using UnityEngine;

[AddComponentMenu("Camera/Top Down Follow Camera")]
public class TopDownCameraController : MonoBehaviour
{
    [Header("Target")]
    public Transform target;

    [Header("Positioning")]
    public float distance = 8f;            // horizontal distance from target
    public float height = 6f;              // vertical offset above target
    [Range(0f, 89f)]
    public float pitch = 80f;              // X rotation in degrees (80 by default)

    [Header("Smoothing")]
    public bool smoothPosition = true;
    public float positionSmoothTime = 0.12f;
    public bool smoothRotation = true;
    public float rotationSmoothTime = 0.08f;

    Vector3 positionVelocity = Vector3.zero;
    float rotationInterpolation = 0f;
    
    // Cached values for optimization
    private Quaternion cachedPitchRotation;
    private Vector3 cachedLocalOffset;
    private bool cachedPitchNeedsUpdate = true;

    void Reset()
    {
        pitch = 80f;
        distance = 8f;
        height = 6f;
    }

    void OnValidate()
    {
        // Invalidate cache when values change in editor
        cachedPitchNeedsUpdate = true;
    }

    void LateUpdate()
    {
        if (target == null) return;

        // Update cached rotation if pitch changed
        if (cachedPitchNeedsUpdate)
        {
            cachedPitchRotation = Quaternion.Euler(pitch, 0f, 0f);
            cachedLocalOffset = cachedPitchRotation * new Vector3(0f, height, -distance);
            cachedPitchNeedsUpdate = false;
        }

        Vector3 desiredPosition = target.position + cachedLocalOffset;

        // Smooth position
        if (smoothPosition)
        {
            transform.position = Vector3.SmoothDamp(transform.position, desiredPosition, ref positionVelocity, positionSmoothTime);
        }
        else
        {
            transform.position = desiredPosition;
            positionVelocity = Vector3.zero;
        }

        // Desired rotation: look at target but keep the pitch
        Vector3 lookDirection = (target.position - transform.position).normalized;
        Quaternion desiredRotation = Quaternion.LookRotation(lookDirection, Vector3.up);

        // Lock X rotation to the pitch value
        Vector3 euler = desiredRotation.eulerAngles;
        euler.x = pitch;
        desiredRotation = Quaternion.Euler(euler);

        // Smooth rotation using exponential decay
        if (smoothRotation)
        {
            float slerp = 1f - Mathf.Exp(-rotationSmoothTime * 60f * Time.deltaTime);
            transform.rotation = Quaternion.Slerp(transform.rotation, desiredRotation, slerp);
        }
        else
        {
            transform.rotation = desiredRotation;
        }
    }
}