using System.Collections.Generic;
using UnityEngine;
using UnityEngine.InputSystem;

namespace Ashwild.UI
{
    /// <summary>
    /// Screenshot/capture utility: one keypress hides (and restores) every Canvas in the scene at
    /// once, so the world can be photographed with no HUD, crosshair, notifications or menus on top.
    /// It toggles each root Canvas's <see cref="Canvas.enabled"/> rather than deactivating GameObjects,
    /// so animations, timers and gameplay keep running untouched behind the hidden UI.
    ///
    /// This is a deliberate, isolated exception to the "InputManager owns all input" rule: it is not a
    /// gameplay action and never goes through the Send-Messages path, so it reads the key straight from
    /// <see cref="Keyboard"/> instead of the action asset. Canvases are re-queried on every toggle, so
    /// windows opened after hiding are still caught the next time the state flips.
    /// </summary>
    [DisallowMultipleComponent]
    public class HudVisibilityToggle : MonoBehaviour
    {
        #region Serialized Fields

        [Header("Input")]
        [Tooltip("Key that toggles all UI on/off (default F8).")]
        [SerializeField] private Key toggleKey = Key.F8;

        [Header("Exclusions")]
        [Tooltip("Root canvases that must stay visible even when the HUD is hidden (e.g. a debug overlay).")]
        [SerializeField] private List<Canvas> alwaysVisible = new List<Canvas>();

        #endregion

        #region State

        /// <summary>
        /// True while the UI is currently hidden — the next press restores it.
        /// </summary>
        private bool hidden;

        #endregion

        #region Unity Lifecycle

        /// <summary>
        /// Polls the toggle key each frame and flips UI visibility on a fresh press.
        /// </summary>
        private void Update()
        {
            Keyboard keyboard = Keyboard.current;
            if (keyboard == null) return;

            if (keyboard[toggleKey].wasPressedThisFrame)
                ToggleHud();
        }

        #endregion

        #region Public API

        /// <summary>
        /// Flips the hidden state and re-applies it to every root canvas in the scene.
        /// </summary>
        public void ToggleHud()
        {
            hidden = !hidden;
            ApplyVisibility();
        }

        #endregion

        #region Internal Helpers

        /// <summary>
        /// Enables or disables every root Canvas to match the current hidden state, skipping any
        /// canvas listed in <see cref="alwaysVisible"/>. Only root canvases are touched — nested
        /// canvases follow their parent's rendering, so toggling them too would be redundant.
        /// </summary>
        private void ApplyVisibility()
        {
            Canvas[] canvases = FindObjectsByType<Canvas>(FindObjectsInactive.Exclude, FindObjectsSortMode.None);
            foreach (Canvas canvas in canvases)
            {
                if (canvas == null || !canvas.isRootCanvas) continue;
                if (alwaysVisible.Contains(canvas)) continue;
                canvas.enabled = !hidden;
            }
        }

        #endregion
    }
}