// Assets/_Project/Scripts/UI/BuildProgressBar.cs
using UnityEngine;
using UnityEngine.UI;
using TD.Gameplay;

namespace TD.UI
{
    // Local (non-networked) world-space progress bar that tracks a BuildSiteVisual.
    // Visible while Constructing (green) or Paused (yellow). Hidden while Queued.
    // Billboards to face Camera.main each LateUpdate.
    // Destroyed automatically when its parent BuildSiteVisual is despawned.
    public class BuildProgressBar : MonoBehaviour
    {
        private BuildSiteVisual source;
        private GameObject canvasGO;
        private Image fillImage;

        private const float BarWorldWidth   = 1.8f;
        private const float BarWorldHeight  = 0.15f;
        private const float HeightAboveSite = 1.5f;

        private static readonly Color ColorConstructing = new Color(0.15f, 0.85f, 0.15f, 1f);
        private static readonly Color ColorPaused       = new Color(0.90f, 0.75f, 0.10f, 1f);

        public void Initialize(BuildSiteVisual visual)
        {
            source = visual;
            BuildHierarchy();
        }

        private void BuildHierarchy()
        {
            // World-space Canvas — 100 canvas units = 1 world unit via localScale 0.01.
            canvasGO = new GameObject("Canvas");
            canvasGO.transform.SetParent(transform, false);

            var canvas = canvasGO.AddComponent<Canvas>();
            canvas.renderMode = RenderMode.WorldSpace;
            canvas.sortingOrder = 10;

            var rt = (RectTransform)canvasGO.transform;
            rt.sizeDelta    = new Vector2(BarWorldWidth * 100f, BarWorldHeight * 100f);
            rt.localPosition = new Vector3(0f, HeightAboveSite, 0f);
            rt.localScale   = Vector3.one * 0.01f;

            // Background
            var bgGO  = new GameObject("Background");
            bgGO.transform.SetParent(canvasGO.transform, false);
            var bgImg = bgGO.AddComponent<Image>();
            bgImg.color = new Color(0.05f, 0.05f, 0.05f, 0.85f);
            Stretch((RectTransform)bgGO.transform);

            // Fill (rendered on top; fillAmount drives visible width)
            var fillGO = new GameObject("Fill");
            fillGO.transform.SetParent(canvasGO.transform, false);
            fillImage             = fillGO.AddComponent<Image>();
            fillImage.color       = ColorConstructing;
            fillImage.type        = Image.Type.Filled;
            fillImage.fillMethod  = Image.FillMethod.Horizontal;
            fillImage.fillOrigin  = 0; // left to right
            fillImage.fillAmount  = 0f;
            Stretch((RectTransform)fillGO.transform);
        }

        private static void Stretch(RectTransform rt)
        {
            rt.anchorMin = Vector2.zero;
            rt.anchorMax = Vector2.one;
            rt.offsetMin = Vector2.zero;
            rt.offsetMax = Vector2.zero;
        }

        private void LateUpdate()
        {
            if (source == null) return;

            var stage = source.CurrentStage;
            bool show = stage == BuildStage.Constructing || stage == BuildStage.Paused;
            canvasGO.SetActive(show);
            if (!show) return;

            fillImage.color      = stage == BuildStage.Paused ? ColorPaused : ColorConstructing;
            fillImage.fillAmount = source.ComputeProgressNormalized();

            var cam = Camera.main;
            if (cam != null)
                canvasGO.transform.rotation = cam.transform.rotation;
        }
    }
}