import 'dart:math' as math;

import 'package:miler/views/Dashboard/pickups/stop_type.dart';
import 'package:miler/views/Dashboard/pickups/route_metrics.dart';
import 'package:miler/data/route_order.dart';
import 'package:miler/data/service_profile.dart';
import 'package:miler/Models/stop_status.dart';

/// ─────────────────────────────────────────────────────────────────────────
/// A TRIP — one slot's worth of work, as a single unit.
///
/// The hub manager does not assign bookings one at a time. He takes every
/// customer booking that falls inside a slot (say 10:00–13:00), orders them
/// into a route, and hands the whole thing to one miler. So the rider's
/// decision is never "do I want this one parcel?" — it is "do I take this
/// trip?". Home used to show loose bookings, which framed the job as a
/// marketplace it isn't, and hid the two facts that actually matter: how long
/// the whole run takes, and where it starts and ends.
///
/// A trip is therefore always shaped:
///
///     HUB → Stop 1 → Stop 2 → … → Stop N → HUB
///
/// with the same hub at both ends. Every duration and distance below includes
/// the return leg, because the rider is not finished until he is back.
///
/// This class is pure — no Flutter, no I/O — so the arithmetic is unit-tested
/// and safe to call from `build`.
/// ─────────────────────────────────────────────────────────────────────────

/// ─────────────────────────────────────────────────────────────────────────
/// WHICH TRIP A STOP IS ON
///
/// A rider's day is three trips, and which one an order lands on is decided by
/// **when the work is due**, not by how many buckets happen to have filled up:
///
///     morning    → Trip 1
///     afternoon  → Trip 2
///     evening    → Trip 3
///
/// ── What this replaces ──
///
/// Stops were bucketed into rolling three-hour windows aligned to the clock —
/// 09:00–12:00, 12:00–15:00, and so on — which produces up to eight buckets a
/// day, folded down to three at the end. Two consequences, both wrong on a
/// real morning: an 08:30 stop and an 11:00 stop are both *the morning run*
/// and landed on different trips, and which trip a stop appeared on depended
/// on what else was in the day. A rider with only afternoon work saw it as
/// "Trip 1", so his Trip 2 and the hub's Trip 2 were different things.
///
/// The boundaries are fixed here rather than derived, because they are a
/// business fact about the shift and not something to infer from the data.
/// ─────────────────────────────────────────────────────────────────────────
enum DayPart {
  morning('Morning'),
  afternoon('Afternoon'),
  evening('Evening');

  const DayPart(this.label);

  /// What this part of the day is called, on a tab and in a sentence.
  final String label;

  /// Afternoon begins at noon.
  static const int afternoonFromHour = 12;

  /// Evening begins at 5pm.
  static const int eveningFromHour = 17;

  /// The day part [at] falls in.
  static DayPart of(DateTime at) {
    if (at.hour < afternoonFromHour) return DayPart.morning;
    if (at.hour < eveningFromHour) return DayPart.afternoon;
    return DayPart.evening;
  }

  /// The window this part covers on [day].
  static (DateTime, DateTime) windowOn(DateTime day, DayPart part) {
    final midnight = DateTime(day.year, day.month, day.day);
    return switch (part) {
      DayPart.morning => (
        midnight,
        midnight.add(const Duration(hours: afternoonFromHour)),
      ),
      DayPart.afternoon => (
        midnight.add(const Duration(hours: afternoonFromHour)),
        midnight.add(const Duration(hours: eveningFromHour)),
      ),
      DayPart.evening => (
        midnight.add(const Duration(hours: eveningFromHour)),
        midnight.add(const Duration(days: 1)),
      ),
    };
  }

  /// True when [from]–[to] is exactly one day part's window, which is how
  /// [Trip.slotLabel] knows to say "Morning" instead of a clock range.
  static bool spans(DateTime from, DateTime to) {
    final (start, end) = windowOn(from, of(from));
    return from.isAtSameMomentAs(start) && to.isAtSameMomentAs(end);
  }
}

/// The three slots of a day, whether or not the rider has work in each.
///
/// Trip 2 is the afternoon even on a day with no morning work — the number is
/// the day part, so the rider's "Trip 2" and the hub's are the same run.
extension TripSlots on List<Trip> {
  /// The day laid out as slots: index 0 is the morning, 1 the afternoon, 2 the
  /// evening, and an empty slot is a part of the day with no work in it.
  ///
  /// Dated trips claim their own part. Anything undated — a tenant that sends
  /// no times, demo data, a trip whose stops carry only addresses — falls back
  /// to the first free slot, in order, because a trip that cannot be placed
  /// still has to be reachable. Guessing a part from the wall clock instead
  /// would quietly move such a trip from Trip 1 to Trip 2 at noon.
  List<Trip?> get slots {
    final out = List<Trip?>.filled(DayPart.values.length, null, growable: true);

    // ── Day parts place the trips only when they can place all of them ──
    //
    // A trip claims the slot its part names — that is what makes an
    // afternoon-only day read as Trip 2 rather than Trip 1. It works because
    // the common day is one run per part.
    //
    // When two trips want the *same* part it stops working, and the first
    // attempt at patching it made things worse: the second trip took the first
    // free slot anywhere, so on an evening with two evening runs the tabs came
    // out `[2, 0]` — trip one under Trip 3, trip two under Trip 1, inverted,
    // and only between 5pm and midnight. A layout that depends on the hour the
    // rider opened the screen is worse than one that ignores day parts.
    //
    // So it is all or nothing. Every trip has its own part, or the run is laid
    // out in the order it arrived — which is already sorted, and which is the
    // honest answer when the data does not fit the model.
    final parts = <int>{};
    var distinct = true;
    for (final t in this) {
      final p = t.dayPart?.index;
      if (p == null || !parts.add(p)) {
        distinct = false;
        break;
      }
    }

    if (distinct) {
      for (final t in this) {
        out[t.dayPart!.index] = t;
      }
      return out;
    }

    for (var i = 0; i < length; i++) {
      if (i < out.length) {
        out[i] = this[i];
      } else {
        out.add(this[i]);
      }
    }
    return out;
  }

  /// The trip in slot [index] (0 = morning), or null when nothing is assigned
  /// to that part of the day.
  Trip? tripAt(int index) {
    final s = slots;
    return index >= 0 && index < s.length ? s[index] : null;
  }
}

class Trip {
  /// Stable identity for this trip (backend slot/trip id, or a derived key).
  final String id;

  /// The customer-facing slot window this trip serves. Null when the backend
  /// sends no usable times — the trip is then simply "today's route".
  final DateTime? slotStart;
  final DateTime? slotEnd;

  /// Stops in the admin's fixed order. Never re-sorted by the app.
  final List<Map<String, dynamic>> stops;

  /// Straight-line round-trip length in metres, hub → stops → hub.
  final double routeMeters;

  /// Sum of the per-stop service estimates (time off the bike).
  final Duration serviceDuration;

  /// Time on the bike, at [RouteMetricsHelper.kDefaultSpeedMps].
  final Duration travelDuration;

  final int totalParcels;
  final int deliverParcels;
  final int collectParcels;
  final double totalWeightKg;
  final double cashToCollect;

  const Trip({
    required this.id,
    required this.slotStart,
    required this.slotEnd,
    required this.stops,
    required this.routeMeters,
    required this.serviceDuration,
    required this.travelDuration,
    required this.totalParcels,
    required this.deliverParcels,
    required this.collectParcels,
    required this.totalWeightKg,
    required this.cashToCollect,
  });

  int get stopCount => stops.length;

  /// The number the rider is actually planning around: ride time plus every
  /// minute spent standing at a door.
  Duration get totalDuration => travelDuration + serviceDuration;

  /// Average time per stop across the whole trip, service only.
  Duration get averageStopDuration => stopCount == 0
      ? Duration.zero
      : Duration(seconds: serviceDuration.inSeconds ~/ stopCount);

  /// `10:00 AM – 1:00 PM`, or a plain label when the slot is unknown.
  String get slotLabel {
    final s = slotStart;
    final e = slotEnd;
    if (s == null || e == null) return "Today's route";
    // A day part is named, not spelled out as a clock range: "Morning" is what
    // the rider and the hub both call it, and "5:00 AM – 12:00 PM" says the
    // same thing in seven characters more and one reading step.
    if (DayPart.spans(s, e)) return DayPart.of(s).label;
    return '${RouteMetricsHelper.formatClock(s)} – '
        '${RouteMetricsHelper.formatClock(e)}';
  }

  /// True when the slot window has already closed.
  bool isExpired([DateTime? now]) {
    final e = slotEnd;
    if (e == null) return false;
    return (now ?? DateTime.now()).isAfter(e);
  }

  /// Order ids in this trip.
  List<String> get orderIds => [
    for (final s in stops)
      if ((s['orderid'] ?? '').toString().isNotEmpty) (s['orderid']).toString(),
  ];

  // ── Per-stop state & completion ────────────────────────────────────────

  /// State of every stop, in route order.
  List<StopState> states({
    required Set<String> acceptedIds,
    required Set<String> rejectedIds,
  }) => [
    for (final s in stops)
      stopStateOf(s, acceptedIds: acceptedIds, rejectedIds: rejectedIds),
  ];

  /// Ids an "accept whole trip" action should operate on — only the stops
  /// still awaiting a decision. Re-accepting one already accepted would be a
  /// wasted call, and re-accepting a rejected one would undo the rider.
  List<String> pendingOrderIds({
    required Set<String> acceptedIds,
    required Set<String> rejectedIds,
  }) => [
    for (final s in stops)
      if (stopStateOf(s, acceptedIds: acceptedIds, rejectedIds: rejectedIds) ==
          StopState.pending)
        (s['orderid'] ?? '').toString(),
  ].where((id) => id.isNotEmpty).toList();

  /// Fraction of the trip that is finished, 0.0 → 1.0.
  ///
  /// Counts **resolved** stops — done or rejected — not just completed ones.
  /// A rejected stop is off the rider's plate; leaving it out of the numerator
  /// would strand the trip below 100% with nothing he could do about it.
  double completion({
    required Set<String> acceptedIds,
    required Set<String> rejectedIds,
  }) {
    if (stops.isEmpty) return 0;
    final resolved = states(
      acceptedIds: acceptedIds,
      rejectedIds: rejectedIds,
    ).where((s) => s.isResolved).length;
    return resolved / stops.length;
  }

  /// Completion as a whole percent, for display.
  int completionPercent({
    required Set<String> acceptedIds,
    required Set<String> rejectedIds,
  }) => (completion(acceptedIds: acceptedIds, rejectedIds: rejectedIds) * 100)
      .round();

  /// True once every stop has been resolved — the rider can head back.
  bool isFinished({
    required Set<String> acceptedIds,
    required Set<String> rejectedIds,
  }) =>
      stops.isNotEmpty &&
      states(
        acceptedIds: acceptedIds,
        rejectedIds: rejectedIds,
      ).every((s) => s.isResolved);

  /// True while any stop still needs an accept/reject decision.
  bool hasPendingStops({
    required Set<String> acceptedIds,
    required Set<String> rejectedIds,
  }) => states(
    acceptedIds: acceptedIds,
    rejectedIds: rejectedIds,
  ).any((s) => s.needsDecision);

  /// Short tab label for a **slot** — `Trip 1`.
  ///
  /// The slot is the day part, not a running count: slot 0 is the morning
  /// whether or not the rider has morning work. See [DayPart].
  static String tabLabel(int index) =>
      'Trip ${index + 1}'; // slot index is the day part's index

  /// Which part of the day this trip belongs to — **null when nothing on it is
  /// dated**.
  ///
  /// Taken from the slot the grouping put it in. A trip the backend named with
  /// its own `tripid` still gets one, from whatever window its stops fall in.
  ///
  /// Null matters: a trip with no times at all cannot be placed by day part,
  /// and guessing one from the wall clock would move it between tabs as the
  /// afternoon wore on. Those keep their position instead — see
  /// [TripSlots.slots].
  DayPart? get dayPart {
    final at = slotStart ?? _earliestDue;
    return at == null ? null : DayPart.of(at);
  }

  /// `1`, `2` or `3` — the number the rider and the hub both use. Zero when
  /// this trip has no time to place it by.
  int get tripNumber => (dayPart?.index ?? -1) + 1;

  DateTime? get _earliestDue {
    DateTime? best;
    for (final s in stops) {
      final due = _parseTimestamp(
        s['expected_pickup_time'] ?? s['expectedpickuptime'] ?? s['eta'],
      );
      if (due == null) continue;
      if (best == null || due.isBefore(best)) best = due;
    }
    return best;
  }

  /// Address components every stop on this trip shares — city, state,
  /// pincode and so on. Cached per build by the caller.
  List<String> get sharedAddressTail => commonAddressTail([
    for (final s in stops) (s['pickupaddress'] ?? '').toString(),
  ]);

  /// The distinguishing part of a stop's address, with the shared tail removed.
  String shortAddress(Map<String, dynamic> stop, List<String> tail) =>
      stripAddressTail((stop['pickupaddress'] ?? '').toString(), tail);

  // ── Per-stop estimates ─────────────────────────────────────────────────

  /// Estimated time OFF the bike at [index].
  ///
  /// Service time is not a constant. Handing a parcel over and reading back an
  /// OTP is quick; weighing and photographing a collection is slower; doing
  /// both at one door is slower still; and counting cash adds real minutes.
  /// These are the numbers the pace warning on Home is measured against, so
  /// they are deliberately not optimistic.
  static Duration serviceTimeFor(Map<String, dynamic> stop) {
    final kind = stopKindOf(stop);

    var seconds = switch (kind) {
      StopKind.delivery => 150, // 2m30 — hand over, OTP, photo
      StopKind.pickup => 240, // 4m00 — collect, weigh, photo
      StopKind.combined => 330, // 5m30 — both, but one walk-up
    };

    // Cash handling is the single biggest variable at a door.
    if (stopCollectionAmount(stop) > 0) seconds += 90;

    // Multi-parcel stops take longer to count and load. First parcel is in
    // the base estimate; each extra adds handling time.
    final parcels = deliveryParcelCount(stop) + pickupParcelCount(stop);
    if (parcels > 1) seconds += (parcels - 1) * 25;

    return Duration(seconds: seconds);
  }

  /// Estimated ride time from the previous point to stop [index]. For index 0
  /// that is the hub → stop 1 leg.
  Duration travelTimeToStop(
    int index, {
    double? hubLat,
    double? hubLng,
    // ── The rail's legs run door to door, not counter to counter ──
    //
    // On the Deliveries rail every stop is the delivery leg, and this walked
    // the route over the PICKUP pairs — so the remaining-time estimate was a
    // tour of the kitchens the rider had already left. The flag mirrors
    // `RouteMetricsHelper.metersToStop(toDrop:)`: the previous stop's exit
    // point and this stop's target are both the drop when the leg is a
    // delivery, with the pickup pair as the payload fallback. Default false —
    // Home's pickup-leg arithmetic is untouched.
    bool deliveryLeg = false,
  }) {
    if (index < 0 || index >= stops.length) return Duration.zero;

    final ({double lat, double lng})? from = index == 0
        ? _origin(hubLat, hubLng)
        : _coordsOf(stops[index - 1], toDrop: deliveryLeg);
    final to = _coordsOf(stops[index], toDrop: deliveryLeg);
    if (from == null || to == null) return Duration.zero;

    final meters = RouteMetricsHelper.distanceMeters(
      from.lat,
      from.lng,
      to.lat,
      to.lng,
    );
    return RouteMetricsHelper.travelTime(meters);
  }

  /// Running clock estimate of when the rider reaches stop [index], assuming
  /// he leaves the hub at [departure].
  DateTime etaForStop(
    int index, {
    required DateTime departure,
    double? hubLat,
    double? hubLng,
  }) {
    var clock = departure;
    for (var i = 0; i <= index && i < stops.length; i++) {
      clock = clock.add(travelTimeToStop(i, hubLat: hubLat, hubLng: hubLng));
      if (i < index) clock = clock.add(serviceTimeFor(stops[i]));
    }
    return clock;
  }

  ({double lat, double lng})? _origin(double? lat, double? lng) =>
      (lat != null && lng != null && lat != 0 && lng != 0)
      ? (lat: lat, lng: lng)
      : null;

  // ── Construction ───────────────────────────────────────────────────────

  /// Builds one trip from an ordered list of stops.
  ///
  /// [hubLat]/[hubLng] anchor both ends of the round trip. The backend does
  /// not yet send hub coordinates, so callers pass the rider's current
  /// position — he is at (or near) the hub when he picks up a trip, which
  /// makes it a workable stand-in. When it is missing, the route length is the
  /// stop-to-stop chain only and the return leg is simply absent rather than
  /// guessed.
  factory Trip.fromStops({
    required String id,
    required List<Map<String, dynamic>> stops,
    DateTime? slotStart,
    DateTime? slotEnd,
    double? hubLat,
    double? hubLng,
  }) {
    final ordered = sortStops(stops);

    int parcels = 0;
    int deliver = 0;
    int collect = 0;
    double weight = 0;
    double cash = 0;
    var service = Duration.zero;

    for (final s in ordered) {
      final d = deliveryParcelCount(s);
      final c = pickupParcelCount(s);
      deliver += d;
      collect += c;
      parcels += (d + c) > 0 ? (d + c) : 1;
      weight += _toDouble(s['weight'] ?? s['Weight']);
      cash += stopCollectionAmount(s);
      service += serviceTimeFor(s);
    }

    // Round trip: hub → every stop in order → back to the hub.
    final chain = <({double lat, double lng})>[];
    final origin =
        (hubLat != null && hubLng != null && hubLat != 0 && hubLng != 0)
        ? (lat: hubLat, lng: hubLng)
        : null;
    if (origin != null) chain.add(origin);
    for (final s in ordered) {
      final c = _coordsOf(s);
      if (c != null) chain.add(c);
    }
    if (origin != null && chain.length > 1) chain.add(origin);

    double meters = 0;
    for (var i = 0; i < chain.length - 1; i++) {
      meters += RouteMetricsHelper.distanceMeters(
        chain[i].lat,
        chain[i].lng,
        chain[i + 1].lat,
        chain[i + 1].lng,
      );
    }
    if (meters == 0) {
      // Fall back to whatever per-stop kilometres the backend sent.
      for (final s in ordered) {
        meters += _toDouble(s['kms'] ?? s['km']) * 1000;
      }
    }

    return Trip(
      id: id,
      slotStart: slotStart,
      slotEnd: slotEnd,
      stops: ordered,
      routeMeters: meters,
      serviceDuration: service,
      travelDuration: RouteMetricsHelper.travelTime(meters),
      totalParcels: parcels,
      deliverParcels: deliver,
      collectParcels: collect,
      totalWeightKg: weight,
      cashToCollect: cash,
    );
  }

  /// Groups loose stops into trips.
  ///
  /// Grouping key, in order of trust:
  ///  1. An explicit backend `tripid` / `slotid` / `routeid`.
  ///  2. An explicit slot window (`slotstarttime` + `slotendtime`).
  ///  3. The `expected_pickup_time` bucketed into a [windowHours] block
  ///     aligned to the clock — 10:00–13:00, 13:00–16:00, and so on. This is
  ///     how the hub builds slots, so bucketing reproduces them closely enough
  ///     to be useful while the backend has no trip field.
  ///  4. Everything else lands in one "today's route" trip rather than being
  ///     dropped.
  ///
  /// Returned trips are ordered by slot start, earliest first.
  /// The most trips a rider's day can contain.
  ///
  /// Three is the operational fact, not a display limit: the hub assigns morning,
  /// afternoon and evening slots. [TripTabs] renders three slots for the same
  /// reason, and [_capToMaxTrips] folds any extra buckets into the last so the
  /// two never disagree.
  static const int maxTripsPerDay = 3;

  static List<Trip> groupIntoTrips(
    List<Map<String, dynamic>> stops, {

    /// No longer used for bucketing — stops are grouped by [DayPart]. Kept so
    /// existing call sites compile; passing it changes nothing.
    @Deprecated('Trips are bucketed by DayPart') int windowHours = 3,
    double? hubLat,
    double? hubLng,
    DateTime? now,
  }) {
    if (stops.isEmpty) return const [];

    final clock = now ?? DateTime.now();
    final buckets = <String, List<Map<String, dynamic>>>{};
    final windows = <String, (DateTime?, DateTime?)>{};

    for (final stop in stops) {
      final explicitId = _firstNonEmpty(stop, [
        'tripid',
        'tripId',
        'slotid',
        'slotId',
        'routeid',
        'routeId',
      ]);

      final slotFrom = _parseTimestamp(
        stop['slotstarttime'] ?? stop['slotStartTime'] ?? stop['slotfrom'],
      );
      final slotTo = _parseTimestamp(
        stop['slotendtime'] ?? stop['slotEndTime'] ?? stop['slotto'],
      );

      String key;
      DateTime? from;
      DateTime? to;

      if (explicitId != null) {
        key = 'id:$explicitId';
        from = slotFrom;
        to = slotTo;
      } else if (slotFrom != null && slotTo != null) {
        key = 'slot:${slotFrom.toIso8601String()}';
        from = slotFrom;
        to = slotTo;
      } else {
        final due = _parseTimestamp(
          stop['expected_pickup_time'] ??
              stop['expectedpickuptime'] ??
              stop['eta'],
        );
        if (due != null) {
          // Morning, afternoon or evening — see [DayPart]. Not a rolling
          // window: two stops due an hour apart are on the same run, and the
          // trip a stop belongs to must not depend on what else is in the day.
          final part = DayPart.of(due);
          final (partFrom, partTo) = DayPart.windowOn(due, part);
          from = partFrom;
          to = partTo;
          key = 'part:${due.year}-${due.month}-${due.day}:${part.name}';
        } else {
          from = null;
          to = null;
          key = 'day:${clock.year}-${clock.month}-${clock.day}';
        }
      }

      buckets.putIfAbsent(key, () => []).add(stop);
      windows.putIfAbsent(key, () => (from, to));
    }

    final trips = <Trip>[
      for (final entry in buckets.entries)
        Trip.fromStops(
          id: entry.key,
          stops: entry.value,
          slotStart: windows[entry.key]?.$1,
          slotEnd: windows[entry.key]?.$2,
          hubLat: hubLat,
          hubLng: hubLng,
        ),
    ];

    trips.sort((a, b) {
      final as = a.slotStart;
      final bs = b.slotStart;
      if (as == null && bs == null) return 0;
      if (as == null) return 1; // undated trips last
      if (bs == null) return -1;
      // Day part first, so Trip 1 is always the morning even on a day that
      // starts at two in the afternoon. Within a part, earliest first.
      final pa = a.dayPart?.index ?? DayPart.values.length;
      final pb = b.dayPart?.index ?? DayPart.values.length;
      if (pa != pb) return pa.compareTo(pb);
      return as.compareTo(bs);
    });

    return _capToMaxTrips(trips, hubLat: hubLat, hubLng: hubLng);
  }

  /// A rider's day is three trips. Anything past that is folded into the last.
  ///
  /// The bucketing above is time-based — a stop with no trip id lands in a
  /// three-hour window — so a long day, or one stop booked well outside the
  /// others, can produce a fourth or fifth bucket. That surfaced as a "Trip 4"
  /// tab, which is not a thing the hub assigns.
  ///
  /// **Merged, never dropped.** Truncating the list would be the one-line fix
  /// and it would silently hide real work: those stops are accepted bookings the
  /// rider is expected to complete, and a stop he cannot see is a stop he cannot
  /// deliver. The tail is therefore folded into the third trip, whose slot then
  /// spans from its own start to the last stop's end, so the label stays honest
  /// about what it now contains.
  static List<Trip> _capToMaxTrips(
    List<Trip> trips, {
    double? hubLat,
    double? hubLng,
  }) {
    if (trips.length <= maxTripsPerDay) return trips;

    final kept = trips.take(maxTripsPerDay - 1).toList();
    final tail = trips.skip(maxTripsPerDay - 1).toList();

    final mergedStops = [for (final t in tail) ...t.stops];
    final starts = tail.map((t) => t.slotStart).whereType<DateTime>();
    final ends = tail.map((t) => t.slotEnd).whereType<DateTime>();

    kept.add(
      Trip.fromStops(
        id: tail.first.id,
        stops: mergedStops,
        slotStart: starts.isEmpty
            ? null
            : starts.reduce((a, b) => a.isBefore(b) ? a : b),
        slotEnd: ends.isEmpty
            ? null
            : ends.reduce((a, b) => a.isAfter(b) ? a : b),
        hubLat: hubLat,
        hubLng: hubLng,
      ),
    );
    return kept;
  }

  /// Puts stops in the admin's intended order.
  ///
  /// `step` is authoritative — it IS the admin's solved sequence, and the app
  /// must never second-guess it. Only when no stop carries one do we fall back
  /// to the booked time, then to the order the backend sent. **Distance is not
  /// one of the options here**: sorting by it would be re-optimising a route
  /// the hub has planned, which the rider is not allowed to do.
  ///
  /// The rule itself lives in [RouteOrder] — one implementation, shared with
  /// the Deliveries tab, which used to keep its own and disagreed. This is the
  /// pickup leg's door onto it.
  static List<Map<String, dynamic>> sortStops(
    List<Map<String, dynamic>> stops,
  ) => orderStops(stops).$1;

  /// [sortStops], plus which rule produced the order.
  static (List<Map<String, dynamic>>, RouteOrderSource) orderStops(
    List<Map<String, dynamic>> stops,
  ) => RouteOrder.sort(
    stops,
    bookedTimeOf: (s) => _parseTimestamp(
      s['expected_pickup_time'] ?? s['expectedpickuptime'] ?? s['eta'],
    ),
  );

  // ── helpers ────────────────────────────────────────────────────────────

  static ({double lat, double lng})? _coordsOf(
    Map<String, dynamic> stop, {
    bool toDrop = false,
  }) {
    if (toDrop) {
      final dLat = _toDouble(stop['droplat'] ?? stop['DropLat']);
      final dLng = _toDouble(stop['droplon'] ?? stop['DropLon']);
      if (dLat != 0 && dLng != 0) return (lat: dLat, lng: dLng);
    }
    final lat = _toDouble(stop['pickuplat'] ?? stop['PickupLat']);
    final lng = _toDouble(stop['pickuplon'] ?? stop['PickupLon']);
    if (lat == 0 || lng == 0) return null;
    return (lat: lat, lng: lng);
  }

  static String? _firstNonEmpty(Map<String, dynamic> m, List<String> keys) {
    for (final k in keys) {
      final v = m[k];
      final s = v?.toString().trim() ?? '';
      if (s.isNotEmpty && s != '0' && s != 'null') return s;
    }
    return null;
  }

  static DateTime? _parseTimestamp(dynamic v) {
    if (v == null) return null;
    return DateTime.tryParse(v.toString().trim());
  }

  static double _toDouble(dynamic v) {
    if (v == null) return 0;
    if (v is num) return v.toDouble();
    final cleaned = v.toString().replaceAll(RegExp(r'[^0-9.\-]'), '');
    return double.tryParse(cleaned) ?? 0;
  }
}

/// ─────────────────────────────────────────────────────────────────────────
/// ADDRESS COMPRESSION
///
/// A raw stop address is written for a postal system, not a rider:
///
///     "5/2, North Avenue, Vadavalli, Coimbatore, Tamil Nadu, 641041"
///
/// On a six-stop trip, "Coimbatore, Tamil Nadu, 641041" is repeated six times
/// and distinguishes nothing — every stop is in the same city, or the hub
/// would not have put them on one route. It is pure noise, and it is the noise
/// that pushes the useful part ("5/2, North Avenue") onto a second line and
/// then off the end of an ellipsis.
///
/// So: find the trailing components EVERY stop on the trip shares, and drop
/// them. What survives is exactly the part that tells one stop from another.
/// The full address is never lost — it goes to the detail sheet and to the
/// navigation hand-off untouched.
///
/// This is data-driven rather than a hardcoded list of cities and states: it
/// works for any city, any country, and degrades to a no-op on a one-stop trip
/// (where nothing is shared, so nothing is dropped).
/// ─────────────────────────────────────────────────────────────────────────

/// Splits an address into trimmed, non-empty components.
List<String> addressParts(String address) =>
    address.split(',').map((p) => p.trim()).where((p) => p.isNotEmpty).toList();

/// The trailing components shared by every address in [addresses].
///
/// Returns an empty list when fewer than two addresses are given, or when the
/// tails differ — there is then nothing redundant to remove.
List<String> commonAddressTail(List<String> addresses) {
  final parts = [
    for (final a in addresses)
      if (addressParts(a).isNotEmpty) addressParts(a),
  ];
  if (parts.length < 2) return const [];

  final shortest = parts.map((p) => p.length).reduce((a, b) => a < b ? a : b);
  final tail = <String>[];

  for (var back = 1; back < shortest; back++) {
    final candidate = parts.first[parts.first.length - back].toLowerCase();
    final shared = parts.every(
      (p) => p[p.length - back].toLowerCase() == candidate,
    );
    if (!shared) break;
    tail.insert(0, parts.first[parts.first.length - back]);
  }
  return tail;
}

/// [address] with [tail] removed. Always leaves at least one component, so a
/// stop can never render a blank address.
String stripAddressTail(String address, List<String> tail) {
  if (tail.isEmpty) return address.trim();
  final parts = addressParts(address);
  var end = parts.length;
  for (var i = tail.length - 1; i >= 0; i--) {
    if (end <= 1) break;
    if (parts[end - 1].toLowerCase() != tail[i].toLowerCase()) break;
    end--;
  }
  return parts.sublist(0, end).join(', ');
}

/// Where a single stop sits in the accept → work → done lifecycle.
///
/// This is what lets one trip card serve both Home and Bookings. A trip does
/// not leave Home the moment it is accepted — the rider still wants to watch
/// it fill up — so every stop carries its own state and the card renders the
/// right control for it: Accept/Reject while pending, a progress tick once
/// it's moving, nothing at all once it's done.
enum StopState {
  /// Awaiting the rider's decision. Shows Accept + Reject.
  pending,

  /// Accepted, not yet started. Lives on the Bookings tab.
  accepted,

  /// Loaded from its source and physically in the rider's hands.
  ///
  /// Service routes only. The parcel ladder has no equivalent — for a parcel,
  /// collecting it from the customer *is* the job — so this state exists only
  /// where accepting and carrying are two different days' work apart. See
  /// [ServiceProfile.handoffAt] and the collected store.
  collected,

  /// The rider is physically on this stop right now.
  active,

  /// Picked up / delivered.
  done,

  /// Skipped, awaiting a return visit. Not a failure.
  skipped,

  /// The rider declined this stop. It stays visible, struck through, so he
  /// can see he handled it rather than wondering where it went.
  rejected,
}

extension StopStateX on StopState {
  /// Counts toward "trip complete". A rejected stop is resolved — the rider
  /// has nothing left to do with it — so it must not hold the trip at 90%
  /// forever.
  bool get isResolved => this == StopState.done || this == StopState.rejected;

  /// Still needs a decision from the rider.
  bool get needsDecision => this == StopState.pending;

  /// Committed to: he has taken it and owes the customer a visit.
  bool get isCommitted =>
      this == StopState.accepted ||
      this == StopState.collected ||
      this == StopState.active ||
      this == StopState.skipped;

  /// In the rider's hands right now.
  bool get isCollected => this == StopState.collected;

  /// What this state is called on a card.
  ///
  /// ── Two vocabularies, one state machine ──
  ///
  /// The Doormile wording is written for a rider who is being *asked* something:
  /// "Awaiting your decision" is true because the card under it carries Accept
  /// and Reject. A service rider is asked nothing — the whole assignment came as
  /// one commitment — so the same state means "the hub has given you this, it is
  /// waiting for you to go and collect it", and calling that a decision invites
  /// him to look for a button that is not there.
  ///
  /// `Delivered` rather than `Completed` for the same reason: on a meal run the
  /// last thing that happens at a door is a hand-over, and naming it is worth
  /// more than a word that covers every stop type in the app.
  String get label => ServiceProfile.active.acceptsPerStop
      ? switch (this) {
          StopState.pending => 'Awaiting your decision',
          StopState.accepted => 'Accepted',
          StopState.collected => 'Collected',
          StopState.active => 'In progress',
          StopState.done => 'Completed',
          StopState.skipped => 'Skipped',
          StopState.rejected => 'Rejected',
        }
      : switch (this) {
          StopState.pending => 'Pending',
          StopState.accepted => 'Accepted',
          StopState.collected => 'Collected',
          StopState.active => 'Out for delivery',
          StopState.done => 'Delivered',
          StopState.skipped => 'Skipped',
          StopState.rejected => 'Cancelled',
        };
}

/// Derives a stop's state from its backend status plus the local
/// accepted/rejected stores.
///
/// Local stores win for accept/reject because those writes are optimistic —
/// the rider's tap is recorded instantly and the network catches up. If the
/// server view won, a slow response would bounce a stop back to "pending"
/// under his thumb.
StopState stopStateOf(
  Map<String, dynamic> stop, {
  required Set<String> acceptedIds,
  required Set<String> rejectedIds,

  /// Orders the rider is carrying. Optional so every existing parcel call site
  /// is unchanged — a Doormile route never populates it.
  Set<String> collectedIds = const <String>{},
}) {
  final id = (stop['orderid'] ?? '').toString();
  final raw = (stop['orderstatus'] ?? '').toString().trim().toLowerCase();

  // 1. Irreversible server states win over everything. A parcel that has been
  //    collected or handed over cannot be un-decided by a local tap.
  if (raw == 'picked' ||
      raw == 'picked up' ||
      raw == 'pickedup' ||
      raw == 'pickuped' ||
      raw == 'delivered' ||
      raw == 'cancelled' ||
      raw == 'canceled') {
    return StopState.done;
  }

  // 2. The rider is physically on the stop — also not a local decision.
  if (raw == 'active' || raw == 'arrived') return StopState.active;
  if (raw == 'skipped') return StopState.skipped;

  // 2b. Released for delivery — which `pickup-complete` does by itself on
  //     hyperlocal work, in the same call that records the collection. It says
  //     the consignment may be delivered, not that the rider has set off, so it
  //     resolves to *carrying* and never to [StopState.active]. Asked ahead of
  //     the local sets because it must also hold after a reinstall, when the
  //     collected set is empty and this row would otherwise fall through to
  //     `pending` — putting a bag already in his box back on Home as work to
  //     accept. See `MilkRun.stageOf`.
  if (raw == 'outfordelivery') return StopState.collected;

  // 3. Carrying it beats every remaining local view. He has the food; no
  //    later tap on this screen can make that untrue, and a refetch that still
  //    reports `accepted` must not put the card back on Home.
  if (collectedIds.contains(id)) return StopState.collected;

  // 4. Local decisions next, and they beat the server's accept/reject.
  //    They are strictly newer: the rider just tapped, and the server view is
  //    at best one poll behind. Without this, un-rejecting a stop would be
  //    undone by the next refetch still reporting `rejected`.
  if (rejectedIds.contains(id)) return StopState.rejected;
  if (acceptedIds.contains(id)) return StopState.accepted;

  // 5. Finally the server's own view.
  if (raw == 'rejected') return StopState.rejected;
  if (raw == 'accepted') return StopState.accepted;
  return StopState.pending;
}

/// How a stop is progressing through the trip, for the progress rail.
enum StopProgress {
  /// Finished — picked up / delivered. Rail turns green here.
  done,

  /// The stop the rider is on right now.
  current,

  /// Not started.
  pending,

  /// Skipped and awaiting a return visit.
  skipped,
}

/// How one stop's lifecycle rung reads on the route rail.
///
/// ── "Physically on" is a question about BOTH legs ──
///
/// This lived inline in `_MyPickupsState._tripProgress` and tested
/// `isActive || arrived` — and both of those are **pickup-leg** rungs. It is
/// read on the Deliveries tab, where every stop is past `pickup-complete` by
/// definition, so on a milk run the rung the rider is actually standing on is
/// [StopStatus.deliveryArrived], which matched neither. The customer's door he
/// was at *that moment* drew grey — indistinguishable from the eleven he had
/// not ridden to yet — and the scooter fell through to the caller's "promote
/// the first pending one" fallback, parking it somewhere up the route behind
/// him.
///
/// The rail's whole job is *where am I*. Answering it from one leg's
/// vocabulary, on the tab that only ever shows the other leg, is why the answer
/// was wrong all round.
///
/// [StopStatusX.isWorkComplete] decides `done`, so the answer is line-aware:
/// `picked` ends a logistics stop and is the middle of the morning on a round.
///
/// Pure, and out here rather than on the State, because `_MyPickupsState`
/// cannot be pumped — Get, Geolocator and a 3s poll — so a mapping left inside
/// it can only ever be verified by reading it. See `trip_progress_test.dart`.
StopProgress stopProgressFor(StopStatus status) {
  if (status.isWorkComplete) return StopProgress.done;
  if (status.isSkipped) return StopProgress.skipped;
  if (status.isActive ||
      status == StopStatus.arrived ||
      status == StopStatus.deliveryArrived) {
    return StopProgress.current;
  }
  return StopProgress.pending;
}

/// Formats a duration the way a rider plans: `2h 15m`, `45 min`.
String formatTripDuration(Duration d) {
  if (d.inMinutes < 1) return '—';
  if (d.inMinutes < 60) return '${d.inMinutes} min';
  final minutes = d.inMinutes.remainder(60);
  return minutes == 0 ? '${d.inHours}h' : '${d.inHours}h ${minutes}m';
}

/// Rounds a duration up to the nearest 5 minutes.
///
/// An estimate printed as "37 min" claims a precision the arithmetic does not
/// have and invites the rider to treat it as a promise. "40 min" reads as
/// what it is.
Duration roundTripDuration(Duration d) {
  if (d.inSeconds <= 0) return Duration.zero;
  final minutes = (d.inMinutes / 5).ceil() * 5;
  return Duration(minutes: math.max(5, minutes));
}