#!/usr/bin/env lua
-- OBBS: An Offline-first BBS Utility
-- Copyright (C) 2024 plugd

-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, either version 3 of the License, or
-- (at your option) any later version.

-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.

-- You should have received a copy of the GNU General Public License
-- along with this program.  If not, see <http://www.gnu.org/licenses/>.

local posix = require "posix"

local usage = [[Usage: obbs [-c config_file] COMMAND [arguments ...]

Here COMMAND is one of:
  newcfg
  init
  qwkout
  repin

You can also use the -c option to specify an alternative configuration
file.  (The default is the file "config.lua" in the current directory.)]]

obbs = {}
local config_file = "config.lua"
local function load_config ()
   io.write("Loading config from file '" .. config_file .. "'... ")
   dofile(config_file)
   print("done.")
end

--- Utility functions ---

local function print_table (t, lev)
   lev = lev or 0
   local ind = string.rep("\t", lev)
   
   for k,v in pairs(t) do
      if type(v)=="table" then
         print(ind ..k .. "= {")
         print_table(v, lev+1)
         print(ind .. "}")
      else
         print(ind .. k .. "=" .. tostring(v))
      end
   end
end

local function space_pad(s, n)
   return string.sub(s,1,n) .. string.rep(" ", math.max(0,n-string.len(s)))
end

local fs = {}

function fs.exists(filename)
   return io.open(filename, "r")
end

function fs.dir(path)
   return posix.dir(path)
end

function fs.mkdir(dirname)
   posix.mkdir(dirname)
end

function fs.rmdir(dirname, force)
   if force then
      for i,fname in ipairs(posix.glob(dirname .. "/*")) do
         posix.unlink(fname)
      end
   end
   assert(posix.rmdir(dirname))
end

function fs.copy(filename, destfilename)
   src = assert(io.open(filename,"r"))
   dest = assert(io.open(destfilename,"w"))

   dest:write(src:read("*all"))
   dest:close()
   src:close()
end

function fs.touch(filename)
   fh = assert(io.open(filename,"w"))
   fh:close()
end

function fs.mktempdir()
   return posix.mkdtemp("/tmp/obbs-XXXXXX")
end

--- Message database parsing ---

local msgs = {}
function Message(msg)
   msgs[msg.number] = msg
end

--- QWK formatting ---

local qwk = {}

function qwk.write_control(target_dir, obbs, user_name)
   local cf = assert(io.open(target_dir .. "/CONTROL.DAT", "w"))

   cf:write(obbs.name .. "\r\n")
   cf:write("\r\n") -- BBS location
   cf:write("\r\n") -- BBS phone number
   cf:write(obbs.sysop .. "\r\n")
   cf:write("12345," .. obbs.bbsid .. "\r\n")
   cf:write(os.date("%d-%m-%Y,%X") .. "\r\n") -- packet creation time
   cf:write(user_name .. "\r\n")
   cf:write("\r\n")
   cf:write(0 .. "\r\n")
   cf:write(0 .. "\r\n") -- TODO: Number of messages in packet
   cf:write(#obbs.conferences-1 .. "\r\n") -- Index of final conference
   for i,v in ipairs(obbs.conferences) do
      cf:write(i-1 .. "\r\n")
      cf:write(v .. "\r\n")
   end

   cf:write("HELLO\r\n")
   cf:write("NEWS\r\n")
   cf:write("GOODBYE\r\n")

   cf:close()
end

function qwk.write_message (target_dir, obbs)
   local mf = assert(io.open(target_dir .. "/MESSAGES.DAT", "w"))

   local pkt_msg_num = 0

   mf:write(space_pad("Produced by OBBS.", 128))

   for cnum,cname in ipairs(obbs.conferences) do
      msgs = {}
      dofile(obbs.path .. "/conferences/" .. cname .. ".msgs")
      for i,msg in ipairs(msgs) do
         pkt_msg_num = pkt_msg_num + 1
         qwk.write_message_header_block(mf, obbs, cnum, pkt_msg_num, msg)
         qwk.write_message_text(mf, obbs, msg)
      end
   end

   mf:close()
end

function qwk.write_message_header_block(mf, obbs, conf_num, pkt_msg_num, msg)
   mf:write(" ") -- Message status flag
   mf:write(space_pad(tostring(msg.number), 7))
   mf:write(msg.date) -- mm-dd-yy
   mf:write(msg.time) -- hh:mm
   mf:write(space_pad(string.upper(msg.to), 25))
   mf:write(space_pad(string.upper(msg.from), 25))
   mf:write(space_pad(msg.subject, 25))
   mf:write(string.rep(" ", 12)) -- Password (blank)

   if msg.reply_to then
      mf:write(space_pad(tostring(msg.reply_to), 8))
   else
      mf:write(string.rep(" ", 8))
   end

   nblocks = math.ceil(string.len(msg.text)/128) + 1
   mf:write(space_pad(tostring(nblocks), 6)) -- number of blocks including header

   mf:write("\xe1") -- flag indicating message is "active" (not "to be killed")
   mf:write(string.pack("I2",conf_num-1))
   mf:write(string.pack("I2",pkt_msg_num))
   mf:write(" ") -- No network tag-line present
end

function qwk.write_message_text(mf, obbs, msg)
   mf:write((string.gsub(msg.text, "\n", "\xe3")))
   
   local padding = (128 - (string.len(msg.text) % 128)) % 128
   mf:write(string.rep("\0",padding))
end

function qwk.read_message(archive_dir, obbs, user_name)

   local msg_filename = archive_dir .. "/" .. obbs.bbsid .. ".MSG"

   if not fs.exists(msg_filename) then
      print("Error: MSG file not found.")
      return false
   end

   local mf = assert(io.open(msg_filename, "r"))
   local block = mf:read(128)

   if not string.find(block, obbs.bbsid .. " *") then
      print("Error: Failed to match BBSID in first block.")
      return false
   end

   while mf:read(0) do
      qwk.read_message_header(mf, obbs)
   end
end

function qwk.read_message_header(mf, obbs)
   local msg = {}

   mf:read(1) -- Message status (ignore for now)
   local conf_num = tonumber(mf:read(7))
   msg.date = mf:read(8)
   msg.time = mf:read(5)
   msg.to = string.lower(string.gsub(mf:read(25), " ", ""))
   msg.from = string.lower(string.gsub(mf:read(25), " ", ""))
   msg.subject = string.gsub(mf:read(25), " ", "")
   mf:read(12) -- Password (unused)
   msg.replyto = tonumber(mf:read(8))

   local nblocks = tonumber(mf:read(6))

   mf:read(1) -- flag (ignore for now)
   mf:read(2) -- conference number (already have this)
   mf:read(2) -- message number in packet (unused)
   mf:read(1) -- network tag flag (ignore)

   msg.text = ""
   for b=2,nblocks do
      msg.text = msg.text .. mf:read(128)
   end
   msg.text = string.gsub(msg.text, "\xe3", "\n")

   print("Message{")
   for k,v in pairs(msg) do
      print("\t" .. k .. "=\'" .. v .. "',")
   end
   print("}")
end

--- Commands ---

local cmd = {}

-- Send default configuration to stdout
function cmd.newcfg ()
   print [[
-- OBBS Configuration File

obbs.path = "." -- Path to OBBS root

obbs.name = "My OBBS Name"
obbs.bbsid = "MYOBBSID" -- max 8 char
obbs.sysop = "Sysop Name"

-- obbs.hello_file = "hello"
-- obbs.news_file = "news"
-- obbs.goodbye_file = "goodbye"

obbs.conferences = {
   "Announcements",
   "General",
   "Meta"
}
]]
end

-- Initialise conference directory structure
function cmd.init ()
   load_config()

   if fs.exists(obbs.path .. "/conferences") or
      fs.exists(obbs.path .. "/outgoing") then
      print("One or more OBBS directories already exist. Aborting.")
      return
   end

   fs.mkdir(obbs.path .. "conferences")
   for i,v in ipairs(obbs.conferences) do
      fs.touch(obbs.path .. "conferences/" .. v .. ".msgs")
   end

   fs.mkdir(obbs.path .. "outgoing")
end

-- qwkout: generate QWK file
function cmd.qwkout ()
   load_config()

   if not arg[1] then
      print "Usage: obbs qwkout USER"
      return
   end

   local user_name = arg[1]

   local work_dir = fs.mktempdir()

   -- CONTROL.DAT
   qwk.write_control(work_dir, obbs, user_name)

   -- Copy BBS welcome, news and goodbye files

   if obbs.hello and fs.exists(obbs.hello) then
      fs.copy(obbs.hello, work_dir .. "/HELLO")
   else
      fs.touch(work_dir .. "/HELLO")
   end

   if obbs.news and fs.exists(obbs.news) then
      fs.copy(obbs.news, work_dir .. "/NEWS")
   else
      fs.touch(work_dir .. "/NEWS")
   end

   if obbs.news and fs.exists(obbs.goodbye) then
      fs.copy(obbs.goodbye, work_dir .. "/GOODBYE")
   else
      fs.touch(work_dir .. "/GOODBYE")
   end

   -- Pack messages

   qwk.write_message(work_dir, obbs)

   -- Create archive in outgoing

   os.execute("zip -rj " .. obbs.path ..
              "/outgoing/" .. obbs.bbsid ..
              ".qwk " .. work_dir)

   fs.rmdir(work_dir, true)
end

-- repin: read REP file in

function cmd.repin()
    load_config()

   if not arg[2] then
      print "Usage: obbs repin FILE USER"
      return
   end

   local rep_filename = arg[1]
   local user_name = arg[2]

   if not fs.exists(rep_filename) then
      print("Error: reply packet file '" .. rep_filename .. "' does not exist.")
      return
   end
   
   local work_dir = fs.mktempdir()

   fs.copy(rep_filename, work_dir .. "/repfile.rep")
   os.execute("unzip " .. work_dir .. "/repfile.rep -d " .. work_dir)

   qwk.read_message(work_dir, obbs, user_name)
   
   fs.rmdir(work_dir, true)
  
end

-- Main

local function main()
   if #arg > 2 and arg[1]=="-c" then
      config_file = arg[2]
      table.remove(arg, 1)
      table.remove(arg, 1)
   end
   
   if #arg < 1 then
      print(usage)
   else
      if cmd[arg[1]] then
         local f = cmd[arg[1]]
         table.remove(arg,1)
         f()
      else
         print("Unknown command '" .. arg[1] .. "'")
         print(usage)
      end
   end
end

main()
.