"""
서비스 의존성 자동 매핑

SSH 경유 netstat/ss 분석으로 서비스 간 upstream/downstream 의존성을 자동 탐지.

엔드포인트:
  POST /api/depmap/discover/{server_id} — 단일 서버 의존성 탐지
  POST /api/depmap/discover-all         — 전체 서버 의존성 탐지
  GET  /api/depmap/                     — 의존성 맵 조회
  GET  /api/depmap/impact/{ci_id}       — 특정 CI 영향 범위 분석
  DELETE /api/depmap/{dep_id}           — 의존성 수동 삭제
"""
from __future__ import annotations

import logging
import re
from datetime import datetime

import paramiko
from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException
from sqlalchemy import select, or_
from sqlalchemy.ext.asyncio import AsyncSession

from core.auth import get_current_user, require_admin_role
from core.ssh_exec import _decrypt_password as decrypt_password
from database import get_db
from models import User, Server, ServiceDependency

logger = logging.getLogger(__name__)
router = APIRouter(prefix="/api/depmap", tags=["서비스 의존성 맵"])


async def _ssh_run(server: Server, cmd: str) -> str:
    try:
        pw = decrypt_password(server.os_pw_enc)
        ssh = paramiko.SSHClient()
        ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        ssh.connect(server.ip_addr, username=server.ssh_user, password=pw, timeout=10)
        _, stdout, _ = ssh.exec_command(cmd, timeout=15)
        result = stdout.read().decode('utf-8', 'replace').strip()
        ssh.close()
        return result
    except Exception as e:
        logger.warning(f"SSH 실패 ({server.ip_addr}): {e}")
        return ""


async def _discover_connections(server: Server) -> list[dict]:
    """netstat/ss로 ESTABLISHED 연결 분석 → 의존성 추출."""
    output = await _ssh_run(
        server,
        "ss -tnp state established 2>/dev/null | awk 'NR>1{print $4,$5}' || "
        "netstat -tnp 2>/dev/null | grep ESTABLISHED | awk '{print $4,$5}'"
    )
    connections = []
    seen = set()
    for line in output.splitlines():
        parts = line.split()
        if len(parts) < 2:
            continue
        local, remote = parts[0], parts[1]
        # 외부 IP:포트 추출
        m = re.match(r'(\d+\.\d+\.\d+\.\d+):(\d+)$', remote)
        if not m:
            continue
        remote_ip, remote_port = m.group(1), int(m.group(2))
        if remote_ip in ("127.0.0.1", "0.0.0.0"):
            continue
        key = f"{remote_ip}:{remote_port}"
        if key in seen:
            continue
        seen.add(key)
        # 포트 → 서비스 유형 추정
        service_map = {
            3306: "MySQL", 5432: "PostgreSQL", 6379: "Redis",
            27017: "MongoDB", 9200: "Elasticsearch",
            80: "HTTP", 443: "HTTPS", 8080: "HTTP-Alt",
            2181: "Zookeeper", 9092: "Kafka", 5672: "RabbitMQ",
        }
        dep_type = service_map.get(remote_port, f"TCP:{remote_port}")
        connections.append({
            "remote_ip": remote_ip, "remote_port": remote_port,
            "dependency_type": dep_type, "protocol": "TCP",
        })
    return connections


async def _do_discover(server_id: int, db: AsyncSession):
    """단일 서버 의존성 탐지 (백그라운드)."""
    srv_row = await db.execute(select(Server).where(Server.id == server_id))
    server = srv_row.scalar_one_or_none()
    if not server:
        return

    connections = await _discover_connections(server)
    new_deps = 0
    for conn in connections:
        # 원격 IP가 CMDB에 있는지 확인
        remote_srv_row = await db.execute(
            select(Server).where(Server.ip_addr == conn["remote_ip"])
        )
        remote_server = remote_srv_row.scalar_one_or_none()
        if not remote_server:
            continue  # CMDB에 없는 서버는 스킵

        # 중복 체크
        existing = await db.execute(
            select(ServiceDependency).where(
                ServiceDependency.upstream_ci_id == server_id,
                ServiceDependency.downstream_ci_id == remote_server.id,
                ServiceDependency.port == conn["remote_port"],
            )
        )
        if existing.scalar_one_or_none():
            continue

        dep = ServiceDependency(
            upstream_ci_id=server_id,
            downstream_ci_id=remote_server.id,
            dependency_type=conn["dependency_type"],
            port=conn["remote_port"],
            protocol=conn["protocol"],
            discovered_at=datetime.utcnow(),
        )
        db.add(dep)
        new_deps += 1

    await db.commit()
    logger.info(f"서버 {server_id} 의존성 {new_deps}개 발견")


@router.post("/discover/{server_id}")
async def discover_server_deps(
    server_id: int,
    background_tasks: BackgroundTasks,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    background_tasks.add_task(_do_discover, server_id, db)
    return {"ok": True, "server_id": server_id, "queued": True}


@router.post("/discover-all")
async def discover_all_deps(
    background_tasks: BackgroundTasks,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(require_admin_role),
):
    rows = await db.execute(select(Server).limit(100))
    servers = rows.scalars().all()
    for s in servers:
        background_tasks.add_task(_do_discover, s.id, db)
    return {"ok": True, "queued": len(servers)}


@router.get("/")
async def get_dependency_map(
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    rows = await db.execute(
        select(
            ServiceDependency,
            Server.hostname.label("up_name"), Server.ip_addr.label("up_ip"),
        ).join(Server, ServiceDependency.upstream_ci_id == Server.id)
        .limit(500)
    )
    deps = rows.all()
    return [
        {
            "id": d.ServiceDependency.id,
            "upstream": {"id": d.ServiceDependency.upstream_ci_id, "name": d.up_name, "ip": d.up_ip},
            "downstream_id": d.ServiceDependency.downstream_ci_id,
            "type": d.ServiceDependency.dependency_type,
            "port": d.ServiceDependency.port,
            "discovered_at": d.ServiceDependency.discovered_at,
        }
        for d in deps
    ]


@router.get("/impact/{ci_id}")
async def get_impact_analysis(
    ci_id: int,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """특정 CI 장애 시 영향 범위 분석 (upstream 서비스 = 영향받는 서비스)."""
    # ci_id에 의존하는 서비스들 (ci_id가 downstream인 경우)
    rows = await db.execute(
        select(ServiceDependency, Server.hostname, Server.ip_addr).join(
            Server, ServiceDependency.upstream_ci_id == Server.id
        ).where(ServiceDependency.downstream_ci_id == ci_id)
    )
    impacted = rows.all()

    # ci_id가 의존하는 서비스들 (ci_id가 upstream인 경우)
    dep_rows = await db.execute(
        select(ServiceDependency, Server.hostname, Server.ip_addr).join(
            Server, ServiceDependency.downstream_ci_id == Server.id
        ).where(ServiceDependency.upstream_ci_id == ci_id)
    )
    dependencies = dep_rows.all()

    return {
        "ci_id": ci_id,
        "impacted_services": [
            {"server": r.hostname, "ip": r.ip_addr, "depends_via": r.ServiceDependency.dependency_type}
            for r in impacted
        ],
        "depends_on": [
            {"server": r.hostname, "ip": r.ip_addr, "type": r.ServiceDependency.dependency_type}
            for r in dependencies
        ],
        "blast_radius": len(impacted),
    }


@router.delete("/{dep_id}")
async def delete_dependency(
    dep_id: int,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(require_admin_role),
):
    row = await db.execute(select(ServiceDependency).where(ServiceDependency.id == dep_id))
    dep = row.scalar_one_or_none()
    if not dep:
        raise HTTPException(404)
    await db.delete(dep)
    await db.commit()
    return {"ok": True}