using System;
using System.Collections.Generic;
using Luneraria.Core;
using NUnit.Framework;
using UnityEngine;

namespace Luneraria.View.Tests
{
    /// <summary>
    /// U2C: the host loop gives the same match at every frame rate. The runner is fed frame
    /// times of 30, 60 and 120 FPS, of an unlimited frame rate (tiny, jittering frames), and of a
    /// stuttering machine (long stalls between short frames); every run must end with the state
    /// fingerprint of the plain core run (LuneTrace.RunCore), step for step and round for round.
    /// </summary>
    public sealed class FrameRateIndependenceTests
    {
        static readonly Dictionary<string, Func<int, double>> Rates = new Dictionary<string, Func<int, double>>
        {
            { "30 fps", frame => 1.0 / 30.0 },
            { "60 fps", frame => 1.0 / 60.0 },
            { "120 fps", frame => 1.0 / 120.0 },
            { "unlimited (0.4-3.9 ms jitter)", frame => 0.0004 + ((frame * 7919) % 97) / 97.0 * 0.0035 },
            { "stutter (stalls up to 0.4 s)", frame => frame % 23 == 0 ? 0.4 : 1.0 / 144.0 },
        };

        static void Compare(int seed, int startRound, int extraGold, double speed)
        {
            var options = new MatchOptions { Seed = seed, HumanSlot = -1 };
            LuneTrace core = LuneTrace.RunCore(options, startRound, extraGold, "");
            foreach (KeyValuePair<string, Func<int, double>> rate in Rates)
            {
                var runner = new LuneMatchRunner(options, startRound, extraGold) { Trace = new LuneTrace(), PlanningSeconds = .5, SettledSeconds = .5 };
                int frames = 0;
                while (runner.Current != LuneMatchRunner.Stage.Over && frames < 20000000)
                    runner.Advance(rate.Value(frames++) * speed);
                Debug.Log(string.Format("LUNE_FPS seed {0} {1}: {2} frames, {3} steps, hash {4:X16} (core {5:X16})", seed, rate.Key, frames, runner.Trace.Steps, runner.Trace.Hash, core.Hash));
                Assert.AreEqual(core.Steps, runner.Trace.Steps, rate.Key + ": steps");
                CollectionAssert.AreEqual(core.RoundHashes, runner.Trace.RoundHashes, rate.Key + ": round fingerprints");
                Assert.AreEqual(core.Hash, runner.Trace.Hash, rate.Key + ": match fingerprint");
                Assert.AreEqual(core.Rounds, runner.Trace.Rounds, rate.Key + ": rounds");
            }
        }

        [Test]
        public void FullBotMatchSeed2IsTheSameAtEveryFrameRate()
        {
            Compare(2, 1, 0, 1.0);
        }

        [Test]
        public void HighWaveMatchFromRound21IsTheSameAtEveryFrameRate()
        {
            Compare(9, 21, 4000, 1.0);
        }

        [Test]
        public void MatchSpeedDoesNotChangeTheMatch()
        {
            Compare(2, 1, 0, 8.0);
        }

        [Test]
        public void ClockRunsWholeStepsOnly()
        {
            var clock = new LuneClock(0.05);
            int steps = 0;
            steps += clock.Advance(0.049, () => true);
            Assert.AreEqual(0, steps);
            Assert.That(clock.Alpha, Is.InRange(0.97, 0.99));
            steps += clock.Advance(0.052, () => true);
            Assert.AreEqual(2, steps);
            Assert.That(clock.Alpha, Is.InRange(0.01, 0.03));
        }
    }
}