alshell

#!/usr/bin/env lua
require 'socket'
local has_linenoise, linenoise = pcall(require,'linenoise')
local has_posix, posix = pcall(require,'posix')

if has_linenoise then
    function readline(prompt)
           local line, err = linenoise.linenoise(prompt)
           if not line then return nil end
           linenoise.historyadd(line)
           return line
    end
else
    function readline(prompt)
        io.write(prompt)
        return io.read()
    end
end

interp = {}

local macros = {}

function interp.macro (def)
    macros[def.name] = def
end

local function expand_macro (m,a)
    if m.arg then
        if not a then
            a = m.last_arg
            if not a then
                return print 'you need to pass a parameter to this macro'
            end
        else
            m.last_arg = a
        end
    else
        a = '' -- keep format happy
    end
    for i,line in ipairs(m) do
        local cmd = line:format(a)
        print('! '..cmd)
        interp.process_line(cmd)
    end
end

local f,err = io.open 'defs.lua'
if f then
    f:close()
    dofile 'defs.lua'
end

local t,c2,err
local addr = arg[1] or 'localhost'
local c = socket.connect(addr,3333)
print('connected to '..addr..':3333')
local req = arg[2] or 'yes'
c:send (req..'\n')
if req == 'yes' then
    if not has_posix then
        print 'you need luaposix for accessing log socket'
    else
        c:receive()
        c2,err = socket.connect(addr,3334)
        if err then
          return print('cannot connect to secondary socket',err)
        end
        t = posix.fork()
        if t == 0 then -- run function as child
           while true do
              local res = c2:receive()
              res = res:gsub('\001','\n')
              io.write(res)
            end
            posix._exit(0)
        end
    end
end

local log = io.open('log.txt','a')

local function prep_for_send (s)
    return (s:gsub('\n','\001'))
end

function readfile(file)
  local f,err = io.open(file)
  if not f then return nil,err end
  local contents = f:read '*a'
  f:close()
  return contents
end

function eval(line)
  c:send(line..'\n')
  local res = c:receive()
  return (res or '?'):gsub('\001','\n')
end

print 'Lua 5.1.4  Copyright (C) 1994-2008 Lua.org, PUC-Rio'
local init,err = readfile 'init.lua'
if init then
  print 'loading init.lua'
  eval(prep_for_send(init))
end

function interp.process_line (line)
    log:write(line,'\n')
    local cmd,file = line:match '^%.(%S+)(.*)$'
    if cmd then
        file = file:gsub('^%s*','')
        file = #file > 0 and file or nil
        if macros[cmd] then
            expand_macro(macros[cmd],file)
            return
        elseif file then -- either .l (load) or .m (upload module)
            local mod,kind = file,'run'
            if cmd == 'm' then -- given in Lua module form
              file = mod:gsub('%.','/')..'.lua'
              kind = 'mod'
            end
            line,err = readfile(file)
            if err then
                return print(err)
            end
            if kind == 'mod' then
                local ok,err = loadstring(line)
                if not ok then return print(err) end
            end
            line = prep_for_send(line)
            line = '--'..kind..':'..mod..'\001'..line
        else
            return print 'unknown command'
        end
    else
        --  = EXPR becomes print(EXPR)
        local expr = line:match '^%s*=%s*(.+)$'
        if expr then
          line = 'print('..expr..')'
        end
    end
    if line then
        local res = eval(line)
        log:write(res,'\n')
        io.write(res)
    else
        print(err)
    end
end

local line = readline '> '

while line do
  interp.process_line(line)
  line = readline '> '
end

log:close()
c:close()

if c2 then
    c2:close()
    if t then posix.kill(t) end    
end