-- handles object collision and updates

require 'util'

local self = {}

local steps = 4 -- the more, the higher quality the collision is, however it becomes laggier
local clipAttempts = 10000

function self.doCollision(i, o, dt)
  -- check if object is already colliding and try to clip it out
  
  -- object collision
  for i2,o2 in ipairs(objects) do
    local touch = rectangleTouchingRectangle(o.x, o.y, o.size, o.size, o2.x, o2.y, o2.size, o2.size) and i ~= i2
    if touch then
      -- clip it out, m64 style
      for i = 0, clipAttempts do
        if not rectangleTouchingRectangle(o.x, o.y, o.size, o.size, o2.x, o2.y, o2.size, o2.size) then break end
        local diffX = (o.x - o2.x) or o.size / 10 -- `or` incase the objects are spawned inside eachother
        local diffY = (o.y - o2.y) or o.size / 10

        o.x = diffX * 1.1 + o2.x
        o.y = diffY * 1.1 + o2.y
      end
    end
  end

  -- tile collision
  for i = 0, clipAttempts do
    local pass = true
    local onTileId = getTile(math.floor(o.x), math.floor(o.y))
    if onTileId[1] ~= 0 then
      local onTile = tiles[onTileId[1]]
      local a = -(onTileId.rotation or 0) * 90
      
      if onTile.collision then
        if onTile.type == 'seller' then
          local movementAngle = math.deg(math.atan2(o.vely, o.velx)) - 90
          if onTileId.rotation then
            local sellerAngle = onTileId.rotation * 90
            if not math.abs(movementAngle - sellerAngle) < 45 then
              pass = false
            end
          end
        else
          pass = false
        end
      end
    end

    if pass then break end

    local diffX = (o.x % 1 - 0.5) or o.size / 10 -- `or` incase the objects are spawned inside eachother
    local diffY = (o.y % 1 - 0.5) or o.size / 10

    o.x = diffX * 1.1 + math.floor(o.x) + 0.5
    o.y = diffY * 1.1 + math.floor(o.y) + 0.5
  end

  -- move
  for step = 1, steps do
    local a = step/steps
    local x = o.x + o.velx * dt * a
    local y = o.y + o.vely * dt * a

    local pass = true

    -- tile collision
    local onTileId = getTile(math.floor(x), math.floor(y))
    if onTileId[1] ~= 0 then
      local onTile = tiles[onTileId[1]]
      local a = -(onTileId.rotation or 0) * 90
      
      if onTile.collision then
        if onTile.type == 'seller' then
          local movementAngle = math.deg(math.atan2(o.vely, o.velx)) - 90
          if onTileId.rotation then
            local sellerAngle = onTileId.rotation * 90
            if not math.abs(movementAngle - sellerAngle) < 45 then
              pass = false
            end
          end
        else
          pass = false
        end
      end
    end

    -- object collision
    for i2,o2 in ipairs(objects) do
      local touch = rectangleTouchingRectangle(o.x, o.y, o.size, o.size, o2.x, o2.y, o2.size, o2.size) and i ~= i2
      if touch then pass = false end
    end

    if pass then
      o.x = x
      o.y = y
    else
      o.velx = -o.velx * 0.25
      o.vely = -o.vely * 0.25
      break
    end
  end
end

function self.updateObject(i, o, dt)
  o.x = o.x or 0
  o.y = o.y or 0
  o.velx = o.velx or 0
  o.vely = o.vely or 0
  o.size = o.size or 0.5
  o.color = o.color or {1, 1, 1}
  o.despawntimer = o.despawntimer or 0

  local object = objectTypes[o.type]

  local onTileId = getTile(math.floor(o.x), math.floor(o.y))
  if onTileId[1] ~= 0 then
    local onTile = tiles[onTileId[1]]
    local a = -(onTileId.rotation or 0) * 90
    
    if onTile.type == 'conveyor' then
      o.velx = o.velx - math.sin(math.rad(a)) * onTile.speed * dt * 40
      o.vely = o.vely - math.cos(math.rad(a)) * onTile.speed * dt * 40
    elseif onTile.type == 'seller' then
      local movementAngle = math.deg(math.atan2(o.vely, o.velx)) - 90
      if onTileId.rotation then
        local sellerAngle = onTileId.rotation * 90
        if math.abs(movementAngle - sellerAngle) < 45 then
          table.remove(objects, i)
          money = money + object.cost
        end
      end
    end
  end

  if math.abs(o.velx) < 0.01 and math.abs(o.vely) < 0.01 then
    o.despawntimer = o.despawntimer + dt
  else
    o.despawntimer = 0
  end

  if o.despawntimer > 5 then
    table.remove(objects, i)
  end

  self.doCollision(i, o, dt)

  o.velx = o.velx * 0.8
  o.vely = o.vely * 0.8
end

return self