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

// Controls intensity and direction of rain.
public class RainBehavior : MonoBehaviour {

    public float debugIntensity = -1;
    public float debugAngle = -9999;

    public float curIntensity { get; private set; } = 0;
    public float curAngle { get; private set; } = 0;

    // Adjust position in front of the camera.
    public float zDist = 40;
    public float yDist = 20;

    public ParticleSystem rain;
    private Dictionary<ParticleSystem, float> psToDefaultEmissionRate = new Dictionary<ParticleSystem, float>();

    void Awake() {
        RecursiveApply(rain, (ParticleSystem ps) => {
            psToDefaultEmissionRate[ps] = ps.emission.rateOverTime.constant;
        });
    }

    // Set the intensity of the rain.
    // 0 = off, 1 = downpour
    public void SetIntensity(float i) {
        curIntensity = i;
        RecursiveApply(rain, (ParticleSystem ps) => {
            var emission = ps.emission;
            if (!psToDefaultEmissionRate.ContainsKey(ps)) {
                Debug.LogWarning($"Unable to find default emission rate for {ps}; have {string.Join(",", psToDefaultEmissionRate.Keys)}");
            }
            emission.rateOverTime = psToDefaultEmissionRate[ps] * i;
        });
    }

    // Recursively apply f to all particle systems under `ps`
    private void RecursiveApply(ParticleSystem ps, Action<ParticleSystem> f) {
        f(ps);
        foreach (Transform t in ps.transform) {
            var child = t.gameObject.GetComponent<ParticleSystem>();
            if (child != null) {
                RecursiveApply(child, f);
            }
        }
    }
}