using System;
using System.Linq;
using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.UIElements;

namespace Ironspore
{
    public sealed partial class GameHud : MonoBehaviour
    {
        GameSession game;
        VisualElement root;
        Label mission, prompt, status, notice, telemetry;
        ProgressBar armor, energy, cargo;
        VisualElement cross, controlsHint;
        CombatInstruments instruments;
        enum View
        {
            Hangar, Field, Cargo, Part, Routes, Pause, Settings
        }
        View view;
        int partSlot, partIndex;
        PanelSettings panelSettings;
        VisualElement languageControl, languageMenu, languageDismiss;
        Button languageButton;
        int lastLanguageActivationFrame = -1;
        int lastLanguageNavigationFrame = -1;
        Label hangarNotice;
        SettingsScreen settingsScreen;
        int menuInputFrame = -1;
        public bool SettingsOpen => view == View.Settings;
        public bool MenuInputConsumedThisFrame => menuInputFrame == Time.frameCount;
        string K(string action) => game.Settings.Bindings.Display(action);
        static string L(string key, params object[] args) => GameLocalization.Text(key, args);
        public void Initialize(GameSession session)
        {
            game = session;
            var document = gameObject.AddComponent<UIDocument>();
            var settings = panelSettings = Instantiate(game.uiPanel);
            settings.scaleMode = PanelScaleMode.ScaleWithScreenSize;
            settings.referenceResolution = new Vector2Int(1920, 1080);
            document.panelSettings = settings;
            root = document.rootVisualElement;
            root.styleSheets.Add(game.uiStyle);
            root.pickingMode = PickingMode.Ignore;
            root.style.unityFontDefinition = FontDefinition.FromSDFFont(game.localization.uiFont);
            root.RegisterCallback<PointerMoveEvent>(DragMove, TrickleDown.TrickleDown);
            root.RegisterCallback<PointerUpEvent>(DragEnd, TrickleDown.TrickleDown);
            root.RegisterCallback<PointerCancelEvent>(_ => ResetDrag(), TrickleDown.TrickleDown);
            root.RegisterCallback<KeyDownEvent>(HandleLanguageKey, TrickleDown.TrickleDown);
            GameLocalization.Changed += RefreshLocale;
            settingsScreen = new SettingsScreen(game.Settings, () => game.Action("Pause").WasPressedThisFrame());
        }
        void HandleLanguageKey(KeyDownEvent evt)
        {
            if (view != View.Hangar)
                return;
            if (languageMenu != null && evt.keyCode == KeyCode.Escape)
            {
                CloseLanguageMenu();
                evt.StopImmediatePropagation();
                return;
            }
            if (languageMenu != null && evt.keyCode == KeyCode.Tab)
            {
                MoveLanguageFocus(evt.shiftKey);
                evt.StopImmediatePropagation();
                return;
            }
            if (evt.keyCode != KeyCode.Return && evt.keyCode != KeyCode.KeypadEnter && evt.keyCode != KeyCode.Space)
                return;
            if (ActivateFocusedLanguage())
                evt.StopImmediatePropagation();
        }
        void MoveLanguageFocus(bool reverse)
        {
            if (lastLanguageNavigationFrame == Time.frameCount)
                return;
            lastLanguageNavigationFrame = Time.frameCount;
            var options = languageMenu.Query<Button>(className: "language-option").ToList();
            int current = options.IndexOf(root.focusController.focusedElement as Button);
            int next = (current + (reverse ? -1 : 1) + options.Count) % options.Count;
            options[next].Focus();
        }
        bool ActivateFocusedLanguage()
        {
            var focused = root.focusController.focusedElement as Button;
            if (focused == languageButton)
                ToggleLanguageMenu(languageControl.parent);
            else if (languageMenu != null && focused != null && focused.ClassListContains("language-option"))
                ChooseLocale((string)focused.userData);
            else
                return false;
            return true;
        }
        VisualElement Element(VisualElement parent, string css)
        {
            var e = new VisualElement();
            e.AddToClassList(css);
            parent.Add(e);
            return e;
        }
        Label Text(VisualElement parent, string text, string css = "body")
        {
            var l = new Label(text);
            l.AddToClassList(css);
            parent.Add(l);
            return l;
        }
        Button Button(VisualElement parent, string text, Action action, string css = "button")
        {
            var b = new Button(action) { text = text };
            foreach (string className in css.Split(' '))
                b.AddToClassList(className);
            parent.Add(b);
            return b;
        }
        void Clear()
        {
            ResetDrag();
            settingsScreen?.Close();
            root.Clear();
            mission = prompt = status = notice = telemetry = null;
            armor = energy = cargo = null;
            cross = controlsHint = null;
            instruments = null;
            hangarNotice = null;
            languageControl = languageMenu = languageDismiss = null;
            languageButton = null;
        }
        void RefreshLocale()
        {
            switch (view)
            {
                case View.Hangar:
                    ShowHangar();
                    languageButton?.Focus();
                    break;
                case View.Field:
                    ShowField();
                    break;
                case View.Cargo:
                    ShowCargo();
                    break;
                case View.Part:
                    ShowPart(partSlot, partIndex);
                    break;
                case View.Routes:
                    ShowRoutes();
                    break;
                case View.Pause:
                    ShowPause();
                    break;
                case View.Settings:
                    settingsScreen.RefreshLocale();
                    break;
            }
        }
        void AddLanguageControl(VisualElement page)
        {
            languageControl = Element(page, "language-control");
            var locale = Array.Find(GameLocalization.Catalog.locales, x => x.code == GameLocalization.CurrentCode);
            languageButton = Button(languageControl, L("ui.home.language", locale.nativeName), () => ToggleLanguageMenu(page), "language-button");
            languageButton.name = "language-toggle";
            languageButton.tooltip = L("ui.home.languageHelp");
        }
        void ToggleLanguageMenu(VisualElement page)
        {
            if (lastLanguageActivationFrame == Time.frameCount)
                return;
            lastLanguageActivationFrame = Time.frameCount;
            if (languageMenu != null)
                CloseLanguageMenu();
            else
                OpenLanguageMenu(page);
        }
        void ChooseLocale(string code)
        {
            if (lastLanguageActivationFrame == Time.frameCount)
                return;
            lastLanguageActivationFrame = Time.frameCount;
            CloseLanguageMenu();
            GameLocalization.SelectLocale(code);
        }
        void OpenLanguageMenu(VisualElement page)
        {
            languageDismiss = Element(page, "language-dismiss");
            languageDismiss.RegisterCallback<PointerDownEvent>(evt => { CloseLanguageMenu(); evt.StopPropagation(); });
            languageControl.BringToFront();
            languageMenu = Element(languageControl, "language-menu");
            languageMenu.name = "language-menu";
            Text(languageMenu, L("ui.home.languageHelp"), "language-heading");
            Button selected = null;
            foreach (var locale in GameLocalization.Catalog.locales)
            {
                string code = locale.code;
                bool current = code == GameLocalization.CurrentCode;
                var option = Button(languageMenu, current ? L("ui.language.current", locale.nativeName) : locale.nativeName, () => ChooseLocale(code), current ? "language-option selected" : "language-option");
                option.name = "locale-" + code;
                option.userData = code;
                if (current)
                    selected = option;
            }
            selected?.Focus();
        }
        public void CloseLanguageMenu()
        {
            languageMenu?.RemoveFromHierarchy();
            languageDismiss?.RemoveFromHierarchy();
            languageMenu = languageDismiss = null;
            languageButton?.Focus();
        }
        public void RefreshHangarNotice()
        {
            if (hangarNotice != null)
            {
                hangarNotice.text = game.Notice;
                hangarNotice.style.display = string.IsNullOrEmpty(game.Notice) ? DisplayStyle.None : DisplayStyle.Flex;
            }
        }
        public void ShowHangar()
        {
            Clear();
            view = View.Hangar;
            var page = Element(root, "hangar");
            var scroll = new ScrollView(ScrollViewMode.Vertical) { horizontalScrollerVisibility = ScrollerVisibility.Hidden };
            scroll.AddToClassList("hangar-scroll");
            page.Add(scroll);
            var content = Element(scroll, "hangar-content");
            Text(content, "IRONSPORE", "title");
            Text(content, L("ui.home.subtitle"), "subtitle");
            Text(content, game.Report, "body");
            var frames = Element(content, "row");
            for (int i = 0; i < game.chassis.Length; i++)
            {
                int choice = i;
                var frame = game.chassis[i];
                Button(frames, frame.LocalizedName + "\n" + frame.LocalizedDescription, () => { game.SelectedChassis = choice; ShowHangar(); }, i == game.SelectedChassis ? "frame selected" : "frame");
            }
            Text(content, L("ui.home.loadout"), "section");
            for (int slot = 0; slot < 4; slot++)
            {
                int s = slot;
                var p = game.Part(s, game.InitialEquipment[s]);
                Button(content, L("ui.home.part", L("ui.slot." + s), p.LocalizedName, p.mass, p.power), () => { game.SelectedInstances[s] = null; game.InitialEquipment[s] = (game.InitialEquipment[s] + 1) % game.PartCount(s); ShowHangar(); }, "loadout");
            }
            float mass = 0, power = 0;
            for (int i = 0; i < 4; i++)
            {
                var p = game.Part(i, game.InitialEquipment[i]);
                mass += p.mass;
                power += p.power;
            }
            var selected = game.chassis[game.SelectedChassis];
            Text(content, L("ui.home.budget", mass, selected.massCapacity, power, selected.powerCapacity), game.Fits(game.SelectedChassis, game.InitialEquipment) ? "budget" : "warning");
            var controls = Element(content, "row");
            var launch = Button(controls, L("ui.home.deploy"), game.BeginSortie, "primary");
            launch.SetEnabled(game.Fits(game.SelectedChassis, game.InitialEquipment) && game.StartingPartsUnlocked() && !game.Store.Data.run.active);
            if (!game.StartingPartsUnlocked())
                Text(content, L("ui.home.locked"), "warning");
            Button(controls, L("ui.home.range"), game.StartTrial);
            Button(controls, L("settings.title"), ShowSettings).name = "home-settings";
            if (game.Store.Data.run.active)
                Button(controls, L("ui.home.resume"), game.Resume, "primary");
            Text(content, L("ui.home.moveHint", K("Move"), K("View"), K("Boost"), K("Jump")), "hint");
            Text(content, L("ui.home.fireHint", K("Fire"), K("Aim"), K("Secondary"), K("Guard"), K("Interact")), "hint");
            var save = game.Store.Data;
            Text(content, L("ui.home.inventory"), "section");
            Text(content, L("ui.home.stock", save.alloy, save.cells, save.blueprints.Count, save.extractions, save.completed), "budget");
            foreach (var item in save.warehouse)
            {
                int slot = InventoryGrid.Slot(item.itemId);
                Button(content, L("ui.home.chooseItem", item.Name, item.uid.Substring(0, Math.Min(6, item.uid.Length))), () =>
                {
                    game.SelectedInstances[slot] = item.uid;
                    game.InitialEquipment[slot] = InventoryGrid.Index(slot, item.itemId);
                    ShowHangar();
                }, game.SelectedInstances[slot] == item.uid ? "loadout selected" : "loadout");
            }
            foreach (string blueprint in save.blueprints)
            {
                string id = blueprint;
                bool unlocked = save.unlocked.Contains(id);
                var b = Button(content, L(unlocked ? "ui.home.researched" : "ui.home.research", GameLocalization.ItemName(id)), () => game.Unlock(id), "loadout");
                b.SetEnabled(!unlocked);
                var recipe = InventoryGrid.Recipe(id);
                if (unlocked && recipe.item != null)
                    Button(content, L("ui.home.manufacture", L("equipment." + recipe.item + ".name"), recipe.alloy, recipe.cells),
                        () => { if (!game.Store.Manufacture(id)) game.Notify("notice.saveFailed"); ShowHangar(); }, "loadout")
                        .SetEnabled(!save.run.active && save.alloy >= recipe.alloy && save.cells >= recipe.cells);
            }
            hangarNotice = Text(content, game.Notice, "warning");
            RefreshHangarNotice();
            Button(content, L("ui.home.quit"), () => Application.Quit(), "quiet");
            AddLanguageControl(page);
        }
        public void ShowField()
        {
            Clear();
            view = View.Field;
            var field = Element(root, "field");
            field.pickingMode = PickingMode.Ignore;
            var top = Element(field, "topbar");
            Text(top, "IRONSPORE", "brand");
            status = Text(top, "", "status");
            var goal = Element(field, "mission");
            Text(goal, L("ui.hud.operation"), "section");
            mission = Text(goal, "", "mission-text");
            telemetry = Text(goal, "", "combat-extraction");
            cross = Element(field, "crosshair");
            cross.style.position = Position.Absolute;
            cross.style.left = Length.Percent(50);
            cross.style.top = Length.Percent(50);
            cross.style.translate = new Translate(-20, -20);
            cross.style.width = 40;
            cross.style.height = 40;
            for (int i = 0; i < 4; i++)
            {
                var arm = Element(cross, "reticle-arm");
                arm.style.position = Position.Absolute;
                arm.style.backgroundColor = new Color(.64f, 1, .9f);
                arm.style.left = i == 0 ? 0 : i == 1 ? 27 : 19;
                arm.style.top = i == 2 ? 0 : i == 3 ? 27 : 19;
                arm.style.width = i < 2 ? 13 : 2;
                arm.style.height = i < 2 ? 2 : 13;
            }
            prompt = Text(field, "", "interact");
            notice = Text(field, "", "notice");
            var bottom = Element(field, "bottom");
            instruments = new CombatInstruments(field, bottom, game);
            armor = new ProgressBar { title = L("ui.hud.armor", 0), lowValue = 0, highValue = 100 };
            armor.AddToClassList("armor");
            bottom.Add(armor);
            energy = new ProgressBar { title = L("ui.hud.energy", 0), lowValue = 0, highValue = 100 };
            energy.AddToClassList("energy");
            bottom.Add(energy);
            cargo = new ProgressBar { title = L("ui.hud.podReady", K("Inventory")), lowValue = 0, highValue = 3 };
            cargo.AddToClassList("cargo-progress");
            bottom.Add(cargo);
            controlsHint = Text(bottom, L("ui.hud.hint", K("View"), K("Boost"), K("Jump"), K("Secondary"), K("Guard"), K("Interact"), K("Inventory"), K("Cargo"), K("Pause")), "hint");
        }
        VisualElement Overlay(string heading, string body)
        {
            ShowField();
            var shade = Element(root, "overlay");
            var panel = Element(shade, "panel");
            Text(panel, heading, "heading");
            Text(panel, body, "body");
            return panel;
        }
        public void ShowPart(int slot, int index)
        {
            index = Mathf.Clamp(index, 0, game.PartCount(slot) - 1);
            int partIndex = index;
            this.partSlot = slot;
            this.partIndex = index;
            var old = game.Part(slot, game.Run.equipment[slot]);
            var next = game.Part(slot, index);
            var panel = Overlay(L("ui.refit.title"), L("ui.refit.help"));
            view = View.Part;
            Text(panel, L("ui.refit.equipped", old?.LocalizedName ?? "—", old?.mass ?? 0, old?.power ?? 0), "body");
            Text(panel, L("ui.refit.recovered", next.LocalizedName, next.mass, next.power), "budget");
            Button(panel, L("ui.refit.install"), () => game.Install(slot, partIndex), "primary");
            Button(panel, L("ui.refit.keep"), game.CloseMenu);
        }
        public void ShowRoutes()
        {
            bool split = game.Run.stage == 1;
            var panel = Overlay(L(split ? "ui.routes.split" : "ui.routes.title"), L(split ? "ui.routes.splitHelp" : "ui.routes.help"));
            view = View.Routes;
            Button(panel, L(split ? "ui.routes.boss" : "ui.routes.freight"), () => game.NextZone(0), "route");
            Button(panel, L(split ? "ui.routes.escort" : "ui.routes.power"), () => game.NextZone(1), "route");
            Button(panel, L("ui.routes.stay"), game.CloseMenu);
        }
        public void ShowPause()
        {
            var panel = Overlay(L("ui.pause.title"), L("ui.pause.help"));
            view = View.Pause;
            Button(panel, L("ui.pause.resume"), game.CloseMenu, "primary");
            Button(panel, L("settings.title"), ShowSettings).name = "pause-settings";
            if (game.Trial)
                Button(panel, L("ui.pause.range"), () => { game.CloseMenu(); game.EndSortie(true); });
            Button(panel, L("ui.pause.quit"), () => Application.Quit());
        }
        public void ShowSettings()
        {
            bool returnToPause = view == View.Pause;
            Clear();
            view = View.Settings;
            menuInputFrame = Time.frameCount;
            settingsScreen.Open(root, () =>
            {
                if (returnToPause) ShowPause();
                else ShowHangar();
                root.Q<Button>(returnToPause ? "pause-settings" : "home-settings")?.Focus();
            });
        }
        public void CancelSettingsInput() => settingsScreen.CancelInput();
        void Update()
        {
            if (SettingsOpen)
            {
                menuInputFrame = Time.frameCount;
                settingsScreen.Tick();
                return;
            }
            if (view == View.Hangar)
            {
                RefreshHangarNotice();
                if (languageMenu != null && game.Action("Pause").WasPressedThisFrame())
                    CloseLanguageMenu();
                // The project uses Input System without a uGUI EventSystem. Handle submit
                // explicitly as well as UI Toolkit events; frame guards prevent double input.
                var keys = Keyboard.current;
                if (keys != null)
                {
                    if (languageMenu != null && keys.tabKey.wasPressedThisFrame)
                        MoveLanguageFocus(keys.shiftKey.isPressed);
                    if (keys.enterKey.wasPressedThisFrame || keys.numpadEnterKey.wasPressedThisFrame || keys.spaceKey.wasPressedThisFrame)
                        ActivateFocusedLanguage();
                }
            }
            if (view == View.Cargo && selectedUid != null && Keyboard.current?.rKey.wasPressedThisFrame == true) RotateSelection();
            if (!game.InField || !game.Pilot)
                return;
            var run = game.Run;
            var p = game.Pilot;
            if (status != null)
                status.text = L("ui.hud.status", game.Trial ? L("ui.home.range") : L("ui.hud.zone", run.stage + 1), TimeSpan.FromSeconds(run.elapsed).ToString(@"mm\:ss"));
            if (mission != null)
                mission.text = L(run.routeCompleted ? "ui.hud.complete" : run.stage == 4 && !game.Trial ? run.branch == 0 ? "ui.hud.boss" : "ui.hud.escort" : run.objectiveDone ? "ui.hud.routeOpen" : "ui.hud.objective");
            if (armor != null)
            {
                armor.value = p.Health / game.chassis[run.chassis].armor * 100;
                armor.title = L("ui.hud.armor", Mathf.CeilToInt(p.Health));
            }
            if (energy != null)
            {
                energy.value = p.Energy;
                energy.title = p.Guard > 0 ? L("ui.hud.shield") : L("ui.hud.energy", Mathf.CeilToInt(p.Energy));
            }
            if (cargo != null)
            {
                cargo.value = game.CargoProgress;
                cargo.title = L(run.podUsed ? "ui.hud.podUsed" : game.CargoProgress > 0 ? "ui.hud.podPreparing" : "ui.hud.podReady", K("Inventory"));
            }
            if (prompt != null)
            {
                prompt.text = game.World.Focused ? game.World.Focused.Prompt : "";
                prompt.style.display = game.World.Focused ? DisplayStyle.Flex : DisplayStyle.None;
            }
            if (notice != null)
                notice.text = game.Notice;
            if (telemetry != null)
                telemetry.text = game.World.ExtractionRemaining < 0 ? L("ui.hud.extractionAvailable") :
                    game.World.TransportReady ? L("ui.hud.transportReady") : L("ui.hud.transportEta", Mathf.CeilToInt(game.World.ExtractionRemaining));
            if (instruments != null)
            {
                instruments.Refresh();
                controlsHint.style.display = game.Action("Aim").IsPressed() ? DisplayStyle.None : DisplayStyle.Flex;
            }
            if (cross != null)
                cross.style.opacity = p.RecentHit ? 1 : .65f;
        }
        void OnDestroy()
        {
            settingsScreen?.Close();
            GameLocalization.Changed -= RefreshLocale;
            if (panelSettings)
                Destroy(panelSettings);
        }
    }
}