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osu-lazer/osu.Game/Beatmaps/DifficultyRecommender.cs

120 lines
4.4 KiB
C#

// 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.Extensions.IEnumerableExtensions;
using osu.Framework.Graphics;
using osu.Game.Online.API;
using osu.Game.Online.API.Requests;
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 RulesetStore rulesets { get; set; }
[Resolved]
private Bindable<RulesetInfo> ruleset { get; set; }
/// <summary>
/// The user for which the last requests were run.
/// </summary>
private int? requestedUserId;
private readonly Dictionary<RulesetInfo, double> recommendedDifficultyMapping = new Dictionary<RulesetInfo, double>();
private readonly IBindable<APIState> apiState = new Bindable<APIState>();
[BackgroundDependencyLoader]
private void load()
{
apiState.BindTo(api.State);
apiState.BindValueChanged(onlineStateChanged, 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 (var r in orderedRulesets)
{
if (!recommendedDifficultyMapping.TryGetValue(r, out var recommendation))
continue;
BeatmapInfo beatmap = beatmaps.Where(b => b.Ruleset.Equals(r)).OrderBy(b =>
{
var difference = b.StarDifficulty - recommendation;
return difference >= 0 ? difference * 2 : difference * -1; // prefer easier over harder
}).FirstOrDefault();
if (beatmap != null)
return beatmap;
}
return null;
}
private void fetchRecommendedValues()
{
if (recommendedDifficultyMapping.Count > 0 && api.LocalUser.Value.Id == requestedUserId)
return;
requestedUserId = api.LocalUser.Value.Id;
// only query API for built-in rulesets
rulesets.AvailableRulesets.Where(ruleset => ruleset.ID <= ILegacyRuleset.MAX_LEGACY_RULESET_ID).ForEach(rulesetInfo =>
{
var req = new GetUserRequest(api.LocalUser.Value.Id, rulesetInfo);
req.Success += result =>
{
// algorithm taken from https://github.com/ppy/osu-web/blob/e6e2825516449e3d0f3f5e1852c6bdd3428c3437/app/Models/User.php#L1505
recommendedDifficultyMapping[rulesetInfo] = Math.Pow((double)(result.Statistics.PP ?? 0), 0.4) * 0.195;
};
api.Queue(req);
});
}
/// <returns>
/// Rulesets ordered descending by their respective recommended difficulties.
/// The currently selected ruleset will always be first.
/// </returns>
private IEnumerable<RulesetInfo> orderedRulesets =>
recommendedDifficultyMapping
.OrderByDescending(pair => pair.Value).Select(pair => pair.Key).Where(r => !r.Equals(ruleset.Value))
.Prepend(ruleset.Value);
private void onlineStateChanged(ValueChangedEvent<APIState> state) => Schedule(() =>
{
switch (state.NewValue)
{
case APIState.Online:
fetchRecommendedValues();
break;
}
});
}
}