"""
클라우드 전환 자동화 체크리스트 — On-prem → K-Cloud/NCloud

공공기관 클라우드 전환 준비도 점검 및 체크리스트 자동 생성.

엔드포인트:
  GET  /api/migration/checklist       — 전환 체크리스트 조회
  POST /api/migration/assess          — 전환 준비도 평가
  GET  /api/migration/readiness       — 준비도 현황
  PUT  /api/migration/checklist/{key} — 체크리스트 항목 완료 처리
"""
from __future__ import annotations

import json
from datetime import datetime
from typing import Optional

from fastapi import APIRouter, Depends
from pydantic import BaseModel
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from core.auth import get_current_user
from database import get_db
from models import User, MigrationChecklist

router = APIRouter(prefix="/api/migration", tags=["클라우드 전환"])

MIGRATION_PHASES = {
    "01_사전평가": [
        {"key": "infra_inventory", "title": "현행 인프라 인벤토리 완성", "priority": "MUST"},
        {"key": "app_compatibility", "title": "애플리케이션 클라우드 호환성 평가", "priority": "MUST"},
        {"key": "network_bandwidth", "title": "네트워크 대역폭 요구사항 측정", "priority": "MUST"},
        {"key": "license_check", "title": "SW 라이선스 클라우드 이전 가능 여부 확인", "priority": "MUST"},
        {"key": "cost_estimate", "title": "TCO(총소유비용) 분석 완료", "priority": "RECOMMEND"},
    ],
    "02_보안준비": [
        {"key": "iam_design", "title": "IAM 역할·정책 설계 완료", "priority": "MUST"},
        {"key": "vpc_design", "title": "VPC·서브넷·보안그룹 설계", "priority": "MUST"},
        {"key": "kms_setup", "title": "암호화 키 관리(KMS) 설정", "priority": "MUST"},
        {"key": "csap_check", "title": "CSAP(클라우드 보안인증) 인증 CSP 확인", "priority": "MUST"},
        {"key": "zero_trust", "title": "제로트러스트 보안 정책 수립", "priority": "RECOMMEND"},
    ],
    "03_이전실행": [
        {"key": "data_migration_plan", "title": "데이터 마이그레이션 계획 수립", "priority": "MUST"},
        {"key": "blue_green", "title": "Blue/Green 전환 전략 수립", "priority": "RECOMMEND"},
        {"key": "rollback_plan", "title": "롤백 계획 수립", "priority": "MUST"},
        {"key": "downtime_plan", "title": "서비스 중단 최소화 방안 확보", "priority": "MUST"},
        {"key": "dr_config", "title": "클라우드 DR 구성 완료", "priority": "RECOMMEND"},
    ],
    "04_운영전환": [
        {"key": "monitoring_setup", "title": "클라우드 모니터링 설정", "priority": "MUST"},
        {"key": "staff_training", "title": "운영 인력 교육 완료", "priority": "MUST"},
        {"key": "runbook_update", "title": "운영 매뉴얼 업데이트", "priority": "RECOMMEND"},
        {"key": "cost_governance", "title": "비용 거버넌스 정책 수립", "priority": "RECOMMEND"},
    ],
}


class ChecklistUpdate(BaseModel):
    completed: bool
    note: Optional[str] = None


@router.get("/checklist")
async def get_checklist(
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    rows = await db.execute(
        select(MigrationChecklist).where(MigrationChecklist.tenant_id == user.tenant_id)
    )
    completed_keys = {c.item_key for c in rows.scalars().all() if c.completed}

    result = {}
    for phase, items in MIGRATION_PHASES.items():
        result[phase] = [
            {**item, "completed": item["key"] in completed_keys}
            for item in items
        ]

    total = sum(len(v) for v in MIGRATION_PHASES.values())
    completed = len(completed_keys)
    return {
        "phases": result,
        "progress": {"completed": completed, "total": total,
                      "pct": round(completed / total * 100, 1) if total else 0},
    }


@router.put("/checklist/{item_key}")
async def update_checklist_item(
    item_key: str,
    req: ChecklistUpdate,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    row = await db.execute(
        select(MigrationChecklist).where(
            MigrationChecklist.tenant_id == user.tenant_id,
            MigrationChecklist.item_key == item_key,
        )
    )
    item = row.scalar_one_or_none()
    if item:
        item.completed = req.completed
        item.note = req.note
        item.updated_at = datetime.utcnow()
    else:
        item = MigrationChecklist(
            tenant_id=user.tenant_id, item_key=item_key,
            completed=req.completed, note=req.note,
            created_at=datetime.utcnow(), updated_at=datetime.utcnow(),
        )
        db.add(item)
    await db.commit()
    return {"ok": True, "item_key": item_key, "completed": req.completed}


@router.get("/readiness")
async def migration_readiness(
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    checklist = await get_checklist(db, user)
    progress = checklist["progress"]
    pct = progress["pct"]
    phase_status = {}
    for phase, items in checklist["phases"].items():
        total = len(items)
        done = sum(1 for i in items if i["completed"])
        must_total = sum(1 for i in items if i["priority"] == "MUST")
        must_done = sum(1 for i in items if i["priority"] == "MUST" and i["completed"])
        phase_status[phase] = {
            "progress": f"{done}/{total}",
            "must_completed": must_done == must_total,
            "status": "READY" if must_done == must_total else "IN_PROGRESS",
        }
    return {
        "overall_pct": pct,
        "readiness": "READY" if pct >= 80 else "IN_PROGRESS" if pct >= 40 else "NOT_STARTED",
        "phases": phase_status,
    }