#!/usr/bin/env bash

# BITSC LICENSE NOTICE (MODIFIED ISC LICENSE)
#
# TIME MACHINE BLESS
#
# Copyright (c) 2022 Lee Ockert <torstenvl@gmail.com>
#                    https://github.com/torstenvl
#
# THIS WORK IS PROVIDED "AS IS" WITH NO WARRANTY OF ANY KIND. THE IMPLIED
# WARRANTIES OF MERCHANTABILITY, FITNESS, NON-INFRINGEMENT, AND TITLE ARE
# EXPRESSLY DISCLAIMED. NO AUTHOR SHALL BE LIABLE UNDER ANY THEORY OF LAW
# FOR ANY DAMAGES OF ANY KIND RESULTING FROM THE USE OF THIS WORK.
#
# Permission to use, copy, modify, and/or distribute this work for any
# purpose is hereby granted, provided this notice appears in all copies.


function dispusage() {
  if [ ${#1} -gt 0 ]; then
    printf "%s\n\n" "${1}"
  fi
  echo "\
TIME MACHINE BLESS

USAGE

    ${0} <snapshot directory>

DESCRIPTION

    Time Machine Blessing modifies the metadata of a snapshot directory
    (i.e., a datestamped directory inside a Backups.backupdb/machinename/
    directory) so that the metadata reflects a backup completed on that date
    and the metadata of the top-level drive matches that of the current drive.

    These modifications should allow restoration of files within the Time
    Machine restore UI. 
"
}

function canonicalname() {
    echo $(stat -f %R ${1})
}

############################################################################
##                   PARSE & MAKE SENSE OF COMMAND LINE                   ##
############################################################################
if [ ! $# -eq 1 ]; then
  dispusage "Invalid number of arguments" && exit
fi

# Try to get canonical name
DATEDIRNAME=$(stat -f %R ${1})
if [[ "${DATEDIRNAME}" == "" ]]; then
    dispusage "Could not get canonical name of directory ${1}" && exit
fi

# Ensure it's a directory
if [ ! -d "${DATEDIRNAME}" ]; then
    dispusage "${DATEDIRNAME} is not a valid directory" && exit
fi 

# Ensure it's a Backups.backupdb dir's subdir's subdir
if [[ ! "${DATEDIRNAME}" =~ ^.*\/Backups\.backupdb\/.*\/.*$ ]]; then
    dispusage "${DATEDIRNAME} does not appear to be in a Backups.backupdb directory" && exit
fi

# Get the basename and ensure it's in a Time Machine timestamp format
DATEDIRBASENAME=$(basename "${DATEDIRNAME}")
if [[ ! "${DATEDIRBASENAME}" =~ ^[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9][0-9][0-9]\/?$ ]]; then
    dispusage "${DATEDIRBASENAME} does not appear to be a snapshot directory" && exit
fi

# Get the Unix timestamp from the directory's Time Machine timestamp format
TIMESTAMP=$(date -j -f "%Y-%m-%d-%H%M%S" "${DATEDIRBASENAME}" +"%s")
TIMESTAMP="${TIMESTAMP}100000"
if [[ ! "${TIMESTAMP}" =~ ^[0-9]*$ ]]; then
    dispusage "Could not automatically set snapshot timestamp due to folder name format" && exit
fi

if [ -d "${DATEDIRNAME}/Macintosh HD - Data" ]; then
    DRVDIRNAME="${DATEDIRNAME}/Macintosh HD - Data"
elif [ -d "${DATEDIRNAME}/Macintosh HD" ]; then
    DRVDIRNAME="${DATEDIRNAME}/Macintosh HD"
else
    ## TODO: Take the output of `ls -d ${DATEDIRNAME}` and try to autodetect?
    dispusage "Could not find a volume name within ${DATEDIRNAME}" && exit
fi

############################################################################
##                    GET NECESSARY SYSTEM INFORMATION                    ##
############################################################################
VOLGRPUUID=`diskutil info / | awk -F' ' '/^   APFS Volume Group/{print $(NF)}'`
VOLDSKUUID=`diskutil info / | awk -F' ' '/^   Volume UUID/{print $(NF)}'`

if [ ! VOLGRPUUID == "" ]; then
   TGTUUID="${VOLGRPUUID}"
elif [ ! VOLDSKUUID == "" ]; then
   TGTUUID="${VOLDSKUUID}"
fi


KERNELVER=`uname -a | sed 's/.*Version \([0-9][0-9]*\).*/\1/g'`
if [ $KERNELVER -lt 20 ]; then
    SIMONSAYS="sudo /System/Library/Extensions/TMSafetyNet.kext/Contents/Helpers/bypass"
else
    SIMONSAYS="sudo"
fi








############################################################################
##                       CONFIRM ACTION INFORMATION                       ##
############################################################################
printf "\n\
Snapshot Directory:  %s\n\
Snapshot Volume:     %s\n\
Computer Volume:     %s\n\
   Volume Group:     %s\n\\n" "${DATEDIRNAME}" "${DRVDIRNAME}" "${VOLDSKUUID}" "${VOLGRPUUID}"

printf "\
Preparing to run the following commands:\n\
    %s xattr -c \"%s\"\n\
    %s xattr -c \"%s\"\n\
    %s xattr -w \"com.apple.backupd.SnapshotCompletionDate\" \"%s\" \"%s\"\n\
    %s xattr -w \"com.apple.backupd.SnapshotState\" %s \"%s\"\n\
    %s xattr -w \"com.apple.backupd.SnapshotVolumeUUID\" \"%s\" \"%s\"\n\
    \n" "${SIMONSAYS}"  "${DATEDIRNAME}" \
        "${SIMONSAYS}"  "${DRVDIRNAME}" \
        "${SIMONSAYS}"  "${TIMESTAMP}"   "${DATEDIRNAME}" \
        "${SIMONSAYS}"  "4"              "${DATEDIRNAME}" \
        "${SIMONSAYS}"  "${TGTUUID}"     "${DRVDIRNAME}"

printf "Does everything look right?\n"

select response in "Bless Time Machine Snapshot" "ABORT ABORT ABORT!"; do
    if [ "${response}" == "Bless Time Machine Snapshot" ]; then
        "${SIMONSAYS}" xattr -c "${DATEDIRNAME}" && \
        "${SIMONSAYS}" xattr -c "${DRVDIRNAME}" && \
        "${SIMONSAYS}" xattr -w "com.apple.backupd.SnapshotCompletionDate" "${TIMESTAMP}" "${DATEDIRNAME}" && \
        "${SIMONSAYS}" xattr -w "com.apple.backupd.SnapshotState" "4" "${DATEDIRNAME}" && \
        "${SIMONSAYS}" xattr -w "com.apple.backupd.SnapshotVolumeUUID" "${TGTUUID}" "${DRVDIRNAME}"

        if [ ! $? -eq 0 ]; then
            printf "\nOperation failed.\n\n"
        else
            printf "\nOperation completed.\n\n"
            printf "The snapshot directory now has the following metadata:\n"
            printf "%s\n" "——————————————————————————————————————————————————————"
            xattr -lv "${DATEDIRNAME}"
            printf "\n\n"
            printf "The snapshot volume now has the following metadata:\n"
            printf "%s\n" "———————————————————————————————————————————————————"
            xattr -lv "${DRVDIRNAME}"
            printf "\n\n"
        fi
        break
    else
        printf "\nOperation aborted. No action has been taken.\n\n"
        break
    fi
done