#!/bin/bash

set -o pipefail
set -e
#set -x

# decrypt like so:
#
# gpg -d ~/.paths/sneak-sync/secrets/backup-encryption-keys/2022-11-16.sneak-longterm-archive-age-key.gpg 2>/dev/null |
# age -d -i - priv.age | tail -1 2>/dev/null |
# age -d -i - archive.age

YYYYMMDD="$(date -u +%Y-%m-%d)"
YYYY="$(date -u +%Y)"
MM="$(date -u +%m)"
THIS="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
MY_PGP="5539AD00DE4C42F3AFE11575052443F4DF2A55C2"
MY_LONGTERM_AGE_PUBKEY="age1278m9q7dp3chsh2dcy82qk27v047zywyvtxwnj4cvt0z65jw6a7q5dqhfj"
TD="$(mktemp -d)"

LOGDIR="$HOME/Documents/_SYSADMIN/$YYYY-$MM/$YYYYMMDD"
if [[ ! -d "$LOGDIR" ]]; then
    mkdir -p "$LOGDIR"
fi
#exec > >(tee -a $LOGDIR/$YYYYMMDD.$(date -u +%s).tocloud-backup.log) 2>&1

function on_exit {
    rm -rf "$TD"
}

function on_terminate {
    echo "### Cleaning up..."
    rm -rfv "$TD"
}

trap on_exit ERR EXIT
trap on_terminate SIGINT SIGTERM

function usage {
    echo "usage: $0 <backupname> <dir>" > /dev/stderr
    exit 1
}

#function getStorageBoxCredentials {
#    gpg -d $HOME/.paths/sneak-sync/secrets/credentials/storagebox-offsite-backup-subaccount.json.gpg
#}

function main {
    if [[ $# -ne 2 ]]; then
        usage
    fi

    if [[ -z "$2" ]]; then
        usage
    fi

    if [[ -d "$2" ]]; then
        SRC="$(cd "$2" && pwd -P)"
    else
        SRC="$2"
    fi

    if [[ ! -r "$SRC" ]]; then
        usage
    fi

    BACKUPNAME="$YYYYMMDD.$1.$(date +%s)"
    time do_backup "$BACKUPNAME" "$SRC"
}

function do_backup {

    BACKUPNAME="$1"
    SRC="$2"

    cd "$TD"
    mkdir "$BACKUPNAME"
    cd "$TD/$BACKUPNAME"
    echo "### Beginning backup $BACKUPNAME"
    echo "### Temporary Working Directory: $TD"
    AGE_PRIV=$(age-keygen 2> ./pub.txt)
    age -r $MY_LONGTERM_AGE_PUBKEY <<< "$AGE_PRIV" > ./priv.age
    PUB="$(awk -F' ' '{print $3}' < ./pub.txt)"
    echo "### Backup Archive Session Pubkey: $PUB"
    echo "$PUB" > ./pub.txt  # overwrite non-clean one
    gpg --trust-model always \
        --compress-algo none \
        -r $MY_PGP --encrypt \
        -a <<< "$AGE_PRIV" \
        > ./priv.sneak-pgp-DF2A55C2.asc
    echo "### Backup Source Size: $(du -sh "$SRC" | awk '{print $1}')"
    echo "### Indexing backup..."
    (find "$SRC" -type f \( -exec sha1sum {} \; \)) |
        tee /dev/stderr |
        age -r $PUB > "$TD/$BACKUPNAME/archive-sums.txt.age"
    echo "### Compressing backup..."
    tar -P -c "$SRC" |
        nice -n 20 zstd --compress -T0 -10 |
        pv --delay-start 3 --progress --eta --size $(du -sb "$SRC" | awk '{print $1}') |
        age -r $PUB |
        split -d -b 1G -a 4 - $TD/$BACKUPNAME/archive.tar.zst.age.
        COUNT="$(cd "$TD/$BACKUPNAME" && ls -1 archive.tar.zst.age.* | wc -l | awk '{print $1}')"
        if [[ "$COUNT" -eq 1 ]]; then
            mv "$TD/$BACKUPNAME/archive.tar.zst.age.0000" "$TD/$BACKUPNAME/archive.tar.zst.age"
        fi
    cd "$TD/$BACKUPNAME"
    echo "### Backup Compressed Archive Size: $(du -sh "$TD/$BACKUPNAME" | awk '{print $1}')"
    echo "### Creating Checksums..."
    shasum archive.tar.zst.age* archive-sums.txt.age | tee -a SHASUMS.txt
    echo "### Signing Checksums..."
    gpg --default-key $MY_PGP --output SHASUMS.txt.gpg --detach-sig SHASUMS.txt
    #tar -c . | pv --progress --eta --size $(du -sb "$TD/$BACKUPNAME" | awk '{print $1}') |
    #ssh fsn1-storagebox-10T "mkdir -p $BACKUPNAME ; cd $BACKUPNAME && tar xvf -"
    #while ! rsync -avvvcP --delete "$TD/$BACKUPNAME/" fsn1-storagebox-10T:"$BACKUPNAME"/
    #    sleep 1
    #done
    echo "### Uploading data..."
    # i want to use rsync here but rclone gives much better total
    # progress/ETA display.
    rclone sync \
        --retries 99999 \
        --progress \
        --progress-terminal-title \
        --stats-unit bits \
        "$TD/$BACKUPNAME" \
        fsn1-storagebox-10T:"$BACKUPNAME"/
    # belt and suspenders
    echo "### Verifying uploaded data checksums..."
    rsync -acP "$TD/$BACKUPNAME/" fsn1-storagebox-10T:"$BACKUPNAME"/
    RETVAL="$?"
    if [[ "$RETVAL" -eq 0 ]]; then
        echo "### Backup successful."
        exit 0
    else
        echo "### Problem detected."
        exit 1
    fi
}

main "$@"