#!/bin/sh
set -eu

# Minimal PATH for cron-like environments
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

log() {
    printf '%s %s\n' "$(date -u +%Y-%m-%dT%H:%M:%SZ)" "$*"
}

err() {
    log "ERROR: $*" >&2
}

log "pg-dump.sh starting"

# Validate required env vars
: "${POSTGRES_USER:?POSTGRES_USER not set}"
: "${POSTGRES_HOST:?POSTGRES_HOST not set}"

date_formatted() {
    local format="${1:-%F_%H-%M}"
    # Use TIMEZONE env var if present; fall back to UTC
    if [ -n "${TIMEZONE:-}" ]; then
        TZ="$TIMEZONE" date +"$format"
    else
        date +"$format"
    fi
}

BACKUP_DIR=/backups/databases
mkdir -p "$BACKUP_DIR"
log "Using backup dir: $BACKUP_DIR"

STATUS_FILE="$BACKUP_DIR/.last_backup_complete"

# Function to dump a specific database
dump_database() {
    local db=$1
    log "Checking existence of $db database..."
    local db_exists
    db_exists=$(psql -U "$POSTGRES_USER" -h "$POSTGRES_HOST" -tAc "SELECT 1 FROM pg_database WHERE datname='$db'")
    if [[ "$db_exists" != "1" ]]; then
        err "Database '$db' does not exist. Skipping dump."
        return 2
    fi

    log "Dumping $db database..."
    local outfile="$BACKUP_DIR/${db}_$(date_formatted).sql.gz"
    if pg_dump -U "$POSTGRES_USER" -h "$POSTGRES_HOST" "$db" | gzip > "$outfile"; then
        log "$db database dumped and compressed: $outfile"
        return 0
    else
        err "Failed to dump $db database"
        return 1
    fi
}

# Dump each database
for db in $DB_LIST; do
    dump_database "$db" || exit 1
done

tmp_status=$(mktemp "$BACKUP_DIR/.last_backup_complete.XXXXXX")
date -u +%s > "$tmp_status"
mv "$tmp_status" "$STATUS_FILE"
log "Recorded database backup completion marker at $STATUS_FILE"

log "pg-dump.sh finished successfully"