#!/bin/bash
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public
# License along with this program.  If not, see
# <http://www.gnu.org/licenses/>.

# Loader
function bootless_load {
  local dest
  local base

  # Determine if we are in a local or system-wide install.
  if [ -h "$0" ]; then
    dest="$(readlink $0)"

    # Check again as the caller might be a symlink as well
    if [ -h "$dest" ]; then
      base="`dirname $dest`"
      dest="$(dirname $(readlink $dest))"
    else
      base="`dirname $0`"
      dest="`dirname $dest`"
    fi

    # Deal with relative or absolute links
    if [ "`basename $dest`" == "$dest" ]; then
      export APP_BASE="$base"
    else
      export APP_BASE="$dest"
    fi
  else
    export APP_BASE="`dirname $0`"
  fi
}

# Usage
function bootless_usage {
  echo "Usage: `basename $0` <action> <folder> [arguments]"
  exit 1
}

# Sync bootless folder
function bootless_rsync {
  # Exclude git folder and follow git-annex symlinks
  rsync -CLavz --exclude boot $1/ $2/

  # Make sure there's a symlink to itself
  ( cd $2 && ln -s . boot )
}

# Repository initiator
function bootless_init {
  if [ -e "$BOOTLESS_DIR" ]; then
    echo "folder $BOOTLESS_DIR already exists"
    exit 1
  fi

  if [ ! -z "$1" ]; then
    # Clone from url
    git clone $1 $BOOTLESS_DIR

    # Support for git-annex
    #( cd $BOOTLESS_DIR && git annex init && git config annex.sshcaching false && git annex sync )
    exit $?
  fi

  # Create a fresh repository
  mkdir -p $BOOTLESS_DIR/{default,custom,grub}
  mkdir -p $BOOTLESS_DIR/custom/{debian,memtest}
  touch $BOOTLESS_DIR/{default,custom,grub}/.empty
  touch $BOOTLESS_DIR/default/{debian,memtest}/.empty
  ( cd $BOOTLESS_DIR && ln -s . boot)

  if [ -f "/boot/memtest86+.bin" ]; then
    cp /boot/memtest86+.bin $BOOTLESS_DIR/default/memtest
  else
    echo "No memtest image found. Please install memtest86+ package"
    echo "and manually copy /boot/memtest86+.bin if you want memtest support"
  fi

  # Grub configuration
  cp $APP_BASE/templates/grub.cfg   $BOOTLESS_DIR/grub/
  cp $APP_BASE/templates/custom.cfg $BOOTLESS_DIR/custom/

  # Initialize git repository
  #(
  #cd $BOOTLESS_DIR
  #git init
  #git annex init
  #git config annex.sshcaching false
  #git add boot
  #git add {default,custom,grub}/.empty
  #git add default/{debian,memtest,ubuntu}/.empty
  #git add grub/grub.cfg
  #git annex add .
  #git commit -a -m "Initial import"
  #)

  echo "Now add your boot images and/or edit $BOOTLESS_DIR/custom/custom.cfg to suit your needs."
}

function bootless_warning {
  local device=$1
  local go

  echo "******************"
  echo "*  ATTENTION!!!  *"
  echo "******************"
  echo ""
  echo "If you continue, all data in device \"${device}\" will be destroyed!"
  echo ""
  echo -n "Are you sure you want to continue? Type uppercase \"YES\": "
  read go

  if [ "${go}" != "YES" ]; then
    false
  else
    true
  fi
}

# Generate a bootless disk image
function bootless_image {
  local output="$1"
  local device="$2"

  if [ ! -d "$BOOTLESS_DIR" ]; then
    echo "missing $BOOTLESS_DIR folder, please initialize first"
    exit 1
  fi

  # Fix parameters
  if echo ${output} | grep -q "/dev/"; then
    output="bootless.iso"
    device="$1"
  elif [ -z "$output" ]; then
    output="bootless.iso"
  fi

  # Set sudo config
  local sudo
  if [ "`whoami`" != 'root' ]; then
    sudo="sudo"
  fi

  # Copy data
  tmpdir=`mktemp --tmpdir=/tmp -d`
  bootless_rsync ${BOOTLESS_DIR} ${tmpdir}/boot

  # Make rescue disk
  grub-mkrescue -o ${output} ${tmpdir}

  # Optionally copy to removable media
  if [ ! -z "$device" ]; then
    # Issue a warning
    bootless_warning ${device}

    if [ "$?" != "0" ]; then
      echo "Skipping copy of ${output} to ${device}..."
    else
      # Check if device is mounted
      if [ "`mount | grep ${device}`" != "" ]; then
        echo "Error: device \"${device}\" is mounted."
        echo "Skipping copy of ${output} to ${device}..."
      else
        $sudo dd if=${output} of=${device}
      fi
    fi

  fi

  # Cleanup
  rm -rf ${tmpdir}

  # Finish
  if [ -z "$device" ]; then
    echo "Image saved at ${output}"
  else
    echo "Removing image ${output}..."
    rm ${output}
  fi

  echo "Checking for changes in upstream grub.cfg, in which case you might want to update it..."
  diff -Naur $APP_BASE/templates/grub.cfg $BOOTLESS_DIR/grub/grub.cfg

  echo "Done."
}

# Check image/device integrity
function bootless_check {
  echo "Not implemented yet :("
  exit 1
}

# Load
bootless_load $*

# Config
NAME="bootless"
BOOTLESS_VERSION="0.0.1"
BOOTLESS_ACTION="$1"
BOOTLESS_DIR="$2"

# Output name and version
echo "$NAME $BOOTLESS_VERSION"

# Parameter verification
if [ -z "$BOOTLESS_DIR" ]; then
  bootless_usage
elif [ "$BOOTLESS_ACTION" == "init" ]; then
  shift 2
  bootless_init $*
elif [ "$BOOTLESS_ACTION" == "image" ]; then
  shift 2
  bootless_image $*
elif [ "$BOOTLESS_ACTION" == "check" ]; then
  shift 2
  bootless_check $*
else
  bootless_usage
fi