-- A dead-simple layout helper for the editor sidebar.  Everything works in the
-- sidebar's local coordinate space (0,0 = top-left of sideBarCanvas) — the same
-- space editorDraw / editorMouseHandler already use — so section rects double as
-- love.graphics.setScissor rects and as hit boxes.  No dependencies, no state of
-- its own beyond the scroll table the caller hands in.

Layout = {}

-- point-in-rect
function Layout.hit(r, x, y)
	return x >= r.x and x < r.x + r.w and y >= r.y and y < r.y + r.h
end

-- Clip drawing to a section.  setScissor ignores the active graphics transform,
-- so multiply the virtual-space rect by editorRenderScale to hit real canvas
-- pixels.  Clamp to non-negative: a too-narrow/short sidebar (e.g. a square
-- window with no room for it) would otherwise hand setScissor a negative size.
function Layout.clip(r)
	local s = editorRenderScale or 1
	love.graphics.setScissor(r.x * s, r.y * s, math.max(0, r.w * s), math.max(0, r.h * s))
end
function Layout.unclip() love.graphics.setScissor() end

-- A vertical scrolling list confined to rect `r`.  `state` is any table the
-- caller keeps between frames to hold `state.scroll`; it is clamped here.
-- Returns helpers to place / cull / hit-test `count` items of height `itemH`.
function Layout.list(state, r, itemH, count, gap)
	gap = gap or 6
	local step = itemH + gap
	local content = count * step
	local maxScroll = math.max(0, content - r.h)
	state.scroll = math.max(0, math.min(state.scroll or 0, maxScroll))
	local scroll = state.scroll
	return {
		rect = r, itemH = itemH, step = step, count = count, maxScroll = maxScroll, scroll = scroll,
		-- top-left corner of item i (1-based), in sidebar space
		pos = function(i) return r.x, r.y + (i - 1) * step - scroll end,
		-- is item i at all inside the visible window? (cheap cull)
		visible = function(i)
			local y = r.y + (i - 1) * step - scroll
			return y + itemH > r.y and y < r.y + r.h
		end,
		-- index at a sidebar-space point, or nil if outside the list / no item
		at = function(x, y)
			if not Layout.hit(r, x, y) then return nil end
			local i = math.floor((y - r.y + scroll) / step) + 1
			if i >= 1 and i <= count then return i end
			return nil
		end,
	}
end

-- Thin scrollbar thumb on the right edge of a list, drawn only when it scrolls.
function Layout.scrollbar(list)
	if list.maxScroll <= 0 then return end
	local r = list.rect
	local thumb = math.max(16, r.h * (r.h / (r.h + list.maxScroll)))
	local ty = r.y + (r.h - thumb) * (list.scroll / list.maxScroll)
	local pr, pg, pb, pa = love.graphics.getColor()
	love.graphics.setColor(255, 255, 255, 90)
	love.graphics.rectangle("fill", r.x + r.w - 4, ty, 3, thumb)
	love.graphics.setColor(pr, pg, pb, pa)
end