"""
장애 관리 (Incident Management) API.

엔드포인트:
  GET    /api/incidents            — 장애 목록 (등급·상태·기관 필터)
  POST   /api/incidents            — 장애 등록
  GET    /api/incidents/{id}       — 장애 상세
  PATCH  /api/incidents/{id}       — 장애 수정
  PATCH  /api/incidents/{id}/status — 상태 전환
  POST   /api/incidents/{id}/link-sr — SR 연결
  DELETE /api/incidents/{id}/link-sr/{sr_id} — SR 연결 해제
  GET    /api/incidents/{id}/srs   — 연결된 SR 목록
  POST   /api/incidents/{id}/close — RCA 포함 종료
  GET    /api/incidents/stats      — 등급별·상태별 통계

장애 번호 형식: INC-YYYYMMDD-NNNNNN (UUID 앞 6자리)
"""
from __future__ import annotations

import logging
from datetime import datetime
from typing import List, Optional
from uuid import uuid4

from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy import select, or_, desc
from sqlalchemy.ext.asyncio import AsyncSession

from core.auth import get_current_user
from database import get_db
from models import (
    Institution, SRRequest,
    Incident, IncidentCreate, IncidentGrade, IncidentOut, IncidentStatus, IncidentUpdate,
    IncidentSR,
    User, UserRole,
)

logger = logging.getLogger(__name__)
router = APIRouter(prefix="/api/incidents", tags=["incidents"])


def _new_incident_id() -> str:
    return f"INC-{datetime.now().strftime('%Y%m%d')}-{str(uuid4())[:6].upper()}"


# ── 장애 목록 ─────────────────────────────────────────────────────────────────

@router.get("", response_model=List[IncidentOut])
async def list_incidents(
    inst_id:    Optional[int] = Query(None),
    grade:      Optional[str] = Query(None, description="P1/P2/P3/P4"),
    status:     Optional[str] = Query(None),
    keyword:    Optional[str] = Query(None),
    skip: int = 0,
    limit: int = 100,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    q = select(Incident)

    if current_user.role == UserRole.CUSTOMER and current_user.inst_code:
        r_i = await db.execute(
            select(Institution).where(Institution.inst_code == current_user.inst_code)
        )
        own = r_i.scalars().first()
        q = q.where(Incident.inst_id == own.id) if own else q.where(Incident.id == -1)
    elif inst_id:
        q = q.where(Incident.inst_id == inst_id)

    if grade:
        q = q.where(Incident.grade == grade)
    if status:
        q = q.where(Incident.status == status)
    if keyword:
        q = q.where(or_(
            Incident.title.contains(keyword),
            Incident.description.contains(keyword),
        ))

    q = q.order_by(desc(Incident.occurred_at)).offset(skip).limit(limit)
    result = await db.execute(q)
    return result.scalars().all()


# ── 장애 등록 ─────────────────────────────────────────────────────────────────

@router.post("", response_model=IncidentOut, status_code=201)
async def create_incident(
    payload: IncidentCreate,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    if current_user.role not in (UserRole.ADMIN, UserRole.PM, UserRole.ENGINEER):
        raise HTTPException(403, "권한이 없습니다.")

    inc = Incident(
        **payload.model_dump(),
        incident_id  = _new_incident_id(),
        reported_by  = payload.reported_by or current_user.username,
        occurred_at  = payload.occurred_at or datetime.now(),
        detected_at  = datetime.now(),
    )
    db.add(inc)
    await db.commit()
    await db.refresh(inc)

    logger.info(
        "장애 등록: %s grade=%s reported_by=%s",
        inc.incident_id, inc.grade, inc.reported_by,
    )

    # P1/P2는 즉시 알림
    if inc.grade in (IncidentGrade.P1, IncidentGrade.P2):
        await _notify_incident(inc)

    return inc


# ── 장애 상세 ─────────────────────────────────────────────────────────────────

@router.get("/stats")
async def incident_stats(
    inst_id: Optional[int] = Query(None),
    db: AsyncSession = Depends(get_db),
    _u: User = Depends(get_current_user),
):
    """장애 통계 — 등급별·상태별 집계."""
    q = select(Incident)
    if inst_id:
        q = q.where(Incident.inst_id == inst_id)
    incs = (await db.execute(q)).scalars().all()

    by_grade: dict[str, int]  = {}
    by_status: dict[str, int] = {}
    for inc in incs:
        by_grade[inc.grade]   = by_grade.get(inc.grade, 0) + 1
        by_status[inc.status] = by_status.get(inc.status, 0) + 1

    # 평균 복구 시간 (MTTRS — resolved 기준)
    resolved = [
        i for i in incs
        if i.resolved_at and i.occurred_at
    ]
    mttr_min = 0
    if resolved:
        total_sec = sum(
            (i.resolved_at - i.occurred_at).total_seconds()
            for i in resolved
        )
        mttr_min = int(total_sec / len(resolved) / 60)

    return {
        "total":     len(incs),
        "by_grade":  by_grade,
        "by_status": by_status,
        "mttr_min":  mttr_min,
        "open_p1_p2": sum(
            1 for i in incs
            if i.grade in (IncidentGrade.P1, IncidentGrade.P2)
            and i.status not in (IncidentStatus.RESOLVED, IncidentStatus.CLOSED)
        ),
    }


@router.get("/{incident_id}", response_model=IncidentOut)
async def get_incident(
    incident_id: str,
    db: AsyncSession = Depends(get_db),
    _u: User = Depends(get_current_user),
):
    r = await db.execute(
        select(Incident).where(Incident.incident_id == incident_id)
    )
    inc = r.scalars().first()
    if not inc:
        raise HTTPException(404, "장애를 찾을 수 없습니다.")
    return inc


# ── 장애 수정 ─────────────────────────────────────────────────────────────────

@router.patch("/{incident_id}", response_model=IncidentOut)
async def update_incident(
    incident_id: str,
    payload: IncidentUpdate,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    if current_user.role not in (UserRole.ADMIN, UserRole.PM, UserRole.ENGINEER):
        raise HTTPException(403, "권한이 없습니다.")

    r = await db.execute(
        select(Incident).where(Incident.incident_id == incident_id)
    )
    inc = r.scalars().first()
    if not inc:
        raise HTTPException(404, "장애를 찾을 수 없습니다.")

    for k, v in payload.model_dump(exclude_unset=True).items():
        setattr(inc, k, v)
    inc.updated_at = datetime.now()
    await db.commit()
    await db.refresh(inc)
    return inc


# ── 상태 전환 ─────────────────────────────────────────────────────────────────

_VALID_TRANSITIONS: dict[str, list[str]] = {
    IncidentStatus.OPEN:          [IncidentStatus.INVESTIGATING, IncidentStatus.CLOSED],
    IncidentStatus.INVESTIGATING: [IncidentStatus.MITIGATED, IncidentStatus.RESOLVED],
    IncidentStatus.MITIGATED:     [IncidentStatus.INVESTIGATING, IncidentStatus.RESOLVED],
    IncidentStatus.RESOLVED:      [IncidentStatus.CLOSED],
    IncidentStatus.CLOSED:        [],
}


@router.patch("/{incident_id}/status", response_model=IncidentOut)
async def change_status(
    incident_id: str,
    new_status: IncidentStatus = Query(...),
    note: Optional[str] = Query(None),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    if current_user.role not in (UserRole.ADMIN, UserRole.PM, UserRole.ENGINEER):
        raise HTTPException(403, "권한이 없습니다.")

    r = await db.execute(
        select(Incident).where(Incident.incident_id == incident_id)
    )
    inc = r.scalars().first()
    if not inc:
        raise HTTPException(404, "장애를 찾을 수 없습니다.")

    allowed = _VALID_TRANSITIONS.get(inc.status, [])
    if new_status not in allowed:
        raise HTTPException(
            422,
            f"'{inc.status}' 상태에서 '{new_status}'로 전환할 수 없습니다. "
            f"허용: {allowed}",
        )

    inc.status = new_status
    inc.updated_at = datetime.now()

    now = datetime.now()
    if new_status == IncidentStatus.MITIGATED:
        inc.mitigated_at = now
    elif new_status == IncidentStatus.RESOLVED:
        inc.resolved_at = now
    elif new_status == IncidentStatus.CLOSED:
        inc.closed_at = now

    await db.commit()
    await db.refresh(inc)
    logger.info(
        "장애 상태 전환: %s → %s by=%s",
        incident_id, new_status, current_user.username,
    )
    return inc


# ── SR 연결 ───────────────────────────────────────────────────────────────────

@router.post("/{incident_id}/link-sr", status_code=201)
async def link_sr(
    incident_id: str,
    sr_id: str = Query(..., description="연결할 SR 번호"),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    if current_user.role not in (UserRole.ADMIN, UserRole.PM, UserRole.ENGINEER):
        raise HTTPException(403, "권한이 없습니다.")

    # 장애 존재 확인
    inc_r = await db.execute(
        select(Incident).where(Incident.incident_id == incident_id)
    )
    if not inc_r.scalars().first():
        raise HTTPException(404, "장애를 찾을 수 없습니다.")

    # SR 존재 확인
    sr_r = await db.execute(select(SRRequest).where(SRRequest.sr_id == sr_id))
    if not sr_r.scalars().first():
        raise HTTPException(404, "SR을 찾을 수 없습니다.")

    # 중복 확인
    dup = (await db.execute(
        select(IncidentSR).where(
            IncidentSR.incident_id == incident_id,
            IncidentSR.sr_id == sr_id,
        )
    )).scalars().first()
    if dup:
        raise HTTPException(409, "이미 연결된 SR입니다.")

    link = IncidentSR(incident_id=incident_id, sr_id=sr_id)
    db.add(link)
    await db.commit()
    return {"incident_id": incident_id, "sr_id": sr_id, "linked": True}


@router.delete("/{incident_id}/link-sr/{sr_id}", status_code=204)
async def unlink_sr(
    incident_id: str,
    sr_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    if current_user.role not in (UserRole.ADMIN, UserRole.PM):
        raise HTTPException(403, "ADMIN 또는 PM 권한이 필요합니다.")
    r = await db.execute(
        select(IncidentSR).where(
            IncidentSR.incident_id == incident_id,
            IncidentSR.sr_id == sr_id,
        )
    )
    link = r.scalars().first()
    if not link:
        raise HTTPException(404, "연결을 찾을 수 없습니다.")
    await db.delete(link)
    await db.commit()


@router.get("/{incident_id}/srs")
async def list_linked_srs(
    incident_id: str,
    db: AsyncSession = Depends(get_db),
    _u: User = Depends(get_current_user),
):
    """장애에 연결된 SR 목록."""
    links = (await db.execute(
        select(IncidentSR).where(IncidentSR.incident_id == incident_id)
    )).scalars().all()

    sr_ids = [lk.sr_id for lk in links]
    if not sr_ids:
        return []

    srs = (await db.execute(
        select(SRRequest).where(SRRequest.sr_id.in_(sr_ids))
    )).scalars().all()

    return [
        {
            "sr_id":      sr.sr_id,
            "title":      sr.title,
            "status":     sr.status,
            "priority":   sr.priority,
            "sr_type":    sr.sr_type,
            "created_at": sr.created_at.isoformat() if sr.created_at else None,
        }
        for sr in srs
    ]


# ── 종료 (RCA 포함) ───────────────────────────────────────────────────────────

@router.post("/{incident_id}/close", response_model=IncidentOut)
async def close_incident(
    incident_id: str,
    rca: str = Query(..., description="근본 원인 분석 (Root Cause Analysis)"),
    prevention: Optional[str] = Query(None, description="재발 방지 조치"),
    kb_doc_id: Optional[str] = Query(None, description="연관 KB 문서 ID"),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    if current_user.role not in (UserRole.ADMIN, UserRole.PM, UserRole.ENGINEER):
        raise HTTPException(403, "권한이 없습니다.")

    r = await db.execute(
        select(Incident).where(Incident.incident_id == incident_id)
    )
    inc = r.scalars().first()
    if not inc:
        raise HTTPException(404, "장애를 찾을 수 없습니다.")

    if inc.status == IncidentStatus.CLOSED:
        raise HTTPException(409, "이미 종료된 장애입니다.")

    inc.status     = IncidentStatus.CLOSED
    inc.rca        = rca
    inc.prevention = prevention
    inc.kb_doc_id  = kb_doc_id
    inc.closed_at  = datetime.now()
    if not inc.resolved_at:
        inc.resolved_at = datetime.now()
    inc.updated_at = datetime.now()

    await db.commit()
    await db.refresh(inc)
    logger.info(
        "장애 종료: %s grade=%s closed_by=%s",
        incident_id, inc.grade, current_user.username,
    )
    return inc


# ── G-5: 자동 RCA 분석 ────────────────────────────────────────────────────────

@router.post("/{incident_id}/auto-rca")
async def auto_rca(
    incident_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Ollama LLM으로 RCA 초안 자동 생성 후 장애 레코드에 저장."""
    inc = (await db.execute(
        select(Incident).where(Incident.incident_id == incident_id)
    )).scalars().first()
    if not inc:
        raise HTTPException(404, f"장애 {incident_id}를 찾을 수 없습니다.")

    try:
        from core.auto_rca import analyze_rca
        result = await analyze_rca(inc.id, db)
    except Exception as e:
        raise HTTPException(500, f"RCA 분석 오류: {str(e)[:200]}")

    # 생성된 RCA를 장애 레코드에 저장
    import json as _json
    rca_data = result["rca"]
    inc.rca = rca_data.get("root_cause", "")
    inc.prevention = _json.dumps(rca_data.get("prevention", []), ensure_ascii=False)
    inc.updated_at = datetime.now()
    await db.commit()

    return result


# ── 내부 알림 ─────────────────────────────────────────────────────────────────

async def _notify_incident(inc: Incident) -> None:
    """P1/P2 장애 긴급 알림."""
    try:
        from core.notify import send_messenger
        import os
        room = os.getenv("MESSENGER_OPS_ROOM", "ops")
        grade_emoji = {"P1": "🚨", "P2": "🔴", "P3": "🟠", "P4": "🟡"}.get(inc.grade, "⚠️")
        msg = (
            f"{grade_emoji} [{inc.grade}] 장애 발생\n"
            f"장애번호: {inc.incident_id}\n"
            f"제목: {inc.title}\n"
            f"발생일시: {inc.occurred_at.strftime('%Y-%m-%d %H:%M')}\n"
            f"담당: {inc.assigned_to or '미지정'}\n"
            f"즉시 확인 바랍니다."
        )
        await send_messenger(room, {"type": "text", "text": msg})
    except Exception as exc:
        logger.warning("장애 알림 발송 실패: %s", exc)