using System;
using TMPro;
using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.UI;

namespace Cielonos.Settings.UI
{
    /// <summary>
    /// 键位绑定条目，用于 <see cref="KeyBindingPage"/> 中的每一行。
    /// <para>
    /// 显示：[Action 名称]  [当前按键文本]  [重新绑定按钮]
    /// 点击重新绑定按钮后进入监听模式，捕获下一个按键输入并更新绑定。
    /// </para>
    /// </summary>
    public class SettingsEntryKeyBinding : MonoBehaviour
    {
        [SerializeField] private TMP_Text actionNameText;
        [SerializeField] private TMP_Text currentKeyText;
        [SerializeField] private Button rebindButton;
        [SerializeField] private TMP_Text rebindButtonText;

        [Header("Visuals")]
        [SerializeField] private string waitingText = "...";
        [SerializeField] private GameObject waitingOverlay;

        private InputAction inputAction;
        private int bindingIndex;
        private InputActionRebindingExtensions.RebindingOperation rebindOperation;

        /// <summary>绑定完成时触发。</summary>
        public event Action OnBindingChanged;

        /// <summary>
        /// 初始化键位绑定条目。
        /// </summary>
        /// <param name="action">要绑定的 InputAction。</param>
        /// <param name="targetBindingIndex">
        /// 要重新绑定的 binding 索引。
        /// 对于非 composite 的 action，通常为 0。
        /// </param>
        /// <param name="displayName">条目显示名称（可为 null，则使用 action 名）。</param>
        public void Initialize(InputAction action, int targetBindingIndex, string displayName = null)
        {
            inputAction = action;
            bindingIndex = targetBindingIndex;

            if (actionNameText != null)
                actionNameText.text = displayName ?? FormatActionName(action.name);

            if (rebindButton != null)
                rebindButton.onClick.AddListener(StartRebind);

            RefreshDisplay();
        }

        /// <summary>
        /// 刷新当前按键的显示文本。
        /// </summary>
        public void RefreshDisplay()
        {
            if (inputAction == null || currentKeyText == null) return;

            string displayString = inputAction.bindings[bindingIndex].ToDisplayString(
                InputBinding.DisplayStringOptions.DontUseShortDisplayNames);

            currentKeyText.text = displayString;
        }

        /// <summary>
        /// 开始交互式重新绑定。
        /// </summary>
        private void StartRebind()
        {
            if (inputAction == null) return;

            // 显示等待提示
            SetWaitingState(true);

            // 先禁用 action 以允许重新绑定
            inputAction.Disable();

            rebindOperation = inputAction.PerformInteractiveRebinding(bindingIndex)
                .WithControlsExcluding("<Mouse>/position")
                .WithControlsExcluding("<Mouse>/delta")
                .WithControlsExcluding("<Pointer>/position")
                .WithControlsExcluding("<Pointer>/delta")
                .WithCancelingThrough("<Keyboard>/escape")
                .OnMatchWaitForAnother(0.1f)
                .OnComplete(operation => FinishRebind(true))
                .OnCancel(operation => FinishRebind(false))
                .Start();
        }

        /// <summary>
        /// 重新绑定完成或取消后的处理。
        /// </summary>
        private void FinishRebind(bool completed)
        {
            rebindOperation?.Dispose();
            rebindOperation = null;

            inputAction.Enable();
            SetWaitingState(false);
            RefreshDisplay();

            if (completed)
            {
                OnBindingChanged?.Invoke();
            }
        }

        /// <summary>
        /// 重置此条目的绑定到默认值。
        /// </summary>
        public void ResetToDefault()
        {
            if (inputAction == null) return;

            inputAction.RemoveBindingOverride(bindingIndex);
            RefreshDisplay();
            OnBindingChanged?.Invoke();
        }

        private void SetWaitingState(bool isWaiting)
        {
            if (currentKeyText != null)
                currentKeyText.text = isWaiting ? waitingText : "";

            if (rebindButton != null)
                rebindButton.interactable = !isWaiting;

            if (waitingOverlay != null)
                waitingOverlay.SetActive(isWaiting);
        }

        /// <summary>
        /// 将 ActionName (camelCase) 格式化为可读文本。
        /// </summary>
        private static string FormatActionName(string actionName)
        {
            if (string.IsNullOrEmpty(actionName)) return actionName;

            var sb = new System.Text.StringBuilder(actionName.Length + 4);
            sb.Append(char.ToUpper(actionName[0]));

            for (int i = 1; i < actionName.Length; i++)
            {
                char c = actionName[i];
                if (char.IsUpper(c) && i > 0 && char.IsLower(actionName[i - 1]))
                    sb.Append(' ');
                sb.Append(c);
            }

            return sb.ToString();
        }

        private void OnDestroy()
        {
            rebindOperation?.Dispose();

            if (rebindButton != null)
                rebindButton.onClick.RemoveListener(StartRebind);
        }
    }
}