using System;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.InputSystem.UI;
using UnityEngine.UIElements;

namespace ProjectM.Client
{
    /// <summary>
    /// Shared UI Toolkit helpers for the code-built menu / settings / pause screens — a small palette + styled
    /// element factories (so every screen reads in one visual language) plus runtime plumbing: loading the
    /// shared <c>PanelSettings</c> (from Resources) and ensuring an <c>EventSystem</c> with an
    /// <c>InputSystemUIInputModule</c> exists. Runtime UITK receives pointer/click events THROUGH the
    /// EventSystem, and this project uses the Input System (1.19.0), so the module must be the Input-System one,
    /// not the legacy StandaloneInputModule — without it the buttons are silently dead.
    /// </summary>
    public static class MenuUi
    {
        public static readonly Color Bg = new(0.04f, 0.05f, 0.07f, 0.96f);
        public static readonly Color PanelBg = new(0.09f, 0.11f, 0.15f, 0.98f);
        public static readonly Color Accent = new(0.30f, 0.85f, 1f, 1f);   // Aether cyan
        public static readonly Color TextCol = new(0.86f, 0.92f, 0.97f, 1f);
        public static readonly Color SubCol = new(0.60f, 0.68f, 0.76f, 1f);

        public static PanelSettings LoadPanelSettings()
            => Resources.Load<PanelSettings>("RuntimePanelSettings");

        public static void EnsureEventSystem()
        {
            if (UnityEngine.Object.FindFirstObjectByType<EventSystem>() != null) return;
            var go = new GameObject("EventSystem");
            go.AddComponent<EventSystem>();
            go.AddComponent<InputSystemUIInputModule>();
        }

        public static VisualElement FullScreenRoot(bool dim)
        {
            var root = new VisualElement();
            root.style.position = Position.Absolute;
            root.style.left = 0; root.style.right = 0; root.style.top = 0; root.style.bottom = 0;
            root.style.alignItems = Align.Center;
            root.style.justifyContent = Justify.Center;
            if (dim) root.style.backgroundColor = Bg;
            return root;
        }

        public static VisualElement Card(string titleText)
        {
            var card = new VisualElement();
            card.style.backgroundColor = PanelBg;
            card.style.paddingLeft = 28; card.style.paddingRight = 28;
            card.style.paddingTop = 22; card.style.paddingBottom = 22;
            card.style.minWidth = 380;
            card.style.alignItems = Align.Stretch;
            Round(card, 10);
            Border(card, new Color(Accent.r, Accent.g, Accent.b, 0.25f), 1);
            if (!string.IsNullOrEmpty(titleText)) card.Add(Title(titleText));
            return card;
        }

        public static Label Title(string text)
        {
            var l = new Label(text);
            l.style.unityFontStyleAndWeight = FontStyle.Bold;
            l.style.fontSize = 26;
            l.style.color = Accent;
            l.style.unityTextAlign = TextAnchor.MiddleCenter;
            l.style.marginBottom = 16;
            var theme = HudTheme.Get();
            if (theme != null) theme.ApplyDisplay(l.style);
            return l;
        }

        public static Label Caption(string text)
        {
            var l = new Label(text);
            l.style.fontSize = 13;
            l.style.color = SubCol;
            l.style.unityTextAlign = TextAnchor.MiddleCenter;
            l.style.marginTop = 8; l.style.marginBottom = 6;
            var theme = HudTheme.Get();
            if (theme != null) theme.ApplyBodyLight(l.style);
            return l;
        }

        public static Button Button(string text, Action onClick)
        {
            var b = new Button(onClick) { text = text };
            b.style.height = 40;
            b.style.fontSize = 16;
            b.style.marginTop = 5; b.style.marginBottom = 5;
            b.style.color = TextCol;
            b.style.backgroundColor = new Color(0.16f, 0.20f, 0.27f, 1f);
            b.style.unityFontStyleAndWeight = FontStyle.Bold;
            Round(b, 6);
            Border(b, new Color(0f, 0f, 0f, 0f), 0);
            var theme = HudTheme.Get();
            if (theme != null) theme.ApplyBody(b.style);
            return b;
        }

        public static Button SmallButton(string text, Action onClick)
        {
            var b = Button(text, onClick);
            b.style.width = 36; b.style.height = 30;
            b.style.marginLeft = 4; b.style.marginRight = 4;
            return b;
        }

        public static void Round(VisualElement e, float r)
        {
            e.style.borderTopLeftRadius = r; e.style.borderTopRightRadius = r;
            e.style.borderBottomLeftRadius = r; e.style.borderBottomRightRadius = r;
        }

        public static void Border(VisualElement e, Color c, float w)
        {
            e.style.borderLeftWidth = w; e.style.borderRightWidth = w;
            e.style.borderTopWidth = w; e.style.borderBottomWidth = w;
            e.style.borderLeftColor = c; e.style.borderRightColor = c;
            e.style.borderTopColor = c; e.style.borderBottomColor = c;
        }
    }
}