match3-unity/Assets/Scripts/Views/GemView.cs

using System.Threading;
using Cysharp.Threading.Tasks;
using Enums;
using Services;
using UnityEngine;
using Utils;

namespace Views {
    public class GemView : MonoBehaviour {
        private Gem gem;
        public Gem Gem => this.gem;

        private bool isFalling;
        [Header("Spawn Scale")]
        [SerializeField] private float spawnScaleFrom = 0f;
        [SerializeField] private float spawnScaleDuration = 0.12f;

        private CancellationTokenSource spawnScaleCts;

        public void Bind(Gem gem) {
            this.gem = gem;
            this.gameObject.SetActive(true);

            PlaySpawnScale();
        }

        public void Unbind() {
            this.spawnScaleCts?.Cancel();
            this.spawnScaleCts?.Dispose();
            this.spawnScaleCts = null;

            this.gem = null;
            this.gameObject.SetActive(false);
            this.isFalling = false;
        }

        private void PlaySpawnScale() {
            this.spawnScaleCts?.Cancel();
            this.spawnScaleCts?.Dispose();
            this.spawnScaleCts = new CancellationTokenSource();

            this.transform.localScale = Vector3.one * this.spawnScaleFrom;
            AnimateSpawnScaleAsync(this.spawnScaleCts.Token).Forget();
        }

        private async UniTask AnimateSpawnScaleAsync(CancellationToken ct) {
            if (this.spawnScaleDuration <= 0f) {
                this.transform.localScale = Vector3.one;
                return;
            }

            float timer = 0f;
            while (timer < this.spawnScaleDuration) {
                ct.ThrowIfCancellationRequested();

                timer += Time.deltaTime;
                float scale = Mathf.Clamp01(timer / this.spawnScaleDuration);

                scale = Mathf.SmoothStep(0f, 1f, scale);

                this.transform.localScale = Vector3.LerpUnclamped(
                    Vector3.one * this.spawnScaleFrom,
                    Vector3.one,
                    scale
                );

                await UniTask.Yield(PlayerLoopTiming.Update, ct);
            }

            this.transform.localScale = Vector3.one;
        }

        private async UniTask FallDelay() {
            float fallDelay = 1 * (this.gem.Position.y / 10f);
            await UniTask.WaitForSeconds(fallDelay);
            this.isFalling = true;
        }
        
        public async UniTaskVoid UpdatePosition(Vector2Int positionBasedOnIndex, float gemSpeed) {
            if (!this.isFalling) {
                await FallDelay();
            }

            if (!this.isFalling)
                return;
            
            if (Vector2.Distance(this.transform.position, positionBasedOnIndex.ToVector2()) > 0.01f) {
                this.transform.position = Vector2.Lerp(this.transform.position, positionBasedOnIndex.ToVector2(), gemSpeed);
            }
        }
    }
}