utilities.lua

local utilities = {}

-- https://stackoverflow.com/questions/41349526/how-to-iterate-lua-table-from-end
local function reversedipairsiter(t, i)
    i = i - 1
    if i ~= 0 then
        return i, t[i]
    end
end
function utilities.ripairs(t)
    return reversedipairsiter, t, #t + 1
end

-- Test collision between any two GameObjects
function utilities.checkBoxCollision(a,b)
  return a:getX() < (b:getX() + b:getWidth()) and 
        (a:getX() + a:getWidth()) > b:getX() and 
         a:getY() < (b:getY() + b:getHeight()) and 
        (a:getY() + a:getHeight()) > b:getY()
end

-- for an object at X location objectX, find whether the nearest enemy (horizontally) is left/right
function utilities.findNearestEnemyX(objectX, enemies)
  local enemyDist = nil
  local enemyDir = 0
  local enemyX = objectX

  -- find closest
  for ii,enemy in ipairs(enemies) do
    ii = ii
    local thisEnemyX = enemy:getX() + enemy:getWidth()/2
    if (enemyDist == nil or (math.abs(objectX - thisEnemyX) < enemyDist)) then
      enemyDist = math.abs(objectX - thisEnemyX)
      enemyX = thisEnemyX
    end
  end

  if(enemyDist < 3) then
    -- stop oscillation
    enemyDir = 0
  elseif(objectX > enemyX) then
    enemyDir = -1
  elseif (objectX < enemyX) then
    enemyDir = 1
  end
  
  return enemyDir
end







function utilities.gradientMesh(dir, ...)
    -- Check for direction
    local isHorizontal = true
    if dir == "vertical" then
        isHorizontal = false
    elseif dir ~= "horizontal" then
        error("bad argument #1 to 'gradient' (invalid value)", 2)
    end

    -- Check for colors
    local colorLen = select("#", ...)
    if colorLen < 2 then
        error("color list is less than two", 2)
    end

    -- Generate mesh
    local meshData = {}
    if isHorizontal then
        for i = 1, colorLen do
            local color = select(i, ...)
            local x = (i - 1) / (colorLen - 1)

            meshData[#meshData + 1] = {x, 1, x, 1, color[1], color[2], color[3], color[4] or 1}
            meshData[#meshData + 1] = {x, 0, x, 0, color[1], color[2], color[3], color[4] or 1}
        end
    else
        for i = 1, colorLen do
            local color = select(i, ...)
            local y = (i - 1) / (colorLen - 1)

            meshData[#meshData + 1] = {1, y, 1, y, color[1], color[2], color[3], color[4] or 1}
            meshData[#meshData + 1] = {0, y, 0, y, color[1], color[2], color[3], color[4] or 1}
        end
    end

    -- Resulting Mesh has 1x1 image size
    return love.graphics.newMesh(meshData, "strip", "static")
end

local showHitbox = false
function utilities.getShowHitbox()
  return showHitbox
end
function utilities.toggleHitbox()
  showHitbox = not showHitbox
end

return utilities