"""派生数据维护 — FTS5 / ChromaDB 等可重建索引。"""

from __future__ import annotations

import logging

from sqlalchemy import select, text
from sqlalchemy.orm import Session

from app.models import Paper

logger = logging.getLogger(__name__)


def _summary_text(paper: Paper) -> str:
    summary = paper.summary
    if not summary:
        return ""
    parts = [
        summary.one_line,
        summary.motivation_problem,
        summary.motivation_goal,
        summary.method_overview,
        summary.method_key_idea,
        summary.results_main_json,
    ]
    return " ".join(p for p in parts if p)


def delete_fts_paper(db: Session, paper_id: int) -> None:
    """删除单篇论文的 FTS5 行。FTS5 以 papers.id 作为 rowid。"""
    db.execute(
        text("DELETE FROM papers_fts WHERE rowid = :paper_id"),
        {"paper_id": paper_id},
    )


def delete_paper_indexes(db: Session, *, paper_id: int, arxiv_id: str) -> None:
    """删除单篇论文的所有派生索引。失败项记录日志但不阻断主删除。"""
    try:
        delete_fts_paper(db, paper_id)
    except Exception:
        logger.warning("Failed to clean FTS index for %s", arxiv_id, exc_info=True)

    try:
        from app.services.embedder import delete_paper

        delete_paper(arxiv_id)
    except Exception:
        logger.warning("Failed to clean ChromaDB index for %s", arxiv_id, exc_info=True)


def reindex_paper_fts(db: Session, paper: Paper) -> None:
    """按 DB 权威数据重建单篇论文的 FTS5 派生索引。"""
    authors_text = ", ".join(
        a.name for a in sorted(paper.authors, key=lambda a: a.position or 0)
    )
    tags_text = ", ".join(t.tag for t in paper.tags)

    delete_fts_paper(db, paper.id)
    db.execute(
        text(
            """
            INSERT INTO papers_fts(
                rowid, title_en, title_zh, abstract, authors, tags, summary_text
            )
            VALUES (
                :id, :title_en, :title_zh, :abstract, :authors, :tags, :summary_text
            )
            """
        ),
        {
            "id": paper.id,
            "title_en": paper.title_en or "",
            "title_zh": paper.title_zh or "",
            "abstract": paper.abstract or "",
            "authors": authors_text,
            "tags": tags_text,
            "summary_text": _summary_text(paper),
        },
    )


def reindex_fts(db: Session, paper_ids: list[int] | None = None) -> dict:
    """全量或局部重建 FTS5 索引。"""
    query = select(Paper)
    if paper_ids:
        query = query.where(Paper.id.in_(paper_ids))
    papers = db.execute(query).scalars().all()

    if paper_ids is None:
        db.execute(text("DELETE FROM papers_fts"))

    count = 0
    for paper in papers:
        reindex_paper_fts(db, paper)
        count += 1
    db.commit()
    logger.info("FTS reindexed: %d papers", count)
    return {"status": "success", "indexed": count}


def reindex_chroma(db: Session) -> dict:
    """按 DB 权威数据重建 ChromaDB 语义索引。"""
    from app.services.embedder import index_paper

    papers = db.execute(select(Paper).where(Paper.summary.has())).scalars().all()
    indexed = 0
    errors: list[str] = []
    for paper in papers:
        try:
            texts_dict = {
                "arxiv_id": paper.arxiv_id,
                "title_zh": paper.title_zh or "",
                "title_en": paper.title_en or "",
                "tags": " ".join(t.tag for t in paper.tags),
                "one_line": paper.summary.one_line if paper.summary else "",
                "motivation_problem": (
                    paper.summary.motivation_problem if paper.summary else ""
                ),
                "method_key_idea": (
                    paper.summary.method_key_idea if paper.summary else ""
                ),
                "paper_date": paper.paper_date.isoformat() if paper.paper_date else "",
            }
            index_paper(paper.arxiv_id, texts_dict)
            indexed += 1
        except Exception as exc:
            errors.append(f"{paper.arxiv_id}: {exc}")
            logger.warning(
                "Failed to reindex ChromaDB for %s",
                paper.arxiv_id,
                exc_info=True,
            )

    return {
        "status": "success" if not errors else "partial",
        "indexed": indexed,
        "errors": errors or None,
    }