using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.Serialization;
using Valve.VR.InteractionSystem;

public class BicycleController : MonoBehaviour
{
    #region Variables

    [Header("Visible Game Objects")] 
    public GameObject rearWheel;
    public GameObject frontWheel;

    [Header("Game Objects for Physics")] public Transform centerOfMass;
    [FormerlySerializedAs("rb")] public Rigidbody rigidBody;
    public WheelConfig wheelConfig;
    
    [Header("Values")] 
    public float offsetCollidersFromWheel = 0.25f;

   

    public float CurrentSteerAngle { get; set; } = 0f;

    public float CurrentMotorTorque { get; set; } = 0f;

    public float CurrentBrakeTorque { get; set; } = 0f;

    public float CurrentLeaningAngle { get; set; } = 0f;
    
    private WheelCollider[] allWheelColliders;
    private float initialWheelColliderY;

    #endregion
    
    // Start is called before the first frame update
    void Start()
    {
        rigidBody.centerOfMass = centerOfMass.localPosition;
        allWheelColliders = wheelConfig.AllWheels;
        wheelConfig.AdjustToGameObjects(frontWheel.transform, rearWheel.transform, offsetCollidersFromWheel);
        initialWheelColliderY = allWheelColliders[0].transform.localPosition.y;
    }


    void FixedUpdate()
    {
        ApplyColliderForces();
        Lean();
        //RotateStraight();
    }

    private void ApplyColliderForces()
    {
        ControlSteer(new[] {wheelConfig.frontLeft, wheelConfig.frontRight});
        ControlTorque(new[] {wheelConfig.rearLeft, wheelConfig.rearRight});
    }

    private void ControlSteer(IEnumerable<WheelCollider> colliders)
    {
        //float steering = maxSteeringAngle * CurrentSteerAngle * 0.2f;
        //leftWheels.localPosition = -Vector3.up * (relativeLeanAmount * CurrentSteerAngle * rigidBody.velocity.magnitude * 0.2f);
        //rightWheels.localPosition = Vector3.up * (relativeLeanAmount * CurrentSteerAngle * rigidBody.velocity.magnitude * 0.2f);
        colliders.ForEach(c => c.steerAngle = CurrentSteerAngle);
    }

    private void ControlTorque(IEnumerable<WheelCollider> colliders)
    {
        foreach (var c in colliders)
        {
            c.motorTorque = CurrentMotorTorque;
            c.brakeTorque = CurrentBrakeTorque;
        }
    }

    private void Lean()
    {
        //reset all wheels to being centered
        if (CurrentLeaningAngle == 0) //TODO: maybe add a threshold for leaning, e.g. < -0.05 and > 0.05 
        {
            //leaning left, left wheels up, right wheels down
            ApplyOffsetToTransform(wheelConfig.frontLeft.transform, initialWheelColliderY);
            ApplyOffsetToTransform(wheelConfig.rearLeft.transform, initialWheelColliderY);
            ApplyOffsetToTransform(wheelConfig.frontRight.transform, initialWheelColliderY);
            ApplyOffsetToTransform(wheelConfig.rearRight.transform, initialWheelColliderY);
        }
        //CurrentLeaningAngle < 0 -> leaning left, > 0 -> right
        var leaningAbs = Mathf.Abs(CurrentLeaningAngle * Mathf.Deg2Rad);

        //calculate offset for wheels; description Docu folder
        //1.57079633 rad = 90 deg
        var verticalOffset = offsetCollidersFromWheel * Mathf.Sin(leaningAbs) / Mathf.Sin(1.57079633f - leaningAbs);
        var yPlusOffset = initialWheelColliderY + verticalOffset;
        var yMinusOffset = initialWheelColliderY - verticalOffset;
        
        if (CurrentLeaningAngle < 0) //TODO: maybe add a threshold for leaning, e.g. < -0.05 and > 0.05 
        {
            //leaning left, left wheels up, right wheels down
            ApplyOffsetToTransform(wheelConfig.frontLeft.transform, yPlusOffset);
            ApplyOffsetToTransform(wheelConfig.rearLeft.transform, yPlusOffset);
            ApplyOffsetToTransform(wheelConfig.frontRight.transform, yMinusOffset);
            ApplyOffsetToTransform(wheelConfig.rearRight.transform, yMinusOffset);
        }
        else if (CurrentLeaningAngle > 0)
        {
            //leaning right, right wheels up, left wheels down
            ApplyOffsetToTransform(wheelConfig.frontLeft.transform, yMinusOffset);
            ApplyOffsetToTransform(wheelConfig.rearLeft.transform, yMinusOffset);
            ApplyOffsetToTransform(wheelConfig.frontRight.transform, yPlusOffset);
            ApplyOffsetToTransform(wheelConfig.rearRight.transform, yPlusOffset);
        }
    }

    private void ApplyOffsetToTransform(Transform t, float newY)
    {
        var oldPos = t.localPosition;
        t.localPosition = new Vector3(oldPos.x, newY, oldPos.z);
    }
}