using System.Collections.Generic;
using TMPro;
using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.SceneManagement;
using UnityEngine.UI;
using UnityEngine.XR;
using XRCommonUsages = UnityEngine.XR.CommonUsages;
using XRInputDevice = UnityEngine.XR.InputDevice;

public class SyncCalibrationOverlay : MonoBehaviour
{
    private const float TickInterval = 1.0f;
    private const int MaxSamples = 8;

    private static Scene pendingReturnScene;

    private readonly List<float> samples = new();
    private readonly List<(Canvas canvas, bool enabled)> hiddenCanvases = new();

    private AudioSource audioSource = null;
    private AudioClip tickClip = null;
    private RectTransform sweepDot = null;
    private RectTransform visualPulse = null;
    private TextMeshProUGUI offsetText = null;
    private TextMeshProUGUI sampleText = null;
    private TextMeshProUGUI guideText = null;

    private float lastTickTime = 0.0f;
    private float nextTickTime = 0.0f;
    private float pendingVisualPulseTime = -1.0f;
    private float visualPulseTimer = 0.0f;
    private bool previousPrimary = false;
    private bool previousSecondary = false;
    private Scene returnScene;
    private Scene syncScene;
    private bool canvasesRestored = false;

    public static void Open()
    {
        if (FindFirstObjectByType<SyncCalibrationOverlay>() != null)
            return;

        pendingReturnScene = SceneManager.GetActiveScene();
        Scene calibrationScene = SceneManager.CreateScene("SyncCalibration");
        SceneManager.SetActiveScene(calibrationScene);

        GameObject overlay = new GameObject("[SyncCalibrationOverlay]");
        overlay.AddComponent<SyncCalibrationOverlay>();
    }

    private void Awake()
    {
        syncScene = gameObject.scene;
        returnScene = pendingReturnScene;

        HideExistingCanvases();
        BuildView();
        tickClip = CreateTickClip();
        audioSource = gameObject.AddComponent<AudioSource>();
        audioSource.playOnAwake = false;
        audioSource.spatialBlend = 0.0f;

        float now = Time.unscaledTime;
        lastTickTime = now;
        nextTickTime = now + 0.8f;
        UpdateTexts();
    }

    private void OnDestroy()
    {
        RestoreCanvases();
    }

    private void Update()
    {
        float now = Time.unscaledTime;

        if (now >= nextTickTime)
        {
            lastTickTime = nextTickTime;
            nextTickTime += TickInterval;
            audioSource.PlayOneShot(tickClip);
            pendingVisualPulseTime = lastTickTime + GlobalSyncSettings.AudioOffsetSeconds;
        }

        if (pendingVisualPulseTime > 0.0f && now >= pendingVisualPulseTime)
        {
            visualPulseTimer = 0.18f;
            pendingVisualPulseTime = -1.0f;
        }

        UpdateMetronomeVisual(now);
        HandleInput(now);
    }

    private void HandleInput(float now)
    {
        bool primary = GetRightButton(XRCommonUsages.primaryButton) || IsKeyboardPressed(Key.Space);
        bool secondary = GetRightButton(XRCommonUsages.secondaryButton) || IsKeyboardPressed(Key.Escape);

        if (primary && !previousPrimary)
            CaptureSample(now);
        if (secondary && !previousSecondary)
            Close();

        previousPrimary = primary;
        previousSecondary = secondary;
    }

    private void CaptureSample(float now)
    {
        float nearestTick = Mathf.Abs(now - lastTickTime) <= Mathf.Abs(now - nextTickTime)
            ? lastTickTime
            : nextTickTime;

        float offsetMs = Mathf.Clamp((now - nearestTick) * 1000.0f, -300.0f, 300.0f);
        samples.Add(offsetMs);
        if (samples.Count > MaxSamples)
            samples.RemoveAt(0);

        float sum = 0.0f;
        for (int i = 0; i < samples.Count; i++)
            sum += samples[i];

        GlobalSyncSettings.AudioOffsetMs = sum / samples.Count;
        UpdateTexts();
    }

    private void AdjustOffset(float deltaMs)
    {
        GlobalSyncSettings.AudioOffsetMs += deltaMs;
        samples.Clear();
        UpdateTexts();
    }

    private void ResetOffset()
    {
        GlobalSyncSettings.Reset();
        samples.Clear();
        UpdateTexts();
    }

    private void Close()
    {
        RestoreCanvases();

        if (returnScene.IsValid() && returnScene.isLoaded)
            SceneManager.SetActiveScene(returnScene);

        if (syncScene.IsValid() && syncScene.isLoaded)
            SceneManager.UnloadSceneAsync(syncScene);
        else
            Destroy(gameObject);
    }

    private void BuildView()
    {
        Camera camera = Camera.main ?? FindFirstObjectByType<Camera>();

        GameObject canvasObject = new GameObject("SyncCalibrationCanvas");
        canvasObject.transform.SetParent(transform, false);
        Canvas canvas = canvasObject.AddComponent<Canvas>();
        canvas.renderMode = RenderMode.WorldSpace;
        canvas.sortingOrder = 400;
        canvas.worldCamera = camera;
        canvasObject.AddComponent<GraphicRaycaster>();

        RectTransform canvasRect = canvasObject.GetComponent<RectTransform>();
        canvasRect.sizeDelta = new Vector2(1080.0f, 660.0f);
        canvasObject.transform.localScale = Vector3.one * 0.0028f;

        if (camera != null)
        {
            Transform camTransform = camera.transform;
            canvasObject.transform.position = camTransform.position + camTransform.forward * 1.9f;
            canvasObject.transform.rotation = Quaternion.LookRotation(canvasObject.transform.position - camTransform.position, camTransform.up);
        }

        Image background = CreateImage("Panel", canvasRect, new Vector2(0, 0), new Vector2(1020, 620), new Color(0.02f, 0.06f, 0.09f, 0.92f));
        background.raycastTarget = false;

        TextMeshProUGUI title = CreateText("Title", canvasRect, "SYNC CALIBRATION", new Vector2(0, 260), new Vector2(920, 58), 42, Color.white, TextAlignmentOptions.Center);
        title.fontStyle = FontStyles.Bold;
        guideText = CreateText("Guide", canvasRect, "", new Vector2(0, 180), new Vector2(920, 92), 26, new Color(0.77f, 0.9f, 1.0f, 1.0f), TextAlignmentOptions.Center);

        Image bar = CreateImage("BeatBar", canvasRect, new Vector2(0, 82), new Vector2(760, 10), new Color(0.25f, 0.85f, 1.0f, 0.28f));
        bar.raycastTarget = false;
        sweepDot = CreateImage("BeatDot", canvasRect, new Vector2(-380, 82), new Vector2(34, 34), new Color(0.35f, 0.95f, 1.0f, 1.0f)).rectTransform;
        visualPulse = CreateImage("VisualPulse", canvasRect, new Vector2(0, 82), new Vector2(140, 140), new Color(0.35f, 0.95f, 1.0f, 0.0f)).rectTransform;

        offsetText = CreateText("Offset", canvasRect, "", new Vector2(0, 0), new Vector2(720, 74), 54, Color.white, TextAlignmentOptions.Center);
        offsetText.fontStyle = FontStyles.Bold;
        sampleText = CreateText("Samples", canvasRect, "", new Vector2(0, -72), new Vector2(760, 44), 24, new Color(0.65f, 0.78f, 0.84f, 1.0f), TextAlignmentOptions.Center);

        CreateButton(canvasRect, "-10ms", new Vector2(-300, -165), () => AdjustOffset(-10.0f));
        CreateButton(canvasRect, "+10ms", new Vector2(-100, -165), () => AdjustOffset(10.0f));
        CreateButton(canvasRect, "RESET", new Vector2(100, -165), ResetOffset);
        CreateButton(canvasRect, "BACK", new Vector2(300, -165), Close);

        CreateText("Footer", canvasRect, "A / Space: capture beat     B / Esc: back", new Vector2(0, -270), new Vector2(860, 40), 22, new Color(0.58f, 0.7f, 0.75f, 1.0f), TextAlignmentOptions.Center);
    }

    private void UpdateMetronomeVisual(float now)
    {
        float phase = Mathf.InverseLerp(lastTickTime, nextTickTime, now);
        if (sweepDot != null)
            sweepDot.anchoredPosition = new Vector2(Mathf.Lerp(-380.0f, 380.0f, phase), 82.0f);

        if (visualPulse == null)
            return;

        visualPulseTimer = Mathf.Max(0.0f, visualPulseTimer - Time.unscaledDeltaTime);
        float alpha = visualPulseTimer / 0.18f;
        visualPulse.sizeDelta = Vector2.one * Mathf.Lerp(190.0f, 80.0f, alpha);
        Image image = visualPulse.GetComponent<Image>();
        if (image != null)
            image.color = new Color(0.35f, 0.95f, 1.0f, alpha * 0.52f);
    }

    private void UpdateTexts()
    {
        float offset = GlobalSyncSettings.AudioOffsetMs;
        if (offsetText != null)
            offsetText.text = $"{offset:+0;-0;0} ms";
        if (sampleText != null)
            sampleText.text = $"samples {samples.Count}/{MaxSamples}   global offset saved";
        if (guideText != null)
            guideText.text = "Tick 소리가 들리는 순간 A / Space를 누르세요.\n파란 원이 박자와 겹치면 보정이 맞습니다.";
    }

    private void HideExistingCanvases()
    {
        hiddenCanvases.Clear();
        foreach (Canvas canvas in FindObjectsByType<Canvas>(FindObjectsSortMode.None))
        {
            hiddenCanvases.Add((canvas, canvas.enabled));
            canvas.enabled = false;
        }
    }

    private void RestoreCanvases()
    {
        if (canvasesRestored)
            return;

        canvasesRestored = true;
        foreach ((Canvas canvas, bool enabled) in hiddenCanvases)
        {
            if (canvas != null)
                canvas.enabled = enabled;
        }
    }

    private static TextMeshProUGUI CreateText(string name, RectTransform parent, string value, Vector2 position, Vector2 size, int fontSize, Color color, TextAlignmentOptions alignment)
    {
        GameObject go = new GameObject(name);
        go.transform.SetParent(parent, false);
        RectTransform rect = go.AddComponent<RectTransform>();
        rect.anchoredPosition = position;
        rect.sizeDelta = size;

        TextMeshProUGUI text = go.AddComponent<TextMeshProUGUI>();
        text.text = value;
        text.fontSize = fontSize;
        text.color = color;
        text.alignment = alignment;
        text.textWrappingMode = TextWrappingModes.Normal;
        text.overflowMode = TextOverflowModes.Overflow;
        text.raycastTarget = false;
        return text;
    }

    private static Image CreateImage(string name, RectTransform parent, Vector2 position, Vector2 size, Color color)
    {
        GameObject go = new GameObject(name);
        go.transform.SetParent(parent, false);
        RectTransform rect = go.AddComponent<RectTransform>();
        rect.anchoredPosition = position;
        rect.sizeDelta = size;

        Image image = go.AddComponent<Image>();
        image.color = color;
        return image;
    }

    private static void CreateButton(RectTransform parent, string label, Vector2 position, UnityEngine.Events.UnityAction action)
    {
        Image image = CreateImage(label + "Button", parent, position, new Vector2(168, 58), new Color(0.07f, 0.18f, 0.24f, 0.96f));
        Button button = image.gameObject.AddComponent<Button>();
        button.onClick.AddListener(action);

        ColorBlock colors = button.colors;
        colors.normalColor = new Color(0.07f, 0.18f, 0.24f, 0.96f);
        colors.highlightedColor = new Color(0.13f, 0.38f, 0.48f, 1.0f);
        colors.pressedColor = new Color(0.08f, 0.72f, 0.85f, 1.0f);
        colors.selectedColor = colors.highlightedColor;
        button.colors = colors;

        TextMeshProUGUI labelText = CreateText(label + "Text", image.rectTransform, label, Vector2.zero, new Vector2(154, 48), 24, Color.white, TextAlignmentOptions.Center);
        labelText.fontStyle = FontStyles.Bold;
    }

    private static bool GetRightButton(InputFeatureUsage<bool> usage)
    {
        var devices = new List<XRInputDevice>();
        InputDevices.GetDevicesWithCharacteristics(InputDeviceCharacteristics.Controller | InputDeviceCharacteristics.Right, devices);
        if (devices.Count == 0)
            return false;

        devices[0].TryGetFeatureValue(usage, out bool pressed);
        return pressed;
    }

    private static bool IsKeyboardPressed(Key key)
    {
        Keyboard keyboard = Keyboard.current;
        return keyboard != null && keyboard[key].isPressed;
    }

    private static AudioClip CreateTickClip()
    {
        const int sampleRate = 48000;
        const float duration = 0.055f;
        int sampleCount = Mathf.CeilToInt(sampleRate * duration);
        float[] data = new float[sampleCount];

        for (int i = 0; i < sampleCount; i++)
        {
            float t = (float)i / sampleRate;
            float envelope = Mathf.Exp(-t * 62.0f);
            float high = Mathf.Sin(2.0f * Mathf.PI * 1760.0f * t);
            float click = i < 80 ? 1.0f - (float)i / 80.0f : 0.0f;
            data[i] = Mathf.Clamp((high * 0.75f + click * 0.35f) * envelope, -1.0f, 1.0f);
        }

        AudioClip clip = AudioClip.Create("SyncTick", sampleCount, 1, sampleRate, false);
        clip.SetData(data, 0);
        return clip;
    }
}