using System.Collections.Generic;
using System.Linq;

namespace Luneraria.Core.Tests
{
    /// <summary>
    /// Determinism of the C# core: the same inputs give the same match, repeatedly, with no
    /// dependence on hashing, object identity, wall-clock time or the order in which matches run.
    /// Each .NET run also randomises string hashing per process, so passing golden replays in
    /// several processes shows that no rule depends on dictionary iteration order.
    /// </summary>
    public sealed class DeterminismSuite : CheckSuite
    {
        public override string Name { get { return "determinism"; } }

        protected override void RunChecks()
        {
            foreach (int seed in new[] { 5, 13, 28 })
            {
                string first = Fingerprint(Play(seed));
                string second = Fingerprint(Play(seed));
                Check(first == second, "seed " + seed + ": two runs of the same match are identical");
            }
            // Interleaving two matches must not change either (no shared static state).
            LuneMatch a = New(7);
            LuneMatch b = New(9);
            for (int round = 0; round < 6; round++)
            {
                foreach (LuneMatch match in new[] { a, b })
                {
                    if (match.Phase == Phase.Over)
                        continue;
                    for (int slot = 0; slot < 6; slot++)
                        LuneBot.Plan(match, slot);
                    match.BeginCombat();
                }
                bool running = true;
                while (running)
                {
                    running = false;
                    foreach (LuneMatch match in new[] { a, b })
                    {
                        if (match.Phase == Phase.Combat)
                        {
                            match.StepCombat();
                            running = true;
                        }
                    }
                }
            }
            LuneMatch aAlone = New(7);
            LuneMatch bAlone = New(9);
            for (int round = 0; round < 6; round++)
            {
                foreach (LuneMatch match in new[] { aAlone, bAlone })
                {
                    if (match.Phase == Phase.Over)
                        continue;
                    for (int slot = 0; slot < 6; slot++)
                        LuneBot.Plan(match, slot);
                    match.BeginCombat();
                    match.FinishCombat();
                }
            }
            Check(Fingerprint(a) == Fingerprint(aAlone) && Fingerprint(b) == Fingerprint(bAlone), "interleaved matches equal matches run alone (no shared state)");
            // Unit ids are sequential per combat and follow spawn order, never object identity.
            LuneMatch ids = New(4);
            for (int slot = 0; slot < 6; slot++)
                LuneBot.Plan(ids, slot);
            ids.BeginCombat();
            Check(ids.Combat.Units.Select(u => u.Id).SequenceEqual(Enumerable.Range(1, ids.Combat.Units.Count)), "unit ids are 1..n in spawn order");
            // The combat step is fixed; the simulation never reads a clock or a frame rate.
            Check(ids.Balance.SimStep == 0.05, "fixed simulation step of 0.05 s (20 steps per combat second)");
        }

        static LuneMatch New(int seed)
        {
            var match = new LuneMatch();
            match.Setup(new MatchOptions { Seed = seed, HumanSlot = -1 });
            return match;
        }

        static LuneMatch Play(int seed)
        {
            LuneMatch match = New(seed);
            while (match.Phase != Phase.Over && match.RoundNumber <= 60)
            {
                for (int slot = 0; slot < 6; slot++)
                    LuneBot.Plan(match, slot);
                match.BeginCombat();
                match.FinishCombat();
            }
            return match;
        }

        static string Fingerprint(LuneMatch match)
        {
            var parts = new List<string> { match.RoundNumber + "/" + match.Winner + "/" + match.Phase };
            foreach (Player player in match.Players)
            {
                parts.Add(player.Gold + ":" + player.Earned + ":" + player.Spent + ":" + string.Join(",", player.Roster.Select(e => e.Uid + e.TypeId + e.Lane)));
                if (player.Hero != null)
                    parts.Add(player.Hero.HeroId + player.Hero.Xp + string.Join("+", player.Hero.Items) + string.Join("+", player.Hero.Talents));
            }
            foreach (KeyValuePair<string, double> pair in match.BuildingHp)
                parts.Add(pair.Key + "=" + pair.Value.ToString("R", System.Globalization.CultureInfo.InvariantCulture));
            foreach (HistoryEntry entry in match.History)
                parts.Add(entry.Round + entry.EndReason + entry.CombatTime.ToString("R", System.Globalization.CultureInfo.InvariantCulture) + string.Join(",", entry.Gold));
            return string.Join("|", parts);
        }
    }
}