#!/bin/bash
# Configuration

# If started by root (e.g., root crontab), re-run as postgres.
if [ "$(id -u)" -eq 0 ] && [ "$(id -un)" != "postgres" ]; then
	if command -v runuser >/dev/null 2>&1; then
		exec runuser -u postgres -- "$0" "$@"
	fi

	# Fallback for systems without runuser.
	exec su - postgres -s /bin/bash -c "$(printf '%q ' "$0" "$@")"
fi

# Avoid permission warnings when root launches this script and postgres inherits /root as cwd.
cd / || exit 1

log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"; }

: "${WAL_CLEANUP_ENABLED:=1}"
WAL_ARCHIVE_DIR="/var/lib/postgresql_archive/18/main/pg_wal"
WAL_MIN_AGE_DAYS=7

clean_walfiles() {
	local newest_backup=""
	local newest_backup_ts=""
	local newest_backup_dt=""
	local age_cutoff_ts=""
	local age_cutoff_dt=""
	local backup_ts=""
	local file_ts=""
	local deleted=0
	local backup_file=""
	local file=""
	local -a backup_files=()
	local -a files_to_delete=()

	if [[ ! -d "$WAL_ARCHIVE_DIR" ]]; then
		log "Archive directory does not exist: $WAL_ARCHIVE_DIR" >&2
		return 1
	fi

	if ! [[ "$WAL_MIN_AGE_DAYS" =~ ^[0-9]+$ ]]; then
		log "WAL_MIN_AGE_DAYS must be a non-negative integer" >&2
		return 1
	fi

	mapfile -d '' backup_files < <(find "$WAL_ARCHIVE_DIR" -maxdepth 1 -type f -name '*.backup' -print0)

	if [[ ${#backup_files[@]} -eq 0 ]]; then
		log "No .backup files found in $WAL_ARCHIVE_DIR; skipping WAL cleanup."
		return 0
	fi

	for backup_file in "${backup_files[@]}"; do
		backup_ts=$(stat -c %Y "$backup_file")
		if [[ -z "$newest_backup_ts" || "$backup_ts" -gt "$newest_backup_ts" ]]; then
			newest_backup_ts="$backup_ts"
			newest_backup="$backup_file"
		fi
	done

	age_cutoff_ts=$(date -d "$WAL_MIN_AGE_DAYS days ago" +%s)
	newest_backup_dt=$(date -d "@$newest_backup_ts" '+%Y-%m-%d %H:%M:%S')
	age_cutoff_dt=$(date -d "@$age_cutoff_ts" '+%Y-%m-%d %H:%M:%S')

	log "WAL archive dir      : $WAL_ARCHIVE_DIR"
	log "Newest .backup file  : $newest_backup"
	log "Newest .backup mtime : $newest_backup_dt"
	log "WAL age cutoff       : $age_cutoff_dt"

	while IFS= read -r -d '' file; do
		file_ts=$(stat -c %Y "$file")

		# Delete only when both constraints are true.
		if [[ "$file_ts" -lt "$newest_backup_ts" && "$file_ts" -lt "$age_cutoff_ts" ]]; then
			files_to_delete+=("$file")
		fi
	done < <(find "$WAL_ARCHIVE_DIR" -maxdepth 1 -type f ! -name '*.backup' -print0)

	if [[ ${#files_to_delete[@]} -eq 0 ]]; then
		log "No WAL files matched cleanup criteria."
		return 0
	fi

	echo ""
	log "WAL files matching cleanup criteria (${#files_to_delete[@]}):"
	for file in "${files_to_delete[@]}"; do
		log "  $file"
	done

	for file in "${files_to_delete[@]}"; do
		rm -f -- "$file"
		((deleted += 1))
	done

	echo ""
	log "Deleted $deleted WAL file(s)."
}

log "Beginning base backup."
BASEBACKUP_ROOT="/var/lib/postgresql_archive/pgbackups"
BACKUP_DIR="/var/lib/postgresql_archive/pgbackups/basebackup"
mkdir -p "$BACKUP_DIR"
# Perform base backup with WAL streaming
pg_basebackup -h localhost -U wjones -D "$BACKUP_DIR" -Fp -Xs -P
# Optional: Compress
BASEBACKUP_ARCHIVE="${BACKUP_DIR}_$(date +%Y%m%d_%H%M%S).tar.gz"
tar -czf "$BASEBACKUP_ARCHIVE" -C "$(dirname "$BACKUP_DIR")" "$(basename "$BACKUP_DIR")"
rm -rf "$BACKUP_DIR"
# Retention: Delete backups older than 7 days
find "$BASEBACKUP_ROOT" -type f -name "*.tar.gz" -mtime +7 -delete

log "Base backup completed.Now backing up individual databases."

BACKUP_DIR="/var/lib/postgresql_archive/pg_dumpfiles"
TIMESTAMP=$(date +%Y%m%d_%H%M%S)
RETENTION_DAYS=7

# Ensure directory exists
mkdir -p "$BACKUP_DIR"

# Get all non-system databases and back each one up.
psql -U postgres -d postgres -Atc "SELECT datname FROM pg_database WHERE datistemplate = false AND datname <> 'postgres' ORDER BY datname" | while IFS= read -r DB_NAME; do
	pg_dump -U postgres -d "$DB_NAME" | gzip > "$BACKUP_DIR/${DB_NAME}_$TIMESTAMP.sql.gz"
	log "Backup completed: ${DB_NAME}_$TIMESTAMP.sql.gz"
done

# Delete backups older than retention period
find "$BACKUP_DIR" -type f -mtime +"$RETENTION_DAYS" -delete

log "Individual database backups completed and old backups cleaned up."
if [[ "$WAL_CLEANUP_ENABLED" -eq 1 ]]; then
	log "Starting WAL archive cleanup."
	clean_walfiles
else
	log "WAL archive cleanup disabled; skipping final cleanup."
fi
log "Backup workflow completed."