#!/usr/bin/env bash
# MariaDB/MySQL 논리 백업 (mysqldump). .env의 MR_DB_* 및 MR_BACKUP_* 사용.
# MR_BACKUP_SCOPE=all 이면 접근 가능한 사용자 DB 전체를 각각 .sql.gz 로 저장.
set -euo pipefail

REPO_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
# shellcheck source=scripts/lib/load-env.sh
source "$REPO_ROOT/scripts/lib/load-env.sh"
# shellcheck source=scripts/lib/common.sh
source "$REPO_ROOT/scripts/lib/common.sh"

load_project_env "$REPO_ROOT/.env"

: "${MR_DB_HOST:?MR_DB_HOST is required in .env}"
: "${MR_DB_USER:?MR_DB_USER is required in .env}"
: "${MR_DB_PASSWORD:?MR_DB_PASSWORD is required in .env}"

MR_DB_PORT="${MR_DB_PORT:-3306}"
MR_DB_NAME="${MR_DB_NAME:-mysql}"
BACKUP_DIR="${BACKUP_DIR:-$REPO_ROOT/backup}"
BACKUP_RETENTION_DAYS="${BACKUP_RETENTION_DAYS:-30}"
MR_BACKUP_SCOPE="${MR_BACKUP_SCOPE:-all}"

MYSQL_BIN="${MYSQL_BIN:-mysql}"
MYSQLDUMP_BIN="${MYSQLDUMP_BIN:-mysqldump}"
MR_DUMP_PY="$REPO_ROOT/scripts/lib/mr_dump.py"

use_python_fallback=0
if ! command -v "$MYSQLDUMP_BIN" >/dev/null 2>&1; then
  if [[ -f "$MR_DUMP_PY" ]] && python3 -c "import pymysql" >/dev/null 2>&1; then
    echo "[$(log_ts)] mr-backup: mysqldump not found; using Python fallback (pymysql)." >&2
    use_python_fallback=1
  else
    echo "mr-backup: mysqldump not found. Install mariadb-client (apt) or mariadb (brew), or install pymysql." >&2
    exit 1
  fi
fi
if [[ "$use_python_fallback" -eq 0 ]] && ! command -v "$MYSQL_BIN" >/dev/null 2>&1; then
  echo "mr-backup: mysql client not found. Install mariadb-client." >&2
  exit 1
fi

mysql_common_args=(
  -h "$MR_DB_HOST"
  -P "$MR_DB_PORT"
  -u "$MR_DB_USER"
  --password="$MR_DB_PASSWORD"
  --batch
  --skip-column-names
)

list_all_databases() {
  if [[ "$use_python_fallback" -eq 1 ]]; then
    python3 - "$MR_DB_HOST" "$MR_DB_PORT" "$MR_DB_USER" "$MR_DB_PASSWORD" <<'PY'
import pymysql, sys
host, port, user, password = sys.argv[1:5]
conn = pymysql.connect(host=host, port=int(port), user=user, password=password, connect_timeout=30)
try:
    with conn.cursor() as cur:
        cur.execute(
            "SELECT schema_name FROM information_schema.schemata "
            "WHERE schema_name NOT IN ('information_schema','performance_schema','sys','mysql') "
            "ORDER BY schema_name"
        )
        for row in cur.fetchall():
            print(row[0])
finally:
    conn.close()
PY
    return
  fi
  "$MYSQL_BIN" "${mysql_common_args[@]}" -e \
    "SELECT schema_name FROM information_schema.schemata
     WHERE schema_name NOT IN ('information_schema','performance_schema','sys','mysql')
     ORDER BY schema_name;"
}

dump_database() {
  local db_name="$1"
  local dump_file="$2"
  if [[ "$use_python_fallback" -eq 1 ]]; then
    python3 "$MR_DUMP_PY" \
      --host "$MR_DB_HOST" \
      --port "$MR_DB_PORT" \
      --user "$MR_DB_USER" \
      --password "$MR_DB_PASSWORD" \
      --database "$db_name" \
      --output "$dump_file"
    return
  fi
  "$MYSQLDUMP_BIN" \
    -h "$MR_DB_HOST" \
    -P "$MR_DB_PORT" \
    -u "$MR_DB_USER" \
    --password="$MR_DB_PASSWORD" \
    --single-transaction \
    --routines \
    --triggers \
    --events \
    --databases "$db_name" \
    | gzip -c > "$dump_file"
}

resolve_run_dir "mariadb"
mkdir -p "$BACKUP_DIR/latest"

echo "[$(log_ts)] mr-backup start → $RUN_DIR (scope=${MR_BACKUP_SCOPE}, retention ${BACKUP_RETENTION_DAYS} days)"

declare -a TARGET_DBS=()
if [[ "$MR_BACKUP_SCOPE" == "single" ]]; then
  TARGET_DBS=("$MR_DB_NAME")
else
  while IFS= read -r db; do
    [[ -n "$db" ]] && TARGET_DBS+=("$db")
  done < <(list_all_databases)
  if [[ ${#TARGET_DBS[@]} -eq 0 ]]; then
    echo "mr-backup: no databases found to backup." >&2
    exit 1
  fi
fi

MANIFEST="$RUN_DIR/00_manifest.txt"
{
  echo "# mr-backup manifest $(log_ts)"
  echo "scope=${MR_BACKUP_SCOPE}"
  echo "host=${MR_DB_HOST}:${MR_DB_PORT}"
  echo "user=${MR_DB_USER}"
} > "$MANIFEST"

dump_ok=0
dump_fail=0
for db_name in "${TARGET_DBS[@]}"; do
  dump_file="$RUN_DIR/${db_name}.sql.gz"
  echo "[$(log_ts)] dumping database: $db_name"
  if dump_database "$db_name" "$dump_file"; then
    bytes="$(wc -c < "$dump_file" | tr -d ' ')"
    echo "[$(log_ts)] dump saved: $dump_file (${bytes} bytes)"
    echo "${db_name}.sql.gz ${bytes}" >> "$MANIFEST"
    dump_ok=$((dump_ok + 1))
  else
    echo "[$(log_ts)] dump failed: $db_name" >&2
    dump_fail=$((dump_fail + 1))
  fi
done

if [[ "$dump_ok" -eq 0 ]]; then
  echo "mr-backup: all database dumps failed." >&2
  exit 1
fi
if [[ "$dump_fail" -gt 0 ]]; then
  echo "[$(log_ts)] warning: ${dump_fail} database dump(s) failed, ${dump_ok} succeeded." >&2
fi

update_latest_link "mariadb"

if [[ -z "${BACKUP_RUN_DIR:-}" ]]; then
  prune_old_backups "$BACKUP_DIR" "$BACKUP_RETENTION_DAYS"
fi

echo "[$(log_ts)] mr-backup done: ${dump_ok} database(s), latest → $BACKUP_DIR/latest/mariadb"