local Tilers = {}
local inspect = require("inspect")

local dirs = {
	left = function(m, w, h, stack, r, gap)
		local masterBase = {
			w = w * r - gap/2,
			h = h,
			x = m.left,
			y = m.top
		}
		local childBase = {
			w = (w * (1-r)) - gap/2,
			h = (masterBase.h / (#stack-1)) - gap + gap / (#stack-1),
			x = masterBase.x + masterBase.w + gap,
			y = m.top
		}
		local childOffset = {
			x = 0, y = childBase.h + gap
		}
		return masterBase, childBase, childOffset
	end,
	top = function(m, w, h, stack, r, gap)
		local masterBase = {
			w = w,
			h = h * r - gap,
			x = m.left,
			y = m.top
		}
		local childBase = {
			w = (masterBase.w / (#stack-1)) - gap + gap / (#stack-1),
			h = (h * (1-r)) - gap,
			x = m.left,
			y = masterBase.y + masterBase.h + gap,
		}
		local childOffset = {
			x = childBase.w + gap, y = 0
		}
		return masterBase, childBase, childOffset
	end
}
dirs.right = function(...)
	local masterBase, childBase, childOffset = dirs.left(...)
	masterBase.x, childBase.x = childBase.x, masterBase.x
	masterBase.w, childBase.w = childBase.w, masterBase.w
	return masterBase, childBase, childOffset
end
dirs.bottom = function(...)
	local masterBase, childBase, childOffset = dirs.top(...)
	masterBase.y, childBase.y = childBase.y, masterBase.y
	masterBase.h, childBase.h = childBase.h, masterBase.h
	return masterBase, childBase, childOffset
end

local function makeTiler(getOff)
	return {
		r = 0.5,
		tile = function(self, stack, monitor)
			local m = monitor.margins
			local w = monitor.width - m.left - m.right
			local h = monitor.height - m.top - m.bottom
			if #stack == 1 then
				stack[1]:setGeometry(m.left, m.top, w, h)
			elseif #stack >= 2 then
				local masterBase, childBase, childOffset = getOff(m, w, h, stack, self.r, self.gap)
				stack[1]:setGeometry(masterBase.x, masterBase.y, masterBase.w, masterBase.h)
				for i=2,#stack do
					stack[i]:setGeometry(childBase.x, childBase.y, childBase.w, childBase.h)
					childBase.x = childBase.x + childOffset.x
					childBase.y = childBase.y + childOffset.y
				end
			end
		end,
		setGap = function(self, gap)
			assert(type(gap) == "number")
			self.gap = gap
		end,
		gap = 0
	}
end

Tilers = {
	masterTop = makeTiler(dirs.top),
	masterLeft = makeTiler(dirs.left),
	masterRight = makeTiler(dirs.right),
	masterBottom = makeTiler(dirs.bottom),
}

return Tilers