/// Small pure helpers for layout, formatting, and user-facing strings.
library;

import 'package:flutter/material.dart';

import 'constants.dart';

/// Horizontal padding that grows a little on wider screens.
double pagePadding(double width) {
  if (width >= Breakpoints.medium) return 32;
  if (width >= Breakpoints.compact) return 24;
  return 16;
}

/// Formats [date] as `MMM d, y` without pulling in `intl`.
String formatDate(DateTime date) {
  const months = [
    'Jan',
    'Feb',
    'Mar',
    'Apr',
    'May',
    'Jun',
    'Jul',
    'Aug',
    'Sep',
    'Oct',
    'Nov',
    'Dec',
  ];
  return '${months[date.month - 1]} ${date.day}, ${date.year}';
}

/// Converts a stored theme key into a [ThemeMode].
ThemeMode themeModeFromName(String name) {
  return switch (name) {
    'light' => ThemeMode.light,
    'dark' => ThemeMode.dark,
    _ => ThemeMode.system,
  };
}

/// Inverse of [themeModeFromName] for persistence.
String nameFromThemeMode(ThemeMode mode) {
  return switch (mode) {
    ThemeMode.light => 'light',
    ThemeMode.dark => 'dark',
    ThemeMode.system => 'system',
  };
}

/// Title-cases a [ThemeMode] for settings labels.
String labelForThemeMode(ThemeMode mode) {
  return switch (mode) {
    ThemeMode.light => 'Light',
    ThemeMode.dark => 'Dark',
    ThemeMode.system => 'System',
  };
}

/// Formats a money amount with currency code, e.g. `1 234,56 EUR`.
String formatMoney(double amount, String currency) {
  final sign = amount < 0 ? '-' : '';
  final abs = amount.abs();
  final fixed = abs.toStringAsFixed(2);
  final parts = fixed.split('.');
  final whole = parts[0];
  final fraction = parts.length > 1 ? parts[1] : '00';

  final buffer = StringBuffer();
  for (var i = 0; i < whole.length; i++) {
    final fromEnd = whole.length - i;
    buffer.write(whole[i]);
    if (fromEnd > 1 && fromEnd % 3 == 1) {
      buffer.write('\u00a0');
    }
  }
  return '$sign${buffer.toString()},$fraction $currency';
}

/// Formats [date] as `MMMM y`, e.g. `September 2026`.
String formatMonthYear(DateTime date) {
  const months = [
    'January',
    'February',
    'March',
    'April',
    'May',
    'June',
    'July',
    'August',
    'September',
    'October',
    'November',
    'December',
  ];
  return '${months[date.month - 1]} ${date.year}';
}

/// Formats an ISO date string (`yyyy-MM-dd` or full ISO) for list rows.
String formatIsoDate(String raw) {
  if (raw.isEmpty) return '';
  final parsed = DateTime.tryParse(raw);
  if (parsed == null) return raw;
  return formatDate(parsed);
}