Load Lua modules from the node_modules folder!

npmify.lua

local string = require("string")
local pathlib = require("pl.path")
local filelib = require("pl.file")

local function split(str, sep)
	local ret = {}
	local last_sep = 1

	for i = 1, #str do
		if string.byte(str, i, i) == string.byte(sep) then
			ret[#ret + 1] = string.sub(str, last_sep, i - 1)
			last_sep = i + 1
		end
	end

	ret[#ret + 1] = string.sub(str, last_sep)

	return ret
end

local function load_lua_module(path)
	return loadfile(path)
end

local function load_as_file(path)
	if pathlib.isfile(path) then
		return load_lua_module(path)
	end

	if pathlib.isfile(path .. ".lua") then
		return load_lua_module(path .. ".lua")
	end

	-- todo: binary modules
end

local function load_as_directory(path)
	if pathlib.isfile(path .. "/package.json") then
		local info = filelib.read(path .. "/package.json")
		local main = string.match(info, "\"main\":%s*\"(.-)\"")
		if main then
			return load_as_file(path .. "/" .. main)
		end
	end

	if pathlib.isfile(path .. "/init.lua") then
		return load_lua_module(path .. "/init.lua")
	end

	-- todo: binary modules
end

local function node_modules_paths(start)
	local parts = split(start, "/")
	local dirs = {}

	for i = #parts, 1, -1 do
		if parts[i] ~= "node_modules" then
			local dir = ""

			for i2 = 1, i do
				dir = dir .. parts[i2] .. "/"
			end

			dirs[#dirs + 1] = dir .. "node_modules"
		end
	end

	return dirs
end

local function load_node_modules(name, start)
	local dirs = node_modules_paths(start)

	for i = 1, #dirs do
		local path = dirs[i] .. "/" .. name

		local filemod = load_as_file(path)
		if filemod then return filemod end

		local dirmod = load_as_directory(path)
		if dirmod then return dirmod end
	end
end

local searchers = package.searchers or package.loaders

searchers[#searchers + 1] = function(name)
	return load_node_modules(name, pathlib.currentdir())
end