using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using ProjectI.Builds;
using ProjectI.Combat;
using ProjectI.Runs;
using ProjectI.Sessions;
using ProjectI.Settings;
using ProjectI.UI;
using UnityEngine;
using UnityEngine.UIElements;
using Cursor = UnityEngine.Cursor;

namespace ProjectI.Menu
{
    [DefaultExecutionOrder(-1000)]
    [RequireComponent(typeof(UIDocument))]
    public sealed class MainMenuController : MonoBehaviour
    {
        [SerializeField] private AbilityDefinition[] abilityDefinitions;
        [SerializeField] private int[] unlockedAbilityIds;
        private readonly MainMenuNavigation navigation = new MainMenuNavigation();
        private readonly Dictionary<int, AbilityDefinition> definitions = new Dictionary<int, AbilityDefinition>();
        private AbilityLibraryState libraryState;
        private AbilityLibraryPresenter library;
        private readonly List<int> weaponIds = new List<int>();
        private PrototypeSessionController session;
        private VisualElement screen;
        private SettingsPanel settings;
        private DamageVignetteElement vignette;
        private DropdownField firstWeapon, secondWeapon;
        private PlayerBuildState preview;
        private AbilityUnlockState unlocks;
        private IVisualElementScheduledItem refreshTask;
        private bool initialized, operation, wasConnected, localReady;
        private int lifetime;
        private string feedback = "";
        private readonly List<(Button Button, Action Callback)> buttonCallbacks = new List<(Button,Action)>();
        private readonly List<(VisualElement Control,EventCallback<FocusInEvent> Callback)> focusCallbacks=new List<(VisualElement,EventCallback<FocusInEvent>)>();

        private void OnEnable() { }
        private void Start() { Initialize(); }
        private void Initialize()
        {
            if (initialized) return;
            session = PrototypeSessionController.Instance;
            if (session == null) session = FindAnyObjectByType<PrototypeSessionController>();
            var documentRoot=GetComponent<UIDocument>().rootVisualElement;
            documentRoot.AddToClassList("prototype-ui-root");
            screen = documentRoot.Q("menuScreen");
            if (screen == null || session == null) return;
            initialized = true; lifetime++; operation=false; navigation.Reset();
            screen.RegisterCallback<KeyDownEvent>(OnKeyDown);
            vignette = new DamageVignetteElement(); screen.Insert(0, vignette);
            settings = new SettingsPanel(screen, () => { navigation.Back(); ShowPage(); });
            ConfigureChoices();
            Bind("openWeapons", () => Open("weapons")); Bind("openAbilities", () => Open("abilities"));
            Bind("lobbyWeapons", () => Open("weapons")); Bind("lobbyAbilities", () => Open("abilities"));
            Bind("openSettings", () => Open("settings")); Bind("openJoin", () => Open("join")); Bind("openLobby", () => Open("lobby"));
            Bind("menuBack", Back); Bind("hostGame", () => RunOperation(session.HostAsync, true));
            Bind("cancelConnection", CancelConnection);
            Bind("joinGame", () => RunOperation(() => session.JoinAsync(screen.Q<TextField>("menuJoinCode").value), true));
            Bind("leaveGame", () => RunOperation(session.LeaveAsync, false));
            Bind("startGame", () => RunOperation(session.StartRunAsync, true));
            Bind("copyJoinCode", () => { GUIUtility.systemCopyBuffer = session.JoinCode; feedback = "Join code copied."; Refresh(); });
            Bind("saveWeapons", ApplyLoadout); Bind("saveAbilities", ApplyLoadout);
            Bind("discardWeapons", DiscardLoadout); Bind("discardAbilities", DiscardLoadout);
            Bind("readyGame", () => { if (operation || session.Busy) return; session.SetReady(!localReady); Refresh(); });
            Bind("quitGame", () => { if (!operation && !session.Busy) Application.Quit(); });
            Bind("acknowledgeResults",()=>{var result=PrototypeRunDirector.CachedResult;RunResultsVisibility.Dismiss(result);if(result!=null)PrototypeRunDirector.AcknowledgeCachedResult(result.RunId);navigation.Reset();ShowPage();});
            session.Changed += Refresh;
            refreshTask = screen.schedule.Execute(Refresh).Every(100);
            LocalPlayerSettings.SetInputBlocked(this, true); Cursor.lockState = CursorLockMode.None; Cursor.visible = true;
            if(RunResultsVisibility.ShouldShow(PrototypeRunDirector.CachedResult))
            {navigation.Open("results");screen.Q<Label>("retainedRunResults").text=RunPanels.FormatResult(PrototypeRunDirector.CachedResult);}
            ShowPage(); Refresh();
        }

        private void Bind(string name, Action callback)
        { var button = screen.Q<Button>(name); button.clicked += callback; buttonCallbacks.Add((button,callback));TrackFocus(button); }
        private void TrackFocus(VisualElement control)
        {
            EventCallback<FocusInEvent> callback=_=>
            {
                if(!initialized)return;var scroll=screen.Q<ScrollView>("pageScroll");
                if(scroll.Contains(control))scroll.ScrollTo(control);
            };
            control.RegisterCallback(callback);focusCallbacks.Add((control,callback));
        }
        private void Open(string page)
        {
            if (!navigation.Open(page)) return;
            if (page == "settings") {settings.Open();screen.Q<Slider>("hipFovSlider")?.Focus();}
            ShowPage();
        }
        private void Back()
        {
            if (navigation.Locked||navigation.Page=="results") return;
            if (settings.IsOpen) { settings.Close(); return; }
            if (navigation.Back()) ShowPage();
        }
        private void ShowPage()
        {
            screen.EnableInClassList("menu-abilities-wide",navigation.Page=="abilities");
            var back=screen.Q<Button>("menuBack");var backParent=navigation.Page=="abilities"?screen.Q(className:"library-footer-actions"):screen.Q(className:"menu-frame");
            if(back.parent!=backParent){if(navigation.Page=="abilities")backParent.Insert(0,back);else backParent.Add(back);}
            screen.Q<Label>("menuEyebrow").text=navigation.Page=="abilities"?"INDIE FPS ROGUELIKE / PREPARE A RUN":"INDIE FPS ROGUELIKE";
            screen.Q("pageScroll").EnableInClassList("hidden",navigation.Page=="abilities");
            foreach (string page in new[] { "home", "weapons", "abilities", "join", "lobby", "results" })
                screen.Q(page + "Page").EnableInClassList("hidden", navigation.Page != page);
            screen.Q<Button>("menuBack").EnableInClassList("hidden", navigation.Page == "home" || navigation.Page == "settings" || navigation.Page=="results");
            screen.Q<Label>("pageTitle").text = navigation.Page switch
            { "weapons" => "Choose your weapons", "abilities" => "Choose your abilities", "join" => "Join a friend", "lobby" => "Private lobby", "settings" => "Local settings", "results"=>"Run results", _ => "Build. Aim. Survive." };
            screen.Q<ScrollView>("pageScroll").scrollOffset = Vector2.zero;
            screen.schedule.Execute(() =>
            {
                if (!initialized || navigation.Page == "settings") return;
                if(navigation.Page=="abilities"){library?.FocusInitialControl();return;}
                var page = screen.Q(navigation.Page + "Page");
                var field = page?.Query<DropdownField>().ToList().FirstOrDefault();
                if (field != null) field.Focus(); else page?.Q<Button>()?.Focus();
            }).ExecuteLater(1);
        }

        private void ConfigureChoices()
        {
            library?.Dispose();definitions.Clear();weaponIds.Clear();screen.Q("weaponChoices").Clear();
            foreach (var definition in abilityDefinitions ?? Array.Empty<AbilityDefinition>())
                if (definition != null && definition.id > 0 && !definitions.ContainsKey(definition.id)) definitions.Add(definition.id, definition);
            unlocks = new AbilityUnlockState(unlockedAbilityIds != null && unlockedAbilityIds.Length > 0 ? unlockedAbilityIds : definitions.Keys);
            var catalog = definitions.ToDictionary(x => x.Key, x => x.Value.Tuning);
            try
            {
                var saved=LocalLoadoutStore.LoadValidated(catalog,unlocks);
                LocalBuildPreference.Selected=saved.Build;LocalWeaponPreference.First=saved.FirstWeapon;LocalWeaponPreference.Second=saved.SecondWeapon;
            }
            catch(InvalidOperationException){feedback="The available roster cannot fill every build slot.";}
            preview = new PlayerBuildState(catalog, unlocks);
            foreach (var weapon in WeaponRoster.Entries) if (weapon != null) weaponIds.Add(weapon.weaponId);
            var names = weaponIds.Select(id => WeaponRoster.Get(id).displayName).ToList();
            firstWeapon = new DropdownField("Weapon 1", names, Math.Max(0,weaponIds.IndexOf(LocalWeaponPreference.First)));
            secondWeapon = new DropdownField("Weapon 2", names, Math.Max(0,weaponIds.IndexOf(LocalWeaponPreference.Second)));
            firstWeapon.AddToClassList("menu-choice"); secondWeapon.AddToClassList("menu-choice");
            screen.Q("weaponChoices").Add(firstWeapon); screen.Q("weaponChoices").Add(secondWeapon);
            TrackFocus(firstWeapon);TrackFocus(secondWeapon);
            firstWeapon.RegisterValueChangedCallback(_ => DraftChanged()); secondWeapon.RegisterValueChangedCallback(_ => DraftChanged());
            libraryState=new AbilityLibraryState(catalog,unlocks,LocalBuildPreference.Selected);
            library=new AbilityLibraryPresenter(screen.Q("abilityLibrary"),definitions,unlocks,libraryState,DraftChanged);
            RefreshDraft();
        }
        private BuildLoadout Draft() => libraryState.Draft;
        private bool DraftValid() => libraryState!=null && preview.TryEquip(Draft(), false) && firstWeapon.index >= 0 && secondWeapon.index >= 0 && firstWeapon.index != secondWeapon.index;
        private void DiscardLoadout()
        {
            if(operation||session.Busy||session.RunLoadoutsLocked||session.RunStarted)return;
            bool changed=!Draft().Equals(LocalBuildPreference.Selected)||weaponIds[firstWeapon.index]!=LocalWeaponPreference.First||weaponIds[secondWeapon.index]!=LocalWeaponPreference.Second;
            firstWeapon.SetValueWithoutNotify(WeaponRoster.Get(LocalWeaponPreference.First).displayName);
            secondWeapon.SetValueWithoutNotify(WeaponRoster.Get(LocalWeaponPreference.Second).displayName);
            libraryState.Restore(LocalBuildPreference.Selected);library.Refresh();if(changed)DraftChanged();RefreshDraft();Refresh();
        }
        private void DraftChanged()
        { if (session.Connected) session.SetReady(false); localReady = false; feedback = "Apply your selection before readying."; RefreshDraft(); Refresh(); }
        private void RefreshDraft()
        {
            var text = new StringBuilder();
            foreach (int index in new[] { firstWeapon.index, secondWeapon.index })
            {
                if (index < 0 || index >= weaponIds.Count) continue;
                var weapon = WeaponRoster.Get(weaponIds[index]);
                text.AppendLine($"{weapon.displayName}: {weapon.pelletCount} × {weapon.damage:0.#} damage · {weapon.rateOfFire:0.##} shots/s · {weapon.magazineSize} rounds · {weapon.reloadDuration:0.#}s reload");
            }
            screen.Q<Label>("weaponDescription").text = text.ToString();
            bool valid = DraftValid(); var stats = preview.Stats;
            screen.Q<Label>("buildPreview").text = valid
                ? $"HP {stats.MaximumHealth:0.#} · normal shield 50 · speed {stats.MoveSpeed:0.##} m/s · gun {stats.AttackDamageMultiplier:0.##}× · ability {stats.AbilityDamageMultiplier:0.##}×"
                : "Choose distinct weapons, two distinct passives and three distinct normal abilities.";
        }
        private void ApplyLoadout()
        {
            if (operation || session.Busy || session.RunLoadoutsLocked || session.RunStarted || !DraftValid()) { feedback = "Complete a valid selection first."; Refresh(); return; }
            LocalBuildPreference.Selected = Draft(); LocalWeaponPreference.First = weaponIds[firstWeapon.index]; LocalWeaponPreference.Second = weaponIds[secondWeapon.index];
            LocalLoadoutStore.Save(new LocalLoadoutRecord{Build=LocalBuildPreference.Selected,FirstWeapon=LocalWeaponPreference.First,SecondWeapon=LocalWeaponPreference.Second});
            session.SubmitLocalLoadout(LocalBuildPreference.Selected,LocalWeaponPreference.First,LocalWeaponPreference.Second);
            feedback = session.Connected?"Loadout saved. Awaiting host acceptance; Apply again to retry.":"Loadout saved locally."; Refresh();
        }
        private async void RunOperation(Func<Task> action, bool lobby)
        {
            if (operation || session.Busy) return;
            operation = true; int token = lifetime; Refresh();
            try
            {
                await action();
                if (!initialized || token != lifetime) return;
                feedback = ""; navigation.Locked = false;
                if (lobby && session.Connected) { navigation.Reset(); navigation.Open("lobby"); }
                else if (!session.Connected) navigation.Reset();
                ShowPage();
            }
            catch (Exception exception) { if (initialized && token == lifetime) feedback = "Operation failed (" + exception.GetType().Name + "). Try again."; }
            finally { if (initialized && token == lifetime) { operation = false; Refresh(); } }
        }
        private async void CancelConnection()
        {
            if(!session.CanCancelConnection)return;int token=lifetime;
            screen.Q<Button>("cancelConnection").SetEnabled(false);
            try{await session.CancelConnectionAsync();}
            catch(Exception error){if(initialized&&token==lifetime){feedback="Could not cancel connection ("+error.GetType().Name+").";Refresh();}}
        }

        private void Refresh()
        {
            if (!initialized || session == null) return;
            if(navigation.Page=="results"&&!RunResultsVisibility.ShouldShow(PrototypeRunDirector.CachedResult)){navigation.Reset();ShowPage();}
            navigation.Locked = operation || session.Busy || session.RunLoadoutsLocked;
            bool connected = session.Connected;
            if (wasConnected && !connected && !operation) { settings.Close(); navigation.Reset(); feedback = ""; ShowPage(); }
            wasConnected = connected;
            screen.Q<Label>("menuStatus").text = string.IsNullOrEmpty(feedback) ? session.Status : feedback + "\n" + session.Status;
            if(navigation.Page=="abilities")
            {bool guided=!screen.Q("guidedBuilds").ClassListContains("hidden");screen.Q<Label>("pageTitle").text=guided?"Start with a build":"Choose your abilities";screen.Q<Label>("menuStatus").text=guided?"Editable recipes for learning the loop. Every slot stays classless.":"Choose a slot, inspect a candidate, then replace or swap.";}
            screen.Q<Label>("loadoutSummary").text = "Weapons: " + WeaponRoster.Get(LocalWeaponPreference.First)?.displayName + " / " + WeaponRoster.Get(LocalWeaponPreference.Second)?.displayName + "\nAbilities: " + LoadoutSummary(LocalBuildPreference.Selected);
            screen.Q<Label>("lobbyCode").text = "Join code: " + session.JoinCode;
            var rosterText = new StringBuilder(); localReady = session.LocalReady;
            foreach (var player in session.Roster)
            {
                rosterText.AppendLine(player.DisplayName + " · " + (player.ValidLoadout ? player.Ready ? "Ready" : "Preparing build" : "Invalid build"));
            }
            screen.Q<Label>("lobbyRoster").text = rosterText.Length > 0 ? rosterText.ToString() : session.PlayerCount + "/4 players";
            screen.Q<Button>("readyGame").text = localReady ? "Not ready" : "Ready";
            screen.Q<Button>("startGame").EnableInClassList("hidden", !session.IsHost);
            screen.Q<Label>("startReason").text = session.IsHost ? session.StartBlockedReason : "Waiting for the host to start the run.";
            screen.Q<Button>("hostGame").EnableInClassList("hidden",connected); screen.Q<Button>("openJoin").EnableInClassList("hidden",connected);
            screen.Q<Button>("openLobby").EnableInClassList("hidden",!connected);
            foreach (var callback in buttonCallbacks) callback.Button.SetEnabled(!navigation.Locked);
            screen.Q<Button>("cancelConnection").EnableInClassList("hidden",!session.CanCancelConnection);
            screen.Q<Button>("cancelConnection").SetEnabled(session.CanCancelConnection);
            library?.SetEditingAllowed(!navigation.Locked&&!session.RunStarted);
            firstWeapon.SetEnabled(!navigation.Locked && !session.RunStarted); secondWeapon.SetEnabled(!navigation.Locked && !session.RunStarted);
            bool validDraft = DraftValid(); screen.Q<Button>("saveWeapons").SetEnabled(!navigation.Locked && validDraft); screen.Q<Button>("saveAbilities").SetEnabled(!navigation.Locked && validDraft);
            bool dirty = !validDraft || !Draft().Equals(LocalBuildPreference.Selected) || weaponIds[firstWeapon.index] != LocalWeaponPreference.First || weaponIds[secondWeapon.index] != LocalWeaponPreference.Second;
            var acknowledged=session.Roster.FirstOrDefault(x=>session.Network!=null&&x.OwnerId==session.Network.LocalClientId);
            bool installed=acknowledged!=null&&acknowledged.ValidLoadout&&acknowledged.Build.Equals(LocalBuildPreference.Selected)&&acknowledged.FirstWeapon==LocalWeaponPreference.First&&acknowledged.SecondWeapon==LocalWeaponPreference.Second;
            if(installed&&!dirty&&feedback.StartsWith("Loadout saved. Awaiting",StringComparison.Ordinal))feedback="Loadout accepted by host.";
            screen.Q<Label>("abilitySaveStatus").text=dirty?"Draft changed · apply before readying. Apply saves weapons and abilities.":!connected?"Saved loadout · saved locally":installed?"Saved loadout · ready to return to lobby":"Awaiting host acceptance. Apply loadout again to retry.";
            screen.Q<Button>("readyGame").SetEnabled(!navigation.Locked && validDraft && !dirty && connected && installed);
            screen.Q<Button>("startGame").SetEnabled(!navigation.Locked && session.CanStart);
            screen.Q<TextField>("menuJoinCode").SetEnabled(!navigation.Locked);
        }
        private string LoadoutSummary(BuildLoadout loadout)
        { string Name(int id) => definitions.TryGetValue(id,out var value) ? value.displayName : "Unavailable"; return Name(loadout.PassiveFirst)+" / "+Name(loadout.PassiveSecond)+" · Q "+Name(loadout.ActiveFirst)+" · F "+Name(loadout.ActiveSecond)+" · C "+Name(loadout.ActiveThird)+" · Z "+Name(loadout.Ultimate); }
        private void Update()
        {
            if (!initialized) Initialize();
        }
        private void OnKeyDown(KeyDownEvent value)
        { if(value.keyCode==KeyCode.Escape&&Application.isFocused){Back();value.StopPropagation();} }
        private void OnDisable()
        {
            lifetime++; initialized = false; refreshTask?.Pause(); refreshTask = null;
            screen?.UnregisterCallback<KeyDownEvent>(OnKeyDown);
            if (session != null) session.Changed -= Refresh;
            foreach (var callback in buttonCallbacks) callback.Button.clicked -= callback.Callback;
            foreach(var callback in focusCallbacks)callback.Control.UnregisterCallback(callback.Callback);
            focusCallbacks.Clear();
            buttonCallbacks.Clear(); settings?.Dispose(); settings = null; vignette?.RemoveFromHierarchy(); vignette = null;
            library?.Dispose();library=null;libraryState=null;
            LocalPlayerSettings.SetInputBlocked(this,false);
        }
    }
}