"""Phase 2A 후보 임베딩 백필 CLI (embedding-phase2a-1 E-1).

    docker compose exec -T fastapi python -m workers.phase2a_cand_backfill \
        --target qwen06 --doc-id-max 41944 --chunk-id-max 104140 [--batch 32]

설계 원칙 (plan r3):
  - resumable/idempotent: 대상 = NOT EXISTS(후보 테이블) — 중단/재실행 시 이어서.
    배치 단위 커밋. C-1 백필 게이트 = "후보 카운트 == 동결셋 카운트".
  - 동결셋: id <= *_id_max AND 베이스라인 embedding IS NOT NULL (AND docs.deleted_at IS NULL).
    cand 테이블은 동결 범위로만 INSERT (retrieval cand path 가 snapshot filter 를 안 타는 전제).
  - 문서/청크 입력 = production 경로와 동일 구성(embed_worker._build_embed_input /
    chunk_worker 의 [제목][섹션][본문]) + plain (instruct prefix 는 쿼리 측 전용 — G-1 불변식).
  - 임베딩 = Ollama /api/embed 배치 호출 (G-1 fixture: 정규화 출력).
  - qwen4m 은 본 CLI 대상이 아님 — qwen4 적재 후 SQL 파생(subvector+l2_normalize), plan E-1.
"""

import argparse
import asyncio
import hashlib
import time

import httpx
from sqlalchemy import text

from core.database import async_session
from core.utils import setup_logger
from models.document import Document
from workers.embed_worker import _build_embed_input

logger = setup_logger("phase2a_cand_backfill")

OLLAMA_EMBED = "http://ollama:11434/api/embed"

TARGETS = {
    "qwen06": {
        "model": "qwen3-embedding:0.6b", "dim": 1024,
        "docs": "documents_cand_qwen06", "chunks": "document_chunks_cand_qwen06",
    },
    "qwen4": {
        "model": "qwen3-embedding:4b", "dim": 2560,
        "docs": "documents_cand_qwen4", "chunks": "document_chunks_cand_qwen4",
    },
}


async def _embed_batch(client: httpx.AsyncClient, model: str, texts: list[str]) -> list[list[float]]:
    r = await client.post(OLLAMA_EMBED, json={"model": model, "input": texts}, timeout=600)
    r.raise_for_status()
    embs = r.json()["embeddings"]
    if len(embs) != len(texts):
        raise RuntimeError(f"embed count mismatch: {len(embs)} != {len(texts)}")
    return embs


async def backfill_docs(target: dict, doc_id_max: int, batch: int, http: httpx.AsyncClient) -> int:
    total = 0
    while True:
        async with async_session() as session:
            rows = (await session.execute(text(f"""
                SELECT d.id FROM documents d
                WHERE d.id <= :m AND d.embedding IS NOT NULL AND d.deleted_at IS NULL
                  AND NOT EXISTS (SELECT 1 FROM {target['docs']} c WHERE c.doc_id = d.id)
                ORDER BY d.id LIMIT :b
            """), {"m": doc_id_max, "b": batch})).scalars().all()
            if not rows:
                break
            docs = [(await session.get(Document, i)) for i in rows]
            inputs = [_build_embed_input(d) for d in docs]
            embs = await _embed_batch(http, target["model"], inputs)
            for d, inp, e in zip(docs, inputs, embs):
                await session.execute(text(f"""
                    INSERT INTO {target['docs']} (doc_id, embed_input_hash, embedding)
                    VALUES (:i, :h, cast(:e AS vector))
                    ON CONFLICT (doc_id) DO NOTHING
                """), {"i": d.id, "h": hashlib.sha256(inp.encode()).hexdigest()[:16], "e": str(e)})
            await session.commit()
            total += len(rows)
            if total % (batch * 10) < batch:
                logger.info(f"[{target['docs']}] +{total} (last id={rows[-1]})")
    return total


async def backfill_chunks(target: dict, chunk_id_max: int, batch: int, http: httpx.AsyncClient) -> int:
    total = 0
    while True:
        async with async_session() as session:
            rows = (await session.execute(text(f"""
                SELECT c.id, c.doc_id, c.chunk_index, c.section_title, c.text, d.title
                FROM corpus_chunks c JOIN documents d ON d.id = c.doc_id
                WHERE c.id <= :m AND c.embedding IS NOT NULL AND d.deleted_at IS NULL
                  AND NOT EXISTS (SELECT 1 FROM {target['chunks']} k WHERE k.id = c.id)
                ORDER BY c.id LIMIT :b
            """), {"m": chunk_id_max, "b": batch})).all()
            if not rows:
                break
            inputs = [
                f"[제목] {r.title or ''}\n[섹션] {r.section_title or ''}\n[본문] {r.text}"
                for r in rows
            ]
            embs = await _embed_batch(http, target["model"], inputs)
            for r, e in zip(rows, embs):
                await session.execute(text(f"""
                    INSERT INTO {target['chunks']} (id, doc_id, chunk_index, section_title, text, embedding)
                    VALUES (:i, :d, :x, :s, :t, cast(:e AS vector))
                    ON CONFLICT (id) DO NOTHING
                """), {"i": r.id, "d": r.doc_id, "x": r.chunk_index,
                       "s": r.section_title, "t": r.text, "e": str(e)})
            await session.commit()
            total += len(rows)
            if total % (batch * 10) < batch:
                logger.info(f"[{target['chunks']}] +{total} (last id={rows[-1]})")
    return total


async def run(target_key: str, doc_id_max: int, chunk_id_max: int, batch: int) -> None:
    target = TARGETS[target_key]
    start = time.monotonic()
    async with httpx.AsyncClient() as http:
        nd = await backfill_docs(target, doc_id_max, batch, http)
        nc = await backfill_chunks(target, chunk_id_max, batch, http)
    mins = (time.monotonic() - start) / 60
    async with async_session() as session:
        cd = (await session.execute(text(f"SELECT count(*) FROM {target['docs']}"))).scalar_one()
        cc = (await session.execute(text(f"SELECT count(*) FROM {target['chunks']}"))).scalar_one()
    logger.info(
        f"[{target_key}] 완료 — 이번 run docs +{nd} chunks +{nc} ({mins:.1f}분) · "
        f"누적 docs {cd} / chunks {cc} (동결 게이트 = 베이스라인 동결셋 카운트와 일치 확인)"
    )


def main() -> None:
    p = argparse.ArgumentParser(description="Phase 2A 후보 임베딩 백필 (resumable)")
    p.add_argument("--target", required=True, choices=sorted(TARGETS))
    p.add_argument("--doc-id-max", type=int, required=True)
    p.add_argument("--chunk-id-max", type=int, required=True)
    p.add_argument("--batch", type=int, default=32)
    a = p.parse_args()
    asyncio.run(run(a.target, a.doc_id_max, a.chunk_id_max, a.batch))


if __name__ == "__main__":
    main()