/*

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

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Top level utility functions.

 */

import Foundation

import Metal

class Camera

{

    var m : matrix_float4x4 = matrix_identity_float4x4

    var position : vector_float3

    {

        didSet {

            _needsMatrixUpdate = true

        }

    }

    fileprivate var _needsMatrixUpdate : Bool = true

    fileprivate var _direction : vector_float3

    var direction : vector_float3

    {

        set { _direction = vector_normalize(newValue); _needsMatrixUpdate = true }

        get { return _direction }

    }

    fileprivate var _up : vector_float3

    var up : vector_float3

    {

        set { _up = vector_normalize(newValue); _needsMatrixUpdate = true }

        get { return _up }

    }

    init()

    {

        position = float3(0.0)

        _direction = float3(0.0)

        _up = float3(0.0)

    }

    func GetViewMatrix() -> matrix_float4x4

    {

        if(_needsMatrixUpdate)

        {

            m = matrix_float4x4()

            var right = crossProduct(up, b: direction)

            m.columns.0 = float4(right.x, right.y, right.z, 0.0)

            m.columns.1 = float4(up.x, up.y, up.z, 0.0)

            m.columns.2 = float4(direction.x, direction.y, direction.z, 0.0)

            m.columns.3 = float4(position.x, position.y, position.z, 1.0)

            m = matrix_invert(m)

            _needsMatrixUpdate = false

        }

        return m

    }

};

func getPerpectiveProjectionMatrix(_ FieldOfView : Float, aspectRatio : Float, zFar : Float, zNear : Float) -> matrix_float4x4

{

    var m : matrix_float4x4 = matrix_float4x4()

    let f : Float = 1.0 / tan(FieldOfView / 2.0)

    m.columns.0.x = f / aspectRatio

    m.columns.1.y = f

    m.columns.2.z = zFar / (zFar - zNear)

    m.columns.2.w = 1.0

    m.columns.3.z = -(zNear*zFar)/(zFar-zNear)

    return m

}

func getLHOrthoMatrix(_ width : Float, height : Float, zFar : Float, zNear : Float) -> matrix_float4x4

{

    var m = matrix_float4x4()

    m.columns.0.x = 2.0 / width

    m.columns.1.y = 2.0 / height

    m.columns.2.z = 1.0 / (zFar-zNear)

    m.columns.3.z = -zNear / (zFar-zNear)

    m.columns.3.w = 1.0

    return m

}

func createPlane(_ device : MTLDevice) -> (MTLBuffer, Int)

{

    var verts : [CFloat] = [ -1000.5, 0.0,  1000.5, 1.0,

                              1000.5, 0.0,  1000.5, 1.0,

                             -1000.5, 0.0, -1000.5, 1.0,

                              1000.5, 0.0,  1000.5, 1.0,

                              1000.5, 0.0, -1000.5, 1.0,

                             -1000.5, 0.0, -1000.5, 1.0,]

    let length = verts.count*MemoryLayout<CFloat>.size

    let geoBuffer = device.makeBuffer(length: length, options: MTLResourceOptions.storageModeManaged)

    let geoPtr = geoBuffer.contents().bindMemory(to: CFloat.self, capacity: length)

    geoPtr.assign(from: &verts, count: verts.count)

    geoBuffer.didModifyRange(NSMakeRange(0, verts.count*MemoryLayout<Float>.size))

    return (geoBuffer, verts.count / 4)

}

func createCube(_ device : MTLDevice) -> (MTLBuffer, MTLBuffer?, Int, Int)

{

    var verts : [CFloat] = [-0.5,  0.5, -0.5, 0.0, 0.0, -1.0,

                             0.5,  0.5, -0.5, 0.0, 0.0, -1.0,// 1

                             0.5, -0.5, -0.5, 0.0, 0.0, -1.0,// 2

                             0.5, -0.5, -0.5, 0.0, 0.0, -1.0,// 2

                            -0.5, -0.5, -0.5, 0.0, 0.0, -1.0,// 3

                            -0.5,  0.5, -0.5, 0.0, 0.0, -1.0,

        0.5,  0.5, -0.5, 1.0,0.0,0.0, // 1

        0.5,  0.5,  0.5, 1.0,0.0,0.0, // 5

        0.5, -0.5,  0.5, 1.0,0.0,0.0, // 6

        0.5, -0.5,  0.5, 1.0,0.0,0.0, // 6

        0.5, -0.5, -0.5, 1.0,0.0,0.0, // 2

        0.5,  0.5, -0.5, 1.0,0.0,0.0, // 1

         0.5,  0.5,  0.5, 0.0,0.0,1.0, // 5

        -0.5,  0.5,  0.5, 0.0,0.0,1.0, // 4

        -0.5, -0.5,  0.5, 0.0,0.0,1.0, // 7

        -0.5, -0.5,  0.5, 0.0,0.0,1.0, // 7

         0.5, -0.5,  0.5, 0.0,0.0,1.0, // 6

         0.5,  0.5,  0.5, 0.0,0.0,1.0, // 5

        -0.5,  0.5,  0.5, -1.0,0.0,0.0, // 4

        -0.5,  0.5, -0.5, -1.0,0.0,0.0, 

        -0.5, -0.5, -0.5, -1.0,0.0,0.0, // 3

        -0.5, -0.5, -0.5, -1.0,0.0,0.0, // 3

        -0.5, -0.5,  0.5, -1.0,0.0,0.0, // 7

        -0.5,  0.5,  0.5, -1.0,0.0,0.0, // 4

        -0.5,  0.5,  0.5, 0.0,1.0,0.0,// 4

         0.5,  0.5,  0.5, 0.0,1.0,0.0, // 5

         0.5,  0.5, -0.5, 0.0,1.0,0.0, // 1

         0.5,  0.5, -0.5, 0.0,1.0,0.0, // 1

        -0.5,  0.5, -0.5, 0.0,1.0,0.0, 

        -0.5,  0.5,  0.5, 0.0,1.0,0.0, // 4

        -0.5, -0.5, -0.5, 0.0,-1.0,0.0, // 3

         0.5, -0.5, -0.5, 0.0,-1.0,0.0, // 2

         0.5, -0.5,  0.5, 0.0,-1.0,0.0, // 6

         0.5, -0.5,  0.5, 0.0,-1.0,0.0, // 6

        -0.5, -0.5,  0.5, 0.0,-1.0,0.0, // 7

        -0.5, -0.5, -0.5, 0.0,-1.0,0.0, // 3

                                    ]

    let length = verts.count*MemoryLayout<CFloat>.size

    let geoBuffer = device.makeBuffer(length: length, options: MTLResourceOptions.storageModeManaged)

    let geoPtr = geoBuffer.contents().bindMemory(to: CFloat.self, capacity: length)

    geoPtr.assign(from: &verts, count: verts.count)

    geoBuffer.didModifyRange(NSMakeRange(0, verts.count*MemoryLayout<Float>.size))

    return (geoBuffer, nil, 0, verts.count/6)

}

func getRotationAroundZ(_ radians : Float) -> matrix_float4x4

{

    var m : matrix_float4x4 = matrix_identity_float4x4;

    m.columns.0.x = cos(radians);

    m.columns.0.y = sin(radians);

    m.columns.1.x = -sin(radians);

    m.columns.1.y = cos(radians);

    return m;

}

func getRotationAroundY(_ radians : Float) -> matrix_float4x4

{

    var m : matrix_float4x4 = matrix_identity_float4x4;

    m.columns.0.x =  cos(radians);

    m.columns.0.z = -sin(radians);

    m.columns.2.x = sin(radians);

    m.columns.2.z = cos(radians);

    return m;

}

func getRotationAroundX(_ radians : Float) -> matrix_float4x4

{

    var m : matrix_float4x4 = matrix_identity_float4x4;

    m.columns.1.y = cos(radians);

    m.columns.1.z = sin(radians);

    m.columns.2.y = -sin(radians);

    m.columns.2.z =  cos(radians);

    return m;

}

func getTranslationMatrix(_ translation : vector_float4) -> matrix_float4x4

{

    var m : matrix_float4x4 = matrix_identity_float4x4

    m.columns.3 = translation

    return m

}

func getScaleMatrix(_ x : Float, y : Float, z : Float) -> matrix_float4x4

{

    var m = matrix_identity_float4x4

    m.columns.0.x = x

    m.columns.1.y = y

    m.columns.2.z = z

    return m

}

//Returns a value from -max to max

func getRandomValue(_ max : Double) -> Double

{

    let r : Int32 = Int32(Int64(arc4random()) - Int64(RAND_MAX))

    let v = (Double(r) / Double(RAND_MAX)) * max

    return v

}

func crossProduct(_ a : vector_float3, b : vector_float3) -> vector_float3

{

    var r : vector_float3 = vector_float3()

    r.x = a.y*b.z - a.z*b.y

    r.y = a.z*b.x - a.x*b.z

    r.z = a.x*b.y - a.y*b.x

    return r

}