using System;
using System.Collections.Generic;
using TMPro;
using UnityEngine;
using UnityEngine.UI;

/// <summary>
/// Binder for the "Paintings" library panel, authored in the PaintHudPanel layout prefab and wired here
/// by stable names (like <see cref="WirePanel"/> for the brush widgets). The list clones Lib_EntryTemplate
/// per saved slot; Save overwrites by name (warned while typing), Load applies immediately (re-broadcast
/// to peers when networked), Delete confirms.
/// </summary>
public partial class PaintHud
{
    // Stable widget names, matching the objects authored in the PaintHudPanel prefab.
    private const string LibListContent = "Lib_ListContent";
    private const string LibEntryTemplate = "Lib_EntryTemplate";
    private const string LibSaveButton = "Lib_Save";
    private const string LibLoadButton = "Lib_Load";
    private const string LibDeleteButton = "Lib_Delete";
    private const string LibResetButton = "Lib_ResetHud";
    private const string LibSaveDialog = "Lib_SaveDialog";
    private const string LibNameInput = "Lib_NameInput";
    private const string LibSaveInfo = "Lib_SaveInfo";
    private const string LibSaveOk = "Lib_SaveOk";
    private const string LibSaveCancel = "Lib_SaveCancel";
    private const string LibConfirmDialog = "Lib_ConfirmDialog";
    private const string LibConfirmText = "Lib_ConfirmText";
    private const string LibConfirmOk = "Lib_ConfirmOk";
    private const string LibConfirmCancel = "Lib_ConfirmCancel";

    private bool _libraryBound;
    private RectTransform _listContent;
    private GameObject _entryTemplate;
    private Button _saveButton, _loadButton, _deleteButton, _resetButton;
    private string _selectedPainting;

    // Save dialog
    private GameObject _saveDialog;
    private TMP_InputField _nameInput;
    private TMP_Text _saveInfo;
    private Button _saveOkButton;

    // Confirmation dialog (reused for Load + Delete)
    private GameObject _confirmDialog;
    private TMP_Text _confirmText;
    private Button _confirmButton;
    private Action _confirmAction;

    private struct EntryRef { public string name; public Image bg; }
    private readonly List<EntryRef> _entries = new List<EntryRef>();

    private static readonly Color EntryNormal = new Color(0.18f, 0.18f, 0.22f, 1f);
    private static readonly Color EntrySelected = new Color(0.20f, 0.45f, 0.80f, 1f);
    private static readonly Color OkDanger = new Color(0.62f, 0.26f, 0.26f, 1f);

    // --- Bind (find authored objects, hook listeners) ---

    /// <summary>
    /// Binds the authored library panel under <paramref name="root"/> (the instantiated layout prefab).
    /// Idempotent: binds exactly once. No-op if the prefab carries no library objects.
    /// </summary>
    private void BindLibrary(Transform root)
    {
        if (_libraryBound || !root) return;

        _listContent = GeometryUtil.FindDeep(root, LibListContent) as RectTransform;
        var template = GeometryUtil.FindDeep(root, LibEntryTemplate);
        _entryTemplate = template ? template.gameObject : null;
        if (!_listContent || !_entryTemplate) return; // panel not present in this layout
        _entryTemplate.SetActive(false);

        _saveButton = Find<Button>(root, LibSaveButton);
        _loadButton = Find<Button>(root, LibLoadButton);
        _deleteButton = Find<Button>(root, LibDeleteButton);
        _resetButton = Find<Button>(root, LibResetButton); // optional: present only if authored in the layout
        Hook(_saveButton, OnSaveClicked);
        Hook(_loadButton, OnLoadClicked);
        Hook(_deleteButton, OnDeleteClicked);
        Hook(_resetButton, OnResetClicked);

        var sd = GeometryUtil.FindDeep(root, LibSaveDialog);
        _saveDialog = sd ? sd.gameObject : null;
        _nameInput = Find<TMP_InputField>(root, LibNameInput);
        _saveInfo = Find<TMP_Text>(root, LibSaveInfo);
        _saveOkButton = Find<Button>(root, LibSaveOk);
        Hook(_saveOkButton, ConfirmSave);
        Hook(Find<Button>(root, LibSaveCancel), () => { if (_saveDialog) _saveDialog.SetActive(false); });
        if (_nameInput) _nameInput.onValueChanged.AddListener(_ => ValidateSaveName());

        var cd = GeometryUtil.FindDeep(root, LibConfirmDialog);
        _confirmDialog = cd ? cd.gameObject : null;
        _confirmText = Find<TMP_Text>(root, LibConfirmText);
        _confirmButton = Find<Button>(root, LibConfirmOk);
        Hook(_confirmButton, OnConfirmClicked);
        Hook(Find<Button>(root, LibConfirmCancel), () => { if (_confirmDialog) _confirmDialog.SetActive(false); });

        HideDialogs();
        _libraryBound = true;
        UpdateButtonStates();
    }

    private static void Hook(Button button, Action onClick)
    {
        if (!button || onClick == null) return;
        button.onClick.RemoveAllListeners();
        button.onClick.AddListener(() => onClick());
    }

    // --- List ---

    private void RefreshList()
    {
        if (!_listContent || !_entryTemplate) return;

        for (int i = _listContent.childCount - 1; i >= 0; i--)
        {
            var child = _listContent.GetChild(i).gameObject;
            if (child != _entryTemplate) Destroy(child);
        }
        _entries.Clear();

        var names = MeshPainter.ListSavedPaintings();
        if (!string.IsNullOrEmpty(_selectedPainting) && !names.Contains(_selectedPainting))
            _selectedPainting = null;

        foreach (var name in names)
        {
            var go = Instantiate(_entryTemplate, _listContent);
            go.name = "Lib_Entry";
            go.SetActive(true);

            var bg = go.GetComponent<Image>();
            if (bg) bg.color = name == _selectedPainting ? EntrySelected : EntryNormal;

            var label = go.GetComponentInChildren<TMP_Text>(true);
            if (label) label.text = name;

            var btn = go.GetComponent<Button>();
            if (btn)
            {
                string captured = name;
                Hook(btn, () => SelectPainting(captured));
            }

            _entries.Add(new EntryRef { name = name, bg = bg });
        }

        UpdateButtonStates();
    }

    private void SelectPainting(string name)
    {
        _selectedPainting = name;
        RefreshHighlights();
        UpdateButtonStates();
    }

    private void RefreshHighlights()
    {
        foreach (var e in _entries)
            if (e.bg) e.bg.color = e.name == _selectedPainting ? EntrySelected : EntryNormal;
    }

    private void UpdateButtonStates()
    {
        bool hasPainter = painter;
        bool hasSel = !string.IsNullOrEmpty(_selectedPainting);
        if (_saveButton) _saveButton.interactable = hasPainter;
        if (_loadButton) _loadButton.interactable = hasPainter && hasSel;
        if (_deleteButton) _deleteButton.interactable = hasSel;
    }

    private void HideDialogs()
    {
        if (_saveDialog) _saveDialog.SetActive(false);
        if (_confirmDialog) _confirmDialog.SetActive(false);
    }

    // --- Actions ---

    private void OnSaveClicked()
    {
        if (!painter || !_saveDialog) return;
        // Pre-fill the currently selected painting's name so "Save" defaults to overwriting it (empty when
        // nothing is selected) and select that text so the first keystroke replaces it for a fresh name.
        if (_nameInput) _nameInput.text = _selectedPainting ?? "";
        if (_saveInfo) _saveInfo.text = "";
        _saveDialog.SetActive(true);
        _saveDialog.transform.SetAsLastSibling(); // a dragged panel may have moved itself in front; stay on top
        ValidateSaveName();
        if (_nameInput)
        {
            _nameInput.ActivateInputField();
            StartCoroutine(SelectNameFieldNextFrame());
        }
    }

    // ActivateInputField only takes focus on a later update and resets the caret, so selecting the text this
    // frame would be cleared. Wait one frame, then select the whole pre-filled name - done explicitly here so
    // it works regardless of the field's authored "On Focus Select All" toggle.
    private System.Collections.IEnumerator SelectNameFieldNextFrame()
    {
        yield return null;
        if (!_nameInput) yield break;
        _nameInput.selectionStringAnchorPosition = _nameInput.text.Length;
        _nameInput.selectionStringFocusPosition = 0;
        _nameInput.ForceLabelUpdate();
    }

    private void ValidateSaveName()
    {
        string name = _nameInput ? _nameInput.text.Trim() : "";
        bool empty = string.IsNullOrEmpty(name);
        bool exists = !empty && MeshPainter.PaintExists(name);
        // Overwrite is allowed -> the OK button stays enabled even when the name exists; the warning is
        // purely informational so you know you are about to replace an existing slot.
        if (_saveOkButton) _saveOkButton.interactable = !empty && painter;
        if (_saveInfo) _saveInfo.text = exists ? "A painting with this name already exists and will be overwritten." : "";
    }

    private void ConfirmSave()
    {
        if (!painter || !_nameInput) return;
        string name = _nameInput.text.Trim();
        if (string.IsNullOrEmpty(name)) { ValidateSaveName(); return; }

        if (painter.SavePaintAs(name, overwrite: true))
        {
            _selectedPainting = name;
            if (_saveDialog) _saveDialog.SetActive(false);
            RefreshList();
        }
        else if (_saveInfo)
        {
            _saveInfo.text = "Save failed.";
        }
    }

    private void OnLoadClicked()
    {
        if (!painter || string.IsNullOrEmpty(_selectedPainting)) return;
        DoLoad(_selectedPainting); // load immediately, no confirmation
    }

    private void OnDeleteClicked()
    {
        if (string.IsNullOrEmpty(_selectedPainting)) return;
        string name = _selectedPainting;
        ShowConfirm($"Delete \"{name}\"?", OkDanger, () => DoDelete(name));
    }

    /// <summary>Reset the panels + brush values to their authored defaults (confirmed; the dialog reuses the
    /// library's confirm path). Falls back to an immediate reset if no confirm dialog is authored.</summary>
    private void OnResetClicked()
    {
        if (_confirmDialog)
            ShowConfirm("Reset the HUD panels and brush values to their defaults?", OkDanger, ResetHudToDefaults);
        else
            ResetHudToDefaults();
    }

    private void DoLoad(string name)
    {
        if (!painter || !painter.LoadPaintByName(name)) return;

        // The load also restored the slot's material scalars onto the painter (emission + camo from v3,
        // the painted-height knobs from v4) -> push them into the sliders so the HUD reflects the loaded
        // look, exactly like a pipette pick does. SyncCamoSliders covers the camo + height sliders.
        SyncFromPainter();
        SyncCamoSliders();

        // Re-sync the loaded baseline to every other peer (no-op offline / single-player). The restored
        // emission/camo replicate on their own via PlayerPaintSync's owner-authoritative NetworkVariables.
        var sync = painter.GetComponentInParent<PlayerPaintSync>();
        if (sync) sync.BroadcastLoadedPaint();
    }

    private void DoDelete(string name)
    {
        MeshPainter.DeletePaint(name);
        if (_selectedPainting == name) _selectedPainting = null;
        RefreshList();
    }

    private void ShowConfirm(string message, Color okColor, Action onConfirm)
    {
        if (!_confirmDialog) return;
        if (_confirmText) _confirmText.text = message;
        _confirmAction = onConfirm;
        if (_confirmButton && _confirmButton.targetGraphic is Image okImg) okImg.color = okColor;
        _confirmDialog.SetActive(true);
        _confirmDialog.transform.SetAsLastSibling(); // a dragged panel may have moved itself in front; stay on top
    }

    private void OnConfirmClicked()
    {
        var act = _confirmAction;
        _confirmAction = null;
        if (_confirmDialog) _confirmDialog.SetActive(false);
        act?.Invoke();
    }
}