82 lines
2.5 KiB
Dart
82 lines
2.5 KiB
Dart
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import 'dart:math' as math;
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/// A class for running lottery-style random number operations.
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///
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/// This class provides functionality for running lottery-style operations
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/// with configurable odds, similar to Laravel's Lottery class.
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class Lottery {
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/// The number of lottery tickets.
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final int tickets;
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/// The number of winning tickets.
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final int winners;
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/// The random number generator.
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final math.Random _random;
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/// Create a new lottery instance.
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///
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/// The [tickets] parameter specifies the total number of tickets in the lottery.
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/// The [winners] parameter specifies how many of those tickets are winners.
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/// An optional [random] parameter can be provided for testing purposes.
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Lottery(this.tickets, this.winners, [math.Random? random])
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: assert(tickets > 0, 'Total tickets must be greater than 0'),
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assert(winners >= 0, 'Winning tickets must be 0 or greater'),
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assert(winners <= tickets,
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'Winning tickets cannot be greater than total tickets'),
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_random = random ?? math.Random();
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/// Create a new lottery instance with odds represented as a fraction.
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///
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/// Example:
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/// ```dart
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/// // 1 in 2 chance (50%)
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/// final lottery = Lottery.odds(1, 2);
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/// ```
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factory Lottery.odds(int winners, int outOf, [math.Random? random]) {
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return Lottery(outOf, winners, random);
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}
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/// Create a new lottery instance with a percentage chance of winning.
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///
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/// Example:
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/// ```dart
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/// // 50% chance of winning
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/// final lottery = Lottery.percentage(50);
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/// ```
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factory Lottery.percentage(int percentage, [math.Random? random]) {
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assert(percentage >= 0 && percentage <= 100,
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'Percentage must be between 0 and 100');
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return Lottery(100, percentage, random);
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}
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/// Determine if the lottery was a winner.
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bool choose() {
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if (winners <= 0) return false;
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if (winners >= tickets) return true;
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return _random.nextInt(tickets) < winners;
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}
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/// Run the given callback if the lottery was a winner.
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Future<T?> run<T>(Future<T> Function() callback) async {
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if (choose()) {
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return await callback();
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}
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return null;
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}
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/// Run the given callback if the lottery was a winner.
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T? sync<T>(T Function() callback) {
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if (choose()) {
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return callback();
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}
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return null;
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}
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/// Get the probability of winning as a percentage.
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double get probability => (winners / tickets) * 100;
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/// Get the odds of winning as a ratio string.
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String get odds => '$winners:$tickets';
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}
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