"""스니펫 API — 프론트 `features/snippets/api/snippets.api.ts` 5개 호출과 1:1. 옛 Tauri 브릿지 규칙 그대로.

  GET    /api/v1/snippets              → Snippet[] (내 usage 합쳐서)
  POST   /api/v1/snippets              {name,desc,body,category} → Snippet (이름 중복이면 409)
  PUT    /api/v1/snippets/{name}       {desc,body,category} → Snippet
  DELETE /api/v1/snippets/{name}       → {name}
  POST   /api/v1/snippets/{name}/use   → {name, usageCount, lastUsed}
"""

import re

from django.db import IntegrityError, transaction
from django.shortcuts import get_object_or_404
from django.utils import timezone
from rest_framework.response import Response
from rest_framework.views import APIView

from common.envelope import CodedError

from .models import Snippet, SnippetUsage


# 이름 규칙 — 프론트 features/snippets/core/name.ts 와 같음(바꾸면 양쪽 같이).
# 영문 대문자·숫자·_, 문자로 시작, 3~50자, _ 연속·앞뒤 금지. 권장 "영역_대상_동작". 한글은 설명에.
NAME_RE = re.compile(r"^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$")
NAME_MIN, NAME_MAX = 3, 50


def normalize_name(name: str) -> str:
    """입력 → 저장될 이름. 대문자, 공백·하이픈·점→_, 그 외 기호·한글 버림, _ 정리."""
    s = re.sub(r"[\s\-.]+", "_", (name or "").upper())
    s = re.sub(r"[^A-Z0-9_]", "", s)
    return re.sub(r"_+", "_", s).strip("_")


def lookup_name(name: str) -> str:
    """URL 의 이름 → DB 키. 옛 규칙 이름(IF_SUBRC-ABAP 등)이 남아 있으면 그대로 찾아야 해서 정규화 안 함(대문자·공백만)."""
    return (name or "").strip().upper().replace(" ", "_")


def name_problem(raw: str) -> str | None:
    name = normalize_name(raw)
    if not name:
        return "이름은 영문으로 — 한글은 설명에 적어" if re.search(r"[가-힣]", raw or "") else "이름을 입력해야 함"
    if not name[0].isalpha():
        return "이름은 영문자로 시작해야 함"
    if not NAME_MIN <= len(name) <= NAME_MAX:
        return f"이름은 {NAME_MIN}~{NAME_MAX}자"
    if not NAME_RE.match(name):
        return "영문 대문자·숫자·_ 만 쓸 수 있음"
    return None


def _validate(body: dict, *, need_name: bool) -> dict:
    name = normalize_name(body.get("name", ""))
    if need_name and (problem := name_problem(body.get("name", ""))):
        raise CodedError(400, "VALIDATION_ERROR", problem)
    if not (body.get("desc") or "").strip():
        raise CodedError(400, "VALIDATION_ERROR", "설명을 입력해야 함 — 한글로 무엇을 하는 코드인지")
    if not (body.get("body") or "").strip():
        raise CodedError(400, "VALIDATION_ERROR", "내용을 입력해야 함")
    return {
        "name": name,
        "desc": body["desc"].strip(),
        "body": body["body"],
        "category": (body.get("category") or "").strip() or "코드",
    }


class SnippetListView(APIView):
    def get(self, request):
        usage = {u.snippet_id: u for u in SnippetUsage.objects.filter(user=request.user)}
        return Response([s.as_dto(usage.get(s.name)) for s in Snippet.objects.all()])

    def post(self, request):
        d = _validate(request.data, need_name=True)
        try:
            with transaction.atomic():  # 중복 INSERT 실패가 바깥 트랜잭션을 깨지 않게(savepoint)
                s = Snippet.objects.create(**d, created_by=request.user)
        except IntegrityError:
            raise CodedError(409, "CONFLICT", f"이미 있는 이름임: {d['name']}")
        return Response(s.as_dto(), status=201)


class SnippetDetailView(APIView):
    def put(self, request, name: str):
        s = get_object_or_404(Snippet, name=lookup_name(name))
        d = _validate({**request.data, "name": s.name}, need_name=False)
        s.desc, s.body, s.category = d["desc"], d["body"], d["category"]
        s.save(update_fields=["desc", "body", "category", "updated_at"])
        usage = SnippetUsage.objects.filter(snippet=s, user=request.user).first()
        return Response(s.as_dto(usage))

    def delete(self, request, name: str):
        s = get_object_or_404(Snippet, name=lookup_name(name))
        deleted = s.name  # delete() 가 pk 를 None 으로 지움
        s.delete()
        return Response({"name": deleted})


class SnippetUseView(APIView):
    def post(self, request, name: str):
        s = get_object_or_404(Snippet, name=lookup_name(name))
        u, _ = SnippetUsage.objects.get_or_create(snippet=s, user=request.user)
        u.count += 1
        u.last_used = timezone.now()
        u.save(update_fields=["count", "last_used"])
        return Response({"name": s.name, "usageCount": u.count, "lastUsed": int(u.last_used.timestamp())})