 * There is exactly one active parking session at a time, so there is exactly one
 * ongoing notification. Both entry points (buying time, checking into a free
 * space) write the same record and post the same countdown, which is why the
 * notification behaves identically whichever way you parked.
 *
 * The notification itself is owned by a native foreground service — see
 * modules/bbp-notify. JS's job is to keep the record truthful; the service
 * renders it and stops itself the moment there's nothing to show.
 */

/** One session at a time, so one reminder id. */
const EXPIRY_REMINDER_ID = 'parking-expiry';
/** Fallback ongoing notification for Expo Go, where the native module is absent. */
const FALLBACK_NOTIF_ID = 'parking-status';
/** How much a city-map session's "extend" button adds, and what it's labelled. */
const EXTEND_MINUTES = 60;
const EXTEND_LABEL = '+1 hr';

function fmtTime(ms: number): string {
  return new Date(ms).toLocaleTimeString([], { hour: 'numeric', minute: '2-digit' });
}

/* ------------------------------------------------------------------ posting */

/** Post (or replace) the ongoing ticking notification for a session. */
async function postNotification(p: ActiveParking): Promise<void> {
  if (!(await getCountdownEnabled())) {
    logLine('[PARKING] countdown disabled — not posting');
    await clearNotification();
    return;
  }
  await ensureNotificationPermission();

  const ends = fmtTime(p.endMs);
  const free = p.kind === 'free';
  const title = free ? `Free parking · ${p.zoneName}` : `Parking · ${p.zoneName}`;
  const body = free ? `Free until ${ends}` : `Paid until ${ends}`;
  // What the second button does depends on what it *can* do. City-map parking has
  // no ParkSmarter zone to buy time in, so there it adds an hour to the local
  // timer and says so; a real zone gets the purchase screen.
  const extendLabel = p.area ? EXTEND_LABEL : free ? 'Pay' : 'Extend';

  if (hasNativeCountdown) {
    const diag = await showSession(title, body, p.endMs, 'End', extendLabel);
    logLine(`[PARKING] ${p.kind} native: ${diag}`);
    return;
  }

  // Expo Go / no native module: a static ongoing notification, no buttons and no
  // ticking, refreshed whenever the app is foregrounded.
  logLine('[PARKING] no native module — static fallback notification');
  await Notifications.scheduleNotificationAsync({
    identifier: FALLBACK_NOTIF_ID,
    content: {
      title,
      body,
      sticky: true,
      autoDismiss: false,
      data: { kind: 'session-status' },
    },
    trigger:
      Platform.OS === 'android'
        ? {
            type: Notifications.SchedulableTriggerInputTypes.DATE,
            date: new Date(Date.now() + 400),
            channelId: 'session-status',
          }
        : null,
  });
}

async function clearNotification(): Promise<void> {
  await clearSession().catch(() => {});
  await Notifications.dismissNotificationAsync(FALLBACK_NOTIF_ID).catch(() => {});
  await Notifications.cancelScheduledNotificationAsync(FALLBACK_NOTIF_ID).catch(() => {});
}

/* ---------------------------------------------------------------- reminders */

async function scheduleExpiryReminder(p: ActiveParking): Promise<void> {
  await Notifications.cancelScheduledNotificationAsync(EXPIRY_REMINDER_ID).catch(() => {});
  if (!(await getRemindersEnabled())) return;
  const fireAt = p.endMs - p.leadMinutes * 60_000;
  if (fireAt <= Date.now()) return;

  const free = p.kind === 'free';
  await Notifications.scheduleNotificationAsync({
    identifier: EXPIRY_REMINDER_ID,
    content: {
      title: free ? 'Free parking ending soon' : 'Parking expiring soon',
      body: `${p.zoneName}: ${free ? 'your free time ends' : 'your session ends'} at ${fmtTime(
        p.endMs,
      )}. Extend if you need more time.`,
      data: { kind: 'parking-expiry' },
    },
    trigger: {
      type: Notifications.SchedulableTriggerInputTypes.DATE,
      date: new Date(fireAt),
      channelId: REMINDER_CHANNEL_ID,
    },
  });
}

/* ------------------------------------------------------------ start / stop */

/** Begin tracking a paid session that ParkSmarter has just confirmed. */
export async function startPaidSession(args: {
  zone: Zone;
  endTime: Date;
  transactionId?: string | number;
}): Promise<void> {
  const state: ActiveParking = {
    kind: 'paid',
    zone: args.zone,
    zoneName: args.zone.ZoneName ?? 'Parking',
    startMs: Date.now(),
    endMs: args.endTime.getTime(),
    transactionId: args.transactionId != null ? String(args.transactionId) : undefined,
    leadMinutes: await getReminderLeadMinutes(),
  };
  await setActiveParking(state);
  await postNotification(state);
  await scheduleExpiryReminder(state);
}

/** Start a local free check-in for `hours` at the given zone. */
export async function startFreeCheckin(
  zone: Zone,
  hours: number,
  labelKind?: LabelKind,
): Promise<void> {
  const now = Date.now();
  const state: ActiveParking = {
    kind: 'free',
    zone,
    zoneName: zone.ZoneName ?? 'Parking',
    startMs: now,
    endMs: now + hours * 3_600_000,
    labelKind: labelKind ?? (`free_${hours}h` as LabelKind),
    leadMinutes: await getReminderLeadMinutes(),
  };
  await setActiveParking(state);
  await postNotification(state);
  await scheduleExpiryReminder(state);
}

/**
 * Start tracking time on an area from the city parking map.
 *
 * Deliberately the whole story: no ParkSmarter call, no account, no network. The
 * area came from the local database, the clock is the phone's, and the countdown
 * is the same foreground service every other session uses. Works in Anonymous
 * Mode, offline, and with the IPS API down.
 */
export async function startAreaParking(args: {
  area: ParkingArea;
  hours: number;
  spot?: ParkedSpot;
}): Promise<void> {
  const now = Date.now();
  const state: ActiveParking = {
    // Only the city lots cost money; everything else on the map is free parking
    // that merely has a posted time limit.
    kind: args.area.kind === 'green_lot' ? 'paid' : 'free',
    area: {
      id: args.area.id,
      kind: args.area.kind,
      name: args.area.name,
      legend: args.area.legend,
      color: args.area.color,
    },
    spot: args.spot,
    zoneName: args.area.name,
    startMs: now,
    endMs: now + Math.round(args.hours * 3_600_000),
    leadMinutes: await getReminderLeadMinutes(),
  };
  await setActiveParking(state);
  if (args.spot) await setParkedPin(args.spot);
  await postNotification(state);
  await scheduleExpiryReminder(state);
  logLine(`[PARKING] city area ${args.area.id} (${args.area.kind}) for ${args.hours}h`);
}

/**
 * Drop the "where is my car" pin. Deliberately independent of any session — you
 * can pin the car without starting a timer, and the pin has to survive that.
 */
export async function pinParkedSpot(spot: ParkedSpot): Promise<void> {
  await setParkedPin(spot);
  const current = await getActiveParking();
  if (current) await setActiveParking({ ...current, spot });
}

/**
 * Add time to a city-map session's local timer. There is nothing to buy here —
 * the app is only tracking a clock — so extending is a local edit, not a purchase.
 */
export async function extendAreaParking(minutes = EXTEND_MINUTES): Promise<void> {
  const current = await getActiveParking();
  if (!current) return;
  // Extend from now if it already lapsed, so "+1 hr" always means a full hour.
  const from = Math.max(current.endMs, Date.now());
  const next = { ...current, endMs: from + minutes * 60_000 };
  await setActiveParking(next);
  await postNotification(next);
  await scheduleExpiryReminder(next);
}

/**
 * Stop tracking the active session and take its notification down.
 *
 * For a free check-in this genuinely ends it. For a paid session it only stops
 * tracking — ParkSmarter has no stop-session endpoint, so the time you bought
 * keeps running at the meter whether or not the app is showing it.
 */
export async function endActiveParking(): Promise<void> {
  await clearActiveParking();
  await clearNotification();
  await Notifications.cancelScheduledNotificationAsync(EXPIRY_REMINDER_ID).catch(() => {});
}

/* ----------------------------------------------------------------- syncing */

/**
 * Ask the server whether a paid session is running. Only used when nothing is
 * tracked locally — a session bought on another device, or before this version
 * started persisting them. The active-session API returns no Zone, so a session
 * found this way has no zone to extend into.
 */
async function discoverPaidSession(): Promise<ActiveParking | null> {
  try {
    const res = await ps.getActiveParkingSessions();
    const soonest = (res.ParkingSession ?? [])
      .map((s: any) => ({ s, end: parseApiTime(s.EndTime ?? s.EndTimeDisplay) }))
      .filter((x) => x.end != null && x.end.getTime() > Date.now())
      .sort((a, b) => a.end!.getTime() - b.end!.getTime())[0];
    if (!soonest) return null;

    const found: ActiveParking = {
      kind: 'paid',
      zoneName: soonest.s.ZoneName ?? 'Parking',
      startMs: parseApiTime(soonest.s.StartTime)?.getTime() ?? Date.now(),
      endMs: soonest.end!.getTime(),
      transactionId:
        soonest.s.TransactionID != null ? String(soonest.s.TransactionID) : undefined,
      leadMinutes: await getReminderLeadMinutes(),
    };
    logLine(`[PARKING] discovered server session ending ${new Date(found.endMs).toISOString()}`);
    await setActiveParking(found);
    await scheduleExpiryReminder(found);
    return found;
  } catch (e: any) {
    logLine(`[PARKING] discover failed: ${e?.serverMessage ?? e?.message ?? e}`);
    return null;
  }
}

/**
 * Reconcile the record, its notification and any button the user pressed while the
 * app was away. Safe to call repeatedly; it's the app's foreground heartbeat.
 */
export async function syncActiveParking(onExtend: (zone?: Zone) => void): Promise<void> {
  const action = await consumePendingAction();

  if (action === 'end') {
    logLine('[PARKING] notification "End" pressed');
    await endActiveParking();
    return;
  }

  let current = await getActiveParking();

  // The meter ran out: the service already removed its own notification when the
  // countdown hit zero, so this just clears the record behind it.
  if (current && current.endMs <= Date.now()) {
    await endActiveParking();
    current = null;
  }

  // "+1 hr" on a city-map session is a local edit, not a purchase — handle it here
  // and stay put rather than sending the user to a payment screen for a free spot.
  if (action === 'extend' && current?.area) {
    logLine(`[PARKING] notification "${EXTEND_LABEL}" pressed on city area ${current.area.id}`);
    await extendAreaParking();
    return;
  }

  // A city-map session is never on the ParkSmarter server, so don't let a stale
  // server session overwrite it.
  if (!current) current = await discoverPaidSession();

  if (current) {
    await postNotification(current);
  } else {
    await clearNotification();
  }

  if (action === 'extend') {
    logLine('[PARKING] notification "Extend" pressed');
    onExtend(current?.zone);
  }
}

/** Called by the tab navigator: sync on open and on every foreground. */
export function useActiveParkingSync(): void {
  const navigation = useNavigation<NativeStackNavigationProp<RootStackParamList>>();

  useEffect(() => {
    const run = () =>
      void syncActiveParking((zone) => {
        // "Extend" means "sell me more time for this exact spot" — go straight to
        // the purchase screen for the stored zone. A server-discovered session has
        // no zone, so fall back to the sessions list rather than guessing.
        if (zone) navigation.navigate('StartSession', { zone });
        else navigation.navigate('Tabs');
      });

    run();
    const sub = AppState.addEventListener('change', (state) => {
      if (state === 'active') run();
    });
    return () => sub.remove();
  }, [navigation]);
}

/** Turn the countdown notification on/off from Settings without touching the record. */
export async function refreshParkingNotification(): Promise<void> {
  const current = await getActiveParking();
  if (current && current.endMs > Date.now()) await postNotification(current);
  else await clearNotification();
}