#!/bin/bash

printf "RESTORE SCRIPT\n"

DISK_TO_RECOVER=/dev/mapper/cachedev_0
RESTORE_PATH=/volumeUSB1/usbshare
RECENT_FILEPATH=/mypath/recentfile.txt

# Find roots with transaction id
printf "Finding all roots..."
ROOTS_RAW=`btrfs-find-root "$DISK_TO_RECOVER" 2> /dev/null | grep 'Well'`
status=$?
if [[ $status != 0 ]]; then
  printf "FAILURE ($status)\n"
  exit 1
fi
printf "$(echo "$ROOTS_RAW" | wc -l) found\n"

# Sort roots block numbers by transaction id
BLOCKNUMBERS=`echo "$ROOTS_RAW" | grep -oE 'Well block [0-9]*' | grep -oE '[0-9]*'`
TRANSIDS=`echo "$ROOTS_RAW" | grep -oE '\(gen: [0-9]*' | grep -oE '[0-9]*'`
TXID_BLOCKID=`paste <(echo "$TRANSIDS") <(echo "$BLOCKNUMBERS")`
SORTED_ROOTS=`echo "$TXID_BLOCKID" | sort -rn | uniq | cut -f 2`
printf "Searching for $RECENT_FILEPATH in the roots block numbers...\n"
printf "Trying roots block numbers: "
FIRST_VALID_ROOT=
for BLOCK in $SORTED_ROOTS; do
  printf "$BLOCK ";
  if [[ `btrfs restore -ivD -t "$BLOCK" "$DISK_TO_RECOVER" /tmp 2> /dev/null | grep "$RECENT_FILEPATH"` != "" ]]; then
    [[ "$FIRST_VALID_ROOT" = "" ]] && FIRST_VALID_ROOT="$BLOCK";
    printf "\nRoot block number $BLOCK contains $RECENT_FILEPATH - ";
    read -p "recover from this root block number? (y/n) [y]: " -r -n 1;
    echo;
    if [[ "$REPLY" != "y" ]]; then
      printf "Continuing... trying roots block numbers: ";
    else
      printf "Recovering $DISK_TO_RECOVER to $RESTORE_PATH with root block number $BLOCK...\n";
      btrfs restore -iv -t "$BLOCK" "$DISK_TO_RECOVER" "$RESTORE_PATH" 2>&1 | tee btrfs-restore.log;
      status=$?;
      printf "\nFinished with status $status\nYou can see the log in btrfs-restore.log\n";
      exit $status
    fi;
  fi;
done;
printf "All roots blocks numbers have been tried, recovering with first valid root block number $FIRST_VALID_ROOT\n"
btrfs restore -iv -t "$FIRST_VALID_ROOT" "$DISK_TO_RECOVER" "$RESTORE_PATH" 2>&1 | tee btrfs-restore.log
printf "\nFinished with status $status\nYou can see the log in btrfs-restore.log\n"
exit $status