#pragma strict
#pragma implicit
#pragma downcast

// Does this script currently respond to input?
var canControl : boolean = true;

var useFixedUpdate : boolean = true;

// For the next variables, @System.NonSerialized tells Unity to not serialize the variable or show it in the inspector view.
// Very handy for organization!

// The current global direction we want the character to move in.
@System.NonSerialized
var inputMoveDirection : Vector3 = Vector3.zero;

// Is the jump button held down? We use this interface instead of checking
// for the jump button directly so this script can also be used by AIs.
@System.NonSerialized
var inputJump : boolean = false;

class CharacterMotorMovement {
    // The maximum horizontal speed when moving
    var maxForwardSpeed : float = 80.0;
    var maxSidewaysSpeed : float = 80.0;
    var maxBackwardsSpeed : float = 80.0;

    // Curve for multiplying speed based on slope (negative = downwards)
    var slopeSpeedMultiplier : AnimationCurve = AnimationCurve(Keyframe(-90, 1), Keyframe(0, 1), Keyframe(90, 0));

    // How fast does the character change speeds?  Higher is faster.
    var maxGroundAcceleration : float = 30.0;
    var maxAirAcceleration : float = 20.0;

    // The gravity for the character
    var gravity : float = 10.0;
    var maxFallSpeed : float = 20.0;

    // For the next variables, @System.NonSerialized tells Unity to not serialize the variable or show it in the inspector view.
    // Very handy for organization!

    // The last collision flags returned from controller.Move
    @System.NonSerialized
    var collisionFlags : CollisionFlags;

    // We will keep track of the character's current velocity,
    @System.NonSerialized
    var velocity : Vector3;

    // This keeps track of our current velocity while we're not grounded
    @System.NonSerialized
    var frameVelocity : Vector3 = Vector3.zero;

    @System.NonSerialized
    var hitPoint : Vector3 = Vector3.zero;

    @System.NonSerialized
    var lastHitPoint : Vector3 = Vector3(Mathf.Infinity, 0, 0);
}

var movement : CharacterMotorMovement = CharacterMotorMovement();

enum MovementTransferOnJump {
    None, // The jump is not affected by velocity of floor at all.
    InitTransfer, // Jump gets its initial velocity from the floor, then gradualy comes to a stop.
    PermaTransfer, // Jump gets its initial velocity from the floor, and keeps that velocity until landing.
    PermaLocked // Jump is relative to the movement of the last touched floor and will move together with that floor.
}

// We will contain all the jumping related variables in one helper class for clarity.
class CharacterMotorJumping {
    // Can the character jump?
    var enabled : boolean = true;

    // How high do we jump when pressing jump and letting go immediately
    var baseHeight : float = 1.0;

    // We add extraHeight units (meters) on top when holding the button down longer while jumping
    var extraHeight : float = 4.1;

    // How much does the character jump out perpendicular to the surface on walkable surfaces?
    // 0 means a fully vertical jump and 1 means fully perpendicular.
    var perpAmount : float = 0.0;

    // How much does the character jump out perpendicular to the surface on too steep surfaces?
    // 0 means a fully vertical jump and 1 means fully perpendicular.
    var steepPerpAmount : float = 0.5;

    // For the next variables, @System.NonSerialized tells Unity to not serialize the variable or show it in the inspector view.
    // Very handy for organization!

    // Are we jumping? (Initiated with jump button and not grounded yet)
    // To see if we are just in the air (initiated by jumping OR falling) see the grounded variable.
    @System.NonSerialized
    var jumping : boolean = false;

    @System.NonSerialized
    var holdingJumpButton : boolean = false;

    // the time we jumped at (Used to determine for how long to apply extra jump power after jumping.)
    @System.NonSerialized
    var lastStartTime : float = 0.0;

    @System.NonSerialized
    var lastButtonDownTime : float = -100;

    @System.NonSerialized
    var jumpDir : Vector3 = Vector3.up;
}

var jumping : CharacterMotorJumping = CharacterMotorJumping();

class CharacterMotorMovingPlatform {
    var enabled : boolean = true;

    var movementTransfer : MovementTransferOnJump = MovementTransferOnJump.PermaTransfer;

    @System.NonSerialized
    var hitPlatform : Transform;

    @System.NonSerialized
    var activePlatform : Transform;

    @System.NonSerialized
    var activeLocalPoint : Vector3;

    @System.NonSerialized
    var activeGlobalPoint : Vector3;

    @System.NonSerialized
    var activeLocalRotation : Quaternion;

    @System.NonSerialized
    var activeGlobalRotation : Quaternion;

    @System.NonSerialized
    var lastMatrix : Matrix4x4;

    @System.NonSerialized
    var platformVelocity : Vector3;

    @System.NonSerialized
    var newPlatform : boolean;
}

var movingPlatform : CharacterMotorMovingPlatform = CharacterMotorMovingPlatform();

class CharacterMotorSliding {
    // Does the character slide on too steep surfaces?
    var enabled : boolean = true;

    // How fast does the character slide on steep surfaces?
    var slidingSpeed : float = 15;

    // How much can the player control the sliding direction?
    // If the value is 0.5 the player can slide sideways with half the speed of the downwards sliding speed.
    var sidewaysControl : float = 1.0;

    // How much can the player influence the sliding speed?
    // If the value is 0.5 the player can speed the sliding up to 150% or slow it down to 50%.
    var speedControl : float = 0.4;
}

var sliding : CharacterMotorSliding = CharacterMotorSliding();

@System.NonSerialized
var grounded : boolean = true;

@System.NonSerialized
var groundNormal : Vector3 = Vector3.zero;

private var lastGroundNormal : Vector3 = Vector3.zero;

private var tr : Transform;

private var controller : CharacterController;

function Awake () {
    controller = GetComponent (CharacterController);
    tr = transform;
}

private function UpdateFunction () {
    // We copy the actual velocity into a temporary variable that we can manipulate.
    var velocity : Vector3 = movement.velocity;

    // Update velocity based on input
    velocity = ApplyInputVelocityChange(velocity);

    // Apply gravity and jumping force
    velocity = ApplyGravityAndJumping (velocity);

    // Moving platform support
    var moveDistance : Vector3 = Vector3.zero;
    if (MoveWithPlatform()) {
        var newGlobalPoint : Vector3 = movingPlatform.activePlatform.TransformPoint(movingPlatform.activeLocalPoint);
        moveDistance = (newGlobalPoint - movingPlatform.activeGlobalPoint);
        if (moveDistance != Vector3.zero)
            controller.Move(moveDistance);

        // Support moving platform rotation as well:
        var newGlobalRotation : Quaternion = movingPlatform.activePlatform.rotation * movingPlatform.activeLocalRotation;
        var rotationDiff : Quaternion = newGlobalRotation * Quaternion.Inverse(movingPlatform.activeGlobalRotation);

        var yRotation = rotationDiff.eulerAngles.y;
        if (yRotation != 0) {
            // Prevent rotation of the local up vector
            tr.Rotate(0, yRotation, 0);
        }
    }

    // Save lastPosition for velocity calculation.
    var lastPosition : Vector3 = tr.position;

    // We always want the movement to be framerate independent.  Multiplying by Time.deltaTime does this.
    var currentMovementOffset : Vector3 = velocity * Time.deltaTime;

    // Find out how much we need to push towards the ground to avoid loosing grouning
    // when walking down a step or over a sharp change in slope.
    var pushDownOffset : float = Mathf.Max(controller.stepOffset, Vector3(currentMovementOffset.x, 0, currentMovementOffset.z).magnitude);
    if (grounded)
        currentMovementOffset -= pushDownOffset * Vector3.up;

    // Reset variables that will be set by collision function
    movingPlatform.hitPlatform = null;
    groundNormal = Vector3.zero;

    // Move our character!
    movement.collisionFlags = controller.Move (currentMovementOffset);

    movement.lastHitPoint = movement.hitPoint;
    lastGroundNormal = groundNormal;

    if (movingPlatform.enabled && movingPlatform.activePlatform != movingPlatform.hitPlatform) {
        if (movingPlatform.hitPlatform != null) {
            movingPlatform.activePlatform = movingPlatform.hitPlatform;
            movingPlatform.lastMatrix = movingPlatform.hitPlatform.localToWorldMatrix;
            movingPlatform.newPlatform = true;
        }
    }

    // Calculate the velocity based on the current and previous position.
    // This means our velocity will only be the amount the character actually moved as a result of collisions.
    var oldHVelocity : Vector3 = new Vector3(velocity.x, 0, velocity.z);
    movement.velocity = (tr.position - lastPosition) / Time.deltaTime;
    var newHVelocity : Vector3 = new Vector3(movement.velocity.x, 0, movement.velocity.z);

    // The CharacterController can be moved in unwanted directions when colliding with things.
    // We want to prevent this from influencing the recorded velocity.
    if (oldHVelocity == Vector3.zero) {
        movement.velocity = new Vector3(0, movement.velocity.y, 0);
    }
    else {
        var projectedNewVelocity : float = Vector3.Dot(newHVelocity, oldHVelocity) / oldHVelocity.sqrMagnitude;
        movement.velocity = oldHVelocity * Mathf.Clamp01(projectedNewVelocity) + movement.velocity.y * Vector3.up;
    }

    if (movement.velocity.y < velocity.y - 0.001) {
        if (movement.velocity.y < 0) {
            // Something is forcing the CharacterController down faster than it should.
            // Ignore this
            movement.velocity.y = velocity.y;
        }
        else {
            // The upwards movement of the CharacterController has been blocked.
            // This is treated like a ceiling collision - stop further jumping here.
            jumping.holdingJumpButton = false;
        }
    }

    // We were grounded but just loosed grounding
    if (grounded && !IsGroundedTest()) {
        grounded = false;

        // Apply inertia from platform
        if (movingPlatform.enabled &&
            (movingPlatform.movementTransfer == MovementTransferOnJump.InitTransfer ||
            movingPlatform.movementTransfer == MovementTransferOnJump.PermaTransfer)
        ) {
            movement.frameVelocity = movingPlatform.platformVelocity;
            movement.velocity += movingPlatform.platformVelocity;
        }

        SendMessage("OnFall", SendMessageOptions.DontRequireReceiver);
        // We pushed the character down to ensure it would stay on the ground if there was any.
        // But there wasn't so now we cancel the downwards offset to make the fall smoother.
        tr.position += pushDownOffset * Vector3.up;
    }
    // We were not grounded but just landed on something
    else if (!grounded && IsGroundedTest()) {
        grounded = true;
        jumping.jumping = false;
        SubtractNewPlatformVelocity();

        SendMessage("OnLand", SendMessageOptions.DontRequireReceiver);
    }

    // Moving platforms support
    if (MoveWithPlatform()) {
        // Use the center of the lower half sphere of the capsule as reference point.
        // This works best when the character is standing on moving tilting platforms.
        movingPlatform.activeGlobalPoint = tr.position + Vector3.up * (controller.center.y - controller.height*0.5 + controller.radius);
        movingPlatform.activeLocalPoint = movingPlatform.activePlatform.InverseTransformPoint(movingPlatform.activeGlobalPoint);

        // Support moving platform rotation as well:
        movingPlatform.activeGlobalRotation = tr.rotation;
        movingPlatform.activeLocalRotation = Quaternion.Inverse(movingPlatform.activePlatform.rotation) * movingPlatform.activeGlobalRotation;
    }
}

function FixedUpdate () {
    if (movingPlatform.enabled) {
        if (movingPlatform.activePlatform != null) {
            if (!movingPlatform.newPlatform) {
                var lastVelocity : Vector3 = movingPlatform.platformVelocity;

                movingPlatform.platformVelocity = (
                    movingPlatform.activePlatform.localToWorldMatrix.MultiplyPoint3x4(movingPlatform.activeLocalPoint)
                    - movingPlatform.lastMatrix.MultiplyPoint3x4(movingPlatform.activeLocalPoint)
                ) / Time.deltaTime;
            }
            movingPlatform.lastMatrix = movingPlatform.activePlatform.localToWorldMatrix;
            movingPlatform.newPlatform = false;
        }
        else {
            movingPlatform.platformVelocity = Vector3.zero;
        }
    }

    if (useFixedUpdate)
        UpdateFunction();
}

function Update () {
    if (!useFixedUpdate)
        UpdateFunction();
}

private function ApplyInputVelocityChange (velocity : Vector3) {
    if (!canControl)
        inputMoveDirection = Vector3.zero;

    // Find desired velocity
    var desiredVelocity : Vector3;
    if (grounded && TooSteep()) {
        // The direction we're sliding in
        desiredVelocity = Vector3(groundNormal.x, 0, groundNormal.z).normalized;
        // Find the input movement direction projected onto the sliding direction
        var projectedMoveDir = Vector3.Project(inputMoveDirection, desiredVelocity);
        // Add the sliding direction, the spped control, and the sideways control vectors
        desiredVelocity = desiredVelocity + projectedMoveDir * sliding.speedControl + (inputMoveDirection - projectedMoveDir) * sliding.sidewaysControl;
        // Multiply with the sliding speed
        desiredVelocity *= sliding.slidingSpeed;
    }
    else
        desiredVelocity = GetDesiredHorizontalVelocity();

    if (movingPlatform.enabled && movingPlatform.movementTransfer == MovementTransferOnJump.PermaTransfer) {
        desiredVelocity += movement.frameVelocity;
        desiredVelocity.y = 0;
    }

    if (grounded)
        desiredVelocity = AdjustGroundVelocityToNormal(desiredVelocity, groundNormal);
    else
        velocity.y = 0;

    // Enforce max velocity change
    var maxVelocityChange : float = GetMaxAcceleration(grounded) * Time.deltaTime;
    var velocityChangeVector : Vector3 = (desiredVelocity - velocity);
    if (velocityChangeVector.sqrMagnitude > maxVelocityChange * maxVelocityChange) {
        velocityChangeVector = velocityChangeVector.normalized * maxVelocityChange;
    }
    // If we're in the air and don't have control, don't apply any velocity change at all.
    // If we're on the ground and don't have control we do apply it - it will correspond to friction.
    if (grounded || canControl)
        velocity += velocityChangeVector;

    if (grounded) {
        // When going uphill, the CharacterController will automatically move up by the needed amount.
        // Not moving it upwards manually prevent risk of lifting off from the ground.
        // When going downhill, DO move down manually, as gravity is not enough on steep hills.
        velocity.y = Mathf.Min(velocity.y, 0);
    }

    return velocity;
}

private function ApplyGravityAndJumping (velocity : Vector3) {

    if (!inputJump || !canControl) {
        jumping.holdingJumpButton = false;
        jumping.lastButtonDownTime = -100;
    }

    if (inputJump && jumping.lastButtonDownTime < 0 && canControl)
        jumping.lastButtonDownTime = Time.time;

    if (grounded)
        velocity.y = Mathf.Min(0, velocity.y) - movement.gravity * Time.deltaTime;
    else {
        velocity.y = movement.velocity.y - movement.gravity * Time.deltaTime;

        // When jumping up we don't apply gravity for some time when the user is holding the jump button.
        // This gives more control over jump height by pressing the button longer.
        if (jumping.jumping && jumping.holdingJumpButton) {
            // Calculate the duration that the extra jump force should have effect.
            // If we're still less than that duration after the jumping time, apply the force.
            if (Time.time < jumping.lastStartTime + jumping.extraHeight / CalculateJumpVerticalSpeed(jumping.baseHeight)) {
                // Negate the gravity we just applied, except we push in jumpDir rather than jump upwards.
                velocity += jumping.jumpDir * movement.gravity * Time.deltaTime;
            }
        }

        // Make sure we don't fall any faster than maxFallSpeed. This gives our character a terminal velocity.
        velocity.y = Mathf.Max (velocity.y, -movement.maxFallSpeed);
    }

    if (grounded) {
        // Jump only if the jump button was pressed down in the last 0.2 seconds.
        // We use this check instead of checking if it's pressed down right now
        // because players will often try to jump in the exact moment when hitting the ground after a jump
        // and if they hit the button a fraction of a second too soon and no new jump happens as a consequence,
        // it's confusing and it feels like the game is buggy.
        if (jumping.enabled && canControl && (Time.time - jumping.lastButtonDownTime < 0.2)) {
            grounded = false;
            jumping.jumping = true;
            jumping.lastStartTime = Time.time;
            jumping.lastButtonDownTime = -100;
            jumping.holdingJumpButton = true;

            // Calculate the jumping direction
            if (TooSteep())
                jumping.jumpDir = Vector3.Slerp(Vector3.up, groundNormal, jumping.steepPerpAmount);
            else
                jumping.jumpDir = Vector3.Slerp(Vector3.up, groundNormal, jumping.perpAmount);

            // Apply the jumping force to the velocity. Cancel any vertical velocity first.
            velocity.y = 0;
            velocity += jumping.jumpDir * CalculateJumpVerticalSpeed (jumping.baseHeight);

            // Apply inertia from platform
            if (movingPlatform.enabled &&
                (movingPlatform.movementTransfer == MovementTransferOnJump.InitTransfer ||
                movingPlatform.movementTransfer == MovementTransferOnJump.PermaTransfer)
            ) {
                movement.frameVelocity = movingPlatform.platformVelocity;
                velocity += movingPlatform.platformVelocity;
            }

            SendMessage("OnJump", SendMessageOptions.DontRequireReceiver);
        }
        else {
            jumping.holdingJumpButton = false;
        }
    }

    return velocity;
}

function OnControllerColliderHit (hit : ControllerColliderHit) {
    if (hit.normal.y > 0 && hit.normal.y > groundNormal.y && hit.moveDirection.y < 0) {
        if ((hit.point - movement.lastHitPoint).sqrMagnitude > 0.001 || lastGroundNormal == Vector3.zero)
            groundNormal = hit.normal;
        else
            groundNormal = lastGroundNormal;

        movingPlatform.hitPlatform = hit.collider.transform;
        movement.hitPoint = hit.point;
        movement.frameVelocity = Vector3.zero;
    }
}

private function SubtractNewPlatformVelocity () {
    // When landing, subtract the velocity of the new ground from the character's velocity
    // since movement in ground is relative to the movement of the ground.
    if (movingPlatform.enabled &&
        (movingPlatform.movementTransfer == MovementTransferOnJump.InitTransfer ||
        movingPlatform.movementTransfer == MovementTransferOnJump.PermaTransfer)
    ) {
        // If we landed on a new platform, we have to wait for two FixedUpdates
        // before we know the velocity of the platform under the character
        if (movingPlatform.newPlatform) {
            var platform : Transform = movingPlatform.activePlatform;
            yield WaitForFixedUpdate();
            yield WaitForFixedUpdate();
            if (grounded && platform == movingPlatform.activePlatform)
                yield 1;
        }
        movement.velocity -= movingPlatform.platformVelocity;
    }
}

private function MoveWithPlatform () : boolean {
    return (
        movingPlatform.enabled
        && (grounded || movingPlatform.movementTransfer == MovementTransferOnJump.PermaLocked)
        && movingPlatform.activePlatform != null
    );
}

private function GetDesiredHorizontalVelocity () {
    // Find desired velocity
    var desiredLocalDirection : Vector3 = tr.InverseTransformDirection(inputMoveDirection);
    var maxSpeed : float = MaxSpeedInDirection(desiredLocalDirection);
    if (grounded) {
        // Modify max speed on slopes based on slope speed multiplier curve
        var movementSlopeAngle = Mathf.Asin(movement.velocity.normalized.y)  * Mathf.Rad2Deg;
        maxSpeed *= movement.slopeSpeedMultiplier.Evaluate(movementSlopeAngle);
    }
    return tr.TransformDirection(desiredLocalDirection * maxSpeed);
}

private function AdjustGroundVelocityToNormal (hVelocity : Vector3, groundNormal : Vector3) : Vector3 {
    var sideways : Vector3 = Vector3.Cross(Vector3.up, hVelocity);
    return Vector3.Cross(sideways, groundNormal).normalized * hVelocity.magnitude;
}

private function IsGroundedTest () {
    return (groundNormal.y > 0.01);
}

function GetMaxAcceleration (grounded : boolean) : float {
    // Maximum acceleration on ground and in air
    if (grounded)
        return movement.maxGroundAcceleration;
    else
        return movement.maxAirAcceleration;
}

function CalculateJumpVerticalSpeed (targetJumpHeight : float) {
    // From the jump height and gravity we deduce the upwards speed
    // for the character to reach at the apex.
    return Mathf.Sqrt (2 * targetJumpHeight * movement.gravity);
}

function IsJumping () {
    return jumping.jumping;
}

function IsSliding () {
    return (grounded && sliding.enabled && TooSteep());
}

function IsTouchingCeiling () {
    return (movement.collisionFlags & CollisionFlags.CollidedAbove) != 0;
}

function IsGrounded () {
    return grounded;
}

function TooSteep () {
    return (groundNormal.y <= Mathf.Cos(controller.slopeLimit * Mathf.Deg2Rad));
}

function GetDirection () {
    return inputMoveDirection;
}

function SetControllable (controllable : boolean) {
    canControl = controllable;
}

// Project a direction onto elliptical quater segments based on forward, sideways, and backwards speed.
// The function returns the length of the resulting vector.
function MaxSpeedInDirection (desiredMovementDirection : Vector3) : float {
    if (desiredMovementDirection == Vector3.zero)
        return 0;
    else {
        var zAxisEllipseMultiplier : float = (desiredMovementDirection.z > 0 ? movement.maxForwardSpeed : movement.maxBackwardsSpeed) / movement.maxSidewaysSpeed;
        var temp : Vector3 = new Vector3(desiredMovementDirection.x, 0, desiredMovementDirection.z / zAxisEllipseMultiplier).normalized;
        var length : float = new Vector3(temp.x, 0, temp.z * zAxisEllipseMultiplier).magnitude * movement.maxSidewaysSpeed;
        return length;
    }
}

function SetVelocity (velocity : Vector3) {
    grounded = false;
    movement.velocity = velocity;
    movement.frameVelocity = Vector3.zero;
    SendMessage("OnExternalVelocity");
}

// Require a character controller to be attached to the same game object
@script RequireComponent (CharacterController)
@script AddComponentMenu ("Character/Character Motor")