// 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 osu.Game.Beatmaps;
using osu.Game.Rulesets.Difficulty;
using osu.Game.Rulesets.Mods;
using osu.Game.Rulesets.Scoring;
using osu.Game.Scoring;
using osu.Game.Scoring.Legacy;

namespace osu.Game.Rulesets.Catch.Difficulty
{
    public class CatchPerformanceCalculator : PerformanceCalculator
    {
        protected new CatchDifficultyAttributes Attributes => (CatchDifficultyAttributes)base.Attributes;

        private Mod[] mods;

        private int fruitsHit;
        private int ticksHit;
        private int tinyTicksHit;
        private int tinyTicksMissed;
        private int misses;

        public CatchPerformanceCalculator(Ruleset ruleset, WorkingBeatmap beatmap, ScoreInfo score)
            : base(ruleset, beatmap, score)
        {
        }

        public override double Calculate(Dictionary<string, double> categoryDifficulty = null)
        {
            mods = Score.Mods;

            var legacyScore = Score as LegacyScoreInfo;

            fruitsHit = legacyScore?.Count300 ?? Score.Statistics[HitResult.Perfect];
            ticksHit = legacyScore?.Count100 ?? 0;
            tinyTicksHit = legacyScore?.Count50 ?? 0;
            tinyTicksMissed = legacyScore?.CountKatu ?? 0;
            misses = Score.Statistics[HitResult.Miss];

            // Don't count scores made with supposedly unranked mods
            if (mods.Any(m => !m.Ranked))
                return 0;

            // We are heavily relying on aim in catch the beat
            double value = Math.Pow(5.0 * Math.Max(1.0, Attributes.StarRating / 0.0049) - 4.0, 2.0) / 100000.0;

            // Longer maps are worth more. "Longer" means how many hits there are which can contribute to combo
            int numTotalHits = totalComboHits();

            // Longer maps are worth more
            double lengthBonus =
                0.95 + 0.4 * Math.Min(1.0, numTotalHits / 3000.0) +
                (numTotalHits > 3000 ? Math.Log10(numTotalHits / 3000.0) * 0.5 : 0.0);

            // Longer maps are worth more
            value *= lengthBonus;

            // Penalize misses exponentially. This mainly fixes tag4 maps and the likes until a per-hitobject solution is available
            value *= Math.Pow(0.97, misses);

            // Combo scaling
            if (Attributes.MaxCombo > 0)
                value *= Math.Min(Math.Pow(Attributes.MaxCombo, 0.8) / Math.Pow(Attributes.MaxCombo, 0.8), 1.0);

            double approachRateFactor = 1.0;
            if (Attributes.ApproachRate > 9.0)
                approachRateFactor += 0.1 * (Attributes.ApproachRate - 9.0); // 10% for each AR above 9
            else if (Attributes.ApproachRate < 8.0)
                approachRateFactor += 0.025 * (8.0 - Attributes.ApproachRate); // 2.5% for each AR below 8

            value *= approachRateFactor;

            if (mods.Any(m => m is ModHidden))
                // Hiddens gives nothing on max approach rate, and more the lower it is
                value *= 1.05 + 0.075 * (10.0 - Math.Min(10.0, Attributes.ApproachRate)); // 7.5% for each AR below 10

            if (mods.Any(m => m is ModFlashlight))
                // Apply length bonus again if flashlight is on simply because it becomes a lot harder on longer maps.
                value *= 1.35 * lengthBonus;

            // Scale the aim value with accuracy _slightly_
            value *= Math.Pow(accuracy(), 5.5);

            // Custom multipliers for NoFail. SpunOut is not applicable.
            if (mods.Any(m => m is ModNoFail))
                value *= 0.90;

            return value;
        }

        private float accuracy() => totalHits() == 0 ? 0 : Math.Clamp((float)totalSuccessfulHits() / totalHits(), 0, 1);
        private int totalHits() => tinyTicksHit + ticksHit + fruitsHit + misses + tinyTicksMissed;
        private int totalSuccessfulHits() => tinyTicksHit + ticksHit + fruitsHit;
        private int totalComboHits() => misses + ticksHit + fruitsHit;
    }
}