#!/bin/bash
#
# Restore drill for the S3 backup leg — proves the backups are not just
# "running" but actually restorable. Non-destructive: reads the repo,
# writes only under a temporary directory, removes it at the end.
#
# Two restores, the two data kinds we back up:
#   1. a filesystem tree   -> restored, then diffed against the live tree
#   2. a database dump     -> restored, then sanity-checked (and with
#                             -d, loaded into a throwaway incus container)
#
# Usage: restic-restore-test.sh [-r <repo>] [-t <tree-path>] [-b <db-dump>]
#                               [-w <workdir>] [-k] [-d]
#   -k  keep the restored files (default: clean up)
#   -d  also load the dump into a scratch container (slower, strongest)
#
# Env from /root/.restic-env.

set -u

REPO=s3:s3.sbg.io.cloud.ovh.net/restic-data
TREE=/var/lib/incus/storage-pools/data/containers/solar/rootfs/var/www/html/solar
DUMP=/backup/dumps/mariadb/freshrss/freshrss.sql
WORK=/backup/restore-test-$(date +%Y%m%d-%H%M%S)
ENVFILE=/root/.restic-env
RESTIC=/usr/local/bin/restic
KEEP=0
DBTEST=0

while getopts r:t:b:w:kd flag; do
    case "${flag}" in
        r) REPO=${OPTARG};; t) TREE=${OPTARG};; b) DUMP=${OPTARG};;
        w) WORK=${OPTARG};; k) KEEP=1;; d) DBTEST=1;;
        *) echo "Usage: $0 [-r repo] [-t tree] [-b dump] [-w workdir] [-k] [-d]" >&2; exit 2;;
    esac
done

[ -r "$ENVFILE" ] || { echo "env file $ENVFILE not readable (run as root)" >&2; exit 2; }
. "$ENVFILE"
log() { echo "[$(date '+%F %T')] $*"; }
rc=0; verdict() { [ "$1" -eq 0 ] && echo "PASS  $2" || { echo "FAIL  $2"; rc=1; }; }

mkdir -p "$WORK" || exit 2
log "repo $REPO"
$RESTIC -r "$REPO" snapshots --latest 1 --compact || { echo "cannot list snapshots" >&2; exit 1; }

# ---- 1. filesystem tree ----------------------------------------------------
log "restoring tree: $TREE"
$RESTIC -r "$REPO" restore latest --target "$WORK/tree" --include "$TREE" >/dev/null 2>&1
verdict $? "tree restored"
if [ -d "$WORK/tree$TREE" ]; then
    files=$(find "$WORK/tree$TREE" -type f | wc -l)
    log "restored $files files; diffing against the live tree"
    # differences are expected if the tree changed since the snapshot —
    # report them, do not fail on them
    if diff -qr "$WORK/tree$TREE" "$TREE" > "$WORK/diff.txt" 2>&1; then
        verdict 0 "restored tree is identical to live ($files files)"
    else
        echo "NOTE  $(wc -l < "$WORK/diff.txt") path(s) differ from live (expected if changed since the snapshot):"
        head -5 "$WORK/diff.txt" | sed 's/^/      /'
        verdict 0 "restored tree readable ($files files)"
    fi
else
    verdict 1 "restored tree missing at $WORK/tree$TREE"
fi

# ---- 2. database dump ------------------------------------------------------
log "restoring dump: $DUMP"
$RESTIC -r "$REPO" restore latest --target "$WORK/db" --include "$DUMP" >/dev/null 2>&1
f="$WORK/db$DUMP"
if [ -s "$f" ]; then
    tables=$(grep -c "^CREATE TABLE" "$f")
    tail -3 "$f" | grep -q "Dump completed"
    complete=$?
    log "dump: $(du -h "$f" | cut -f1), $tables CREATE TABLE, completed-marker=$([ $complete -eq 0 ] && echo yes || echo NO)"
    verdict $(( complete != 0 || tables == 0 ? 1 : 0 )) "dump restored and well-formed"

    if [ "$DBTEST" -eq 1 ]; then
        ct=restore-drill-$$
        log "loading it into a scratch container ($ct) — this takes a few minutes"
        if incus launch images:debian/13 "$ct" >/dev/null 2>&1 &&
           incus exec "$ct" -- sh -c "DEBIAN_FRONTEND=noninteractive apt-get -qq update && DEBIAN_FRONTEND=noninteractive apt-get -qq install -y mariadb-server" >/dev/null 2>&1; then
            incus file push "$f" "$ct/root/dump.sql" >/dev/null 2>&1
            incus exec "$ct" -- sh -c "mariadb < /root/dump.sql" && loaded=0 || loaded=1
            got=$(incus exec "$ct" -- mariadb -N -B -e \
                 "SELECT COUNT(*) FROM information_schema.tables WHERE table_schema NOT IN ('mysql','information_schema','performance_schema','sys')" 2>/dev/null)
            log "tables in the restored database: ${got:-0} (dump declared $tables)"
            verdict $(( loaded != 0 || ${got:-0} == 0 ? 1 : 0 )) "dump loads into a live MariaDB"
        else
            verdict 1 "could not prepare the scratch container"
        fi
        incus delete -f "$ct" >/dev/null 2>&1
    fi
else
    verdict 1 "dump restored at $f"
fi

# ---- cleanup ---------------------------------------------------------------
if [ "$KEEP" -eq 1 ]; then log "keeping $WORK"; else rm -rf "$WORK"; log "cleaned up $WORK"; fi
log "restore drill done (rc=$rc)"
exit $rc