using System;
using UnityEngine;
using UnityEngine.UIElements;

namespace ProjectM.Client
{
    /// <summary>
    /// Code-built UI Toolkit settings panel (Graphics + Audio) shared by the main menu and the in-game pause
    /// overlay. Binds to <see cref="SettingsService"/>: edits a working copy, previews audio live, and persists
    /// + applies on Apply/Back. Enum settings use compact "&lt; value &gt;" cycle rows (robust, no dropdown-popup
    /// theming); volumes use sliders with a live percentage readout.
    /// </summary>
    public static class SettingsScreen
    {
        public static VisualElement Build(Action onBack)
        {
            var working = SettingsService.Current;

            var root = MenuUi.FullScreenRoot(true);
            var card = MenuUi.Card("SETTINGS");
            card.style.minWidth = 480;
            root.Add(card);

            // ---------------- Graphics ----------------
            card.Add(MenuUi.Caption("— GRAPHICS —"));

            var resolutions = Screen.resolutions;
            int resIndex = FindResIndex(resolutions, working.ResWidth, working.ResHeight);
            card.Add(CycleRow("Resolution",
                () => resolutions.Length > 0 ? ResLabel(resolutions[Mathf.Clamp(resIndex, 0, resolutions.Length - 1)]) : $"{working.ResWidth}x{working.ResHeight}",
                dir =>
                {
                    if (resolutions.Length == 0) return;
                    resIndex = Wrap(resIndex + dir, resolutions.Length);
                    var r = resolutions[resIndex];
                    working.ResWidth = r.width;
                    working.ResHeight = r.height;
                    working.RefreshHz = Mathf.RoundToInt((float)r.refreshRateRatio.value);
                }));

            string[] modes = { "Exclusive", "Borderless", "Maximized", "Windowed" };
            card.Add(CycleRow("Display Mode",
                () => modes[Mathf.Clamp(working.FullScreenMode, 0, 3)],
                dir => working.FullScreenMode = Wrap(working.FullScreenMode + dir, 4)));

            var qnames = QualitySettings.names;
            card.Add(CycleRow("Quality",
                () => qnames.Length > 0 ? qnames[Mathf.Clamp(working.QualityLevel, 0, qnames.Length - 1)] : "—",
                dir => { if (qnames.Length > 0) working.QualityLevel = Wrap(working.QualityLevel + dir, qnames.Length); }));

            string[] vsync = { "Off", "On", "Half" };
            card.Add(CycleRow("V-Sync",
                () => vsync[Mathf.Clamp(working.VSync, 0, 2)],
                dir => working.VSync = Wrap(working.VSync + dir, 3)));

            // ---------------- Audio ----------------
            card.Add(MenuUi.Caption("— AUDIO —"));
            card.Add(VolumeRow("Master", working.Master, v => { working.Master = v; AudioListener.volume = v; }));
            card.Add(VolumeRow("Music", working.Music, v => { working.Music = v; GameVolume.Music = v; }));
            card.Add(VolumeRow("SFX", working.Sfx, v => { working.Sfx = v; GameVolume.Sfx = v; }));

            // ---------------- Buttons ----------------
            var apply = MenuUi.Button("Apply", () => SettingsService.SaveAndApply(working));
            apply.style.backgroundColor = new Color(0.12f, 0.30f, 0.22f, 1f);
            card.Add(apply);
            card.Add(MenuUi.Button("Back", () =>
            {
                SettingsService.SaveAndApply(working);
                onBack?.Invoke();
            }));

            return root;
        }

        static VisualElement CycleRow(string name, Func<string> getValue, Action<int> onCycle)
        {
            var row = Row(name);
            var val = new Label(getValue());
            val.style.flexGrow = 1;
            val.style.unityTextAlign = TextAnchor.MiddleCenter;
            val.style.color = MenuUi.TextCol;
            val.style.fontSize = 15;
            var dec = MenuUi.SmallButton("<", () => { onCycle(-1); val.text = getValue(); });
            var inc = MenuUi.SmallButton(">", () => { onCycle(+1); val.text = getValue(); });
            row.Add(dec); row.Add(val); row.Add(inc);
            return row;
        }

        static VisualElement VolumeRow(string name, float initial, Action<float> onChange)
        {
            var row = Row(name);
            var slider = new Slider(0f, 1f) { value = initial };
            slider.style.flexGrow = 1;
            var pct = new Label(Pct(initial));
            pct.style.minWidth = 52;
            pct.style.unityTextAlign = TextAnchor.MiddleRight;
            pct.style.color = MenuUi.TextCol;
            slider.RegisterValueChangedCallback(evt => { onChange(evt.newValue); pct.text = Pct(evt.newValue); });
            row.Add(slider); row.Add(pct);
            return row;
        }

        static VisualElement Row(string name)
        {
            var row = new VisualElement();
            row.style.flexDirection = FlexDirection.Row;
            row.style.alignItems = Align.Center;
            row.style.marginTop = 4; row.style.marginBottom = 4;
            var label = new Label(name);
            label.style.minWidth = 120;
            label.style.color = MenuUi.SubCol;
            label.style.fontSize = 14;
            row.Add(label);
            return row;
        }

        static string ResLabel(Resolution r) => $"{r.width} x {r.height} @ {Mathf.RoundToInt((float)r.refreshRateRatio.value)}";
        static string Pct(float v) => Mathf.RoundToInt(v * 100f) + "%";
        static int Wrap(int i, int n) => n <= 0 ? 0 : ((i % n) + n) % n;

        static int FindResIndex(Resolution[] all, int w, int h)
        {
            for (int i = 0; i < all.Length; i++)
                if (all[i].width == w && all[i].height == h) return i;
            return Mathf.Max(0, all.Length - 1); // default to the highest available
        }
    }
}