profiler.lua

---@class Profiler
local profiler = {
	internal_fns = {},
	call_stack = {},
	call_tree = {},
	clock = function()
		return get_ticks() / get_tick_frequency()
	end
}

local function get_filename_without_extension(path)
    local filename = string.match(path, "^.+[\\/](.+)$") or path or "?"
    return string.match(filename, "(.+)%..+$") or filename
end

local function find_child(parent, id)
	for _, child in ipairs(parent.children) do if child.id == id then return child end end
end

local function on_function_call(info)
	local parent = (#profiler.call_stack > 0 and profiler.call_stack[#profiler.call_stack]) or { children = profiler.call_tree }
	local node_id = (parent.id or "[ROOT]")..string.format(":%s:%d", info.name or "?", info.currentline)

	local node = find_child(parent, node_id)
	if not node then
		node = {
			id = node_id,
			name = info.name or "?",
			src = get_filename_without_extension(info.short_src or "?"),
			defined_line = info.linedefined,
			line = info.currentline,
			calls = 0,
			duration = 0,
			parent = parent,
			children = {}
		}

		if parent then
			table.insert(parent.children, node)
		end
	end

	node.called_at = profiler.clock()
	node.calls = node.calls + 1

	table.insert(profiler.call_stack, node)
end

local function on_function_return()
	if (#profiler.call_stack == 0) then return end

	local node = table.remove(profiler.call_stack)
	local dt = profiler.clock() - node.called_at

	node.duration = node.duration + dt
end

local function hook(event, info)
	info = info or debug.getinfo(2, "flnS")
	local f = info.func

	-- ignore functions from the profiler
	if profiler.internal_fns[f] then
		return
	end

	if event == "call" then
		on_function_call(info)
	elseif event == "tail call" then
		local prev = debug.getinfo(3, "fnS")
		hook("return", prev)
		hook("call", info)
	elseif event == "return" then
		on_function_return()
	end
end

function profiler.reset()
	profiler.call_stack = {}
	profiler.call_tree = {}
end

function profiler.start()
	debug.sethook(hook, "cr")
end

function profiler.stop()
	debug.sethook()
end

local function imgui_call_tree_node(tree)
	if (not tree) then return end
	for _, node in ipairs(tree) do
		local line_number = (node.parent.line or node.line_defined or -1)
		local label = string.format("%s.%s%s - %.6f seconds (called %d times)", node.src, node.name, (line_number > -1 and ":"..line_number) or "", node.duration, node.calls)
		if imgui_tree_node(node.id, #node.children == 0 and ImGuiTreeNodeFlags_Leaf or ImGuiTreeNodeFlags_None, label) then
			if #node.children > 0 then
				imgui_call_tree_node(node.children)
			end
			imgui_tree_pop()
		end
	end
end

function profiler.imgui_call_tree()
	imgui_text("Call Tree")
	imgui_call_tree_node(profiler.call_tree)
end

for _, v in pairs(profiler) do
	if type(v) == "function" then
		profiler.internal_fns[v] = true
	end
end

return profiler