using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Wave : MonoBehaviour
{
    public WaveSettings settings;

    const float DISTANCE = 30f;

    float ticksPerSpawn;
    int spawnsPer;
    int ticks;
    int spawns;

    void Start()
    {
        var dur = settings.duration;
        if (dur <= Time.fixedDeltaTime)
        {
            dur = Time.fixedDeltaTime;
        }
        ticksPerSpawn = dur / settings.count / Time.fixedDeltaTime;
        spawnsPer = Mathf.CeilToInt(settings.count * Time.fixedDeltaTime / dur);
        ticks = spawns = 0;
    }

    void FixedUpdate()
    {
        var groups = Mathf.FloorToInt(ticks / ticksPerSpawn);
        ticks++;
        if (Mathf.FloorToInt(ticks / ticksPerSpawn) > groups)
        {
            doSpawn();
            if (spawns >= settings.count)
            {
                Destroy(gameObject);
            }
        }
    }

    void doSpawn()
    {
        var n = spawnsPer;
        if (n > settings.count - spawns)
        {
            n = settings.count - spawns;
        }
        for (int i = 0; i < n; i++)
        {
            var k = Random.Range(0, settings.enemies.Count);
            var p = nextLoc(spawns);
            Instantiate(settings.enemies[k], p, Quaternion.identity);
            spawns++;
        }
    }

    Vector3 nextLoc(int i)
    {
        switch (settings.strategy)
        {
            case WaveSettings.SpawnStrategy.Uniform:
                var angle = (float)i / (float)settings.count * 2*Mathf.PI;
                return new Vector3(Mathf.Cos(angle), Mathf.Sin(angle)) * DISTANCE;
            case WaveSettings.SpawnStrategy.Random:
                return Random.insideUnitCircle.normalized * DISTANCE;
            case WaveSettings.SpawnStrategy.DiskRandom:
                return Random.insideUnitCircle * DISTANCE;
            default:
                throw new System.Exception("unknown strategy");
        }
    }
}