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

import '../../about/external/data/Goal.dart';
import '../../about/external/initial/GoalRequest.dart';
import '../../about/internal/application/CommitmentClass.dart';
import '../../about/internal/application/NotificationType.dart';
import '../../about/internal/application/TextType.dart';
import '../../designs/Component.dart';
import '../../designs/Responsive.dart';
import '../../designs/Shell.dart';
import '../../designs/buttons/Buttons.dart';
import '../../designs/input/InputFields.dart';
import '../../designs/text/Text.dart';
import '../../utils/Colors.dart';
import '../../utils/CommonUtils.dart';
import '../../utils/Validators.dart';
import 'ConnectGoalEditor.dart';
import 'GoalEditor.dart';
import 'ViewGoalEditor.dart';

class GoalEditorState extends State<GoalEditor> implements ConnectGoalEditor {
  ViewGoalEditor? _model;

  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();

  final TextEditingController _title = TextEditingController();

  final TextEditingController _description = TextEditingController();

  final TextEditingController _category = TextEditingController();

  CommitmentClass _defaultClass = CommitmentClass.Standard;

  Color _accent = goalAccents.first;

  DateTime? _targetDate;

  bool get _editing {
    return widget.goal != null;
  }

  @override
  void initState() {
    super.initState();

    final goal = widget.goal;
    if (goal != null) {
      _title.text = goal.title;
      _description.text = goal.description;
      _category.text = goal.category;
      _defaultClass = goal.defaultClass;
      _targetDate = goal.targetDate;
      if (goal.colourHex.isNotEmpty) {
        _accent = goalColor(goal.colourHex);
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return ViewModelBuilder<ViewGoalEditor>.reactive(
      viewModelBuilder: () => ViewGoalEditor(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() {}

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

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

  void _onTitleChanged(String value) {
    setState(() {});
  }

  void _onAccentSelected(Color colour) {
    setState(() {
      _accent = colour;
    });
  }

  void _onClassSelected(CommitmentClass value) {
    setState(() {
      _defaultClass = value;
    });
  }

  void _onPickTarget() async {
    final DateTime now = DateTime.now();

    final DateTime? picked = await showDatePicker(
      context: context,
      initialDate: _targetDate ?? now.add(const Duration(days: 30)),
      firstDate: now,
      lastDate: now.add(const Duration(days: 365 * 5)),
    );

    if (picked == null) {
      return;
    }

    setState(() {
      _targetDate = picked;
    });
  }

  void _onClearTarget() {
    setState(() {
      _targetDate = null;
    });
  }

  void _onSave() {
    if (_formKey.currentState?.validate() != true) {
      return;
    }

    _model?.save(GoalRequest(
      id: widget.goal?.id,
      title: _title.text.trim(),
      description: _description.text.trim(),
      category: _category.text.trim(),
      defaultClass: _defaultClass.name,
      startDate: (widget.goal?.startDate ?? DateTime.now()).toIso8601String(),
      targetDate: _targetDate?.toIso8601String() ?? "",
      colourHex: colorToHex(_accent),
    ));
  }

  void _onArchive() {
    _model?.showApplicationNotification(
      NotificationType.warning,
      "Archive this goal?",
      "It leaves your goals list. Its tasks and their history stay on the record, and any debt they carry is not forgiven.",
      true,
      true,
      null,
      action: "Archive",
      positiveAction: _onConfirmArchive,
    );
  }

  void _onConfirmArchive() {
    Navigator.pop(context);
    _model?.archive(widget.goal?.id ?? "");
  }

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

  Widget _mobileView(BoxConstraints constraints) {
    return Sheet(
      eyebrow: _editing ? "Edit" : "New",
      title: "Goal",
      onBack: _onBack,
      child: Form(
        key: _formKey,
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          mainAxisSize: MainAxisSize.min,
          children: [
            displayTitle(_editing ? "Adjust the goal." : "What are you\nworking toward?"),
            const SizedBox(height: 24),
            _preview(),
            const SizedBox(height: 28),
            inputField(
              "Goal",
              _title,
              hint: "Workout, thesis, get the flat sorted…",
              validator: Validators.title,
              onChanged: _onTitleChanged,
            ),
            const SizedBox(height: 16),
            inputField(
              "Why it matters",
              _description,
              hint: "Optional, but it helps on the bad days",
              maxLines: 3,
            ),
            const SizedBox(height: 16),
            inputField(
              "Category",
              _category,
              hint: "Health, work, home…",
            ),
            const SizedBox(height: 28),
            sectionBreak("Colour", caption: "how it reads everywhere"),
            _swatches(),
            const SizedBox(height: 28),
            sectionBreak("Deadline", caption: "optional"),
            Row(
              crossAxisAlignment: CrossAxisAlignment.end,
              children: [
                Expanded(
                  child: selectField(
                    "Target date",
                    _targetDate == null ? "" : formatDate(_targetDate),
                    _onPickTarget,
                    hint: "No deadline",
                    icon: CupertinoIcons.calendar,
                  ),
                ),
                if (_targetDate != null) ...[
                  const SizedBox(width: 8),
                  iconButton(
                    Icon(CupertinoIcons.xmark, size: 15, color: colorGrey2),
                    _onClearTarget,
                    bordered: true,
                    background: colorWhite,
                    radius: 12,
                    size: 50,
                  ),
                ],
              ],
            ),
            const SizedBox(height: 10),
            text(
              "A deadline is for the goal as a whole. The tasks and routines inside it keep their own windows.",
              12,
              TextType.Regular,
              color: colorGrey2,
              height: 1.5,
            ),
            const SizedBox(height: 28),
            sectionBreak("Tasks default to", caption: "you can change each one"),
            segmentedSelector<CommitmentClass>(
              options: CommitmentClass.values,
              selected: _defaultClass,
              label: classLabel,
              onSelected: _onClassSelected,
              activeColor: classColor(_defaultClass),
            ),
            const SizedBox(height: 10),
            text(
              "The goal never carries debt itself — the tasks and routines inside it do.",
              12,
              TextType.Regular,
              color: colorGrey2,
              height: 1.5,
            ),
            const SizedBox(height: 32),
            roundedCornerButton(
              _editing ? "Save changes" : "Create goal",
              _onSave,
              icon: _editing ? CupertinoIcons.checkmark : CupertinoIcons.add,
            ),
            if (_editing) ...[
              const SizedBox(height: 8),
              Center(
                child: textButton("Archive goal", _onArchive,
                    color: colorDestructive, textSize: 13),
              ),
            ],
          ],
        ),
      ),
    );
  }

  /// A live preview of the goal card, so colour and deadline are chosen by
  /// looking, not imagining.
  Widget _preview() {
    final String title =
        _title.text.trim().isEmpty ? "Your goal" : _title.text.trim();

    return Container(
      padding: const EdgeInsets.all(18),
      decoration: BoxDecoration(
        borderRadius: BorderRadius.zero,
        gradient: LinearGradient(
          begin: Alignment.topLeft,
          end: Alignment.bottomRight,
          colors: <Color>[_accent, Color.lerp(_accent, colorBlack, 0.45)!],
        ),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        mainAxisSize: MainAxisSize.min,
        children: [
          Row(
            children: [
              Icon(CupertinoIcons.flag_fill,
                  size: 14, color: colorWhite.withValues(alpha: 0.7)),
              const SizedBox(width: 8),
              text(
                _targetDate == null
                    ? "NO DEADLINE"
                    : targetLabel(_targetDate).toUpperCase(),
                9,
                TextType.Bold,
                color: colorWhite.withValues(alpha: 0.6),
                letterSpacing: 1.2,
              ),
            ],
          ),
          const SizedBox(height: 14),
          text(title, 24, TextType.Light,
              color: colorWhite, maxLines: 2, overflow: TextOverflow.ellipsis),
          const SizedBox(height: 16),
          meter(_editing ? widget.goal!.progress : 0,
              fill: colorWhite,
              track: colorWhite.withValues(alpha: 0.16),
              height: 5),
        ],
      ),
    );
  }

  Widget _swatches() {
    return Wrap(
      spacing: 9,
      runSpacing: 9,
      children: goalAccents.map((colour) {
        final bool selected = colour.toARGB32() == _accent.toARGB32();

        return GestureDetector(
          onTap: () => _onAccentSelected(colour),
          child: AnimatedContainer(
            duration: const Duration(milliseconds: 150),
            width: 36,
            height: 36,
            alignment: Alignment.center,
            decoration: BoxDecoration(
              color: colour,
              border: Border.all(
                color: selected ? colorWhite : Colors.transparent,
                width: 3,
              ),
              boxShadow: selected
                  ? [BoxShadow(color: colour, spreadRadius: 1.5)]
                  : null,
            ),
            child: selected
                ? Icon(Icons.check_rounded, size: 18, color: colorWhite)
                : null,
          ),
        );
      }).toList(),
    );
  }

  // ── ConnectGoalEditor ─────────────────────────────────────────────────────

  /// Pops the goal as saved, carrying over the server-derived counts, so the
  /// screen underneath can update in place without a reload.
  @override
  void onSaved() {
    final Goal? before = widget.goal;

    Navigator.pop(
      context,
      Goal(
        id: before?.id,
        title: _title.text.trim(),
        description: _description.text.trim(),
        category: _category.text.trim(),
        defaultClass: _defaultClass,
        startDate: before?.startDate ?? DateTime.now(),
        targetDate: _targetDate,
        colourHex: colorToHex(_accent),
        totalTasks: before?.totalTasks ?? 0,
        completedTasks: before?.completedTasks ?? 0,
        overdueTasks: before?.overdueTasks ?? 0,
        debtContribution: before?.debtContribution ?? 0,
      ),
    );
  }

  @override
  void onArchived() {
    Navigator.pop(context, "archived");
  }

  @override
  void dispose() {
    _title.dispose();
    _description.dispose();
    _category.dispose();
    super.dispose();
  }
}