-- Loading the ECS
local Sniper = require("sniper")

local Entity    = Sniper.entity
local Component = Sniper.component
local System    = Sniper.system

-- Setting up textures
local Textures = {
   love.graphics.newImage("stone.png"),
}

-- Setting up components
local Position = Component([[
   float x, y;
]])

local Velocity = Component([[
   float x, y;
]])

local Sprite = Component([[
   int texture;
]])

-- Setting up systems
local Physics = System({Position, Velocity})
function Physics:update(dt)
   for i = 1, Physics.count do
      local id = Physics:get(i)

      local position = Position:get(id)
      local velocity = Velocity:get(id)

      position.x = position.x + velocity.x * dt
      position.y = position.y + velocity.y * dt

      if position.x > love.graphics.getWidth() or
         position.y > love.graphics.getHeight() then

         position.x = 0
         position.y = 0
      end
   end
end

local SpriteRenderer = System({Position, Sprite})
function SpriteRenderer:draw()
   for i = 1, SpriteRenderer.count do
      local id = Physics:get(i)

      local position = Position:get(id)
      local sprite   = Sprite:get(id)

      local texture = Textures[sprite.texture]
      love.graphics.draw(texture, position.x, position.y, nil, 0.1, 0.1)
   end
end

-- Creating 100 entities
for i = 1, 100 do
   Entity()
   :give(Position, 0, 0)
   :give(Velocity, love.math.random(10, 30), love.math.random(10, 30))
   :give(Sprite, 1)
   :filter()
end

-- Callbacks
function love.update(dt)
   Physics:update(dt)
end

function love.draw()
   SpriteRenderer:draw()
end