// Flutter
import 'package:flutter/material.dart';

// Local
import '/models/expense.dart';
import '/models/frequency.dart';

List<Expense> expenses = [];

class ExpensePage extends StatefulWidget {
  const ExpensePage({
    super.key,
  });

  @override
  State<ExpensePage> createState() => _ExpensePageState();
}

class _ExpensePageState extends State<ExpensePage> {
  refresh() {
    setState(() {});
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    expenses.sort(
      (a, b) => (b.calcComparableCost() - a.calcComparableCost()).toInt(),
    );

    return expenses.isEmpty
        ? Text("Add expenses to get started!")
        : ListView.builder(
            itemCount: expenses.length,
            itemBuilder: (_, index) {
              final Expense curr = expenses[index];
              final String estimateSymbol = switch (curr.frequency.timesPerYear
                  .toStringAsFixed(2)
                  .endsWith(".00")) {
                true => "",
                false => "~",
              };
              return Padding(
                padding: const EdgeInsets.all(4.0),
                child: Dismissible(
                  key: Key(curr.toString()),
                  background: Container(
                    color: Colors.red,
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.start,
                      children: [
                        Icon(Icons.delete),
                        Text("Delete"),
                      ],
                    ),
                  ),
                  secondaryBackground: Container(
                    color: Colors.orange,
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.end,
                      children: [
                        Text("Edit"),
                        Icon(Icons.edit),
                      ],
                    ),
                  ),
                  onDismissed: (direction) {
                    setState(() {
                      expenses.remove(curr);
                    });
                    switch (direction) {
                      case DismissDirection.startToEnd:
                        // Only remove the item from the list.
                        break;
                      case DismissDirection.endToStart:
                        // Open an edit dialog, then remove the item from the list.
                        showDialog(
                          context: context,
                          builder: (_) => AlertDialog(
                            content: ExpenseInputDialog(
                              notifyParent: refresh,
                              expense: curr,
                            ),
                          ),
                        );
                        break;
                      default:
                        UnimplementedError(
                          "Direction ${direction.toString()} not recognized.",
                        );
                    }
                  },
                  child: Container(
                    decoration: BoxDecoration(
                      borderRadius: BorderRadius.circular(4),
                      color: theme.colorScheme.onPrimary,
                    ),
                    child: Padding(
                      padding: const EdgeInsets.all(4.0),
                      child: Row(
                        mainAxisSize: MainAxisSize.max,
                        children: [
                          Column(
                            mainAxisSize: MainAxisSize.min,
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: [
                              Text(
                                curr.name,
                                style: TextStyle(fontSize: 20.0),
                              ),
                              Text(
                                "${curr.cost.toStringAsFixed(2)} ${curr.frequency.title}",
                                style: TextStyle(fontSize: 12.0),
                              ),
                              if (curr.frequency != Frequency.yearly)
                                Text(
                                  "$estimateSymbol${curr.calcComparableCost().toStringAsFixed(2)} Yearly",
                                  style: TextStyle(fontSize: 12.0),
                                ),
                            ],
                          ),
                          Expanded(
                            child: Center(
                              child: Text(
                                curr.description,
                                style: TextStyle(
                                  fontSize: 12.0,
                                ),
                                softWrap: true,
                                textAlign: TextAlign.center,
                              ),
                            ),
                          ),
                        ],
                      ),
                    ),
                  ),
                ),
              );
            },
          );
  }
}

class ExpenseInputDialog extends StatefulWidget {
  final Function() notifyParent;
  final Expense? expense;

  const ExpenseInputDialog({
    super.key,
    required this.notifyParent,
    this.expense,
  });

  @override
  State<ExpenseInputDialog> createState() => _ExpenseInputDialogState();
}

class _ExpenseInputDialogState extends State<ExpenseInputDialog> {
  final _expenseFormKey = GlobalKey<FormState>();

  String _name = "";
  double _cost = 0;
  Frequency _freq = Frequency.monthly;
  String _desc = "";

  @override
  Widget build(BuildContext context) {
    if (widget.expense != null) {
      _name = widget.expense!.name;
      _cost = widget.expense!.cost;
      _freq = widget.expense!.frequency;
      _desc = widget.expense!.description;
    }

    return Column(
      // prevent AlertDialog from taking full vertical height.
      mainAxisSize: MainAxisSize.min,
      children: [
        Container(
          alignment: FractionalOffset.topRight,
          child: IconButton(
            onPressed: () {
              if (widget.expense != null) {
                setState(() {
                  expenses.add(widget.expense!);
                  widget.notifyParent();
                });
              }
              Navigator.of(context).pop();
            },
            icon: Icon(Icons.clear),
          ),
        ),
        AlertDialog(
          insetPadding: EdgeInsets.all(0),
          title: Center(
            child: widget.expense == null
                ? Text("New Expense")
                : Text("Edit Expense"),
          ),
          content: Form(
            key: _expenseFormKey,
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                TextFormField(
                  keyboardType: TextInputType.text,
                  decoration: InputDecoration(
                    labelText: "Name",
                    hintText: "Example: Red Pocket",
                    hintStyle: TextStyle(fontSize: 10.0),
                    errorStyle: TextStyle(fontSize: 10.0),
                  ),
                  initialValue: _name,
                  validator: (value) {
                    if (value!.isEmpty) {
                      return "Name must be provided.";
                    }
                    if (!expenses.every((expense) => expense.name != value)) {
                      return "Name must be unique, already in use.";
                    }
                    return null;
                  },
                  onSaved: (value) {
                    _name = value!;
                  },
                ),
                TextFormField(
                  keyboardType: TextInputType.numberWithOptions(decimal: true),
                  decoration: InputDecoration(
                    labelText: "Cost",
                    hintText: "Example: 10.00",
                    hintStyle: TextStyle(fontSize: 10.0),
                    errorStyle: TextStyle(fontSize: 10.0),
                  ),
                  initialValue: _cost != 0 ? _cost.toString() : "",
                  validator: (value) {
                    if (value == null || value.isEmpty) {
                      return "Cost must be provided.";
                    }
                    if (double.parse(value) < 0) {
                      return "Please use the Income page rather than having negative expenses.";
                    }
                    if (double.parse(value) < 0.01) {
                      return "Cost must be one hundreth (0.01) or higher.";
                    }
                    if (double.tryParse(value) == null) {
                      return "Cost must be a valid number.";
                    }
                    return null;
                  },
                  onSaved: (value) {
                    _cost = double.parse(value!);
                  },
                ),
                DropdownButtonFormField(
                  items: Frequency.values
                      .map(
                        (freq) => DropdownMenuItem(
                          value: freq,
                          child: Row(
                            children: [
                              Text(
                                freq.title,
                              ),
                              Padding(
                                padding: EdgeInsets.all(1.0),
                                child: Text(
                                  " (${freq.hint})",
                                  style: TextStyle(fontSize: 10.0),
                                ),
                              ),
                            ],
                          ),
                        ),
                      )
                      .toList(),
                  value: _freq,
                  decoration: InputDecoration(
                    labelText: "Frequency",
                    errorStyle: TextStyle(fontSize: 10.0),
                  ),
                  validator: (value) {
                    if (value == null) {
                      return "Frequency must be provided.";
                    }
                    if (!Frequency.values.contains(value)) {
                      return "Value not valid.";
                    }
                    return null;
                  },
                  onChanged: (value) {
                    _freq = value!;
                  },
                ),
                TextFormField(
                  keyboardType: TextInputType.text,
                  decoration: InputDecoration(
                    labelText: "Description",
                    hintText: "Example: 1GB data, unlimited talk & text.",
                    hintStyle: TextStyle(fontSize: 10.0),
                    errorStyle: TextStyle(fontSize: 10.0),
                  ),
                  initialValue: _desc,
                  validator: (value) {
                    return null;
                  },
                  onSaved: (value) {
                    _desc = value!;
                  },
                ),
              ],
            ),
          ),
          actions: [
            Center(
              child: ElevatedButton.icon(
                onPressed: () {
                  if (_expenseFormKey.currentState!.validate()) {
                    _expenseFormKey.currentState!.save();
                    setState(() {
                      expenses.add(
                        Expense(
                            name: _name,
                            cost: _cost,
                            frequency: _freq,
                            description: _desc),
                      );
                    });
                    widget.notifyParent();
                    Navigator.of(context).pop();
                  }
                },
                icon: Icon(Icons.save),
                label: Text('Submit'),
              ),
            )
          ],
        ),
      ],
    );
  }
}