local m_type = math.type;

local function unescape_token(escaped_token)

	local unescaped = escaped_token:gsub("~1", "/"):gsub("~0", "~")

	return unescaped

end

local function resolve_json_pointer(ref, path)

	local ptr_len = #path + 1

	for part, pos in path:gmatch("/([^/]*)()") do

		local token = unescape_token(part)

		if not (type(ref) == "table") then

			return nil

		end

		local idx = next(ref)

		local new_ref

		if type(idx) == "string" then

			new_ref = ref[token]

		elseif m_type(idx) == "integer" then

			local i = tonumber(token)

			if token == "-" then

				i = #ref + 1

			end

			new_ref = ref[i + 1]

		else

			return nil, "invalid-table"

		end

		if pos == ptr_len then

			return new_ref

		elseif type(new_ref) == "table" then

			ref = new_ref

		elseif not (type(ref) == "table") then

			return nil, "invalid-path"

		end

	end

	return ref

end

return { resolve = resolve_json_pointer }