#!/bin/bash
# Pear Admin Flask - SQLite 在线热备脚本
#
# 用法：  docker exec pear-admin-nas /app/deploy/nas/backup.sh
#        （也支持本地直接 ./backup.sh）
#
# 关键：不能用 cp 复制 pear.db —— WAL 模式下 .db 文件单独 cp 不含未刷盘的页。
#        改用 SQLite 自带的 `sqlite3 pear.db ".backup target"` 或
#        `VACUUM INTO 'target'`，两者都在 SQLite 内部完成拷贝，含 WAL 的一致性快照。
#
# 产物：${DATA_DIR}/backup/pear-YYYYMMDD_HHMMSS.db
# 保留：最近 14 份（可通过 BACKUP_KEEP 覆盖）

set -e

DATA_DIR=${PEAR_DATA_DIR:-/app/data}
DB_PATH="${DATA_DIR}/pear.db"
BACKUP_DIR="${DATA_DIR}/backup"
KEEP=${BACKUP_KEEP:-14}
TIMESTAMP=$(date +%Y%m%d_%H%M%S)
TARGET="${BACKUP_DIR}/pear-${TIMESTAMP}.db"

if [[ ! -f "${DB_PATH}" ]]; then
    echo "FATAL: 数据库文件不存在: ${DB_PATH}" >&2
    exit 1
fi

mkdir -p "${BACKUP_DIR}"

echo "[backup] db:    ${DB_PATH}"
echo "[backup] -> :   ${TARGET}"
# sqlite3 二进制在 Dockerfile 里 apt install 了；镜像外本机有的话也用得上
sqlite3 "${DB_PATH}" ".backup '${TARGET}'"

# 压缩一份小的；同时保留原文件方便快速恢复
gzip -f "${TARGET}"

# 清理旧备份：保留文件名最近 KEEP 个（含 .gz 后缀）
KEPT=0
for f in $(ls -1t "${BACKUP_DIR}"/pear-*.db.gz 2>/dev/null); do
    KEPT=$((KEPT + 1))
    if [[ "${KEPT}" -gt "${KEEP}" ]]; then
        rm -f "${f}"
        echo "[backup] removed old: ${f}"
    fi
done

# 健康检查：备份文件必须 > 0 字节且能正常打开
LATEST="${BACKUP_DIR}/pear-${TIMESTAMP}.db.gz"
if [[ ! -s "${LATEST}" ]]; then
    echo "FATAL: 备份文件为空: ${LATEST}" >&2
    exit 1
fi
echo "[backup] done.  latest = ${LATEST}"
echo "[backup] current keep: $(ls -1 "${BACKUP_DIR}"/pear-*.db.gz 2>/dev/null | wc -l) of ${KEEP}"