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

import '../../about/external/initial/GroupGoalRequest.dart';
import '../../about/external/initial/ObjectiveDraft.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 'ConnectGroupGoalEditor.dart';
import 'GroupGoalEditor.dart';
import 'ViewGroupGoalEditor.dart';

/// The three fields of one objective while it is being typed.
typedef _ObjectiveFields = ({
  TextEditingController title,
  TextEditingController target,
  TextEditingController unit,
});

class GroupGoalEditorState extends State<GroupGoalEditor>
    implements ConnectGroupGoalEditor {
  ViewGroupGoalEditor? _model;

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

  final TextEditingController _title = TextEditingController();

  final TextEditingController _description = TextEditingController();

  final List<_ObjectiveFields> _objectives = <_ObjectiveFields>[];

  DateTime? _targetDate;

  @override
  void initState() {
    super.initState();
    _objectives.add(_blankObjective());
  }

  @override
  void dispose() {
    _title.dispose();
    _description.dispose();
    for (_ObjectiveFields fields in _objectives) {
      fields.title.dispose();
      fields.target.dispose();
      fields.unit.dispose();
    }
    super.dispose();
  }

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

  _ObjectiveFields _blankObjective() {
    return (
      title: TextEditingController(),
      target: TextEditingController(),
      unit: TextEditingController(),
    );
  }

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

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

  void _onAddObjective() {
    setState(() {
      _objectives.add(_blankObjective());
    });
  }

  void _onRemoveObjective(_ObjectiveFields fields) {
    setState(() {
      _objectives.remove(fields);
    });
    fields.title.dispose();
    fields.target.dispose();
    fields.unit.dispose();
  }

  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 * 3)),
    );

    if (picked == null) {
      return;
    }

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

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

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

    _model?.save(GroupGoalRequest(
      groupId: widget.group.id,
      title: _title.text.trim(),
      description: _description.text.trim(),
      targetDate: _targetDate?.toIso8601String() ?? "",
      colourHex: widget.group.colourHex,
      objectives: _objectives
          .map((fields) => ObjectiveDraft(
                title: fields.title.text.trim(),
                unit: fields.unit.text.trim(),
                target: double.tryParse(fields.target.text.trim()) ?? 0,
              ))
          .toList(),
    ));
  }

  String? _validateTarget(String? value) {
    final double? target = double.tryParse((value ?? "").trim());
    if (target == null || target <= 0) {
      return "A number above 0.";
    }
    return null;
  }

  String? _validateUnit(String? value) {
    return Validators.required(value, "Unit");
  }

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

  Widget _mobileView(BoxConstraints constraints) {
    return Sheet(
      eyebrow: widget.group.name,
      title: "Shared goal",
      onBack: _onBack,
      child: Form(
        key: _formKey,
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          mainAxisSize: MainAxisSize.min,
          children: [
            displayTitle("What are you\nall going for?"),
            const SizedBox(height: 24),
            inputField(
              "Goal",
              _title,
              hint: "Run 200 km this month, finish the drafts…",
              validator: Validators.title,
            ),
            const SizedBox(height: 16),
            inputField(
              "Why it matters",
              _description,
              hint: "Optional",
              maxLines: 2,
            ),
            const SizedBox(height: 28),
            sectionBreak("Objectives",
                caption: "what everyone logs toward"),
            text(
              "Break the goal into numbers people can add to: kilometres, sessions, pages, hours. Each member logs their share and the totals add up.",
              12,
              TextType.Regular,
              color: colorGrey2,
              height: 1.5,
            ),
            const SizedBox(height: 14),
            for (int index = 0; index < _objectives.length; index++)
              _objectiveEditor(index, _objectives[index]),
            outlinedActionButton("Add objective", _onAddObjective,
                icon: CupertinoIcons.add),
            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,
                    size: 50,
                  ),
                ],
              ],
            ),
            const SizedBox(height: 32),
            roundedCornerButton("Share with the group", _onSave,
                icon: CupertinoIcons.person_3_fill),
          ],
        ),
      ),
    );
  }

  Widget _objectiveEditor(int index, _ObjectiveFields fields) {
    return Container(
      margin: const EdgeInsets.only(bottom: 12),
      child: card(
        padding: const EdgeInsets.fromLTRB(16, 12, 8, 16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          mainAxisSize: MainAxisSize.min,
          children: [
            Row(
              children: [
                text("OBJECTIVE ${index + 1}", 10, TextType.Bold,
                    color: colorGrey2, letterSpacing: 1.0),
                const Spacer(),
                if (_objectives.length > 1)
                  iconButton(
                    Icon(CupertinoIcons.xmark, size: 15, color: colorGrey2),
                    () => _onRemoveObjective(fields),
                    size: 36,
                  ),
              ],
            ),
            const SizedBox(height: 6),
            Padding(
              padding: const EdgeInsets.only(right: 8),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                mainAxisSize: MainAxisSize.min,
                children: [
                  inputField("Name", fields.title,
                      hint: "Distance run", validator: Validators.title),
                  const SizedBox(height: 12),
                  Row(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Expanded(
                        child: inputField(
                          "Target",
                          fields.target,
                          hint: "200",
                          validator: _validateTarget,
                          keyboard: const TextInputType.numberWithOptions(
                              decimal: true),
                          formatters: <TextInputFormatter>[
                            FilteringTextInputFormatter.allow(RegExp(r"[0-9.]")),
                          ],
                        ),
                      ),
                      const SizedBox(width: 10),
                      Expanded(
                        child: inputField("Unit", fields.unit,
                            hint: "km", validator: _validateUnit),
                      ),
                    ],
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  // ── ConnectGroupGoalEditor ────────────────────────────────────────────────

  @override
  void onGoalSaved() {
    Navigator.pop(context, true);
  }
}