using System.Collections.Generic;

namespace Luneraria.Core
{
    /// <summary>Static data of one building (18 per match).</summary>
    public sealed class BuildingDef
    {
        public string Id = "";
        public int Team;
        /// <summary>top, mid, bot, or base for base towers and Ancients.</summary>
        public string Lane = "";
        /// <summary>outer (Grenzwacht), inner (Bastion), base (Kernwacht) or core (Ancient).</summary>
        public string Tier = "";
        /// <summary>Lane progress from the own base; -1 for base buildings.</summary>
        public double Progress;
        public Vec2 Position;
        public double MaxHp;
        public double Damage;
        public double Range;
        public int Bounty;
    }

    /// <summary>
    /// Lane polyline with cumulative lengths. Points are float vectors; the cumulative table is
    /// stored as float and the total length as double, as in the reference.
    /// </summary>
    public sealed class LanePath
    {
        public readonly Vec2[] Points;
        public readonly float[] Cumulative;
        public readonly double Length;

        public LanePath(List<Vec2> source)
        {
            Points = source.ToArray();
            Cumulative = new float[Points.Length];
            Cumulative[0] = 0f;
            double length = 0.0;
            for (int i = 1; i < Points.Length; i++)
            {
                length += Points[i].DistanceTo(Points[i - 1]);
                Cumulative[i] = (float)length;
            }
            Length = length;
        }

        /// <summary>Index i of the segment [i - 1, i] that contains lane coordinate d.</summary>
        int Segment(double d)
        {
            int low = 1;
            int high = Points.Length - 1;
            while (low < high)
            {
                int middle = (low + high) >> 1;
                if (d <= Cumulative[middle])
                    high = middle;
                else
                    low = middle + 1;
            }
            return low;
        }

        public Vec2 PointAt(double s)
        {
            double d = GdMath.Clamp(s, 0.0, Length);
            int i = Segment(d);
            double span = GdMath.Max(0.0001, (double)Cumulative[i] - (double)Cumulative[i - 1]);
            return Points[i - 1].Lerp(Points[i], GdMath.Clamp((d - Cumulative[i - 1]) / span, 0.0, 1.0));
        }

        public Vec2 TangentAt(double s)
        {
            int i = Segment(GdMath.Clamp(s, 0.0, Length));
            return (Points[i] - Points[i - 1]).Normalized();
        }

        /// <summary>Point and unnormalised tangent (b - a) / span at s in one pass.</summary>
        public void Sample(double s, out Vec2 point, out Vec2 tangent)
        {
            double d = GdMath.Clamp(s, 0.0, Length);
            int i = Segment(d);
            Vec2 a = Points[i - 1];
            Vec2 b = Points[i];
            double span = GdMath.Max(0.0001, (double)Cumulative[i] - (double)Cumulative[i - 1]);
            point = a.Lerp(b, GdMath.Clamp((d - Cumulative[i - 1]) / span, 0.0, 1.0));
            tangent = (b - a) / span;
        }

        /// <summary>Lane coordinate of the closest point on the polyline.</summary>
        public double Project(Vec2 position)
        {
            double best = double.PositiveInfinity;
            double bestS = 0.0;
            for (int i = 1; i < Points.Length; i++)
            {
                Vec2 a = Points[i - 1];
                Vec2 b = Points[i];
                Vec2 ab = b - a;
                double t = GdMath.Clamp((double)(position - a).Dot(ab) / GdMath.Max(0.0001, (double)ab.LengthSquared()), 0.0, 1.0);
                double d = position.DistanceSquaredTo(a + ab * t);
                if (d < best)
                {
                    best = d;
                    bestS = (double)Cumulative[i - 1] + (double)ab.Length() * t;
                }
            }
            return bestS;
        }
    }

    /// <summary>
    /// Map in ground coordinates (x, z): Blau (team 0) in the south-west, Rot (team 1) in the
    /// north-east, Rot the mirror image of Blau across x = z. Every lane is built from its Blau
    /// half and that half mirrored, so lanes, towers and spawns are equal by construction
    /// (reference: lune_map.gd, G1 layout). Top and Bottom have exactly the same length.
    /// </summary>
    public sealed class LuneMap
    {
        public static readonly string[] Lanes = { "top", "mid", "bot" };
        public static readonly Dictionary<string, string> LaneNames = new Dictionary<string, string> { { "top", "Top" }, { "mid", "Mid" }, { "bot", "Bottom" } };
        /// <summary>Catmull-Rom control points of each Blau half, base to symmetry axis.</summary>
        public static readonly Vec2[] TopControl = { new Vec2(-27.4, 21.0), new Vec2(-26.4, 13.0), new Vec2(-28.4, 4.0), new Vec2(-26.2, -5.0),
            new Vec2(-28.6, -13.5), new Vec2(-28.4, -21.2), new Vec2(-25.0, -25.0) };
        public static readonly Vec2[] MidControl = { new Vec2(-21.6, 21.6), new Vec2(-16.4, 17.2), new Vec2(-10.9, 11.5), new Vec2(-5.6, 5.9), new Vec2(0.0, 0.0) };
        public static readonly Vec2 CoreBlue = new Vec2(-30.0, 30.0);
        /// <summary>Two base towers per Ancient, 6 m out and 40° either side of the Mid direction.</summary>
        public static readonly Vec2[] BaseTowersBlue = { new Vec2(-29.477, 24.023), new Vec2(-24.023, 29.477) };
        /// <summary>Neutral boss grotto on the symmetry axis between Top and Mid.</summary>
        public static readonly Vec2 Grotto = new Vec2(-13.5, -13.5);
        public const double HalfExtent = 36.0;
        public static readonly Vec2 Axis = new Vec2(0.70710678, 0.70710678);
        public static readonly Vec2 BlueSide = new Vec2(-0.70710678, 0.70710678);
        public const double SampleSpacing = 2.0;
        public const string GrottoZone = "grotto";

        public readonly LuneBalance Balance;
        public readonly Dictionary<string, LanePath> LanePaths = new Dictionary<string, LanePath>();
        public readonly List<BuildingDef> Buildings = new List<BuildingDef>();
        readonly Dictionary<string, BuildingDef> _index = new Dictionary<string, BuildingDef>();

        public LuneMap(LuneBalance balance = null)
        {
            Balance = balance ?? LuneBalance.Default();
            LanePaths["top"] = new LanePath(FullLane(SampleHalf(TopControl)));
            LanePaths["mid"] = new LanePath(FullLane(SampleHalf(MidControl)));
            LanePaths["bot"] = new LanePath(SolveBottom(LanePaths["top"].Length));
            BuildBuildings();
        }

        public static int LaneIndex(string lane)
        {
            return System.Array.IndexOf(Lanes, lane);
        }

        public static Vec2 Mirror(Vec2 v) { return new Vec2(v.Y, v.X); }

        public static Vec2 MirrorMid(Vec2 v) { return new Vec2(-v.Y, -v.X); }

        public static List<Vec2> FullLane(List<Vec2> half)
        {
            var result = new List<Vec2>(half);
            for (int i = half.Count - 2; i >= 0; i--)
                result.Add(Mirror(half[i]));
            return result;
        }

        /// <summary>
        /// Samples the Catmull-Rom curve through the control points of a Blau half. The phantom
        /// point after the axis point mirrors the one before it, so the joined lane has no kink.
        /// </summary>
        public static List<Vec2> SampleHalf(IList<Vec2> control)
        {
            var ext = new List<Vec2> { control[0] * 2.0 - control[1] };
            ext.AddRange(control);
            ext.Add(Mirror(control[control.Count - 2]));
            var result = new List<Vec2>();
            for (int i = 1; i < ext.Count - 2; i++)
            {
                Vec2 p0 = ext[i - 1];
                Vec2 p1 = ext[i];
                Vec2 p2 = ext[i + 1];
                Vec2 p3 = ext[i + 2];
                int steps = GdMath.Max(2, GdMath.CeilI(p1.DistanceTo(p2) / SampleSpacing));
                for (int k = 0; k < steps; k++)
                {
                    double t = (double)k / steps;
                    double t2 = t * t;
                    double t3 = t2 * t;
                    result.Add(0.5 * (2.0 * p1 + (p2 - p0) * t + (2.0 * p0 - 5.0 * p1 + 4.0 * p2 - p3) * t2 + (3.0 * p1 - p0 - 3.0 * p2 + p3) * t3));
                }
            }
            result.Add(control[control.Count - 1]);
            return result;
        }

        /// <summary>Bottom half through the south-eastern lowland; bend pulls the meander inwards.</summary>
        public static Vec2[] BottomControl(double bend)
        {
            return new[] { new Vec2(-21.0, 27.4), new Vec2(-12.5, 27.0), new Vec2(-4.0, 27.6), new Vec2(4.0, 27.0 - bend),
                new Vec2(12.0, 27.4 - 0.6 * bend), new Vec2(19.5, 27.0), new Vec2(22.2, 27.8), new Vec2(25.0, 25.0) };
        }

        /// <summary>Bisection on the meander so Bottom is exactly as long as Top.</summary>
        public static List<Vec2> SolveBottom(double targetLength)
        {
            double low = 0.0;
            double high = 8.0;
            for (int i = 0; i < 60; i++)
            {
                double bend = (low + high) * 0.5;
                if (new LanePath(FullLane(SampleHalf(BottomControl(bend)))).Length < targetLength)
                    low = bend;
                else
                    high = bend;
            }
            return FullLane(SampleHalf(BottomControl((low + high) * 0.5)));
        }

        /// <summary>Lane coordinate s for a team's own marching progress (0 at its own base).</summary>
        public double SFor(int team, string lane, double progress)
        {
            return team == 0 ? progress : LanePaths[lane].Length - progress;
        }

        public double ProgressFor(int team, string lane, double s)
        {
            return team == 0 ? s : LanePaths[lane].Length - s;
        }

        /// <summary>Blau frame point, mirrored for Rot so both sides are exact images.</summary>
        public Vec2 LanePoint(int team, string lane, double progress, double lateral = 0.0)
        {
            Vec2 point;
            Vec2 tangent;
            LanePaths[lane].Sample(progress, out point, out tangent);
            Vec2 blue = point + new Vec2(-tangent.Y, tangent.X) * lateral;
            return team == 0 ? blue : new Vec2(blue.Y, blue.X);
        }

        public Vec2 LaneForward(int team, string lane, double progress)
        {
            LanePath path = LanePaths[lane];
            Vec2 tangent = path.TangentAt(GdMath.Clamp(progress, 0.0, path.Length));
            return team == 0 ? tangent : Mirror(tangent);
        }

        /// <summary>Grotto entrance of a team (mirrored); the boss rests slightly inside.</summary>
        public Vec2 GrottoEntry(int team)
        {
            Vec2 blue = Grotto + new Vec2(1.2, 4.6);
            return team == 0 ? blue : Mirror(blue);
        }

        public Vec2 GrottoBossPoint() { return Grotto + new Vec2(-1.5, -1.5); }

        public Vec2 GrottoCenter() { return Grotto; }

        /// <summary>Army formation area on a lane: progress from/to and lateral half width.</summary>
        public static void DeploymentSpan(out double from, out double to, out double halfWidth)
        {
            from = 0.4;
            to = 7.2;
            halfWidth = 2.4;
        }

        public Vec2 CorePosition(int team) { return team == 0 ? CoreBlue : Mirror(CoreBlue); }

        void BuildBuildings()
        {
            Buildings.Clear();
            _index.Clear();
            for (int team = 0; team < 2; team++)
            {
                string prefix = team == 0 ? "blau" : "rot";
                foreach (string lane in Lanes)
                {
                    LanePath path = LanePaths[lane];
                    foreach (string tier in new[] { "inner", "outer" })
                    {
                        double fraction = tier == "inner" ? Balance.InnerTowerFraction : Balance.OuterTowerFraction;
                        double progress = path.Length * fraction;
                        Add(new BuildingDef { Id = prefix + "_" + lane + "_" + tier, Team = team, Lane = lane, Tier = tier, Progress = progress,
                            Position = LanePoint(team, lane, progress, Balance.TowerSideOffset),
                            MaxHp = tier == "inner" ? Balance.TowerInnerHp : Balance.TowerOuterHp, Damage = Balance.TowerDamage, Range = Balance.TowerRange,
                            Bounty = tier == "inner" ? Balance.BountyInnerTower : Balance.BountyOuterTower });
                    }
                }
                for (int index = 0; index < 2; index++)
                {
                    Vec2 point = BaseTowersBlue[index];
                    Add(new BuildingDef { Id = prefix + "_base_" + (index + 1), Team = team, Lane = "base", Tier = "base", Progress = -1.0,
                        Position = team == 0 ? point : Mirror(point), MaxHp = Balance.BaseTowerHp, Damage = Balance.BaseTowerDamage,
                        Range = Balance.TowerRange, Bounty = Balance.BountyBaseTower });
                }
                Add(new BuildingDef { Id = prefix + "_ancient", Team = team, Lane = "base", Tier = "core", Progress = -1.0,
                    Position = CorePosition(team), MaxHp = Balance.CoreHp, Damage = 0.0, Range = 0.0, Bounty = 0 });
            }
        }

        void Add(BuildingDef definition)
        {
            Buildings.Add(definition);
            _index[definition.Id] = definition;
        }

        public BuildingDef BuildingDef(string id)
        {
            BuildingDef definition;
            return _index.TryGetValue(id, out definition) ? definition : null;
        }

        /// <summary>
        /// Gate rule shared by every damage source: outer first, inner after its outer, base
        /// towers once any lane is fully open, the Ancient after both base towers.
        /// alive maps building id to alive; missing ids count as destroyed.
        /// </summary>
        public static bool IsAttackable(BuildingDef definition, IDictionary<string, bool> alive)
        {
            string prefix = definition.Team == 0 ? "blau" : "rot";
            switch (definition.Tier)
            {
                case "outer":
                    return true;
                case "inner":
                    return !Get(alive, prefix + "_" + definition.Lane + "_outer");
                case "base":
                    foreach (string lane in Lanes)
                    {
                        if (!Get(alive, prefix + "_" + lane + "_outer") && !Get(alive, prefix + "_" + lane + "_inner"))
                            return true;
                    }
                    return false;
                case "core":
                    return !Get(alive, prefix + "_base_1") && !Get(alive, prefix + "_base_2");
            }
            return false;
        }

        static bool Get(IDictionary<string, bool> alive, string id)
        {
            bool value;
            return alive.TryGetValue(id, out value) && value;
        }
    }
}