local Class = require("middleclass")

local Balls = {}

local Ball = Class("Ball")
Ball.radius = 2

function Ball:initialize()
    self.x = love.math.random() * love.graphics.getWidth()
    self.y = love.math.random() * love.graphics.getHeight()

    local angle = love.math.random() * math.pi * 2
    local speed = 30
    self.vx = speed * math.cos(angle)
    self.vy = speed * math.sin(angle)
end

function Ball:update(dt, index)
    self.x = self.x + self.vx * dt
    self.y = self.y + self.vy * dt

    self:checkWallCollision()
    self:checkBallCollisions(index)
end

function Ball:checkWallCollision()
    if (self.x < 0) then
        self.x = 0
        self.vx = self.vx * -1
    end

    if (self.x > love.graphics.getWidth()) then
        self.x = love.graphics.getWidth()
        self.vx = self.vx * -1
    end

    if (self.y < 0) then
        self.y = 0
        self.vy = self.vy * -1
    end

    if (self.y > love.graphics.getHeight()) then
        self.y = love.graphics.getHeight()
        self.vy = self.vy * -1
    end
end

function Ball:checkBallCollisions(index)
    for i = index + 1, #Balls do
        local other = Balls[i]

        local dx = other.x - self.x
        local dy = other.y - self.y
        local distanceSquared = dx * dx + dy * dy
        local combinedRadius = self.radius + other.radius
        local combinedRadiusSquared = combinedRadius * combinedRadius

        if distanceSquared < combinedRadiusSquared then
            local midX = (self.x + other.x) * 0.5
            local midY = (self.y + other.y) * 0.5

            local normalX = (self.x - midX) / combinedRadius
            local normalY = (self.y - midY) / combinedRadius

            self.x = midX + normalX * combinedRadius * 1.01
            self.y = midY + normalY * combinedRadius * 1.01

            other.x = midX - normalX * combinedRadius * 1.01
            other.y = midY - normalY * combinedRadius * 1.01

            self.vx, other.vx = other.vx, self.vx
            self.vy, other.vy = other.vy, self.vy
        end
    end
end

function Ball:draw()
    love.graphics.circle("fill", self.x, self.y, self.radius)
end

local function spawnBalls(amount)
    for i = 1, amount do
        table.insert(Balls, Ball())
    end
end

function love.load()
    spawnBalls(8000)
end

function love.update(dt)
    for i, ball in ipairs(Balls) do
        ball:update(dt, i)
    end
end

function love.draw()
    for _, ball in ipairs(Balls) do
        ball:draw()
    end

    love.graphics.print(love.timer.getFPS())
end