Infinite loop in Tower video.

class Enemy {
    //...

    func decreaseHealth(factor: Int) {    
        // Was: life -= life - factor
        // You can either write life = life - factor or
        life -= factor
    }
}

struct Point {
    let x: Int
    let y: Int

    init(x: Int, y: Int) {
        self.x = x
        self.y = y
    }

    func surroundingPoints(withRange range: Int = 1) -> [Point] {
        var results:[Point] = []
        for xCoord in (x-range)...(x+range) {
            for yCoord in (y-range)...(y+range) {
                let coordinatePoint = Point(x: xCoord, y:yCoord)
                results.append(coordinatePoint)
            }
        }
        return results
    }
}

let coordinatePoint = Point (x: 2, y:2)
coordinatePoint.surroundingPoints()

class Enemy {
    var life: Int = 2
    let position: Point

    init(x: Int, y: Int) {
        self.position = Point(x: x, y: y)
    }
    func decreaseHealth(factor: Int) {
        life -= life - factor
    }
}

class Tower {
    let position: Point
    var range: Int = 1
    var strenght: Int = 1

    init (x: Int, y: Int){
        self.position = Point(x: x, y: y)
    }
    func fireAtEnemy(enemy: Enemy) {
        if inRange(self.position, range: self.range, target: enemy.position) {
            while enemy.life > 0 {
                enemy.decreaseHealth(self.strenght)
                print("Enemy vanquished!")
            }
        } else {
            print("Darn! The enemy is out of range!")
        }
    }
    func inRange(position: Point, range: Int, target: Point) -> Bool {
        let availablePositions = position.surroundingPoints(withRange: range)
        for point in availablePositions {
            if (point.x == target.x) && (point.y == target.y) {
                return true
            }
        }
        return false
    }
}

// Inheretance

class SuperEnemy: Enemy {
    let isSuper: Bool = true

    override init(x: Int, y: Int) {
        super.init(x: x, y: y)
        self.life = 50
    }
}

class LaserTower: Tower {
    override init(x: Int, y: Int) {
        super.init(x: x, y: y)
        self.range = 100
        self.strenght = 100
    }
    override func fireAtEnemy(enemy: Enemy) {
        while enemy.life >= 0 {
            enemy.decreaseHealth(strenght)
        }
        print("Enemy vanquished!")
    }
}

let tower = Tower(x: 0, y: 0)
let enemy1 = Enemy(x: 1, y: 1)

//let superEnemy = SuperEnemy(x: 20, y: 20)
//let laserTower = LaserTower(x: 0, y: 0)
//tower.fireAtEnemy(enemy1)