using System;
using System.Collections.Generic;
using GeometryTD.DataTable;
using GeometryTD.Definition;
using UnityEngine;

namespace GeometryTD.CustomComponent
{
    internal sealed class EnemySpawnDirector
    {
        private sealed class SpawnEntryRuntime
        {
            public DRLevelSpawnEntry Entry;
            public bool Completed;
            public float NextTriggerTime;
            public float EndTime;
            public int RemainingCount;
        }

        private const float MinStreamInterval = 0.05f;
        private const float MinBurstGap = 0.01f;

        private readonly List<SpawnEntryRuntime> _spawnRuntimes = new();
        private float _phaseElapsed;

        public bool IsPhaseSpawnCompleted { get; private set; } = true;
        public bool IsPhaseRunning { get; private set; }

        public void Reset()
        {
            EndPhase();
        }

        public void BeginPhase(IReadOnlyList<DRLevelSpawnEntry> spawnEntries)
        {
            EndPhase();

            _phaseElapsed = 0f;
            IsPhaseRunning = true;
            IsPhaseSpawnCompleted = false;
            if (spawnEntries != null)
            {
                for (int i = 0; i < spawnEntries.Count; i++)
                {
                    SpawnEntryRuntime runtime = BuildSpawnRuntime(spawnEntries[i]);
                    if (runtime != null)
                    {
                        _spawnRuntimes.Add(runtime);
                    }
                }
            }

            IsPhaseSpawnCompleted = _spawnRuntimes.Count <= 0;
        }

        public void OnUpdate(float elapseSeconds, Action<DRLevelSpawnEntry, int> spawnAction)
        {
            if (!IsPhaseRunning || spawnAction == null)
            {
                return;
            }

            _phaseElapsed += elapseSeconds;
            UpdateSpawnRuntimes(spawnAction);
        }

        public void EndPhase()
        {
            IsPhaseRunning = false;
            _phaseElapsed = 0f;
            _spawnRuntimes.Clear();
            IsPhaseSpawnCompleted = true;
        }

        private SpawnEntryRuntime BuildSpawnRuntime(DRLevelSpawnEntry entry)
        {
            if (entry == null || entry.EntryType == EntryType.None)
            {
                return null;
            }

            SpawnEntryRuntime runtime = new SpawnEntryRuntime
            {
                Entry = entry,
                Completed = false,
                NextTriggerTime = Mathf.Max(0f, entry.StartTime),
                EndTime = Mathf.Max(0f, entry.StartTime),
                RemainingCount = Mathf.Max(0, entry.Count)
            };

            switch (entry.EntryType)
            {
                case EntryType.Stream:
                {
                    float duration = Mathf.Max(0f, entry.Duration);
                    runtime.EndTime = duration > 0f ? runtime.NextTriggerTime + duration : runtime.NextTriggerTime;
                    runtime.Completed = entry.Count <= 0;
                    return runtime;
                }
                case EntryType.Burst:
                case EntryType.Boss:
                    runtime.Completed = runtime.RemainingCount <= 0;
                    return runtime;
                default:
                    return null;
            }
        }

        private void UpdateSpawnRuntimes(Action<DRLevelSpawnEntry, int> spawnAction)
        {
            bool allCompleted = true;
            for (int i = 0; i < _spawnRuntimes.Count; i++)
            {
                SpawnEntryRuntime runtime = _spawnRuntimes[i];
                if (runtime.Completed)
                {
                    continue;
                }

                switch (runtime.Entry.EntryType)
                {
                    case EntryType.Stream:
                        ProcessStreamRuntime(runtime, spawnAction);
                        break;
                    case EntryType.Burst:
                    case EntryType.Boss:
                        ProcessBurstRuntime(runtime, spawnAction);
                        break;
                    default:
                        runtime.Completed = true;
                        break;
                }

                if (!runtime.Completed)
                {
                    allCompleted = false;
                }
            }

            IsPhaseSpawnCompleted = allCompleted;
        }

        private void ProcessStreamRuntime(SpawnEntryRuntime runtime, Action<DRLevelSpawnEntry, int> spawnAction)
        {
            if (_phaseElapsed < runtime.NextTriggerTime)
            {
                return;
            }

            int countPerWave = Mathf.Max(0, runtime.Entry.Count);
            if (countPerWave <= 0)
            {
                runtime.Completed = true;
                return;
            }

            float interval = runtime.Entry.Interval > 0f ? runtime.Entry.Interval : MinStreamInterval;
            while (_phaseElapsed >= runtime.NextTriggerTime && runtime.NextTriggerTime <= runtime.EndTime)
            {
                spawnAction(runtime.Entry, countPerWave);
                runtime.NextTriggerTime += interval;
            }

            if (runtime.NextTriggerTime > runtime.EndTime)
            {
                runtime.Completed = true;
            }
        }

        private void ProcessBurstRuntime(SpawnEntryRuntime runtime, Action<DRLevelSpawnEntry, int> spawnAction)
        {
            if (_phaseElapsed < runtime.NextTriggerTime)
            {
                return;
            }

            if (runtime.RemainingCount <= 0)
            {
                runtime.Completed = true;
                return;
            }

            float gap = runtime.Entry.Gap;
            if (gap <= 0f)
            {
                spawnAction(runtime.Entry, runtime.RemainingCount);
                runtime.RemainingCount = 0;
                runtime.Completed = true;
                return;
            }

            gap = Mathf.Max(gap, MinBurstGap);
            while (_phaseElapsed >= runtime.NextTriggerTime && runtime.RemainingCount > 0)
            {
                spawnAction(runtime.Entry, 1);
                runtime.RemainingCount--;
                runtime.NextTriggerTime += gap;
            }

            runtime.Completed = runtime.RemainingCount <= 0;
        }
    }
}