function love.load()
    arenaWidth = 800
    arenaHeight = 600

    shipX = arenaWidth / 2
    shipY = arenaHeight / 2
    shipAngle = 0
    shipSpeedX = 0
    shipSpeedY = 0
    shipRadius = 30

    bullets = {}
    bulletTimerLimit = 0.5
    bulletTimer = bulletTimerLimit

    asteroids = {
        {
            x = 100,
            y = 100,
        },
        {
            x = arenaWidth - 100,
            y = 100,
        },
        {
            x = arenaWidth / 2,
            y = arenaHeight - 100,
        }
    }

    for asteroidIndex, asteroid in ipairs(asteroids) do
        asteroid.angle = love.math.random() * (2 * math.pi)
    end
end

function love.update(dt)
    local turnSpeed = 10

    if love.keyboard.isDown('right') then
         shipAngle = shipAngle + turnSpeed * dt
    end

    if love.keyboard.isDown('left') then
        shipAngle = shipAngle - turnSpeed * dt
    end

    shipAngle = shipAngle % (2 * math.pi)

    if love.keyboard.isDown('up') then
        local shipSpeed = 100
        shipSpeedX = shipSpeedX + math.cos(shipAngle) * shipSpeed * dt
        shipSpeedY = shipSpeedY + math.sin(shipAngle) * shipSpeed * dt
    end

    shipX = (shipX + shipSpeedX * dt) % arenaWidth
    shipY = (shipY + shipSpeedY * dt) % arenaHeight

    for bulletIndex = #bullets, 1, -1 do
        local bullet = bullets[bulletIndex]

        bullet.timeLeft = bullet.timeLeft - dt

        if bullet.timeLeft <= 0 then
            table.remove(bullets, bulletIndex)
        else
            local bulletSpeed = 500
            bullet.x = (bullet.x + math.cos(bullet.angle) * bulletSpeed * dt)
                % arenaWidth
            bullet.y = (bullet.y + math.sin(bullet.angle) * bulletSpeed * dt)
                % arenaHeight
        end
    end

    bulletTimer = bulletTimer + dt

    if love.keyboard.isDown('s') then
        if bulletTimer >= bulletTimerLimit then
            bulletTimer = 0

            table.insert(bullets, {
                x = shipX + math.cos(shipAngle) * shipRadius,
                y = shipY + math.sin(shipAngle) * shipRadius,
                angle = shipAngle,
                timeLeft = 4,
            })
        end
    end

    for asteroidIndex, asteroid in ipairs(asteroids) do
        local asteroidSpeed = 20
        asteroid.x = (asteroid.x + math.cos(asteroid.angle)
            * asteroidSpeed * dt) % arenaWidth
        asteroid.y = (asteroid.y + math.sin(asteroid.angle)
            * asteroidSpeed * dt) % arenaHeight
    end
end

function love.draw()
    for y = -1, 1 do
        for x = -1, 1 do
            love.graphics.origin()
            love.graphics.translate(x * arenaWidth, y * arenaHeight)

            love.graphics.setColor(0, 0, 1)
            love.graphics.circle('fill', shipX, shipY, shipRadius)

            local shipCircleDistance = 20
            love.graphics.setColor(0, 1, 1)
            love.graphics.circle(
                'fill',
                shipX + math.cos(shipAngle) * shipCircleDistance,
                shipY + math.sin(shipAngle) * shipCircleDistance,
                5
            )

            for bulletIndex, bullet in ipairs(bullets) do
                love.graphics.setColor(0, 1, 0)
                love.graphics.circle('fill', bullet.x, bullet.y, 5)
            end

            for asteroidIndex, asteroid in ipairs(asteroids) do
                love.graphics.setColor(1, 1, 0)
                love.graphics.circle('fill', asteroid.x, asteroid.y, 80)
            end
        end
    end
end