#!/usr/bin/lua5.2

local posix = require 'posix'
local config_file = "/etc/aaudit/aaudit.conf"

local function load_config(filename)
	local F = io.open(filename, "r")
	local cfg = "return {" .. F:read("*all").. "}"
	F:close()
	return loadstring(cfg, "config:"..filename)()
end

local function match_file(fn, match_list)
	if not match_list then return false end
	local i, m
	for i, pattern in ipairs(match_list) do
		if posix.fnmatch(pattern, fn) then return true end
	end
	return false
end

local CONF = load_config(config_file)
if CONF.notify_email == nil or CONF.smtp_server == nil then return end

local visible, has_data = false, false
local diff = {}
for l in io.lines() do
	local fn = l:match("^diff [^ \t]* a/([^ \t]*)")
	if fn then
		visible = not match_file(fn, CONF.no_notify_files)
		if visible then
			has_data = true
			visible = not match_file(fn, CONF.private_files)
			if not visible then
				table.insert(diff, "Private file "..fn.." changed")
			end
		end
	end
	if visible then table.insert(diff, l) end
end

if has_data then
	local EMAIL = io.popen(string.format("sendmail -t -S %s", CONF.smtp_server),  "w")
	EMAIL:write(string.format([[
From: %s <%s>
To: %s
Subject: Configuration change on %s
Date: %s

This is automatically generated e-mail about the following configuration change:

%s
]],
	CONF.author_name or "Alpine Auditor", CONF.author_email or "auditor@alpine.local",
	table.concat(CONF.notify_email, ", "),
	arg[1],
	os.date("%a, %d %b %Y %H:%M:%S"),
	table.concat(diff, '\n')
	))
	EMAIL:close()
end