publictext

#!/usr/bin/env lua

--
-- publictext
-- ucspi-tcp text://protocol server
--

local assert = assert
local io = require( 'io' )
local ipairs = ipairs
local os = require( 'os' )
local pcall = pcall
local table = require( 'table' )
local tonumber = tonumber
local tostring = tostring

_ENV = nil

local EOL = '\r\n'
local SP = ' '

local _request = nil

local function REQUEST( aRequest )
  _request = aRequest or _request or io.stdin:read() or os.exit( false )

  return _request
end

local function LOG( aStatus, aSize )
  local aBuffer = {}

  aBuffer[ #aBuffer + 1 ] = os.getenv( 'TCPREMOTEHOST' ) or os.getenv( 'TCPREMOTEIP' ) or '-' -- remotehost
  aBuffer[ #aBuffer + 1 ] = os.getenv( 'TCPREMOTEINFO' ) or '-' -- rfc931
  aBuffer[ #aBuffer + 1 ] = '-' -- authuser
  aBuffer[ #aBuffer + 1 ] = ( '[%s]' ):format( os.date( '!%Y-%m-%dT%TZ' ) ) -- [date]
  aBuffer[ #aBuffer + 1 ] = ( '%q' ):format( REQUEST() or '' ) -- "request"
  aBuffer[ #aBuffer + 1 ] = tostring( aStatus or '-' ) -- status
  aBuffer[ #aBuffer + 1 ] = tostring( aSize or '0' ) -- bytes

  io.stderr:write( table.concat( aBuffer, ' ' ), '\n' )
end

local function STATUS( aStatus, aDescription )
  local aStatus = assert( tonumber( aStatus ) )

  assert( aDescription )
  assert( 0 ~= aDescription:len() )
  assert( 1024 >= aDescription:len() )
  assert( not aDescription:find( '%c' ) )

  io.stdout:write( aStatus, SP, aDescription, EOL )
  io.stdout:flush()
end

local function CHUNK( aFile )
  return function() return aFile:read( 4096 ) end
end

local function OK( aFile, aType, aSize )
  STATUS( 20, assert( aType ) )
  LOG( 20, assert( aSize ) )

  for aChunk in CHUNK( assert( aFile ) ) do
    io.stdout:write( aChunk )
    io.stdout:flush()
  end

  aFile:close()
  os.exit( true )
end

local function REDIRECT( aLocation )
  STATUS( 30, aLocation )
  LOG( 30 )
  os.exit( true )
end

local function NOK()
  STATUS( 40, 'NOK' )
  LOG( 40 )
  os.exit( false )
end

local function LINK( aFile, aType )
  if aType ~= '.lnk' then return end

  local aLocation = assert( aFile:read():match( '^(%C+)' ) )
  assert( aFile:close() )

  REDIRECT( aLocation )
end

local function QUOTE( anArgument )
  return ( "'%s'" ):format( assert( anArgument ):gsub( "'", "'\\''" ) )
end

local function TYPE( aFileName )
  local aCommand = ( 'file --brief --mime-type --mime-encoding %s 2>/dev/null' ):format( assert( QUOTE( aFileName ) ) )
  local aHandle = assert( io.popen( aCommand, 'r' ) )
  local aType = assert( aHandle:read() )

  assert( aHandle:close() )

  return aType
end

local function FILE( aName, anExtension )
  local someTypes = { '.lnk', '' }

  for _, aType in ipairs( someTypes ) do
    local aFileName = ( '%s.%s%s' ):format( aName, anExtension, aType )
    local aFile = io.open( aFileName, 'rb' )

    if aFile then
      local aSize = assert( aFile:seek( 'end' ) )
            assert( aFile:seek( 'set' ) )

      LINK( aFile, aType )

      return aFile, TYPE( aFileName ), aSize
    end
  end
end

local function HANDLE()
  local aRequest = REQUEST()
        assert( aRequest )
        aRequest = assert( REQUEST( aRequest:match( '^(%C+)' ) ) )
        assert( 0 ~= aRequest:len() )
        assert( 1024 >= aRequest:len() )
        assert( not aRequest:find( '%s' ) )
        assert( aRequest == aRequest:lower() )
        assert( 'text://' == aRequest:sub( 1, 7 ) )
  local aName, anExtension = aRequest:match( '/([%w-]+)%.(%w+)$' )
        if '/' ==  aRequest:sub( -1, -1 ) then aName = 'index' anExtension = 'txt' end
        if not aName then REDIRECT( ( '%s/' ):format( aRequest ) ) end
        assert( aName )
        assert( 0 ~= aName:len() )
        assert( 128 >= aName:len() )
        assert( anExtension )
        assert( 0 ~= anExtension:len() )
        assert( 3 >= anExtension:len() )
  local aFile, aType, aSize = FILE( aName, anExtension )

  OK( aFile, aType, aSize )
end

if not pcall( HANDLE ) then NOK() end