import 'package:flutter/cupertino.dart';
import 'package:stacked/stacked.dart';

import '../../about/internal/application/ProgressPeriod.dart';
import '../../about/internal/application/ProgressTargets.dart';
import '../../about/internal/application/RoutineKind.dart';
import '../../about/internal/application/RoutineRunRecord.dart';
import '../../about/internal/application/TextType.dart';
import '../../configs/Navigator.dart';
import '../../designs/Component.dart';
import '../../designs/Responsive.dart';
import '../../designs/Shell.dart';
import '../../designs/buttons/Buttons.dart';
import '../../designs/text/Text.dart';
import '../../utils/Colors.dart';
import '../../utils/CommonUtils.dart';
import '../../utils/ProgressEngine.dart';
import '../reportcard/ReportCardScreen.dart';
import 'ConnectProgress.dart';
import 'Progress.dart';
import 'TargetSetup.dart';
import 'ViewProgress.dart';

class ProgressState extends State<Progress> implements ConnectProgress {
  ViewProgress? _model;

  List<RoutineRunRecord> _records = <RoutineRunRecord>[];

  ProgressTargets _targets = ProgressTargets();

  ProgressPeriod _period = ProgressPeriod.Week;

  bool _loaded = false;

  static const List<String> _weekLetters = <String>[
    "M", "T", "W", "T", "F", "S", "S"
  ];

  @override
  Widget build(BuildContext context) {
    return ViewModelBuilder<ViewProgress>.reactive(
      viewModelBuilder: () => ViewProgress(context, this),
      onViewModelReady: (viewModel) {
        _model = viewModel;
        _initiate();
      },
      builder: (context, viewModel, child) => LayoutBuilder(
        builder: (BuildContext context, BoxConstraints constraints) {
          return Responsive(
            mobile: _mobileView(constraints),
            tablet: _mobileView(constraints),
            desktop: _mobileView(constraints),
          );
        },
      ),
    );
  }

  void _initiate() {
    _model?.initialise();
  }

  // ── Handlers ──────────────────────────────────────────────────────────────

  void _onBack() {
    Navigator.pop(context);
  }

  void _onPeriodSelected(ProgressPeriod period) {
    setState(() {
      _period = period;
    });
  }

  void _onOpenTargets() async {
    final dynamic saved = await GroundedNavigation()
        .navigateToPageWithData(const TargetSetup(), context);
    if (saved == true) {
      _model?.initialise();
    }
  }

  void _onOpenReportCard() {
    GroundedNavigation()
        .navigateToPageWithData(const ReportCardScreen(), context);
  }

  // ── Derived ───────────────────────────────────────────────────────────────

  DateTime get _start => ProgressEngine.periodStart(_period, DateTime.now());

  List<RoutineRunRecord> get _current => ProgressEngine.between(
      _records, _start, ProgressEngine.periodEnd(_period, _start));

  /// The previous period only up to the same point, so eight days into a
  /// month is not measured against all thirty of the last one.
  List<RoutineRunRecord> get _previous {
    final DateTime start = ProgressEngine.previousStart(_period, _start);
    final DateTime full = ProgressEngine.periodEnd(_period, start);
    final DateTime samepoint = start.add(DateTime.now().difference(_start));
    return ProgressEngine.between(
        _records, start, samepoint.isBefore(full) ? samepoint : full);
  }

  String get _periodNoun {
    switch (_period) {
      case ProgressPeriod.Day:
        return "today";
      case ProgressPeriod.Week:
        return "this week";
      case ProgressPeriod.Month:
        return "this month";
    }
  }

  String get _previousNoun {
    switch (_period) {
      case ProgressPeriod.Day:
        return "this time yesterday";
      case ProgressPeriod.Week:
        return "this point last week";
      case ProgressPeriod.Month:
        return "this point last month";
    }
  }

  // ── Views ─────────────────────────────────────────────────────────────────

  Widget _mobileView(BoxConstraints constraints) {
    return Sheet(
      eyebrow: "Over time",
      title: "Progress",
      onBack: _onBack,
      action: chromeAction(CupertinoIcons.slider_horizontal_3, _onOpenTargets),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        mainAxisSize: MainAxisSize.min,
        children: [
          displayTitle("Kept, not\nplanned."),
          const SizedBox(height: 22),
          segmentedSelector<ProgressPeriod>(
            options: ProgressPeriod.values,
            selected: _period,
            label: periodLabel,
            onSelected: _onPeriodSelected,
            activeColor: colorNight,
          ),
          const SizedBox(height: 20),
          if (_loaded && !_targets.set) ...[
            _setupPrompt(),
            const SizedBox(height: 16),
          ],
          _headline(),
          const SizedBox(height: 12),
          Row(
            children: [
              Expanded(child: _activeTile()),
              const SizedBox(width: 12),
              Expanded(child: _streakTile()),
            ],
          ),
          const SizedBox(height: 28),
          sectionBreak(
            _period == ProgressPeriod.Day ? "Today's runs" : "Runs",
            caption: "${_current.length} $_periodNoun",
          ),
          if (_current.isEmpty)
            _emptyRuns()
          else
            ..._current.reversed
                .take(_period == ProgressPeriod.Day ? 20 : 6)
                .map(_runRow),
          const SizedBox(height: 22),
          outlinedActionButton(
            "Weekly report card",
            _onOpenReportCard,
            icon: CupertinoIcons.doc_text,
            radius: 0,
          ),
          const SizedBox(height: 12),
        ],
      ),
    );
  }

  /// Shown until the targets have been saved once: the numbers below use
  /// defaults until then, and say so.
  Widget _setupPrompt() {
    return GestureDetector(
      onTap: _onOpenTargets,
      child: Container(
        padding: const EdgeInsets.fromLTRB(18, 16, 14, 16),
        color: colorNight,
        child: Row(
          children: [
            Icon(CupertinoIcons.scope, size: 22, color: colorLime),
            const SizedBox(width: 14),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                mainAxisSize: MainAxisSize.min,
                children: [
                  text("Set your weekly target", 15, TextType.Medium,
                      color: colorWhite),
                  const SizedBox(height: 4),
                  text(
                    "Measuring against your schedule, ${_targets.routinesPerWeek} routines a week, until you choose. Reminders are off.",
                    12,
                    TextType.Regular,
                    color: colorWhite.withValues(alpha: 0.7),
                    height: 1.4,
                  ),
                ],
              ),
            ),
            const SizedBox(width: 10),
            Icon(CupertinoIcons.chevron_right,
                size: 16, color: colorWhite.withValues(alpha: 0.7)),
          ],
        ),
      ),
    );
  }

  /// Held routines against the target, the change on the previous period,
  /// and the bars underneath.
  Widget _headline() {
    final int held = ProgressEngine.held(_current);
    final int target =
        ProgressEngine.routineTarget(_targets, _period, _start);
    final int delta = held - ProgressEngine.held(_previous);

    return card(
      padding: const EdgeInsets.fromLTRB(20, 18, 20, 20),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        mainAxisSize: MainAxisSize.min,
        children: [
          text("ROUTINES HELD ${_periodNoun.toUpperCase()}", 10, TextType.Bold,
              color: colorInkSoft, letterSpacing: 1.1),
          const SizedBox(height: 8),
          Row(
            crossAxisAlignment: CrossAxisAlignment.end,
            children: [
              text("$held", 46, TextType.Light, color: colorInk, height: 1),
              const SizedBox(width: 8),
              Padding(
                padding: const EdgeInsets.only(bottom: 6),
                child: text("of $target target", 13, TextType.Regular,
                    color: colorInkSoft),
              ),
              const Spacer(),
              Padding(
                padding: const EdgeInsets.only(bottom: 6),
                child: _deltaChip(delta),
              ),
            ],
          ),
          const SizedBox(height: 18),
          if (_period == ProgressPeriod.Day)
            meter(target == 0 ? 0 : held / target,
                fill: held >= target ? colorPositive : colorNight,
                track: colorMuted,
                height: 10)
          else
            _bars(),
        ],
      ),
    );
  }

  Widget _deltaChip(int delta) {
    final Color tone = delta > 0
        ? colorPositive
        : (delta < 0 ? colorNegative : colorInkSoft);
    final String sign = delta > 0 ? "+" : "";

    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 9, vertical: 5),
      color: tone.withValues(alpha: 0.12),
      child: text("$sign$delta vs $_previousNoun", 11, TextType.Medium,
          color: tone),
    );
  }

  /// One bar per day (week) or per week (month). The current one is night,
  /// the rest are muted, and future ones are a stub so the shape of the
  /// period is still visible.
  Widget _bars() {
    final DateTime now = DateTime.now();
    final List<int> values = ProgressEngine.buckets(_records, _period, _start);
    final int current = ProgressEngine.currentBucket(_period, _start, now);

    int peak = 1;
    for (int value in values) {
      if (value > peak) {
        peak = value;
      }
    }

    return SizedBox(
      height: 132,
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.end,
        children: List<Widget>.generate(values.length, (index) {
          final bool isCurrent = index == current;
          final bool future = index > current;
          final double fraction = values[index] / peak;

          return Expanded(
            child: Padding(
              padding: const EdgeInsets.symmetric(horizontal: 5),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.end,
                children: [
                  if (!future && values[index] > 0)
                    text("${values[index]}", 11, TextType.Medium,
                        color: isCurrent ? colorInk : colorInkSoft),
                  const SizedBox(height: 4),
                  Container(
                    height: future ? 4 : 6 + 84 * fraction,
                    color: isCurrent
                        ? colorNight
                        : (future ? colorMuted : colorChartGrid),
                  ),
                  const SizedBox(height: 8),
                  text(
                    _period == ProgressPeriod.Week
                        ? _weekLetters[index]
                        : "W${index + 1}",
                    11,
                    isCurrent ? TextType.Bold : TextType.Regular,
                    color: isCurrent ? colorInk : colorInkSoft,
                  ),
                ],
              ),
            ),
          );
        }),
      ),
    );
  }

  Widget _activeTile() {
    final int minutes = ProgressEngine.minutes(_current);
    final int target =
        ProgressEngine.minuteTarget(_targets, _period, _start);

    return _tile(
      CupertinoIcons.clock,
      formatMinutes(minutes),
      "active of ${formatMinutes(target)}",
      footer: meter(target == 0 ? 0 : minutes / target,
          fill: minutes >= target ? colorPositive : colorNight,
          track: colorMuted,
          height: 5),
    );
  }

  Widget _streakTile() {
    final int streak = ProgressEngine.streak(_records, DateTime.now());

    return _tile(
      CupertinoIcons.flame_fill,
      "$streak ${streak == 1 ? 'day' : 'days'}",
      "streak, held daily",
      iconColor: streak > 0 ? colorOverdueWarm : colorInkSoft,
    );
  }

  Widget _tile(IconData icon, String value, String label,
      {Color? iconColor, Widget? footer}) {
    return card(
      padding: const EdgeInsets.fromLTRB(16, 16, 16, 16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(icon, size: 18, color: iconColor ?? colorInkSoft),
          const SizedBox(height: 14),
          text(value, 24, TextType.Light, color: colorInk),
          const SizedBox(height: 2),
          text(label, 11, TextType.Regular, color: colorInkSoft),
          const SizedBox(height: 12),
          footer ?? const SizedBox(height: 5),
        ],
      ),
    );
  }

  Widget _runRow(RoutineRunRecord record) {
    final RoutineKind kind = RoutineKind.values.firstWhere(
        (value) => value.name == record.kind,
        orElse: () => RoutineKind.MustDo);

    return Container(
      margin: const EdgeInsets.only(bottom: 10),
      padding: const EdgeInsets.fromLTRB(14, 12, 16, 12),
      color: colorCard,
      child: Row(
        children: [
          Container(
            width: 42,
            height: 42,
            alignment: Alignment.center,
            color: kindColor(kind).withValues(alpha: 0.14),
            child: Icon(kindIcon(kind), size: 20, color: kindColor(kind)),
          ),
          const SizedBox(width: 14),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisSize: MainAxisSize.min,
              children: [
                text(record.title, 15, TextType.Medium,
                    color: colorInk,
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis),
                const SizedBox(height: 3),
                text(
                  "${_when(record.startedAt)} · ${formatMinutes(record.seconds / 60)}",
                  12,
                  TextType.Regular,
                  color: colorInkSoft,
                ),
              ],
            ),
          ),
          const SizedBox(width: 10),
          text(
            record.held
                ? "Held"
                : "${record.completedSteps}/${record.totalSteps}",
            12,
            TextType.Medium,
            color: record.held ? colorPositive : colorWarning,
          ),
        ],
      ),
    );
  }

  String _when(DateTime value) {
    final String clock = formatStartMinute(value.hour * 60 + value.minute);
    if (_period == ProgressPeriod.Day) {
      return clock;
    }
    return "${formatDate(value)} · $clock";
  }

  Widget _emptyRuns() {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 18),
      child: emptyState(
        CupertinoIcons.chart_bar,
        "Nothing run $_periodNoun",
        "Finished routines land here, held or partial.",
      ),
    );
  }

  // ── ConnectProgress ───────────────────────────────────────────────────────

  @override
  void onProgressLoaded(
      List<RoutineRunRecord> records, ProgressTargets targets) {
    setState(() {
      _records = records
        ..sort((first, second) => first.startedAt.compareTo(second.startedAt));
      _targets = targets;
      _loaded = true;
    });
  }
}