#!/bin/bash
# MySQL 数据库备份脚本
# 用法: ./backup-db.sh
# 需要 .env 中配置 DATABASE_URL 或 DB_* 环境变量

set -e

BACKUP_DIR="${BACKUP_DIR:-./backups}"
RETENTION_DAYS="${RETENTION_DAYS:-30}"
TIMESTAMP=$(date +"%Y%m%d_%H%M%S")
BACKUP_FILE="${BACKUP_DIR}/db_backup_${TIMESTAMP}.sql.gz"

# 从 DATABASE_URL 解析连接信息
# 格式: mysql://user:password@host:port/dbname
DATABASE_URL="${DATABASE_URL:-}"

if [ -z "$DATABASE_URL" ]; then
  echo "ERROR: DATABASE_URL not set"
  exit 1
fi

# 解析 URL
DB_USER=$(echo $DATABASE_URL | sed -n 's/.*:\/\/\([^:]*\):.*/\1/p')
DB_PASS=$(echo $DATABASE_URL | sed -n 's/.*:\/\/[^:]*:\([^@]*\)@.*/\1/p')
DB_HOST=$(echo $DATABASE_URL | sed -n 's/.*@\([^:]*\):.*/\1/p')
DB_PORT=$(echo $DATABASE_URL | sed -n 's/.*:\([0-9]*\)\/.*/\1/p')
DB_NAME=$(echo $DATABASE_URL | sed -n 's/.*\/\([^?]*\).*/\1/p')

echo "Backing up database: $DB_NAME from $DB_HOST:$DB_PORT"

# 创建备份目录
mkdir -p "$BACKUP_DIR"

# 执行备份
mysqldump -h "$DB_HOST" -P "$DB_PORT" -u "$DB_USER" -p"$DB_PASS" "$DB_NAME" | gzip > "$BACKUP_FILE"

echo "Backup created: $BACKUP_FILE"
echo "Size: $(du -h $BACKUP_FILE | cut -f1)"

# 清理旧备份
find "$BACKUP_DIR" -name "db_backup_*.sql.gz" -mtime +$RETENTION_DAYS -delete
echo "Cleaned up backups older than $RETENTION_DAYS days"

# 列出当前备份
echo "Current backups:"
ls -lh "$BACKUP_DIR"/db_backup_*.sql.gz 2>/dev/null | tail -10