import 'package:flutter/material.dart';

import '../../data/models.dart';
import '../format.dart';
import '../tokens.dart';
import 'buttons.dart';
import 'cards.dart';

/// The customer's journey: seven milestones, not nine backend states.
///
/// Operational detail — "Miler on the way", "Order created" — is shown as
/// context beneath the milestone that is currently happening, so a transition
/// informs without becoming another permanent row.
///
/// ── Newest first, and only as many as matter ──
///
/// The list used to run oldest-to-newest, full height, every time: seven rows
/// of which four were grey placeholders for things that have not happened. On
/// a screen whose job is "where is my parcel right now", the answer was at the
/// bottom, below the scroll. It now leads with what just happened and, when
/// [maxRows] is set, keeps the rest behind one line — the same compression the
/// design applies to the live tracking card.
class DmMilestones extends StatelessWidget {
  const DmMilestones({
    super.key,
    required this.booking,
    this.stage,
    this.title = 'Recent updates',
    this.maxRows,
    this.onExpand,
  });

  final Booking booking;

  /// Journey to show. Defaults to the pickup's own stage; a destination order
  /// passes its own.
  final JourneyStage? stage;

  final String title;

  /// Show at most this many rows, newest first. Null shows the whole journey.
  final int? maxRows;

  /// Tapped from the "All n stages" action. Null hides the action.
  final VoidCallback? onExpand;

  @override
  Widget build(BuildContext context) {
    final current = stage ?? booking.stage;
    final currentMilestone = CustomerMilestone.of(current);
    final milestones = CustomerMilestone.values;
    final currentIndex = currentMilestone.index;

    // Newest first: the current milestone, then everything already done, then
    // — only if there is room — what is still to come.
    final ordered = [
      for (var i = currentIndex; i >= 0; i--) i,
      for (var i = currentIndex + 1; i < milestones.length; i++) i,
    ];
    final shown = maxRows == null ? ordered : ordered.take(maxRows!).toList();

    return DmCard(
      children: [
        DmCardCell(
          padding: const EdgeInsets.fromLTRB(16, 15, 16, 16),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Row(
                children: [
                  Expanded(
                    child: Text(
                      title.toUpperCase(),
                      style: DmText.eyebrow.copyWith(color: DmColors.brand),
                    ),
                  ),
                  if (onExpand != null && shown.length < ordered.length)
                    DmTextAction(
                      label: 'All ${milestones.length} stages',
                      onPressed: onExpand,
                      minHeight: 24,
                    )
                  else
                    Text(
                      'Step ${currentIndex + 1} of ${milestones.length}',
                      style: DmText.monoSm,
                    ),
                ],
              ),
              const SizedBox(height: 14),
              for (var n = 0; n < shown.length; n++)
                _MilestoneRow(
                  milestone: milestones[shown[n]],
                  done: shown[n] < currentIndex,
                  isCurrent: shown[n] == currentIndex,
                  last: n == shown.length - 1,
                  time: shown[n] <= currentIndex
                      ? relativeTime(booking.timeOf(milestones[shown[n]].firstStage))
                      : '',
                  detail: shown[n] == currentIndex ? _detailFor(current) : null,
                ),
            ],
          ),
        ),
      ],
    );
  }

  /// One line of operational context for the stage actually in progress.
  String? _detailFor(JourneyStage current) => switch (current) {
    JourneyStage.booked => 'Matching the nearest available Miler',
    JourneyStage.assigned =>
      booking.miler == null
          ? null
          : '${booking.miler!.name} accepted this pickup',
    JourneyStage.onTheWay =>
      booking.milerDistanceKm == null
          ? 'Miler on the way'
          : 'Miler on the way · ${booking.milerDistanceKm} km away, '
                'about ${booking.milerEtaMinutes} min',
    JourneyStage.arrived => 'Miler arrived at your door · verification OTP ready',
    JourneyStage.pickedUp => 'Weighing and sealing your packages',
    JourneyStage.orderCreated =>
      booking.isMultiDestination
          ? 'Order created for each destination · tracking issued'
          : 'Order created · tracking number issued',
    JourneyStage.inTransit => 'Moving through our network',
    JourneyStage.outForDelivery => 'Out with the delivery Miler',
    JourneyStage.delivered => null,
  };
}

class _MilestoneRow extends StatelessWidget {
  const _MilestoneRow({
    required this.milestone,
    required this.done,
    required this.isCurrent,
    required this.last,
    required this.time,
    this.detail,
  });

  final CustomerMilestone milestone;
  final bool done;
  final bool isCurrent;
  final bool last;
  final String time;
  final String? detail;

  @override
  Widget build(BuildContext context) {
    final upcoming = !done && !isCurrent;

    return IntrinsicHeight(
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          SizedBox(
            width: 12,
            child: Column(
              children: [
                const SizedBox(height: 3),
                _Marker(done: done, isCurrent: isCurrent),
                if (!last)
                  Expanded(
                    child: Padding(
                      padding: const EdgeInsets.symmetric(vertical: 3),
                      child: Container(width: 1.5, color: DmColors.border),
                    ),
                  ),
              ],
            ),
          ),
          const SizedBox(width: 14),
          Expanded(
            child: Padding(
              padding: EdgeInsets.only(bottom: last ? 0 : 15),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                mainAxisSize: MainAxisSize.min,
                children: [
                  Row(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Expanded(
                        child: Text(
                          milestone.label,
                          style: upcoming
                              ? DmText.small.copyWith(color: DmColors.ink3)
                              : DmText.cardTitle.copyWith(fontSize: 14.5),
                        ),
                      ),
                      if (time.isNotEmpty) ...[
                        const SizedBox(width: 10),
                        Text(time, style: DmText.monoSm),
                      ],
                    ],
                  ),
                  if (detail != null) ...[
                    const SizedBox(height: 4),
                    Text(detail!, style: DmText.small),
                  ],
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class _Marker extends StatelessWidget {
  const _Marker({required this.done, required this.isCurrent});

  final bool done;
  final bool isCurrent;

  @override
  Widget build(BuildContext context) {
    if (isCurrent) {
      return Container(
        width: 12,
        height: 12,
        decoration: const BoxDecoration(
          color: DmColors.brand,
          shape: BoxShape.circle,
          boxShadow: [
            BoxShadow(color: DmColors.brandSoft, spreadRadius: 4),
          ],
        ),
      );
    }
    return Container(
      width: 12,
      height: 12,
      decoration: BoxDecoration(
        color: done ? DmColors.brand : DmColors.border,
        shape: BoxShape.circle,
      ),
    );
  }
}