#!/usr/bin/env bash
# =============================================================================
# 系统业务库备份脚本 (backup-system-db.sh)
#
# 作用:
#   1. 按环境 (dev/test/main) 定位 Docker 容器与数据库；
#   2. 采用 pg_dump -Fc 导出系统业务库（含 task_runs、工作流治理等）；
#   3. 生成 manifest.json 记录 RPO 基准元数据与 SHA256。
#
# 用法:
#   ./scripts/backup-system-db.sh <dev|test|main> <目标备份目录>
# =============================================================================

set -eo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
ROOT_DIR="$(cd "${SCRIPT_DIR}/.." && pwd)"

show_help() {
    cat <<EOF
用法:
    $0 <dev|test|main> <目标备份目录>

示例:
    $0 dev ./backups/system_dev_20260912
    $0 test /tmp/agent_system_test_backup
EOF
    exit 0
}

if [[ $# -lt 2 ]] || [[ "$1" == "--help" ]] || [[ "$1" == "-h" ]]; then
    show_help
fi

ENV_NAME="$1"
TARGET_DIR="$2"

case "${ENV_NAME}" in
    dev)
        CONTAINER_NAME="shuimu-context-pg-dev"
        DB_NAME="agent_system_dev"
        DB_USER="app"
        DB_PASS="dev_secret_db_pass"
        ;;
    test)
        CONTAINER_NAME="shuimu-system-pg-test"
        DB_NAME="agent_system_test"
        DB_USER="app"
        DB_PASS="test_secret_db_pass"
        ;;
    main)
        CONTAINER_NAME="shuimu-system-pg-main"
        DB_NAME="agent_system_main"
        DB_USER="app"
        DB_PASS="prod_highly_secure_db_pass"
        ;;
    *)
        echo "[错误] 未知环境: ${ENV_NAME}（仅支持 dev/test/main）"
        exit 1
        ;;
esac

mkdir -p "${TARGET_DIR}"
TARGET_DIR="$(cd "${TARGET_DIR}" && pwd)"

if ! command -v docker >/dev/null 2>&1; then
    echo "[错误] 未找到 docker 命令"
    exit 1
fi

if ! docker ps --format '{{.Names}}' | grep -q "^${CONTAINER_NAME}$"; then
    echo "[警告] 容器 ${CONTAINER_NAME} 未运行，尝试启动 ${ENV_NAME} 环境..."
    if [[ -f "${ROOT_DIR}/scripts/env-service.sh" ]]; then
        "${ROOT_DIR}/scripts/env-service.sh" "${ENV_NAME}" start
    else
        docker compose -f "${ROOT_DIR}/docker-compose.${ENV_NAME}.yml" up -d system-db
    fi
fi

echo "[等待] 检查 ${ENV_NAME} 系统库连接..."
for i in {1..30}; do
    if docker exec -i "${CONTAINER_NAME}" pg_isready -U "${DB_USER}" -d "${DB_NAME}" >/dev/null 2>&1; then
        break
    fi
    sleep 1
    if [ "$i" -eq 30 ]; then
        echo "[错误] 数据库连接超时"
        exit 1
    fi
done

echo "[统计] 采集 ${ENV_NAME} 系统库指标..."
TASK_RUNS=$(docker exec -i "${CONTAINER_NAME}" psql -U "${DB_USER}" -d "${DB_NAME}" -t -A -c \
    "SELECT count(*) FROM task_runs;" 2>/dev/null || echo "0")
PROJECTS=$(docker exec -i "${CONTAINER_NAME}" psql -U "${DB_USER}" -d "${DB_NAME}" -t -A -c \
    "SELECT count(*) FROM projects;" 2>/dev/null || echo "0")
DB_SIZE=$(docker exec -i "${CONTAINER_NAME}" psql -U "${DB_USER}" -d "${DB_NAME}" -t -A -c \
    "SELECT pg_size_pretty(pg_database_size('${DB_NAME}'));" 2>/dev/null || echo "0 MB")
GOOSE_VER=$(docker exec -i "${CONTAINER_NAME}" psql -U "${DB_USER}" -d "${DB_NAME}" -t -A -c \
    "SELECT version_id FROM goose_db_version ORDER BY id DESC LIMIT 1;" 2>/dev/null || echo "0")

DUMP_FILENAME="system_db_${ENV_NAME}.dump"
TMP_CONTAINER_DUMP="/tmp/${DUMP_FILENAME}"
DEST_DUMP_PATH="${TARGET_DIR}/${DUMP_FILENAME}"

echo "[导出] pg_dump -Fc ${DB_NAME} ..."
START_TIME=$(date +%s)
docker exec "${CONTAINER_NAME}" pg_dump -U "${DB_USER}" -d "${DB_NAME}" -Fc -Z 6 -f "${TMP_CONTAINER_DUMP}"
docker cp "${CONTAINER_NAME}:${TMP_CONTAINER_DUMP}" "${DEST_DUMP_PATH}"
docker exec "${CONTAINER_NAME}" rm -f "${TMP_CONTAINER_DUMP}"
DUMP_DURATION=$(( $(date +%s) - START_TIME ))

DUMP_SIZE_HUMAN=$(ls -lh "${DEST_DUMP_PATH}" | awk '{print $5}')
DUMP_SIZE_BYTES=$(stat -c "%s" "${DEST_DUMP_PATH}" 2>/dev/null || stat -f "%z" "${DEST_DUMP_PATH}" 2>/dev/null || echo "0")

if command -v sha256sum >/dev/null 2>&1; then
    DUMP_SHA256=$(sha256sum "${DEST_DUMP_PATH}" | awk '{print $1}')
elif command -v shasum >/dev/null 2>&1; then
    DUMP_SHA256=$(shasum -a 256 "${DEST_DUMP_PATH}" | awk '{print $1}')
else
    DUMP_SHA256="unavailable"
fi

NOW_ISO=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
MANIFEST_FILE="${TARGET_DIR}/manifest.json"
cat <<EOF > "${MANIFEST_FILE}"
{
  "manifest_version": "1.0",
  "created_at": "${NOW_ISO}",
  "environment": "${ENV_NAME}",
  "rpo_target_minutes": 60,
  "database": {
    "container_name": "${CONTAINER_NAME}",
    "database_name": "${DB_NAME}",
    "user": "${DB_USER}",
    "dump_file": "${DUMP_FILENAME}",
    "dump_sha256": "${DUMP_SHA256}",
    "dump_size_bytes": ${DUMP_SIZE_BYTES},
    "dump_size_human": "${DUMP_SIZE_HUMAN}",
    "goose_version": ${GOOSE_VER:-0},
    "task_runs_count": ${TASK_RUNS:-0},
    "projects_count": ${PROJECTS:-0},
    "database_size": "${DB_SIZE}"
  }
}
EOF

echo "============================================================"
echo ">>> [SUCCESS] 系统库备份完成 (${ENV_NAME})"
echo ">>> Dump: ${DEST_DUMP_PATH} (${DUMP_SIZE_HUMAN}, ${DUMP_DURATION}s)"
echo ">>> Manifest: ${MANIFEST_FILE}"
echo ">>> 恢复演练: ./scripts/restore-system-db-drill.sh \"${TARGET_DIR}\""
echo "============================================================"