using UnityEngine;

namespace FloodSWE.Debugging
{
    [ExecuteAlways]
    public sealed class SweHeightmapPreview : MonoBehaviour
    {
        [Header("Source")]
        public SweTileSimulator simulator;
        public RenderTexture overrideTexture;

        [Header("Target")]
        public Renderer targetRenderer;
        public bool createQuadIfMissing = true;
        public Vector2 quadSize = new Vector2(10.0f, 10.0f);

        [Header("Display")]
        [Range(0.0f, 5.0f)]
        public float intensity = 1.0f;
        public float minValue = 0.0f;
        public float maxValue = 1.0f;

        [Header("Material")]
        public Shader previewShader;

        private Material runtimeMaterial;

        private void OnEnable()
        {
            EnsureTarget();
            EnsureMaterial();
            ApplyTexture();
        }

        private void OnDisable()
        {
            if (runtimeMaterial != null)
            {
                DestroyImmediate(runtimeMaterial);
                runtimeMaterial = null;
            }
        }

        private void Update()
        {
            ApplyTexture();
        }

        private void EnsureTarget()
        {
            if (targetRenderer != null || !createQuadIfMissing)
            {
                return;
            }

            GameObject quad = GameObject.CreatePrimitive(PrimitiveType.Quad);
            quad.name = "SWE_HeightmapPreview";
            quad.transform.SetParent(transform, false);
            quad.transform.localRotation = Quaternion.Euler(90f, 0f, 0f);
            quad.transform.localScale = new Vector3(quadSize.x, quadSize.y, 1f);

            targetRenderer = quad.GetComponent<Renderer>();
        }

        private void EnsureMaterial()
        {
            if (targetRenderer == null)
            {
                return;
            }

            Shader shaderToUse = previewShader != null
                ? previewShader
                : Shader.Find("FloodSWE/HeightmapPreview");

            if (shaderToUse == null)
            {
                Debug.LogWarning("SweHeightmapPreview: preview shader not found.");
                return;
            }

            runtimeMaterial = new Material(shaderToUse);
            targetRenderer.sharedMaterial = runtimeMaterial;
        }

        private void ApplyTexture()
        {
            if (runtimeMaterial == null)
            {
                return;
            }

            RenderTexture tex = overrideTexture;
            if (tex == null && simulator != null)
            {
                tex = simulator.debugWater;
            }

            if (tex == null)
            {
                return;
            }

            runtimeMaterial.SetTexture("_MainTex", tex);
            runtimeMaterial.SetFloat("_Intensity", intensity);
            runtimeMaterial.SetFloat("_MinValue", minValue);
            runtimeMaterial.SetFloat("_MaxValue", maxValue);
        }
    }
}