using System.Collections.Generic;
using UnityEngine;

public class WaveObserver : Singleton<WaveObserver>
{
    private List<SpawnerTile> _subjects = new List<SpawnerTile>();
    private List<float> _aliveEnemyCount = new List<float>();
    private List<int> _copyConstantSpawn;
    private List<GroupList> _copyGroupSpawn;
    private List<float> _groupSpawnTimers;
    private WaveConfig _levelConfig;
    private const int MAXTOUGHNESS = 10;
    private int _spawnerTiming = 0;
    private List<int> _intervalTiming = new List<int>();
    private bool _once = true;
    private int _currentGroupIndex = 0;

    public void SetLevelConfig(WaveConfig config)
    {
        _levelConfig = config;
        _copyConstantSpawn = new List<int>();
        _copyGroupSpawn = new List<GroupList>();
        _groupSpawnTimers = new List<float>();
        foreach (EnemyType enemy in _levelConfig.ConstantSpawn)
        {
            _copyConstantSpawn.Add(enemy.Count);
        }
        for (int index = 0; index < _levelConfig.NestedGroupSpawn.Count; index++)
        {
            _copyGroupSpawn.Add(_levelConfig.NestedGroupSpawn[index]);
            _groupSpawnTimers.Add(_levelConfig.NestedGroupSpawn[index].triggerTime);
        }
    }

    /**
     * Called by spawner at the start of the game
     * Assigns enemy to spawn and registers them
     */
    public void Attach(SpawnerTile spawnerSubject)
    {

        spawnerSubject.Prefab = _levelConfig.GetRandomSpawn().GetEnemyObject();
        _subjects.Add(spawnerSubject);
        _aliveEnemyCount.Add(0);
        _intervalTiming.Add(++_spawnerTiming);
        //  Ensures that only one spawner keeps track of the grouped spawn timer.
        if (_once)
        {
            _once = false;
            spawnerSubject.SetGroupSpawnTimers(_groupSpawnTimers);
        }
    }

    /**
     * Called by spawner when making enemies
     * Assigns a new interval
     */
    public void NotifySpawned(SpawnerTile spawnerSubject)
    {
        GameObject paramPrefab = spawnerSubject.Prefab;
        spawnerSubject.ChangeSpawnSpeed(_levelConfig.Interval * _spawnerTiming);
        if (paramPrefab.Equals(_levelConfig.ConstantSpawn[0].GetEnemyObject()))
        {
            int currentCount = 0;
            for (int i = 0; i < _copyConstantSpawn.Count; i++)
            {
                if (_levelConfig.ConstantSpawn[i].GetEnemyObject() == paramPrefab)
                {
                    currentCount = --_copyConstantSpawn[i];
                    break;
                }
            }
            if (currentCount <= 0)
            {
                foreach (SpawnerTile spawner in _subjects)
                {
                    if (spawner.Prefab.Equals(paramPrefab))
                    {
                        spawner.StopSpawn();
                    }
                }
            }
        }
    }

    /**
     * Called by enemy when they spawn
     * Keeps track of their row
     */
    public int NotifyEnemy(float yPosition, float toughness)
    {
        int index = FindEnemyIndex(yPosition);
        _aliveEnemyCount[index] += toughness;
        if (_aliveEnemyCount[index] >= MAXTOUGHNESS)
        {
            _subjects[index].StopSpawn();
        }
        return index;
    }

    /**
     * Called when an enemy dies
     * Reactivates spawning on that row if disabled before
     */
    public void NotifyDies(int position, float toughness)
    {
        _aliveEnemyCount[position] -= toughness;
        if (_aliveEnemyCount[position] < MAXTOUGHNESS)
        {
            _subjects[position].StartSpawn();
        }
    }

    /**
     * Called when an enemy is spawned automatically at the start of the game
     * Adjusts the intervall between spawns
     */
    public void NotifyOnStart(SpawnerTile spawnerSubject)
    {
        float interval = _levelConfig.GetUpdatedInterval();
        foreach (var subject in _subjects)
        {
            subject.ChangeSpawnSpeed(interval);
        }
        NotifySpawned(spawnerSubject);
    }

    // To find which spawner an ennemy came from.
    private int FindEnemyIndex(float yPosition)
    {
        for (int i = 0; i < _subjects.Count; i++)
        {
            if (_subjects[i].Position.y == yPosition)
            {
                return i;
            }
        }
        return -1;
    }

    /**
     * Spawners wait 1 second to have time to register them all
     * Then gets assigned a random spawn interval
     */
    public void NotifyEndCooldown(SpawnerTile spawnerTile)
    {
        System.Random rand = new System.Random();
        int index;
        do
        {
            index = rand.Next(_subjects.Count);
        } while (_intervalTiming.Count <= index);
        spawnerTile.ChangeSpawnSpeed(_levelConfig.Interval * _intervalTiming[index]);
        _intervalTiming.Remove(index);
    }

    /**
     * Called when it is time to spawn a group
     * Assigns a random element of the group to a random spawner
     */
    public void NotifyGroupSpawn()
    {
        System.Random rand = new System.Random();
        foreach (EnemyType groupEnemy in _copyGroupSpawn[_currentGroupIndex].groupSpawn)
        {
            for (int i = 0; i < groupEnemy.Count; i++)
            {
                _subjects[rand.Next(_subjects.Count)].TriggerSpawn(groupEnemy.GetEnemyObject());
            }
        }
        _currentGroupIndex++;
    }
}