using System.Diagnostics;
using ADOFAIRenderer.Core;
using TMPro;
using UnityEngine;
using UnityEngine.UI;

namespace ADOFAIRenderer.UI;

/// <summary>
/// Hold-Escape-to-cancel handler shown during a render.
/// <para>
/// Created by <c>RenderManager</c> when the render reaches the OnScene stage, on a GameObject kept across scene loads.
/// While Escape is held, a centered panel shows a countdown from 3 seconds; holding it for the full 3 seconds
/// (measured in real time with a <see cref="Stopwatch"/>, independent of the patched game time) calls
/// <c>RenderManager.CancelRender</c>. Releasing Escape earlier hides the panel and resets the countdown.
/// The component destroys its GameObject as soon as <c>RenderManager.IsActive</c> is false (stage below OnScene).
/// Runs on the main Unity thread.
/// </para>
/// </summary>
internal class EscapeHandlerUI : MonoBehaviour
{
    /// <summary>Centered countdown panel (background and text); inactive while Escape is not held.</summary>
    private GameObject _containerObj = null!;
    /// <summary>Countdown text inside <see cref="_containerObj"/>.</summary>
    private TextMeshProUGUI _textComponent = null!;
    /// <summary>Real-time hold duration of the current Escape press; <c>null</c> while Escape is not held.</summary>
    private Stopwatch? _escapeStopwatch;

    /// <summary>
    /// Builds the overlay canvas and the hidden countdown panel. Layout values are canvas units at the 1920x1080
    /// reference resolution.
    /// </summary>
    private void Start()
    {
        // Set UI layer (5, Unity's built-in "UI" layer)
        gameObject.layer = 5;

        // Canvas setup
        var canvas = gameObject.AddComponent<Canvas>();
        canvas.renderMode = RenderMode.ScreenSpaceOverlay;
        canvas.sortingOrder = 10000; // Placed above debug monitor

        // Canvas Scaler: 1920x1080 reference resolution, width and height matched equally (0.5)
        var scaler = gameObject.AddComponent<CanvasScaler>();
        scaler.uiScaleMode = CanvasScaler.ScaleMode.ScaleWithScreenSize;
        scaler.referenceResolution = new Vector2(1920, 1080);
        scaler.screenMatchMode = CanvasScaler.ScreenMatchMode.MatchWidthOrHeight;
        scaler.matchWidthOrHeight = 0.5f;

        gameObject.AddComponent<GraphicRaycaster>();

        // 1. Create container and background panel object: 460x160 units at the screen center
        _containerObj = new GameObject("EscapeContainer");
        _containerObj.transform.SetParent(transform, false);
        _containerObj.layer = 5;

        var bgImage = _containerObj.AddComponent<Image>();
        bgImage.color = new Color(0.05f, 0.05f, 0.07f, 0.85f); // Dark tone acrylic style

        var containerRect = _containerObj.GetComponent<RectTransform>();
        containerRect.anchorMin = new Vector2(0.5f, 0.5f);
        containerRect.anchorMax = new Vector2(0.5f, 0.5f);
        containerRect.pivot = new Vector2(0.5f, 0.5f);
        containerRect.anchoredPosition = Vector2.zero; // Screen center
        containerRect.sizeDelta = new Vector2(460, 160);

        // 2. Create text object: 60 pt centered rich text, no wrapping, 10-unit margin inside the panel
        var textObj = new GameObject("EscapeText");
        textObj.transform.SetParent(_containerObj.transform, false);
        textObj.layer = 5;

        _textComponent = textObj.AddComponent<TextMeshProUGUI>();
        _textComponent.alignment = TextAlignmentOptions.Center;
        _textComponent.fontSize = 60;
        _textComponent.textWrappingMode = TextWrappingModes.NoWrap;
        _textComponent.richText = true;

        // Apply the game's TextMeshPro font for the current language (RDString.fontData.fontTMP, assigned in
        // RDString.Setup). It is null before RDString.Setup has run; TextMeshPro's default font is kept then.
        if (RDString.fontData.fontTMP != null)
            _textComponent.font = RDString.fontData.fontTMP;

        var textRect = textObj.GetComponent<RectTransform>();
        textRect.anchorMin = Vector2.zero;
        textRect.anchorMax = Vector2.one;
        textRect.offsetMin = new Vector2(10, 10);
        textRect.offsetMax = new Vector2(-10, -10);

        // Initial state disabled
        _containerObj.SetActive(false);
    }

    /// <summary>
    /// Tracks the Escape key every frame: shows and updates the countdown while it is held, cancels the render after
    /// 3 seconds of holding, and hides the panel when it is released.
    /// </summary>
    private void Update()
    {
        // Destroy self once the render is inactive (stage below OnScene: finished, cancelled or failed)
        if (!RenderManager.IsActive)
        {
            Destroy(gameObject);
            return;
        }

        if (Input.GetKey(KeyCode.Escape))
        {
            // First frame of the press: start timing and show the panel
            if (_escapeStopwatch == null)
            {
                _escapeStopwatch = new Stopwatch();
                _escapeStopwatch.Start();
                _containerObj.SetActive(true);
            }

            var elapsed = (float)_escapeStopwatch.Elapsed.TotalSeconds;
            var remaining = Mathf.Max(0f, 3f - elapsed);

            // Update remaining time text (seconds, one decimal). The text is fixed English, not localized.
            _textComponent.text = $"<color=#FF5252>Cancelling in {remaining:F1}s..</color>\n<size=40><color=#DDDDDD>Hold Esc to cancel render</color></size>";

            // Grow animation: the panel scales linearly from 1.0 to 1.15 over the 3-second hold
            var scale = 1.0f + elapsed / 3.0f * 0.15f;
            _containerObj.transform.localScale = new Vector3(scale, scale, 1f);

            // Held for the full 3 seconds: reset the panel, then cancel
            if (elapsed < 3f) return;
                
            _escapeStopwatch.Stop();
            _escapeStopwatch = null;
            _containerObj.transform.localScale = Vector3.one; // Reset scale
            _containerObj.SetActive(false);

            // Cancel rendering: RenderManager.CancelRender resets the render state, stops the encoder as cancelled and
            // ends the render. StopFFmpeg also destroys this handler's GameObject.
            if (RenderManager.Instance)
                RenderManager.Instance.CancelRender();
        }
        else
        {
            // Escape released before 3 seconds: stop timing and hide the panel
            if (_escapeStopwatch == null) return;
            _escapeStopwatch.Stop();
            _escapeStopwatch = null;
            _containerObj.transform.localScale = Vector3.one; // Reset scale
            _containerObj.SetActive(false);
        }
    }

    /// <summary>Stops the hold stopwatch if a press is in progress.</summary>
    private void OnDestroy()
    {
        if (_escapeStopwatch == null) return;
        _escapeStopwatch.Stop();
        _escapeStopwatch = null;
    }
}