using UnityEngine;
using Unheimlich.Features.Player;

namespace Unheimlich.World.HouseOfLeaves
{
    /// <summary>
    /// Simulates a Dolly Zoom (Vertigo effect) by applying a speed-driven additive FOV offset
    /// on top of the base FOV already written by <see cref="HouseOfLeavesController"/> and
    /// <see cref="CameraEffects"/> earlier in the frame.
    ///
    /// Runs in <c>LateUpdate</c> — after both <see cref="HouseOfLeavesController.Update"/> and
    /// <see cref="CameraEffects.Update"/> — so it always layers on top of the final written value.
    /// Subtracts the previous frame's offset before adding the new one to avoid compounding.
    ///
    /// The faster the player moves, the more the FOV pinches inward,
    /// compressing the perceived corridor space and amplifying claustrophobia.
    /// </summary>
    public class DollyZoomEffect : MonoBehaviour
    {
        // ─────────────────────────────────────────────────────────────────────────
        // Serialized Fields
        // ─────────────────────────────────────────────────────────────────────────

        [Header("Effect")]
        [Tooltip("Enable or disable the effect at runtime.")]
        [SerializeField] private bool _isEnabled = true;

        [Tooltip("Maximum negative FOV offset at full speed (degrees). " +
                 "Negative value pinches the FOV inward.")]
        [SerializeField] private float _maxFovOffset = -15f;

        [Tooltip("Walk speed (km/h) at which the effect starts fading in.")]
        [SerializeField] private float _speedThreshold = 12f;

        [Tooltip("Walk speed (km/h) at which the effect reaches its maximum.")]
        [SerializeField] private float _maxSpeedForEffect = 22f;

        [Tooltip("Lerp speed for the FOV offset transitions.")]
        [SerializeField] private float _smoothSpeed = 3f;

        [Header("Pulse (optional)")]
        [Tooltip("Adds a subtle sinusoidal oscillation to the FOV offset for extra unease.")]
        [SerializeField] private bool _enablePulse;

        [Tooltip("Amplitude of the pulse oscillation (degrees).")]
        [SerializeField] private float _pulseAmplitude = 1.5f;

        [Tooltip("Frequency of the pulse oscillation (Hz).")]
        [SerializeField] private float _pulseFrequency = 0.4f;

        // ─────────────────────────────────────────────────────────────────────────
        // Private Fields
        // ─────────────────────────────────────────────────────────────────────────

        private Camera _playerCamera;
        private float  _currentFovOffset;
        private bool   _isInitialized;

        private float _previousFovOffset;

        // ─────────────────────────────────────────────────────────────────────────
        // Unity Messages
        // ─────────────────────────────────────────────────────────────────────────

        private void Start()
        {
            if (PlayerController.Instance?.PlayerCamera == null)
            {
                Debug.LogError("[DollyZoomEffect] PlayerCamera could not be resolved.");
                return;
            }

            _playerCamera  = PlayerController.Instance.PlayerCamera;
            _isInitialized = true;
        }

        // LateUpdate ensures this runs after HouseOfLeavesController and CameraEffects
        // have both written their FOV values in Update.
        private void LateUpdate()
        {
            if (!_isInitialized || !_isEnabled) return;

            TickDollyZoom();
        }

        // ─────────────────────────────────────────────────────────────────────────
        // Tick
        // ─────────────────────────────────────────────────────────────────────────

        /// <summary>
        /// Computes the speed-driven FOV delta and applies it additively on top of
        /// the current <c>fieldOfView</c>. Strips the previous frame's offset first
        /// to avoid compounding the delta across frames.
        /// </summary>
        // Dans DollyZoomEffect, stocker le FOV base séparément
        private void TickDollyZoom()
        {
            float speedKmh = GetHorizontalSpeedKmh();
            float speedT   = Mathf.Clamp01(
                (speedKmh - _speedThreshold) / Mathf.Max(0.01f, _maxSpeedForEffect - _speedThreshold)
            );

            float targetOffset    = _maxFovOffset * speedT;
            if (_enablePulse && speedT > 0.01f)
                targetOffset += Mathf.Sin(Time.time * _pulseFrequency * Mathf.PI * 2f) * _pulseAmplitude * speedT;

            _currentFovOffset = Mathf.Lerp(_currentFovOffset, targetOffset, Time.deltaTime * _smoothSpeed);

            _playerCamera.fieldOfView += _currentFovOffset - _previousFovOffset;
            _previousFovOffset         = _currentFovOffset;
        }

        // ─────────────────────────────────────────────────────────────────────────
        // Helpers
        // ─────────────────────────────────────────────────────────────────────────

        private float GetHorizontalSpeedKmh()
        {
            CharacterController charController = PlayerController.Instance?.CharController;
            if (charController == null) return 0f;

            Vector3 horizontalVelocity = charController.velocity;
            horizontalVelocity.y       = 0f;

            return horizontalVelocity.magnitude * 3.6f;
        }

        // ─────────────────────────────────────────────────────────────────────────
        // Public API
        // ─────────────────────────────────────────────────────────────────────────

        public void SetEnabled(bool value) => _isEnabled = value;
    }
}