// Assets/_Project/Scripts/Dev/DebugConsole.cs
using System.Collections;
using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.UIElements;
using TD.UI;

namespace TD.Dev
{
    /// <summary>
    /// Standalone debug console overlay: press the toggle key to open a text
    /// input, type a command, Enter to submit, Escape to cancel.
    /// </summary>
    /// <remarks>
    /// Deliberately decoupled from <see cref="HUDController"/> — own
    /// GameObject, own UIDocument/PanelSettings — so it can be dropped out of
    /// a build entirely by not including that GameObject, the same way
    /// <see cref="DevWaveControls"/> is kept separate from shipping systems.
    ///
    /// This first pass only wires up open/close/focus/text-capture. Submit
    /// currently just logs the typed text — command parsing/dispatch (e.g.
    /// unlocking spells) comes next.
    /// </remarks>
    [RequireComponent(typeof(UIDocument))]
    public class DebugConsole : MonoBehaviour
    {
        public static DebugConsole Instance { get; private set; }

        [Tooltip("Keyboard shortcut that opens and closes the console. Uses the new Input " +
                 "System (UnityEngine.InputSystem.Key). Backquote is the physical ` / ~ key.")]
        [SerializeField] private Key toggleKey = Key.Backquote;

        private VisualElement consoleContainer;
        private TextField commandInput;
        private bool consoleOpen;

        // Frame on which the console was opened or closed. The toggle key and Enter
        // are ignored on that frame and the next so the keypress that opened/closed
        // the console doesn't also get typed into the field or immediately submit it.
        // Mirrors HUDController's chatToggleSuppressFrame.
        private int toggleSuppressFrame = -1;

        private void Awake()
        {
            if (Instance != null && Instance != this)
            {
                Debug.LogError("[DebugConsole] Duplicate instance detected. Destroying the new one.");
                Destroy(gameObject);
                return;
            }
            Instance = this;
        }

        private void Start()
        {
            var doc = GetComponent<UIDocument>();
            if (doc == null)
            {
                Debug.LogError("[DebugConsole] No UIDocument component found.");
                return;
            }

            var root = doc.rootVisualElement;
            if (root == null)
            {
                Debug.LogError("[DebugConsole] rootVisualElement is null. " +
                                "Check that Panel Settings is assigned.");
                return;
            }

            BuildConsoleUi(root);
        }

        private void BuildConsoleUi(VisualElement uiRoot)
        {
            // Top-anchored bar, closed by default. Distinct position from the HUD's
            // bottom-left chat panel so the two never overlap.
            consoleContainer = new VisualElement();
            consoleContainer.pickingMode = PickingMode.Ignore;
            consoleContainer.style.position = Position.Absolute;
            consoleContainer.style.left = 0;
            consoleContainer.style.right = 0;
            consoleContainer.style.top = 0;
            consoleContainer.style.paddingTop = 8;
            consoleContainer.style.paddingBottom = 8;
            consoleContainer.style.paddingLeft = 12;
            consoleContainer.style.paddingRight = 12;
            consoleContainer.style.backgroundColor = new Color(0f, 0f, 0f, 0.75f);
            consoleContainer.style.display = DisplayStyle.None;

            commandInput = new TextField();
            commandInput.style.minHeight = 28;
            commandInput.style.width = Length.Percent(100);
            commandInput.maxLength = 200;
            commandInput.isDelayed = false;
            StyleConsoleInput(commandInput);

            // Focus tracking — contributes to the same flag HUDController's chat
            // input sets, so camera/builder/spell input all stay gated correctly
            // regardless of which text field currently has focus.
            commandInput.RegisterCallback<FocusInEvent>(_ => HUDController.IsTextInputActive = true);
            commandInput.RegisterCallback<FocusOutEvent>(_ => HUDController.IsTextInputActive = false);

            consoleContainer.Add(commandInput);
            uiRoot.Add(consoleContainer);
        }

        // Mirrors HUDController.StyleChatInputDark — dark background, white text,
        // a thin border, and inner padding so ascenders/descenders don't clip.
        // Green border (vs. chat's neutral gray) as a quick visual "this is the
        // debug console, not chat" cue.
        private static void StyleConsoleInput(TextField field)
        {
            var darkBg = new Color(0.05f, 0.05f, 0.05f, 0.95f);
            var borderClr = new Color(0.35f, 0.75f, 0.35f);

            field.style.backgroundColor = darkBg;
            field.style.color = Color.white;
            field.style.borderTopWidth = field.style.borderBottomWidth =
                field.style.borderLeftWidth = field.style.borderRightWidth = 1;
            field.style.borderTopColor = field.style.borderBottomColor =
                field.style.borderLeftColor = field.style.borderRightColor = borderClr;

            var inner = field.Q("unity-text-input");
            if (inner != null)
            {
                inner.style.backgroundColor = darkBg;
                inner.style.color = Color.white;
                inner.style.paddingTop = 4;
                inner.style.paddingBottom = 4;
                inner.style.paddingLeft = 6;
                inner.style.paddingRight = 6;
            }
        }

        private void Update()
        {
            var kb = Keyboard.current;
            if (kb == null) return; // no keyboard connected (e.g. headless server)

            if (Time.frameCount <= toggleSuppressFrame) return;

            if (toggleKey != Key.None && kb[toggleKey].wasPressedThisFrame)
            {
                if (consoleOpen) CloseConsole();
                else OpenConsole();
                return;
            }

            if (!consoleOpen) return;

            bool enterDown = kb.enterKey.wasPressedThisFrame || kb.numpadEnterKey.wasPressedThisFrame;
            bool escDown = kb.escapeKey.wasPressedThisFrame;

            if (enterDown) SubmitCommand();
            else if (escDown) CloseConsole();
        }

        private void OpenConsole()
        {
            if (commandInput == null) return;
            consoleContainer.style.display = DisplayStyle.Flex;
            consoleContainer.pickingMode = PickingMode.Position;
            commandInput.SetValueWithoutNotify(string.Empty);

            // Suppress the toggle key and Enter for this frame and the next so the
            // keypress that opened the console doesn't also get typed into the field.
            // Focus is deferred a frame for the same reason — UI Toolkit would
            // otherwise route the open keypress to the freshly-focused TextField.
            toggleSuppressFrame = Time.frameCount + 1;
            consoleOpen = true;
            StartCoroutine(FocusNextFrame());
        }

        private IEnumerator FocusNextFrame()
        {
            yield return null;
            if (consoleOpen && commandInput != null)
            {
                commandInput.Focus();
                commandInput.SelectAll();
            }
        }

        private void CloseConsole()
        {
            if (commandInput != null)
            {
                commandInput.SetValueWithoutNotify(string.Empty);
                commandInput.Blur();
            }
            if (consoleContainer != null)
            {
                consoleContainer.style.display = DisplayStyle.None;
                consoleContainer.pickingMode = PickingMode.Ignore;
            }

            consoleOpen = false;
            toggleSuppressFrame = Time.frameCount + 1;

            // The Enter that submitted/cancelled this console also gets polled by
            // HUDController's chat this same frame — suppress its "Enter opens chat"
            // branch so closing the debug console doesn't pop chat open too.
            HUDController.SuppressChatOpenUntilFrame = Time.frameCount + 1;
        }

        // Placeholder — command parsing/dispatch (unlocking spells, granting gold,
        // etc.) comes next. For now this just proves the text made it through.
        private void SubmitCommand()
        {
            string text = commandInput?.value ?? string.Empty;
            if (!string.IsNullOrWhiteSpace(text))
                Debug.Log($"[DebugConsole] Command entered: \"{text}\"");

            CloseConsole();
        }

        private void OnDestroy()
        {
            if (Instance == this) Instance = null;
        }
    }
}