"""테마/카테고리 API.

토스 '주식 골라보기' 의 테마 그리드와 비슷한 결.
정적 매핑(seed/themes.py)을 베이스로, DB 에서 최신 종가/등락만 채워 응답.

GET /api/themes
  - 모든 테마 인덱스 (slug/name/description/code_count)

GET /api/themes/{slug}
  ?limit=20
  - 해당 테마의 종목 카드 (종목명/시장/종가/등락률). 거래량 기준 정렬.
  - ohlcv_daily 가 아직 안 채워져 있으면 close/pct_change 가 NULL.
"""
from __future__ import annotations

from fastapi import APIRouter, HTTPException, Query
from sqlalchemy import text

from app.db.connection import get_engine
from app.seed.themes import THEMES, theme_by_slug, themes_for_code, themes_index

router = APIRouter(prefix="/api/themes", tags=["themes"])


@router.get("")
def list_themes() -> dict:
    return {"items": themes_index(), "total": len(THEMES)}


@router.get("/peer/{code}")
def peer_compare(
    code: str,
    window: int = Query(default=21, ge=2, le=252),
    limit: int = Query(default=5, ge=1, le=20),
) -> dict:
    """동일 테마(들) 내 동종목 비교.

    - 대상 종목이 속한 모든 테마의 코드 합집합 (자기 자신 제외) 을 peer 풀로 잡고,
      각 종목의 최근 거래일 종가 / window 영업일 전 종가로 누적수익률을 구한다.
    - peer 평균, 대상 종목 값, 상/하위 N 개 반환.
    - 테마 무소속이면 themes=[] 빈 응답 (404 아님 — UI 가 그냥 패널을 숨기게).
    """
    themes = themes_for_code(code)
    if not themes:
        return {
            "code": code,
            "window": window,
            "themes": [],
            "self_pct": None,
            "peer_avg_pct": None,
            "top": [],
            "bottom": [],
        }

    # 테마 합집합 코드 풀 (자기 자신 제외)
    peer_codes: set[str] = set()
    for t in themes:
        peer_codes.update(t.codes)
    peer_codes.discard(code)
    pool = [code, *sorted(peer_codes)]

    sql = text(
        """
        WITH ranked AS (
          SELECT code, date, close,
                 ROW_NUMBER() OVER (PARTITION BY code ORDER BY date DESC) AS rn
            FROM ohlcv_daily
           WHERE code = ANY(:codes) AND close IS NOT NULL
        ),
        latest AS (
          SELECT code, close AS close_now, date AS date_now FROM ranked WHERE rn = 1
        ),
        base AS (
          SELECT code, close AS close_base, date AS date_base FROM ranked WHERE rn = :w
        )
        SELECT s.code, s.name, s.market,
               l.close_now, b.close_base,
               CASE WHEN b.close_base > 0
                    THEN (l.close_now - b.close_base) / b.close_base * 100
                    ELSE NULL
               END AS pct
          FROM symbols s
          LEFT JOIN latest l ON l.code = s.code
          LEFT JOIN base   b ON b.code = s.code
         WHERE s.code = ANY(:codes)
        """
    )

    eng = get_engine()
    with eng.connect() as conn:
        rows = conn.execute(sql, {"codes": pool, "w": window}).all()

    by_code: dict[str, dict] = {}
    for r in rows:
        by_code[r[0]] = {
            "code": r[0],
            "name": r[1],
            "market": r[2],
            "close": float(r[3]) if r[3] is not None else None,
            "base_close": float(r[4]) if r[4] is not None else None,
            "pct_change": float(r[5]) if r[5] is not None else None,
        }

    self_row = by_code.get(code)
    self_pct = self_row["pct_change"] if self_row else None

    peers = [
        v for k, v in by_code.items() if k != code and v["pct_change"] is not None
    ]
    if peers:
        peer_avg_pct = sum(p["pct_change"] for p in peers) / len(peers)
        peers_sorted = sorted(peers, key=lambda x: x["pct_change"], reverse=True)
        top = peers_sorted[:limit]
        bottom = peers_sorted[-limit:][::-1]
    else:
        peer_avg_pct = None
        top = []
        bottom = []

    return {
        "code": code,
        "name": self_row["name"] if self_row else code,
        "window": window,
        "themes": [
            {"slug": t.slug, "name": t.name, "code_count": len(t.codes)}
            for t in themes
        ],
        "self_pct": self_pct,
        "peer_avg_pct": peer_avg_pct,
        "peer_count": len(peers),
        "top": top,
        "bottom": bottom,
    }


@router.get("/{slug}")
def get_theme(slug: str, limit: int = Query(default=30, ge=1, le=100)) -> dict:
    th = theme_by_slug(slug)
    if th is None:
        raise HTTPException(status_code=404, detail=f"unknown theme: {slug}")

    codes = list(th.codes)[:limit]
    if not codes:
        return {
            "slug": th.slug,
            "name": th.name,
            "description": th.description,
            "items": [],
        }

    sql = text(
        """
        WITH last2 AS (
          SELECT DISTINCT date FROM ohlcv_daily ORDER BY date DESC LIMIT 2
        ),
        bounds AS (SELECT MAX(date) AS d0, MIN(date) AS d1 FROM last2),
        latest AS (
          SELECT o.code, o.close AS close0, o.volume AS vol0
            FROM ohlcv_daily o, bounds WHERE o.date = bounds.d0
        ),
        prev AS (
          SELECT o.code, o.close AS close1
            FROM ohlcv_daily o, bounds WHERE o.date = bounds.d1
        )
        SELECT s.code, s.name, s.market,
               l.close0  AS close,
               p.close1  AS prev_close,
               l.vol0    AS volume,
               CASE WHEN p.close1 > 0 THEN (l.close0 - p.close1) / p.close1 * 100 ELSE NULL END AS pct_change
          FROM symbols s
          LEFT JOIN latest l ON l.code = s.code
          LEFT JOIN prev   p ON p.code = s.code
         WHERE s.code = ANY(:codes)
         ORDER BY vol0 DESC NULLS LAST, s.name ASC
        """
    )

    eng = get_engine()
    with eng.connect() as conn:
        rows = conn.execute(sql, {"codes": codes}).all()

    # symbols 테이블에 시드만 있고 codes 일부가 누락된 경우, 그래도 코드/이름 자리는 비워서 카드 표시.
    by_code = {r[0]: r for r in rows}
    items: list[dict] = []
    for c in codes:
        r = by_code.get(c)
        if r is None:
            items.append(
                {
                    "code": c,
                    "name": c,  # symbols 미등재 — 코드로 노출
                    "market": None,
                    "close": None,
                    "prev_close": None,
                    "volume": None,
                    "pct_change": None,
                }
            )
        else:
            items.append(
                {
                    "code": r[0],
                    "name": r[1],
                    "market": r[2],
                    "close": float(r[3]) if r[3] is not None else None,
                    "prev_close": float(r[4]) if r[4] is not None else None,
                    "volume": int(r[5]) if r[5] is not None else None,
                    "pct_change": float(r[6]) if r[6] is not None else None,
                }
            )

    return {
        "slug": th.slug,
        "name": th.name,
        "description": th.description,
        "items": items,
    }