using UnityEngine;

namespace NeonTea.Quakeball.Player {
    /// <summary>The central glue class for players (both local and remote).</summary>
    /// <remarks>Other classes will handle netcode/inputs, and then speak to this class in order to make the little people run around.</remarks>
    [RequireComponent(typeof(CharacterController))]
    public class Player : MonoBehaviour {

        /// <summary>How long after running off a cliff should the player be considered "on ground"?</summary>
        public float CoyoteTime;

        public MoveStyle RunningMoveStyle;
        public MoveStyle CrouchingMoveStyle;
        public Transform Head;
        public Transform Body;

        [Header("Player rotation status")]
        /// <summary>The pitch of the player's head.</summary>
        public float Pitch;
        /// <summary>The total yaw of the player. Head yaw is Yaw - BodyYaw.</summary>
        public float Yaw;
        /// <summary>The yaw of the player body. Calculated from MoveDirection.</summary>
        public float BodyYaw;

        [Header("Player movement status")]
        /// <summary>The direction the player is going.</summary>
        public Vector3 MoveDirection;

        /// <summary>The player's desire to jump currently.</summary>
        public bool Jumping;

        /// <summary>The amount of movement the player wants to happen.</summary>
        /// <remarks>Without analog controls, always 0 or 1.</remarks>
        public float InputSpeed;

        /// <summary>The way the player is moving.</summary>
        public MoveStyle MoveStyle;

        [Header("Runtime computed values")]
        /// <summary>The speed at which the player is currently moving across the ground.</summary>
        public Vector3 GroundVelocity;

        /// <summary>The speed at which the player is rising or falling.</summary>
        public Vector3 GravitationalVelocity;

        /// <summary>The timestamp of when the player was last on the ground.</summary>
        public float GroundedTime;

        [Header("Misc. technical knobs")]
        public float GroundCastLength = 0.2f;
        public LayerMask GroundLayer;

        [Header("Debug settings")]
        public bool ShowGroundCast;

        private CharacterController CharacterController;
        private Vector3 FeetPosition;

        /// <summary>The normal of the ground below the player. If there is no ground, it's <c>Vector3.up</c> by default.</summary>
        public Vector3 GroundCast() {
            RaycastHit Hit;
            if (ShowGroundCast) {
                Debug.DrawLine(FeetPosition, FeetPosition - Vector3.up, Color.red, 1f);
            }
            if (Physics.Raycast(FeetPosition, -Vector3.up, out Hit, GroundCastLength, GroundLayer)) {
                return Hit.normal;
            } else {
                return Vector3.up;
            }
        }

        public bool IsGrounded() {
            return Time.time - GroundedTime <= CoyoteTime && Vector3.Dot(GravitationalVelocity, Vector3.down) >= 0;
        }

        private void Awake() {
            CharacterController = GetComponent<CharacterController>();
            FeetPosition = transform.position + CharacterController.center - Vector3.up * (CharacterController.height / 2 + CharacterController.skinWidth / 2);
        }

        private void Update() {
            if (MoveDirection.magnitude > 0) {
                BodyYaw = Vector3.SignedAngle(Vector3.forward, MoveDirection, Vector3.up);
            }
            Body.localRotation = Quaternion.Lerp(Body.localRotation, Quaternion.Euler(0, BodyYaw, 0), 20f * Time.deltaTime);
            Head.localRotation = Quaternion.Lerp(Head.localRotation, Quaternion.Euler(Pitch, Yaw - BodyYaw, 0), 15f * Time.deltaTime);
            UpdateMovement();
        }

        private void UpdateMovement() {
            bool Grounded = IsGrounded();

            if (Grounded) {
                if (Vector3.Dot(Vector3.down, GravitationalVelocity) > 0) {
                    GravitationalVelocity = Vector3.zero;
                }
                if (Jumping) {
                    GravitationalVelocity = Vector3.up * MoveStyle.JumpVelocity;
                }
            } else {
                GravitationalVelocity += Physics.gravity * Time.deltaTime;
            }

            float FrictionVelocityFactor = Mathf.Max(GroundVelocity.magnitude, MoveStyle.StopVelocity);
            float Deccel = FrictionVelocityFactor * Time.deltaTime;
            if (Grounded) {
                Deccel *= MoveStyle.Friction;
            } else {
                Deccel *= MoveStyle.AirFriction;
            }
            float FrictionedVelocity = Mathf.Max(0, GroundVelocity.magnitude - Deccel);
            GroundVelocity = GroundVelocity.normalized * FrictionedVelocity;

            Vector3 GroundNormal = GroundCast();
            Vector3 FixedHeading = Vector3.ProjectOnPlane(MoveDirection, GroundNormal).normalized;
            float CurrentSpeed = Vector3.Dot(GroundVelocity, FixedHeading);
            float Acceleration = MoveStyle.TargetVelocity * Time.deltaTime;
            if (Grounded) {
                Acceleration *= MoveStyle.Acceleration;
            } else {
                Acceleration *= MoveStyle.AirAcceleration;
            }
            Acceleration = Mathf.Min(Acceleration, MoveStyle.TargetVelocity - CurrentSpeed);
            GroundVelocity += FixedHeading * Acceleration;

            CharacterController.Move((GroundVelocity + GravitationalVelocity) * Time.deltaTime);
            if (CharacterController.isGrounded) {
                GroundedTime = Time.time;
            }
        }
    }
}