using System;
using UnityEngine;

namespace ProjectI.Enemies
{
    [Serializable]
    public struct EncounterPacingBeat
    {
        public string name;
        public float duration, spawnIntervalMultiplier;
        public int aliveCap;
        public EncounterPacingBeat(string name,float duration,float multiplier,int cap)
        {this.name=name;this.duration=duration;spawnIntervalMultiplier=multiplier;aliveCap=cap;}
    }

    public readonly struct EncounterPressure
    {
        public readonly int BeatIndex, AliveCap;
        public readonly float SpawnInterval;
        public EncounterPressure(int index,int cap,float interval)
        {BeatIndex=index;AliveCap=cap;SpawnInterval=interval;}
    }

    public static class EncounterPacing
    {
        private static readonly EncounterPacingBeat[] defaults=CreateDefaults();
        private static readonly float[] earlyStageDefaults=CreateEarlyStageDefaults();
        public static float[] CreateEarlyStageDefaults()=>new[]{2f,1.6f,1.3f};
        public static float StageMultiplier(int stage,float[] authored)
        {
            var scales=authored??earlyStageDefaults;
            int index=Math.Max(1,stage)-1;
            if(index>=scales.Length)return 1;
            return Finite(scales[index])?Mathf.Clamp(scales[index],1,4):1;
        }
        public static EncounterPressure SampleForStage(double elapsed,float baseInterval,int maximumAlive,EncounterPacingBeat[] authored,int stage,float[] stageScales)
        {
            var pressure=Sample(elapsed,baseInterval,maximumAlive,authored);
            return new EncounterPressure(pressure.BeatIndex,pressure.AliveCap,pressure.SpawnInterval*StageMultiplier(stage,stageScales));
        }
        public static EncounterPacingBeat[] CreateDefaults()=>new[]
        {
            new EncounterPacingBeat("Build pressure",20,.8f,10),
            new EncounterPacingBeat("High pressure",25,.36f,16),
            new EncounterPacingBeat("Recovery",15,1.6f,5)
        };

        public static EncounterPressure Sample(double elapsed,float baseInterval,int maximumAlive,EncounterPacingBeat[] authored)
        {
            var beats=authored==null||authored.Length==0?defaults:authored;
            int count=Mathf.Min(16,beats.Length),cap=Mathf.Clamp(maximumAlive,1,16);
            float interval=Finite(baseInterval)?Mathf.Clamp(baseInterval,.25f,30):2.5f;
            double total=0;
            for(int i=0;i<count;i++)total+=Duration(beats[i]);
            if(total<=0)return new EncounterPressure(-1,cap,interval);
            double offset=double.IsNaN(elapsed)||double.IsInfinity(elapsed)||elapsed<0?0:elapsed%total;
            for(int i=0;i<count;i++)
            {
                float duration=Duration(beats[i]);if(duration<=0)continue;
                if(offset<duration)
                {
                    float multiplier=Finite(beats[i].spawnIntervalMultiplier)?Mathf.Clamp(beats[i].spawnIntervalMultiplier,.1f,8):1;
                    return new EncounterPressure(i,Mathf.Clamp(beats[i].aliveCap,1,cap),Mathf.Clamp(interval*multiplier,.25f,30));
                }
                offset-=duration;
            }
            return new EncounterPressure(-1,cap,interval);
        }
        private static float Duration(EncounterPacingBeat beat)=>Finite(beat.duration)?Mathf.Clamp(beat.duration,0,600):0;
        private static bool Finite(float value)=>!float.IsNaN(value)&&!float.IsInfinity(value);
    }
}