// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence. // See the LICENCE file in the repository root for full licence text. using System; using System.Collections.Generic; using System.Linq; using JetBrains.Annotations; using osu.Framework.Allocation; using osu.Framework.Bindables; using osu.Framework.Graphics; using osu.Game.Online.API; using osu.Game.Rulesets; namespace osu.Game.Beatmaps { /// <summary> /// A class which will recommend the most suitable difficulty for the local user from a beatmap set. /// This requires the user to be logged in, as it sources from the user's online profile. /// </summary> public class DifficultyRecommender : Component { [Resolved] private IAPIProvider api { get; set; } [Resolved] private Bindable<RulesetInfo> ruleset { get; set; } private readonly Dictionary<string, double> recommendedDifficultyMapping = new Dictionary<string, double>(); [BackgroundDependencyLoader] private void load() { api.LocalUser.BindValueChanged(_ => populateValues(), true); } /// <summary> /// Find the recommended difficulty from a selection of available difficulties for the current local user. /// </summary> /// <remarks> /// This requires the user to be online for now. /// </remarks> /// <param name="beatmaps">A collection of beatmaps to select a difficulty from.</param> /// <returns>The recommended difficulty, or null if a recommendation could not be provided.</returns> [CanBeNull] public BeatmapInfo GetRecommendedBeatmap(IEnumerable<BeatmapInfo> beatmaps) { foreach (string r in orderedRulesets) { if (!recommendedDifficultyMapping.TryGetValue(r, out double recommendation)) continue; BeatmapInfo beatmapInfo = beatmaps.Where(b => b.Ruleset.ShortName.Equals(r)).OrderBy(b => { double difference = b.StarRating - recommendation; return difference >= 0 ? difference * 2 : difference * -1; // prefer easier over harder }).FirstOrDefault(); if (beatmapInfo != null) return beatmapInfo; } return null; } private void populateValues() { if (api.LocalUser.Value.RulesetsStatistics == null) return; foreach (var kvp in api.LocalUser.Value.RulesetsStatistics) { // algorithm taken from https://github.com/ppy/osu-web/blob/e6e2825516449e3d0f3f5e1852c6bdd3428c3437/app/Models/User.php#L1505 recommendedDifficultyMapping[kvp.Key] = Math.Pow((double)(kvp.Value.PP ?? 0), 0.4) * 0.195; } } /// <returns> /// Rulesets ordered descending by their respective recommended difficulties. /// The currently selected ruleset will always be first. /// </returns> private IEnumerable<string> orderedRulesets { get { if (LoadState < LoadState.Ready || ruleset.Value == null) return Enumerable.Empty<string>(); return recommendedDifficultyMapping .OrderByDescending(pair => pair.Value) .Select(pair => pair.Key) .Where(r => !r.Equals(ruleset.Value.ShortName)) .Prepend(ruleset.Value.ShortName); } } } }