using System;
using System.Collections.Generic;
using Luneraria.Core;

namespace Luneraria.View
{
    /// <summary>
    /// Fingerprint of a match (U2C): FNV-1a over every combat step (step, time, and per unit id,
    /// alive, hit points, position, target) and every settlement (gains, lost buildings, winner).
    /// Two runs are the same match exactly when their fingerprints are equal; the Unity match and
    /// the plain core run are compared this way at any frame rate.
    /// </summary>
    public sealed class LuneTrace
    {
        const ulong Offset = 14695981039346656037UL;
        const ulong Prime = 1099511628211UL;
        ulong _hash = Offset;
        public int Steps;
        public readonly List<ulong> RoundHashes = new List<ulong>();
        public readonly List<string> Rounds = new List<string>();

        public ulong Hash { get { return _hash; } }

        void Mix(ulong value)
        {
            for (int i = 0; i < 8; i++)
            {
                _hash ^= (value >> (i * 8)) & 0xFF;
                _hash *= Prime;
            }
        }

        void Mix(double value) { Mix((ulong)BitConverter.DoubleToInt64Bits(value)); }
        void Mix(float value) { Mix((ulong)(uint)BitConverter.ToInt32(BitConverter.GetBytes(value), 0)); }

        public void RecordStep(LuneCombat combat)
        {
            Steps++;
            Mix((ulong)combat.Steps);
            Mix(combat.Elapsed);
            foreach (LuneUnit unit in combat.Units)
            {
                Mix((ulong)unit.Id);
                Mix(unit.Alive ? 1UL : 0UL);
                Mix(unit.Hp);
                Mix(unit.Position.X);
                Mix(unit.Position.Y);
                Mix((ulong)(unit.Target != null ? unit.Target.Id : 0));
            }
        }

        public void RecordSettlement(LuneMatch match)
        {
            Settlement settlement = match.LastSettlement;
            foreach (int gain in settlement.Gains)
                Mix((ulong)(uint)gain);
            foreach (string building in settlement.BuildingsLost)
                foreach (char c in building)
                    Mix((ulong)c);
            Mix((ulong)(uint)match.Winner);
            RoundHashes.Add(_hash);
            Rounds.Add(string.Format("round {0}: {1} steps, lost [{2}], winner {3}", settlement.Round, match.Combat != null ? match.Combat.Steps : 0,
                string.Join(",", settlement.BuildingsLost), match.Winner));
        }

        /// <summary>The same match without Unity: plan, begin, step to the end, round after round.</summary>
        public static LuneTrace RunCore(MatchOptions options, int startRound, int extraGold, string profile, int maxRound = 60)
        {
            var match = LuneMatchRunner.NewMatch(options, startRound, extraGold);
            var trace = new LuneTrace();
            while (match.Phase != Phase.Over && match.RoundNumber <= maxRound)
            {
                for (int slot = 0; slot < 6; slot++)
                    LuneBot.Plan(match, slot, profile);
                match.BeginCombat();
                while (match.Phase == Phase.Combat)
                {
                    match.StepCombat();
                    trace.RecordStep(match.Combat);
                }
                trace.RecordSettlement(match);
            }
            return trace;
        }
    }
}