/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    An enumeration that converts between rotations (in radians) and 16-point compass point orientations (with east as zero). Used when determining which animation to use for an entity's current orientation.

*/

import CoreGraphics

/// The different directions that an animated character can be facing.

enum CompassDirection: Int {

    case east = 0, eastByNorthEast, northEast, northByNorthEast

    case north, northByNorthWest, northWest, westByNorthWest

    case west, westBySouthWest, southWest, southBySouthWest

    case south, southBySouthEast, southEast, eastBySouthEast

    /// Convenience array of all available directions.

    static let allDirections: [CompassDirection] =

        [

            .east, .eastByNorthEast, .northEast, .northByNorthEast,

            .north, .northByNorthWest, .northWest, .westByNorthWest,

            .west, .westBySouthWest, .southWest, .southBySouthWest,

            .south, .southBySouthEast, .southEast, .eastBySouthEast

        ]

    /// The angle of rotation that the orientation represents.

    var zRotation: CGFloat {

        // Calculate the number of radians between each direction.

        let stepSize = CGFloat(M_PI * 2.0) / CGFloat(CompassDirection.allDirections.count)

        return CGFloat(self.rawValue) * stepSize

    }

    /// Creates a new `FacingDirection` for a given `zRotation` in radians.

    init(zRotation: CGFloat) {

        let twoPi = M_PI * 2

        // Normalize the node's rotation.

        let rotation = (Double(zRotation) + twoPi).truncatingRemainder(dividingBy: twoPi)

        // Convert the rotation of the node to a percentage of a circle.

        let orientation = rotation / twoPi

        // Scale the percentage to a value between 0 and 15.

        let rawFacingValue = round(orientation * 16.0).truncatingRemainder(dividingBy: 16.0)

        // Select the appropriate `CompassDirection` based on its members' raw values, which also run from 0 to 15.

        self = CompassDirection(rawValue: Int(rawFacingValue))!

    }

    init(string: String) {

        switch string {

            case "North":

                self = .north

            case "NorthEast":

                self = .northEast

            case "East":

                self = .east

            case "SouthEast":

                self = .southEast

            case "South":

                self = .south

            case "SouthWest":

                self = .southWest

            case "West":

                self = .west

            case "NorthWest":

                self = .northWest

            default:

                fatalError("Unknown or unsupported string - \(string)")

        }

    }

}