using System;
using System.Globalization;
using System.IO;
using System.Text;

namespace Luneraria.Core.Tests
{
    /// <summary>
    /// Step-by-step trace of one combat round of a bot match, for comparing two runtimes
    /// (docs/port/U1.5-UNITY.md): per step and unit the discrete state (alive, target, hits,
    /// zone) and the raw bits of position and hit points. Two traces are diffed outside
    /// (tools/port/trace_diff.py) to find the first step where a decision differs.
    /// </summary>
    public static class DivergenceTrace
    {
        /// <summary>Plays rounds 1..round of a bot match; writes the trace of the last round.</summary>
        public static void Write(string path, int seed, string[] bunds, string profile, int round)
        {
            var match = new LuneMatch();
            var options = new MatchOptions { Seed = seed, HumanSlot = -1 };
            if (bunds != null)
                options.Bunds = new System.Collections.Generic.List<string>(bunds);
            match.Setup(options);
            using (var writer = new StreamWriter(path, false, new UTF8Encoding(false)))
            {
                while (match.Phase != Phase.Over && match.RoundNumber <= round)
                {
                    for (int slot = 0; slot < 6; slot++)
                        LuneBot.Plan(match, slot, profile);
                    int fought = match.RoundNumber;
                    bool traced = fought == round;
                    match.BeginCombat();
                    if (traced)
                    {
                        Dump(writer, match.Combat);
                        while (!match.Combat.Finished)
                        {
                            match.StepCombat();
                            Dump(writer, match.Combat);
                        }
                    }
                    match.FinishCombat();
                    writer.WriteLine("settled round {0} combat_time {1} phase {2}", fought, match.LastSettlement.CombatTime.ToString("R", CultureInfo.InvariantCulture), match.Phase);
                }
            }
        }

        static void Dump(StreamWriter writer, LuneCombat combat)
        {
            var line = new StringBuilder();
            line.Append("step ").Append(combat.Steps).Append(" t ").Append(combat.Elapsed.ToString("R", CultureInfo.InvariantCulture));
            line.Append(" finished ").Append(combat.Finished ? 1 : 0).Append(" reason ").Append(combat.EndReason);
            writer.WriteLine(line.ToString());
            foreach (LuneUnit unit in combat.Units)
            {
                if (!unit.Alive && unit.DeathTime < combat.Elapsed - 0.001)
                    continue;
                writer.WriteLine("  u {0} {1} t{2} {3} {4} alive {5} target {6} hits {7} | hp {8:X16} pos {9:X8} {10:X8}",
                    unit.Id, unit.Kind, unit.Team, unit.Lane, unit.Zone, unit.Alive ? 1 : 0, unit.Target != null ? unit.Target.Id : -1, unit.HitCount,
                    BitConverter.DoubleToInt64Bits(unit.Hp), BitConverter.ToInt32(BitConverter.GetBytes(unit.Position.X), 0), BitConverter.ToInt32(BitConverter.GetBytes(unit.Position.Y), 0));
            }
        }
    }
}