#!/bin/bash -p
###############################################################################
# BRLTTY - A background process providing access to the console screen (when in
#          text mode) for a blind person using a refreshable braille display.
#
# Copyright (C) 1995-2021 by The BRLTTY Developers.
#
# BRLTTY comes with ABSOLUTELY NO WARRANTY.
#
# This is free software, placed under the terms of the
# GNU Lesser General Public License, as published by the Free Software
# Foundation; either version 2.1 of the License, or (at your option) any
# later version. Please see the file LICENSE-LGPL for details.
#
# Web Page: http://brltty.app/
#
# This software is maintained by Dave Mielke <dave@mielke.cc>.
###############################################################################

programName="${0##*/}"
programMessage() {
   echo >&2 "${programName}: ${1}"
}
programError() {
   [ -n "${1}" ] && programMessage "${1}"
   exit "${2:-3}"
}
syntaxError() {
   programError "${1}" 2
}

mount_ext2() {
   mount -o loop -t ext2 "${2}" "${1}"
}
unmount_ext2() {
   umount "${1}"
}
check_ext2() {
   set -- $(stat -c '%a %s' -f -- "${initrdRoot}")
   initrdAvailableBlocks="${1}"
   initrdBlockSize="${2}"
   set -- $(du --block-size="${initrdBlockSize}" -s "${brlttyInstallRoot}")
   brlttyInstallBlocks="${1}"
   set -- $(stat -c '%s' -- "${initrdImage}")
   initrdImageBytes="${1}"
   initrdImageBlocks=$(( (initrdImageBytes + initrdBlockSize - 1) / initrdBlockSize ))
   initrdPadBlocks=$(( brlttyInstallBlocks - initrdAvailableBlocks ))
   (( (initrdPadBlocks += 200) > 0 )) && {
      initrdMounted=false
      "unmount_${initrdType}" "${initrdRoot}" "${initrdImage}"

      dd bs="${initrdBlockSize}" count="${initrdPadBlocks}" if="/dev/zero" of="${initrdImage}" seek="${initrdImageBlocks}"
      e2fsck -y -f "${initrdImage}" && resize2fs "${initrdImage}" || {
         newImage="${temporaryDirectory}/new.${initrdType}"
         cp -RpPd -- "${initrdImage}" "${newImage}"
         mke2fs -q -b "${initrdBlockSize}" -F "${newImage}"

         newRoot="${temporaryDirectory}/new"
         mkdir "${newRoot}"

         "mount_${initrdType}" "${newRoot}" "${newImage}"
         newMounted=true

         "mount_${initrdType}" "${initrdRoot}" "${initrdImage}"
         initrdMounted=true
         cp -RpPd -- "${initrdRoot}/." "${newRoot}"
         initrdMounted=false
         "unmount_${initrdType}" "${initrdRoot}" "${initrdImage}"

         newMounted=false
         "unmount_${initrdType}" "${newRoot}" "${newImage}"

         cp -- "${newImage}" "${initrdImage}"
      }

      "mount_${initrdType}" "${initrdRoot}" "${initrdImage}"
      initrdMounted=true
   }
}

mount_cpio() {
   cd "${1}"
   cpio --quiet -i -I "${2}"
   cd "${workingDirectory}"
}
unmount_cpio() {
   cd "${1}"
   [ -n "${2}" ] && {
      find . -print |
      sed -e '/^\.$/d' -e 's/^\.\///' |
      cpio --quiet -o -H newc -O "${2}"
   }
   rm -f -r -- $(ls -1 -A)
   cd "${workingDirectory}"
}
check_cpio() {
   :
}

originalImage="boot.iso"
modifiedImage="brltty.iso"
brlttyPattern="brltty-*"
brailleDrivers="all"
textTable="en-nabcc"
invokeShell=false

showUsage() {
   cat <<EOF
Usage: ${programName} [-option ...]
The following options are supported:
-i file         The original (input) image (default: ${originalImage}).
-o file         The modified (output) image (default: ${modifiedImage}).
-a file         The BRLTTY archive (default: ${brlttyPattern}).
-b driver,...   The braille driver(s) to include (default: ${brailleDrivers}).
-t file         The text table to build in (default: ${textTable}).
-s              Invoke an interactive shell to inspect the modified image.
-h              Display usage information and exit.
EOF
   exit 0
}

while getopts ":i:o:a:b:t:sh" option
do
   case "${option}"
   in
      i) originalImage="${OPTARG}";;
      o) modifiedImage="${OPTARG}";;
      a) brlttyPattern="${OPTARG}";;
      b) brailleDrivers="${OPTARG}";;
      t) textTable="${OPTARG}";;
      s) invokeShell=true;;
      h) showUsage;;
     \?) syntaxError "unknown option: -${OPTARG}";;
      :) syntaxError "missing operand: -${OPTARG}";;
      *) syntaxError "unimplemented option: -${option}";;
   esac
done
shift $((OPTIND - 1))
[ "${#}" -gt 0 ] && syntaxError "too many parameters."

[ -f "${originalImage}" ] || programError "original image not found: ${originalImage}"

shopt -s nullglob extglob
set -- $brlttyPattern
[ "${#}" -eq 0 ] && programError "brltty archive not found: ${brlttyPattern}"
[ "${#}" -gt 1 ] && {
   brlttyArchives="$(echo "${*}" | sed -e 's% %,&%g')"
   programError "more than one brltty archive: ${brlttyArchives}"
}
brlttyArchive="${1}"

cleanup() {
   set +e
   cd /
   "${newMounted}" && "unmount_${initrdType}" "${newRoot}"
   "${initrdMounted}" && "unmount_${initrdType}" "${initrdRoot}"
   "${originalMounted}" && umount "${originalRoot}"
   [ -n "${temporaryDirectory}" ] && rm -r "${temporaryDirectory}"
}
set -e
originalMounted=false
initrdMounted=false
newMounted=false
trap "cleanup" 0

workingDirectory="${PWD}"
temporaryDirectory="$(mktemp -d "${TMPDIR:-/tmp}/${programName}.XXXXXX")"

originalRoot="${temporaryDirectory}/original"
mkdir "${originalRoot}"
mount -o loop -t iso9660 "${originalImage}" "${originalRoot}"
originalMounted=true

modifiedRoot="${temporaryDirectory}/modified"
mkdir "${modifiedRoot}"
cp -RpPd -- "${originalRoot}/." "${modifiedRoot}"

loaderDirectory=""
for directory in boot/isolinux isolinux
do
   [ -d "${originalRoot}/${directory}" ] && {
      loaderDirectory="${directory}"
      break
   }
done

configurationFile="isolinux.cfg"
sed -n -e '
1i\
prompt 1\
timeout 0\
default text\

/^ *prompt /d
/^ *timeout /d
/^ *default /d
/^ *menu  *default *$/d
/^ *append.* text/s/$/ nofb/
/^ *append.* rescue/s/$/ text nofb/
p
' <"${originalRoot}/${loaderDirectory}/${configurationFile}" >"${modifiedRoot}/${loaderDirectory}/${configurationFile}"

# bootMessage="boot.msg"
# echo -n -e '\a' >"${modifiedRoot}/${loaderDirectory}/${bootMessage}"
# cat "${originalRoot}/${loaderDirectory}/${bootMessage}" >>"${modifiedRoot}/${loaderDirectory}/${bootMessage}"

initrdImage="${temporaryDirectory}/initrd.img"
initrdPath="${modifiedRoot}/${loaderDirectory}/initrd.img"
gunzip -c "${initrdPath}" >"${initrdImage}"

initrdDescription="`file -b "${initrdImage}"`"
case "${initrdDescription}"
in
   *" ext2 "*) initrdType=ext2;;
   *" cpio "*) initrdType=cpio;;
   *) programError "unsupported initrd image format: ${initrdDescription}"
esac

initrdRoot="${temporaryDirectory}/initrd"
mkdir "${initrdRoot}"
"mount_${initrdType}" "${initrdRoot}" "${initrdImage}"
initrdMounted=true

found=false
for name in linuxrc init
do
   linuxrcPath="${initrdRoot}/${name}"
   initPath="$(readlink "${linuxrcPath}")" && {
      found=true
      break
   }
done
"${found}" || programError "linuxrc not found."
rm "${linuxrcPath}"
ln -s /bin/brltty "${linuxrcPath}"

deviceDirectory="${initrdRoot}/dev"
ensureDevices() {
   typeset type="${1}"
   typeset major="${2}"
   typeset minor="${3}"
   typeset prefix="${4}"
   typeset last="${5}"
   typeset suffix="${6}"
   typeset number=0
   while ((number <= last))
   do
      typeset path="${deviceDirectory}/${prefix}${suffix}"
      [ -e "${path}" ] || mknod -m 600 "${path}" "${type}" "${major}" "$((minor++))"
      suffix=$((++number))
   done
}
ensureDevices c 7 0 vcs 12
ensureDevices c 7 128 vcsa 12
ensureDevices c 5 1 console 0
ensureDevices c 4 0 tty 12 0
ensureDevices c 4 64 ttyS 3 0
ensureDevices c 188 0 ttyUSB 1 0

case "${brlttyArchive}"
in
   *.tar.gz|*.tgz)
      tar x -z -C "${temporaryDirectory}" -f "${brlttyArchive}"
      ;;

   *.tar)
      tar x -C "${temporaryDirectory}" -f "${brlttyArchive}"
      ;;

   *)
      programError "unsupported brltty archive name: ${brlttyArchive}"
      ;;
esac

shopt -s nullglob
set -- ${temporaryDirectory}/brltty*
[ "${#}" -eq 0 ] && programError "brltty build directory not found."
brlttyBuildRoot="${1}"

brlttyInstallRoot="${temporaryDirectory}/install"
(
   set -e
   trap "" 0
   cd "${brlttyBuildRoot}"

   shopt -s nullglob
   set -- ./autogen*
   for autogen
   do
      [ -f "${autogen}" -a -r "${autogen}"  -a -x "${autogen}" ]  && "${autogen}"
   done

   ./configure --quiet --with-install-root="${brlttyInstallRoot}" \
	       --with-init-path="${initPath}" --with-stderr-path="/dev/tty5" \
               --with-writable-directory="/tmp" \
               --with-screen-driver="lx,-all" \
	       --with-braille-driver="-tt,-vr,${brailleDrivers}" \
	       --with-text-table="${textTable}" \
	       --disable-speech-support --without-libbraille --without-curses --disable-x \
	       --disable-pcm-support --disable-fm-support --disable-midi-support \
               --enable-standalone-programs --disable-api --disable-gpm --disable-icu
   make -s -C Programs all
   strip Programs/brltty
   make -s -C Programs install-programs install-data-files install-tables
) || exit "${?}"

"check_${initrdType}"
(
   set -e
   cd "${brlttyInstallRoot}"
   cp --parents -- $(find . -type f -printf '%P ') "${initrdRoot}"
) || exit 1

"${invokeShell}" && (
   set +e
   trap "" 0

   cd "${temporaryDirectory}"
   "${SHELL:-/bin/sh}"
   exit 0
)

initrdMounted=false
"unmount_${initrdType}" "${initrdRoot}" "${initrdImage}"
gzip -c -9 "${initrdImage}" >"${initrdPath}"

isoVolumeIdentifier="$(isoinfo -d -i "${originalImage}" | grep '^Volume id:' | cut -d' ' -f3-)"
isoApplicationIdentifier="$(isoinfo -d -i "${originalImage}" | grep '^Application id:' | cut -d' ' -f3-)"
mkisofs -quiet -J -R -T -boot-load-size 4 -boot-info-table -no-emul-boot \
	-A "${isoApplicationIdentifier}" -V "${isoVolumeIdentifier}" \
	-b "${loaderDirectory}/isolinux.bin" -c "${loaderDirectory}/boot.cat" \
	-o "${modifiedImage}" "${modifiedRoot}"
exit 0