LD39/game/Assets/Scripts/Station.cs

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

public class Station : MonoBehaviour
{
    public float maxPower;
    public Transform gauge;
    public float powerSuckDelay = 1;
    public float powerLevel;

    public LineRenderer lineRenderer;

    private IEnumerator drainCoroutine;
    private Transform lineTarget;

    // Use this for initialization
	void Start ()
	{
	    powerLevel = 0;
	    lineTarget = lineRenderer.transform;
        lineRenderer.SetPositions(new Vector3[]{
            lineRenderer.transform.position,
            lineTarget.position,
        });
	}
	
	// Update is called once per frame
	void Update () {
		UpdatePowerBar();
	}

    void PowerUp(float delta)
    {
        powerLevel += delta;

        if (powerLevel >= maxPower)
            Debug.Log("Station at max power!");

        UpdatePowerBar();
    }

    private void UpdatePowerBar()
    {
        var level = powerLevel / maxPower;
        gauge.localScale = new Vector3(1, level, 1);
        lineRenderer.SetPosition(1, lineTarget.position);
    }

    void OnTriggerEnter(Collider other)
    {
        if (other.CompareTag("Player"))
        {
            lineTarget = other.transform;
            drainCoroutine = DrainPower(other.GetComponent<Player>());
            StartCoroutine(drainCoroutine);
        }
    }

    void OnTriggerExit(Collider other)
    {
        if (other.CompareTag("Player"))
        {
            lineTarget = lineRenderer.transform;
            if (drainCoroutine != null)
                StopCoroutine(drainCoroutine);
        }
    }

    private IEnumerator DrainPower(Player player)
    {
        while (player.PowerLevel >= 2f)
        {
            if (powerLevel >= maxPower)
            {
                yield break;
            }
            yield return new WaitForSeconds(powerSuckDelay);
            PowerUp(1);
            player.PowerLevel -= 1f;
            UpdatePowerBar();
        }
    }
}