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

namespace Vanguard.UI.Overlays
{
    public sealed class CardActionMenuItem
    {
        public CardActionMenuItem(string label, Action action, bool enabled = true)
        {
            Label = label;
            Action = action;
            Enabled = enabled;
        }

        public string Label { get; }
        public Action Action { get; }
        public bool Enabled { get; }
    }

    /// <summary>Экранное контекстное меню над картой.</summary>
    public sealed class CardActionMenuView
    {
        private RectTransform _root;
        private RectTransform _popup;
        private Action _onClose;

        public bool IsVisible => _root != null && _root.gameObject.activeSelf;

        public RectTransform Root => _root;

        public void Build(Transform parent)
        {
            var prefabRoot = OverlayPrefabs.Instantiate("CardActionMenu", parent);
            if (prefabRoot != null)
            {
                _root = prefabRoot;
                _popup = (RectTransform)_root.Find("Popup");
                WireBackdrop();
                _root.gameObject.SetActive(false);
                return;
            }

            _root = UiKit.CreatePanel(parent, "CardActionMenu", new Color(0f, 0f, 0f, 0.01f));
            var image = _root.GetComponent<Image>();
            image.raycastTarget = true;

            var backdrop = _root.gameObject.AddComponent<Button>();
            backdrop.targetGraphic = image;

            _popup = UiKit.CreatePanel(_root, "Popup", new Color(0.045f, 0.06f, 0.09f, 0.98f));
            _popup.anchorMin = new Vector2(0f, 1f);
            _popup.anchorMax = new Vector2(0f, 1f);
            _popup.pivot = new Vector2(0f, 1f);
            _popup.sizeDelta = new Vector2(250f, 380f);
            UiKit.AddVerticalLayout(_popup, 8, 4);

            WireBackdrop();
            _root.gameObject.SetActive(false);
        }

        private void WireBackdrop()
        {
            if (_root == null)
                return;

            var image = _root.GetComponent<Image>();
            if (image != null)
                image.raycastTarget = true;

            var backdrop = _root.GetComponent<Button>();
            if (backdrop == null)
            {
                backdrop = _root.gameObject.AddComponent<Button>();
                backdrop.targetGraphic = image;
            }

            backdrop.onClick.AddListener(Hide);
        }

        public void Show(
            Vector2 screenPosition,
            string title,
            IReadOnlyList<CardActionMenuItem> items,
            Action onClose)
        {
            if (_root == null)
                return;

            _onClose = onClose;
            ClearChildren(_popup);

            var heading = UiKit.CreateText(
                _popup,
                "Title",
                title,
                15,
                new Color(0.86f, 0.91f, 1f),
                TextAnchor.MiddleLeft);
            heading.fontStyle = FontStyle.Bold;
            UiKit.MakeLiteral(heading);
            UiKit.SetPreferredHeight(heading, 26f);

            if (items == null || items.Count == 0)
            {
                var empty = UiKit.CreateText(
                    _popup,
                    "Empty",
                    "Нет доступных действий",
                    13,
                    new Color(0.62f, 0.68f, 0.82f));
                UiKit.SetPreferredHeight(empty, 34f);
            }
            else
            {
                foreach (var item in items)
                {
                    var button = UiKit.CreateButton(
                        _popup,
                        "Action_" + item.Label,
                        item.Label,
                        () =>
                        {
                            var action = item.Action;
                            Hide();
                            action?.Invoke();
                        },
                        14);
                    button.interactable = item.Enabled;
                    UiKit.SetPreferredHeight(button, 36f);
                }
            }

            _root.SetAsLastSibling();
            _root.gameObject.SetActive(true);

            if (!RectTransformUtility.ScreenPointToLocalPointInRectangle(
                    _root,
                    screenPosition,
                    null,
                    out var local))
            {
                return;
            }

            var rect = _root.rect;
            var fromLeft = local.x + rect.width * 0.5f;
            var fromTop = rect.height * 0.5f - local.y;
            var x = Mathf.Clamp(
                fromLeft + 18f,
                8f,
                Mathf.Max(8f, rect.width - 258f));
            var y = Mathf.Clamp(
                -fromTop - 18f,
                -Mathf.Max(8f, rect.height - 388f),
                -8f);
            _popup.anchoredPosition = new Vector2(x, y);
        }

        public void Hide()
        {
            if (_root == null || !_root.gameObject.activeSelf)
                return;

            _root.gameObject.SetActive(false);
            var callback = _onClose;
            _onClose = null;
            callback?.Invoke();
        }

        private static void ClearChildren(Transform parent)
        {
            for (var i = parent.childCount - 1; i >= 0; i--)
            {
                var child = parent.GetChild(i).gameObject;
                child.SetActive(false);
                if (Application.isPlaying)
                    UnityEngine.Object.Destroy(child);
                else
                    UnityEngine.Object.DestroyImmediate(child);
            }
        }
    }
}