Darktide-Mod-Loader/scripts/mods/dml/hook.lua

--[[
	Mods Hook v2:
		New version with better control
--]]

-- Hook structure
MODS_HOOKS = MODS_HOOKS or {}
MODS_HOOKS_BY_FILE = MODS_HOOKS_BY_FILE or {}

local item_template = {
	name = "",
	func = EMPTY_FUNC,
	hooks = {},
}

local item_hook_template = {
	name = "",
	func = EMPTY_FUNC,
	enable = false,
	exec = EMPTY_FUNC,
}
local Log = Log

local print_log_info = function(mod_name, message)
	Log = Log or rawget(_G, "Log")
	if Log then
		Log._info(mod_name, message)
	else
		print("[" .. mod_name .. "]: " .. message)
	end
end

local print_log_warning = function(mod_name, message)
	Log = Log or rawget(_G, "Log")
	if Log then
		Log._warning(mod_name, message)
	else
		print("[" .. mod_name .. "]: " .. message)
	end
end

Mods.hook = {
	--
	-- Set hook
	--
	set = function(mod_name, func_name, hook_func)
		local item = Mods.hook._get_item(func_name)
		local item_hook = Mods.hook._get_item_hook(item, mod_name)
		
		print_log_info(mod_name, "Hooking " .. func_name)
		
		item_hook.enable = true
		item_hook.func = hook_func
		
		Mods.hook._patch()
	end,
	
	--
	-- Set hook on every instance of the given file
	--
	set_on_file = function(mod_name, filepath, func_name, hook_func)
		-- Add hook create function to list for the file
		MODS_HOOKS_BY_FILE[filepath] = MODS_HOOKS_BY_FILE[filepath] or {}	
		local hook_create_func = function(this_filepath, this_index)
			local dynamic_func_name = "Mods.require_store[\"" .. this_filepath .. "\"][" .. tostring(this_index) .. "]." .. func_name
			Mods.hook.set(mod_name, dynamic_func_name, hook_func, false)
		end
		table.insert(MODS_HOOKS_BY_FILE[filepath], hook_create_func)
		
		-- Add the new hook to every instance of the file
		local all_file_instances = Mods.require_store[filepath]
		if all_file_instances then
			for i, item in ipairs(all_file_instances) do
				if item then
					hook_create_func(filepath, i)
				end
			end
		end
	end,
	
	--
	-- Enable/Disable hook
	--
	enable = function(value, mod_name, func_name)
		for _, item in ipairs(MODS_HOOKS) do
			if item.name == func_name or func_name == nil then
				for _, hook in ipairs(item.hooks) do
					if hook.name == mod_name then
						hook.enable = value
						Mods.hook._patch()
					end
				end
			end
		end
		
		return
	end,
	
	--
	-- Enable all hooks on a stored file
	--
	enable_by_file = function(filepath, store_index)
		local all_file_instances = Mods.require_store[filepath]
		local file_instance = all_file_instances and all_file_instances[store_index]
		
		local all_file_hooks = MODS_HOOKS_BY_FILE[filepath]
		
		if all_file_hooks and file_instance then
			for i, hook_create_func in ipairs(all_file_hooks) do
				hook_create_func(filepath, store_index)
			end
		end
	end,
	
	--
	-- Remove hook from chain
	--
	["remove"] = function(func_name, mod_name)
		for i, item in ipairs(MODS_HOOKS) do
			if item.name == func_name then
				if mod_name ~= nil then
					for j, hook in ipairs(item.hooks) do
						if hook.name == mod_name then
							table.remove(item.hooks, j)
							
							Mods.hook._patch()
						end
					end
				else
					local item_name = "MODS_HOOKS[" .. tostring(i) .. "]"
					
					-- Restore orginal function
					assert(loadstring(item.name .. " = " .. item_name .. ".func"))()
					
					-- Remove hook function
					table.remove(MODS_HOOKS, i)
					
					return
				end
			end
		end
		
		return
	end,
	
	--
	-- Move hook to front of the hook chain
	--
	front = function(mod_name, func_name)
		for _, item in ipairs(MODS_HOOKS) do
			if item.name == func_name or func_name == nil then
				for i, hook in ipairs(item.hooks) do
					if hook.name == mod_name then
						local saved_hook = table.clone(hook)
						table.remove(item.hooks, i)
						table.insert(item.hooks, saved_hook)
						
						Mods.hook._patch()
					end
				end
			end
		end
		
		return
	end,
	
	--
	-- Get function by function name
	--
	_get_func = function(func_name)
		return assert(loadstring("return " .. func_name))()
	end,
	
	--
	-- Get item by function name
	--
	_get_item = function(func_name)
		-- Find existing item
		for _, item in ipairs(MODS_HOOKS) do
			if item.name == func_name then
				return item
			end
		end
		
		-- Create new item
		local item = table.clone(item_template)
		item.name = func_name
		item.func = Mods.hook._get_func(func_name)
		
		-- Save
		table.insert(MODS_HOOKS, item)
		
		return item
	end,
	
	--
	-- Get item hook by mod name
	--
	_get_item_hook = function(item, mod_name)
		-- Find existing item
		for _, hook in ipairs(item.hooks) do
			if hook.name == mod_name then
				return hook
			end
		end
		
		-- Create new item
		local item_hook = table.clone(item_hook_template)
		item_hook.name = mod_name
		
		-- Save
		table.insert(item.hooks, 1, item_hook)
		
		return item_hook
	end,
	
	--
	-- If settings are changed the hook itself needs to be updated
	--
	_patch = function(mods_hook_item)
		for i, item in ipairs(MODS_HOOKS) do
			local item_name = "MODS_HOOKS[" .. i .. "]"
			
			local last_j = 1
			for j, hook in ipairs(item.hooks) do
				local hook_name = item_name .. ".hooks[" .. j .. "]"
				local before_hook_name = item_name .. ".hooks[" .. (j - 1) .. "]"
				
				if j == 1 then
					if hook.enable then
						assert(
							loadstring(
								hook_name .. ".exec = function(...)" ..
								"	return " .. hook_name .. ".func(" .. item_name .. ".func, ...)" ..
								"end"
							)
						)()
					else
						assert(
							loadstring(
								hook_name .. ".exec = function(...)" ..
								"	return " .. item_name .. ".func(...)" ..
								"end"
							)
						)()
					end
				else
					if hook.enable then
						assert(
							loadstring(
								hook_name .. ".exec = function(...)" ..
								"	return " .. hook_name .. ".func(" .. before_hook_name .. ".exec, ...)" ..
								"end"
							)
						)()
					else
						assert(
							loadstring(
								hook_name .. ".exec = function(...)" ..
								"	return " .. before_hook_name .. ".exec(...)" ..
								"end"
							)
						)()
					end
				end
				
				last_j = j
			end
			
			-- Patch orginal function call
			assert(loadstring(item.name .. " = " .. item_name .. ".hooks[" .. last_j .. "].exec"))()
		end
	end,
}