#!/usr/bin/env bash
# ShopDB backup one-shot.
#
# Produces one recoverable set per run and stores it two ways: a plain
# db.sql.gz + manifest.json on the local /backups volume for a fast, repo-free
# restore, and a restic snapshot (db dump + instance tree + manifest) at
# RESTIC_REPOSITORY for a deduped, encrypted, offsite copy.
#
# Sequence:
#   1. mysqldump --single-transaction (InnoDB-consistent, non-blocking)
#   2. manifest.py stamps core+plugin Alembic revisions + image tag
#   3. restic backup the dump + /app/instance + manifest as ONE snapshot
#   4. restic forget --keep-daily 5 --keep-weekly 4 --keep-monthly 6 --prune
#   5. restic check - fail loudly if the repo is unhealthy, so a bad repo is
#      caught on backup night, not restore night.
#
# ASCII only, no emojis - matches the repo style gate.
set -euo pipefail

BACKUPS_ROOT="${SHOPDB_BACKUPS_ROOT:-/backups}"
SITE="${SHOPDB_SITE:-shopdb}"
STAMP="$(date -u +%Y-%m-%dT%H%M%SZ)"
SETNAME="${SITE}-${STAMP}"
SETDIR="${BACKUPS_ROOT}/${SETNAME}"

# shellcheck source=scripts/backup/status.sh
. /opt/backup/status.sh

log() { echo "[backup] $*"; }

# Record the run outcome on any exit so a failed backup is visible in the UI
# history, not just a silent gap.
BACKUP_DONE=false
_on_exit() {
	code=$?
	if [ "${BACKUP_DONE}" = true ]; then
		status_write backup done "${SETNAME}" "Backup complete"
		history_append backup success "${SETNAME}" "Backup complete"
	else
		status_write backup failed "${SETNAME}" "Backup failed (exit ${code})"
		history_append backup failed "${SETNAME}" "Backup failed (exit ${code})"
	fi
}
trap _on_exit EXIT

mkdir -p "${SETDIR}"
status_write backup database "${SETNAME}" "Dumping database"

# 1. Database: whole-DB logical dump, consistent and non-blocking on InnoDB.
log "dumping database ${MYSQL_DATABASE} from ${MYSQL_HOST}"
mysqldump \
	--host="${MYSQL_HOST}" \
	--user="${MYSQL_USER}" \
	--password="${MYSQL_PASSWORD}" \
	--single-transaction \
	--routines \
	--triggers \
	--databases "${MYSQL_DATABASE}" \
	| gzip -c > "${SETDIR}/db.sql.gz"
log "database dump written ($(du -h "${SETDIR}/db.sql.gz" | cut -f1))"

# 2. Manifest: the schema stamp that makes a restore a checked operation.
# Capture the revision actually applied to the DATABASE (its alembic_version),
# not just the code head. A restore must gate on the DATA revision; stamping
# only the code head hides an image that has outrun its own database and lets a
# behind-schema dump restore under ahead-schema code (1054 Unknown column on
# every affected table). Query it straight from the dumped DB.
log "reading applied database revision (alembic_version)"
DATAREV="$(mysql \
	--host="${MYSQL_HOST}" \
	--user="${MYSQL_USER}" \
	--password="${MYSQL_PASSWORD}" \
	--skip-column-names --batch \
	-e "SELECT version_num FROM alembic_version LIMIT 1;" \
	"${MYSQL_DATABASE}" 2>/dev/null | tr -d '\r')"
[ -n "${DATAREV}" ] || log "WARN could not read alembic_version - datarev will be empty"

# The same question for every PLUGIN chain. Each plugin owns an
# alembic_version_<plugin> table, and those move independently of the core one:
# code rolled back to an older plugin revision can sit at an identical core
# head while the dump carries plugin tables it has never heard of. Stamping only
# the core revision let that combination pass the restore gate, load, and then
# fail during the plugin upgrade with the data already replaced. Read straight
# from the dumped DB, same as the core revision above.
log "reading applied plugin revisions (alembic_version_*)"
DATAPLUGINS="$(mysql \
	--host="${MYSQL_HOST}" \
	--user="${MYSQL_USER}" \
	--password="${MYSQL_PASSWORD}" \
	--skip-column-names --batch \
	-e "SELECT table_name FROM information_schema.tables
	     WHERE table_schema = '${MYSQL_DATABASE}'
	       AND table_name LIKE 'alembic\\_version\\_%';" 2>/dev/null \
	| tr -d '\r' \
	| while read -r table; do
		[ -n "${table}" ] || continue
		plugin="${table#alembic_version_}"
		rev="$(mysql \
			--host="${MYSQL_HOST}" \
			--user="${MYSQL_USER}" \
			--password="${MYSQL_PASSWORD}" \
			--skip-column-names --batch \
			-e "SELECT version_num FROM \`${table}\` LIMIT 1;" \
			"${MYSQL_DATABASE}" 2>/dev/null | tr -d '\r')"
		[ -n "${rev}" ] && printf '%s\t%s\n' "${plugin}" "${rev}"
	 done \
	| python3 -c 'import json,sys; print(json.dumps(dict(l.rstrip("\n").split("\t",1) for l in sys.stdin if "\t" in l)))')"
[ -n "${DATAPLUGINS}" ] || DATAPLUGINS='{}'
log "plugin revisions: ${DATAPLUGINS}"

log "writing manifest"
python3 /opt/backup/manifest.py \
	--out "${SETDIR}/manifest.json" \
	--takenat "${STAMP}" \
	--site "${SITE}" \
	--imagetag "${SHOPDB_IMAGE_TAG:-source}" \
	--datarev "${DATAREV}" \
	--dataplugins "${DATAPLUGINS}" \
	--migrations /app/migrations \
	--plugins /app/plugins

# Consistency guard: if the DATA revision does not match the CODE head, this
# backup captures a database the running image has outrun. It is still stored
# (losing it would be worse) but flagged loudly so a restore of it is a
# deliberate choice, not a surprise.
CODEREV="$(python3 -c \
	'import json,sys;print(",".join(sorted(json.load(open(sys.argv[1]))["schemarev"]["core"])))' \
	"${SETDIR}/manifest.json" 2>/dev/null || echo "")"
if [ -n "${DATAREV}" ] && [ "${DATAREV}" != "${CODEREV}" ]; then
	log "WARN schema drift: database is at '${DATAREV}' but code head is '${CODEREV}'"
	log "WARN this DB has not run 'flask db upgrade' to the running image; restore will upgrade it"
	history_append backup warning "${SETNAME}" "Schema drift: data ${DATAREV} vs code ${CODEREV}"
fi

# 3. restic snapshot: db dump + instance tree + manifest, one point in time.
#    Skips gracefully when restic/repo are not configured (local-only sites).
IS_CHECK_PASSED=false
status_write backup snapshot "${SETNAME}" "Snapshotting to backup store"
if command -v restic >/dev/null 2>&1 && [ -n "${RESTIC_REPOSITORY:-}" ]; then
	if ! restic snapshots >/dev/null 2>&1; then
		log "initializing restic repository at ${RESTIC_REPOSITORY}"
		restic init
	fi
	log "restic backup (db dump + instance tree + manifest)"
	restic backup \
		--tag "${SITE}" \
		--tag "${SETNAME}" \
		"${SETDIR}/db.sql.gz" \
		"${SETDIR}/manifest.json" \
		/app/instance

	# 4. Retention: any day in the last 5, plus weekly/monthly tail.
	log "pruning per retention policy"
	restic forget \
		--tag "${SITE}" \
		--keep-daily 5 \
		--keep-weekly 4 \
		--keep-monthly 6 \
		--prune

	# 5. Integrity: learn about corruption now, not at restore time.
	log "verifying repository integrity"
	if restic check; then
		IS_CHECK_PASSED=true
		log "restic check passed"
	else
		log "restic check FAILED - repository may be corrupt"
	fi
else
	log "restic not configured - local db.sql.gz + manifest only"
fi

# Record the verification result into the manifest so the UI can badge the set.
python3 /opt/backup/manifest.py \
	--amend "${SETDIR}/manifest.json" \
	--ischeckpassed "${IS_CHECK_PASSED}"

# Clear the request sentinel the UI drops when an operator clicks "Back up now".
rm -f "${BACKUPS_ROOT}/.backup-requested" 2>/dev/null || true

BACKUP_DONE=true
log "backup set ${SETNAME} complete"