"""
证据包组装：跨 memory + story 的检索结果合并（业务层，非纯 repo）。

权威层级（可靠性 hardening）：
- **Chunk 原文**（未 excluded）为首要证据；rolling 摘要/故事摘录为便利视图，不得压过冲突的 chunk。
- **MemoryFact**：`confirmed` 为检索默认集；`candidate` 可被上游提升；`stale` 由 compaction 等标出，检索时应排除。
- 事实 FTS 无命中时是否退回「最近事实」由 `memory_fact_search_use_recent_fallback` 控制（默认可避免串台）。

Celery 使用 sync；`HybridRetriever` 使用 async + RRF chunk 合并。
"""

from __future__ import annotations

from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import Session

from app.core.config import settings
from app.features.memory.repo import (
    list_summaries_for_evidence_async,
    list_summaries_for_evidence_sync,
    search_chunks_fts,
    search_chunks_fts_sync,
    search_facts_for_user_async,
    search_facts_for_user_sync,
    search_timeline_events_for_user_async,
    search_timeline_events_for_user_sync,
)
from app.features.story.repo import (
    list_recent_stories_for_evidence,
    list_recent_stories_for_evidence_sync,
)

EMPTY_EVIDENCE_BUNDLE: dict = {
    "relevant_chunks": [],
    "relevant_summaries": [],
    "relevant_facts": [],
    "timeline_hints": [],
    "relevant_stories": [],
}


def _facts_to_dicts(facts) -> list[dict]:
    return [
        {
            "id": f.id,
            "fact_type": f.fact_type,
            "subject": f.subject,
            "predicate": f.predicate,
            "object_json": f.object_json,
        }
        for f in facts
    ]


def _timeline_to_dicts(events) -> list[dict]:
    return [
        {
            "id": e.id,
            "event_year": e.event_year,
            "event_date": e.event_date,
            "title": e.title,
            "description": e.description,
        }
        for e in events
    ]


def _stories_to_dicts(story_rows) -> list[dict]:
    return [
        {
            "id": s.id,
            "title": s.title,
            "summary": s.summary,
            "stage": s.stage,
            "story_type": s.story_type,
        }
        for s in story_rows
    ]


def fetch_evidence_metadata_sync(
    session: Session, user_id: str, q: str, top_k: int
) -> dict:
    """非 chunk 证据：摘要、事实、时间线、故事（sync）。"""
    facts = search_facts_for_user_sync(session, user_id, q, top_k)
    events = search_timeline_events_for_user_sync(session, user_id, q, top_k)
    relevant_summaries = list_summaries_for_evidence_sync(
        session, user_id=user_id, q=q, limit=top_k
    )
    story_rows = list_recent_stories_for_evidence_sync(
        session, user_id, query=q, limit=top_k
    )
    return {
        "relevant_facts": _facts_to_dicts(facts),
        "timeline_hints": _timeline_to_dicts(events),
        "relevant_summaries": relevant_summaries,
        "relevant_stories": _stories_to_dicts(story_rows),
    }


async def fetch_evidence_metadata_async(
    db: AsyncSession, user_id: str, q: str, top_k: int
) -> dict:
    """非 chunk 证据（async）。"""
    facts = await search_facts_for_user_async(db, user_id, q, top_k)
    events = await search_timeline_events_for_user_async(db, user_id, q, top_k)
    relevant_summaries = await list_summaries_for_evidence_async(
        db, user_id=user_id, q=q, limit=top_k
    )
    story_rows = await list_recent_stories_for_evidence(
        db, user_id=user_id, query=q, limit=top_k
    )
    return {
        "relevant_facts": _facts_to_dicts(facts),
        "timeline_hints": _timeline_to_dicts(events),
        "relevant_summaries": relevant_summaries,
        "relevant_stories": _stories_to_dicts(story_rows),
    }


def _empty_query_bundle_sync(session: Session, user_id: str, top_k: int) -> dict:
    """无 FTS query 时的「浏览」降级：rolling 摘要 + 事实/时间线 fallback。"""
    from app.features.memory.models import MemorySummary
    from sqlalchemy import select

    from app.features.memory.repo import (
        get_facts_for_user_sync,
        get_timeline_events_for_user_sync,
    )

    rolling = (
        session.execute(
            select(MemorySummary)
            .where(
                MemorySummary.user_id == user_id,
                MemorySummary.summary_type == "rolling",
            )
            .order_by(MemorySummary.updated_at.desc())
            .limit(1)
        )
        .unique()
        .scalar_one_or_none()
    )
    summaries = []
    if rolling:
        summaries = [
            {
                "id": rolling.id,
                "summary_type": rolling.summary_type,
                "content": rolling.content,
                "source_chunk_ids": rolling.source_chunk_ids,
            }
        ]
    facts = get_facts_for_user_sync(session, user_id, top_k)
    events = get_timeline_events_for_user_sync(session, user_id, top_k)
    return {
        "relevant_chunks": [],
        "relevant_summaries": summaries,
        "relevant_facts": _facts_to_dicts(facts),
        "timeline_hints": _timeline_to_dicts(events),
        "relevant_stories": [],
    }


async def _empty_query_bundle_async(db: AsyncSession, user_id: str, top_k: int) -> dict:
    from sqlalchemy import select

    from app.features.memory.models import MemorySummary
    from app.features.memory.repo import (
        get_facts_for_user,
        get_timeline_events_for_user,
    )

    roll_stmt = (
        select(MemorySummary)
        .where(
            MemorySummary.user_id == user_id,
            MemorySummary.summary_type == "rolling",
        )
        .order_by(MemorySummary.updated_at.desc())
        .limit(1)
    )
    r_result = await db.execute(roll_stmt)
    rolling = r_result.unique().scalar_one_or_none()
    summaries = []
    if rolling:
        summaries = [
            {
                "id": rolling.id,
                "summary_type": rolling.summary_type,
                "content": rolling.content,
                "source_chunk_ids": rolling.source_chunk_ids,
            }
        ]
    facts = await get_facts_for_user(db, user_id=user_id, limit=top_k)
    events = await get_timeline_events_for_user(db, user_id=user_id, limit=top_k)
    return {
        "relevant_chunks": [],
        "relevant_summaries": summaries,
        "relevant_facts": _facts_to_dicts(facts),
        "timeline_hints": _timeline_to_dicts(events),
        "relevant_stories": [],
    }


def retrieve_evidence_bundle_sync(
    session: Session, user_id: str, query: str, *, top_k: int = 10
) -> dict:
    """Celery / 叙事流水线：FTS-only chunks + 元数据。"""
    if not query or not query.strip():
        if settings.memory_evidence_empty_query_include_rolling:
            return _empty_query_bundle_sync(session, user_id, top_k)
        return dict(EMPTY_EVIDENCE_BUNDLE)
    q = query.strip()
    chunk_rows = search_chunks_fts_sync(session, user_id, q, top_k)
    relevant_chunks = [
        {"id": r["id"], "content": r["content"], "chunk_index": r["chunk_index"]}
        for r in chunk_rows
    ]
    meta = fetch_evidence_metadata_sync(session, user_id, q, top_k)
    return {
        "relevant_chunks": relevant_chunks,
        **meta,
    }


async def retrieve_evidence_bundle_async(
    db: AsyncSession,
    user_id: str,
    query: str,
    *,
    top_k: int = 10,
    merged_chunk_dicts: list[dict],
) -> dict:
    """
    异步路径：chunk 已由调用方 RRF 合并；此处只拼元数据。

    merged_chunk_dicts: [{"id","content","chunk_index"}, ...]
    """
    if not query or not query.strip():
        if settings.memory_evidence_empty_query_include_rolling:
            return await _empty_query_bundle_async(db, user_id, top_k)
        return dict(EMPTY_EVIDENCE_BUNDLE)
    q = query.strip()
    meta = await fetch_evidence_metadata_async(db, user_id, q, top_k)
    return {
        "relevant_chunks": merged_chunk_dicts,
        **meta,
    }