Project-M/Assets/_Project/Scripts/Client/UI/HowToPlayPanel.cs

using System;
using System.Collections.Generic;
using ProjectM.Simulation;
using UnityEngine;
using UnityEngine.UIElements;

namespace ProjectM.Client
{
    /// <summary>
    /// The replayable "How to Play" reference card (UI Toolkit), built on <see cref="MenuUi"/> like
    /// <see cref="SettingsScreen"/> and reachable from BOTH the main menu and the in-game pause overlay. Tabbed,
    /// one glanceable page each: Controls (for the chosen class), The Loop (the annotated win-condition diagram —
    /// the single highest-value page, since the inverted goal "clear expeditions to win" is the #1 new-player
    /// confusion), Build &amp; Economy, Threats, Win/Lose. Static + stateless: <see cref="Build"/> returns a fresh
    /// full-screen panel each call; the caller owns its lifetime (RemoveFromHierarchy on close).
    /// </summary>
    public static class HowToPlayPanel
    {
        static readonly string[] Tabs = { "Controls", "The Loop", "Build & Economy", "Threats", "Win / Lose" };

        public static VisualElement Build(Action onClose)
        {
            var root = MenuUi.FullScreenRoot(true);
            var card = MenuUi.Card("HOW TO PLAY");
            card.style.minWidth = 640;
            card.style.maxWidth = 780;
            root.Add(card);

            var tabBar = new VisualElement();
            tabBar.style.flexDirection = FlexDirection.Row;
            tabBar.style.justifyContent = Justify.Center;
            tabBar.style.marginBottom = 12;
            card.Add(tabBar);

            var content = new VisualElement();
            content.style.minHeight = 230;
            card.Add(content);

            var tabButtons = new List<Button>();
            void Show(int idx)
            {
                content.Clear();
                BuildTab(content, idx);
                for (int i = 0; i < tabButtons.Count; i++)
                    tabButtons[i].style.backgroundColor = i == idx
                        ? new Color(0.16f, 0.34f, 0.42f, 1f)
                        : new Color(0.16f, 0.20f, 0.27f, 1f);
            }

            for (int i = 0; i < Tabs.Length; i++)
            {
                int idx = i;
                var b = MenuUi.Button(Tabs[i], () => Show(idx));
                b.style.height = 32; b.style.fontSize = 13;
                b.style.marginLeft = 3; b.style.marginRight = 3;
                b.style.flexGrow = 1;
                tabButtons.Add(b);
                tabBar.Add(b);
            }

            card.Add(MenuUi.Button("Back", () => onClose?.Invoke()));
            Show(0);
            return root;
        }

        static void BuildTab(VisualElement c, int idx)
        {
            switch (idx)
            {
                case 0: // Controls (chosen class)
                    bool ranger = WorldLauncher.SelectedClass == (byte)CharacterId.Ranger;
                    Head(c, ranger ? "CLASS:  Ranger (ranged anchor)" : "CLASS:  Warrior (melee anchor)");
                    Body(c, "Move  —  WASD  /  Left Stick");
                    Body(c, "Aim  —  Mouse cursor  /  Right Stick");
                    Body(c, "Attack  —  LMB  /  RT   (your primary verb)");
                    Body(c, "Build menu  —  Tab  /  Y");
                    Body(c, "Place / Cancel (in build)  —  LMB / RMB   (A / B on gamepad)");
                    Body(c, "Deposit at base  —  G");
                    Body(c, "Inventory  —  I");
                    Body(c, "Pause  —  Esc");
                    break;
                case 1: // The Loop
                    Head(c, "THE LOOP  —  expeditions are how you win");
                    Body(c, "1.  BASE (Calm) — mine Ore, build Turrets + a Fabricator to defend your Engine Core.");
                    Body(c, "2.  EXPEDITION — walk to the Gate and fight the wave. CLEARING it is the progress beat.");
                    Body(c, "3.  RETURN — come home to bank the clear:  +1 on the Engine meter.");
                    Body(c, "4.  SIEGE — returning provokes a retaliation attack. Defend the Core!");
                    Body(c, "5.  WIN — fill the Engine meter, then hold the final siege.");
                    Body(c, "The Engine meter (top of screen) is the goal — base sieges are a consequence, not the win.");
                    break;
                case 2: // Build & Economy
                    Head(c, "RESOURCES & BUILDING");
                    Body(c, "Ore  —  main currency. Mine it by attacking the glowing nodes at base.");
                    Body(c, "Turret (40 Ore)  —  auto-fires at enemies. Needs Charge as ammo.");
                    Body(c, "Fabricator (30 Ore)  —  converts Ore → Charge so turrets keep firing.");
                    Body(c, "Wall (Biomass)  —  a cheap barrier that blocks enemies.");
                    Body(c, "Aether  —  spend it on UPGRADE DMG to boost your damage.");
                    Body(c, "Open Build with Tab (Y), pick a piece, click a green tile to place it.");
                    break;
                case 3: // Threats
                    Head(c, "THREATS");
                    Body(c, "Husks assault the base during a Siege — keep them off the Engine Core.");
                    Body(c, "A Husk that reaches the Core drains it. Lose the Core in the final siege and the run ends.");
                    Body(c, "Expeditions throw waves at you — clear them all to bank the win.");
                    Body(c, "Enemy variety scales the deeper you push.");
                    break;
                default: // Win / Lose
                    Head(c, "WIN  /  LOSE");
                    Body(c, "WIN — clear expeditions to fill the Engine meter, then hold the final siege.");
                    Body(c, "LOSE — the Engine Core falls during the final siege.");
                    Body(c, "A Core breach mid-run is only a setback: resources lost, the Core recovers in Calm.");
                    break;
            }
        }

        static void Head(VisualElement c, string t)
        {
            var l = new Label(t);
            l.style.color = MenuUi.Accent;
            l.style.fontSize = 16;
            l.style.unityFontStyleAndWeight = FontStyle.Bold;
            l.style.marginBottom = 8;
            l.style.whiteSpace = WhiteSpace.Normal;
            var th = HudTheme.Get();
            if (th != null) th.ApplyDisplay(l.style);
            c.Add(l);
        }

        static void Body(VisualElement c, string t)
        {
            var l = new Label(t);
            l.style.color = MenuUi.TextCol;
            l.style.fontSize = 14;
            l.style.marginBottom = 5;
            l.style.whiteSpace = WhiteSpace.Normal;
            var th = HudTheme.Get();
            if (th != null) th.ApplyBody(l.style);
            c.Add(l);
        }
    }
}