PlayerController.cs

using JetBrains.Annotations;
using System.Collections;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.SceneManagement;

public class PlayerController : MonoBehaviour
{
	[SerializeField] private float m_JumpForce = 400f;                          // Amount of force added when the player jumps.
	[Range(0, 1)] [SerializeField] private float m_CrouchSpeed = .36f;          // Amount of maxSpeed applied to crouching movement. 1 = 100%
	[Range(0, .3f)] [SerializeField] private float m_MovementSmoothing = .05f;  // How much to smooth out the movement
	[SerializeField] private bool m_AirControl = false;                         // Whether or not a player can steer while jumping;
	[SerializeField] private LayerMask m_WhatIsGround;                          // A mask determining what is ground to the character
	[SerializeField] private Transform m_GroundCheck;                           // A position marking where to check if the player is grounded.
	[SerializeField] private Transform m_CeilingCheck;                          // A position marking where to check for ceilings
	[SerializeField] private Collider2D m_CrouchDisableCollider;                // A collider that will be disabled when crouching

	const float k_GroundedRadius = .2f; // Radius of the overlap circle to determine if grounded
	private bool m_Grounded;            // Whether or not the player is grounded.
	const float k_CeilingRadius = .2f; // Radius of the overlap circle to determine if the player can stand up
	private Rigidbody2D m_Rigidbody2D;
	private bool m_FacingRight = true;  // For determining which way the player is currently facing.
	private Vector3 m_Velocity = Vector3.zero;
	public int score { get { return diamondAmount; } }
	private int diamondAmount = 0; // For counting how many diamonds the player has collected.
	public int maxHealth = 3;
	public int health { get { return currentHealth; } }
	private int currentHealth;
	public Animator animator;
	public PlayerController controller;


	[Header("Events")]
	[Space]

	public UnityEvent OnLandEvent;

	[System.Serializable]
	public class BoolEvent : UnityEvent<bool> { }

	public BoolEvent OnCrouchEvent;
	private bool m_wasCrouching = false;

	void Start()
	{
		controller = gameObject.GetComponent<PlayerController>();
		animator = GetComponent<Animator>();
		currentHealth = maxHealth;
	}

	private void Awake()
	{
		m_Rigidbody2D = GetComponent<Rigidbody2D>();

		if (OnLandEvent == null)
			OnLandEvent = new UnityEvent();

		if (OnCrouchEvent == null)
			OnCrouchEvent = new BoolEvent();
	}

	private void Update()
	{
		bool wasGrounded = m_Grounded;
		m_Grounded = false;

		// The player is grounded if a circlecast to the groundcheck position hits anything designated as ground
		// This can be done using layers instead but Sample Assets will not overwrite your project settings.
		Collider2D[] colliders = Physics2D.OverlapCircleAll(m_GroundCheck.position, k_GroundedRadius, m_WhatIsGround);
		for (int i = 0; i < colliders.Length; i++)
		{
			if (colliders[i].gameObject != gameObject)
			{
				m_Grounded = true;
				if (!wasGrounded)
					OnLandEvent.Invoke();
			}
		}
	}

	public void Move(float move, bool crouch, bool jump)
	{
		// If crouching, check to see if the character can stand up
		if (!crouch)
		{
			// If the character has a ceiling preventing them from standing up, keep them crouching
			if (Physics2D.OverlapCircle(m_CeilingCheck.position, k_CeilingRadius, m_WhatIsGround))
			{
				crouch = true;
			}
		}

		//only control the player if grounded or airControl is turned on
		if (m_Grounded || m_AirControl)
		{

			// If crouching
			if (crouch)
			{
				if (!m_wasCrouching)
				{
					m_wasCrouching = true;
					OnCrouchEvent.Invoke(true);
				}

				// Reduce the speed by the crouchSpeed multiplier
				move *= m_CrouchSpeed;

				// Disable one of the colliders when crouching
				if (m_CrouchDisableCollider != null)
					m_CrouchDisableCollider.enabled = false;
			}
			else
			{
				// Enable the collider when not crouching
				if (m_CrouchDisableCollider != null)
					m_CrouchDisableCollider.enabled = true;

				if (m_wasCrouching)
				{
					m_wasCrouching = false;
					OnCrouchEvent.Invoke(false);
				}
			}

			// Move the character by finding the target velocity
			Vector3 targetVelocity = new Vector2(move * 10f, m_Rigidbody2D.velocity.y);
			// And then smoothing it out and applying it to the character
			m_Rigidbody2D.velocity = Vector3.SmoothDamp(m_Rigidbody2D.velocity, targetVelocity, ref m_Velocity, m_MovementSmoothing);

			// If the input is moving the player right and the player is facing left...
			if (move > 0 && !m_FacingRight)
			{
				// ... flip the player.
				Flip();
			}
			// Otherwise if the input is moving the player left and the player is facing right...
			else if (move < 0 && m_FacingRight)
			{
				// ... flip the player.
				Flip();
			}
		}
		// If the player should jump...
		if (m_Grounded && jump)
		{
			// Add a vertical force to the player.
			m_Grounded = false;
			m_Rigidbody2D.AddForce(new Vector2(0f, m_JumpForce));
		}
	}

	private void Flip()
	{
		// Switch the way the player is labelled as facing.
		m_FacingRight = !m_FacingRight;

		// Multiply the player's x local scale by -1.
		Vector3 theScale = transform.localScale;
		theScale.x *= -1;
		transform.localScale = theScale;
	}

	public void ChangeDiamondAmount()
	{
		diamondAmount = diamondAmount + 1;
		Debug.Log(diamondAmount);
		if (diamondAmount == 20)
		{
			Debug.Log("YOU WON!!!!!!");
		}
	}

	public void ChangeHealth(int amount)
	{
		int prevHealth = currentHealth;
		currentHealth = Mathf.Clamp(currentHealth + amount, 0, maxHealth);

		if (currentHealth == 0)
		{
			animator.SetTrigger("Hit");
			diamondAmount = 0;
			FindObjectOfType<GameManager>().EndGame();
		} 
		else if (prevHealth > currentHealth)
		{
			animator.SetTrigger("Hit");
			Debug.Log(currentHealth + "/" + maxHealth);
		}
		else
		{
			Debug.Log(currentHealth + "/" + maxHealth);
		}
	}

}

// Source: https://github.com/Brackeys/2D-Character-Controller/blob/master/CharacterController2D.cs