"""Memory repository — MemorySource, MemoryChunk, MemoryFact, TimelineEvent data access."""

import uuid
from datetime import datetime, timezone

from sqlalchemy import select, text
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import Session

from app.features.memory.models import (
    MemoryChunk,
    MemoryFact,
    MemorySource,
    TimelineEvent,
)


def _new_id() -> str:
    return str(uuid.uuid4())


def create_source_sync(
    session: Session,
    *,
    user_id: str,
    source_type: str,
    raw_text: str | None = None,
    conversation_id: str | None = None,
    captured_at: datetime | None = None,
) -> MemorySource:
    """Create a memory source (sync). Caller must commit."""
    source = MemorySource(
        id=_new_id(),
        user_id=user_id,
        source_type=source_type,
        raw_text=raw_text,
        conversation_id=conversation_id,
        captured_at=captured_at or datetime.now(timezone.utc),
    )
    session.add(source)
    return source


async def create_source(
    db: AsyncSession,
    *,
    user_id: str,
    source_type: str,
    raw_text: str | None = None,
    conversation_id: str | None = None,
    captured_at: datetime | None = None,
) -> MemorySource:
    """Create a memory source. Caller must commit."""
    source = MemorySource(
        id=_new_id(),
        user_id=user_id,
        source_type=source_type,
        raw_text=raw_text,
        conversation_id=conversation_id,
        captured_at=captured_at or datetime.now(timezone.utc),
    )
    db.add(source)
    return source


def create_chunk_sync(
    session: Session,
    *,
    source_id: str,
    user_id: str,
    content: str,
    chunk_index: int,
) -> MemoryChunk:
    """Create a memory chunk (sync). Caller must commit."""
    chunk = MemoryChunk(
        id=_new_id(),
        source_id=source_id,
        user_id=user_id,
        content=content,
        chunk_index=chunk_index,
    )
    session.add(chunk)
    return chunk


async def create_chunk(
    db: AsyncSession,
    *,
    source_id: str,
    user_id: str,
    content: str,
    chunk_index: int,
) -> MemoryChunk:
    """Create a memory chunk. Caller must commit."""
    chunk = MemoryChunk(
        id=_new_id(),
        source_id=source_id,
        user_id=user_id,
        content=content,
        chunk_index=chunk_index,
    )
    db.add(chunk)
    return chunk


def update_chunk_fts_sync(session: Session, chunk_id: str) -> None:
    """Populate content_tsv for FTS (sync). Caller must commit."""
    session.execute(
        text(
            "UPDATE memory_chunks SET content_tsv = to_tsvector('simple', content) WHERE id = :id"
        ),
        {"id": chunk_id},
    )


async def update_chunk_embedding(
    db: AsyncSession, chunk_id: str, embedding: list[float]
) -> None:
    """Update chunk embedding. Caller must commit."""
    chunk = await db.get(MemoryChunk, chunk_id)
    if chunk:
        chunk.embedding = embedding


async def update_chunk_fts(db: AsyncSession, chunk_id: str) -> None:
    """Populate content_tsv for FTS. Caller must commit."""
    await db.execute(
        text(
            "UPDATE memory_chunks SET content_tsv = to_tsvector('simple', content) WHERE id = :id"
        ),
        {"id": chunk_id},
    )


async def search_chunks_fts(
    db: AsyncSession, user_id: str, query: str, limit: int = 20
) -> list[dict]:
    """FTS search on memory_chunks. Returns list of {id, content, chunk_index}."""
    if not query or not query.strip():
        return []
    q = query.strip()
    stmt = text("""
        SELECT id, content, chunk_index
        FROM memory_chunks
        WHERE user_id = :user_id AND (is_excluded IS NOT TRUE OR is_excluded = false)
          AND content_tsv IS NOT NULL AND content_tsv @@ plainto_tsquery('simple', :q)
        ORDER BY ts_rank_cd(content_tsv, plainto_tsquery('simple', :q2)) DESC
        LIMIT :lim
    """)
    result = await db.execute(stmt, {"user_id": user_id, "q": q, "q2": q, "lim": limit})
    rows = result.mappings().all()
    return [
        {"id": r["id"], "content": r["content"], "chunk_index": r["chunk_index"]}
        for r in rows
    ]


async def get_chunks_by_ids(
    db: AsyncSession, chunk_ids: list[str]
) -> list[MemoryChunk]:
    """Fetch chunks by IDs."""
    if not chunk_ids:
        return []
    stmt = select(MemoryChunk).where(MemoryChunk.id.in_(chunk_ids))
    result = await db.execute(stmt)
    chunks = list(result.unique().scalars().all())
    order = {cid: i for i, cid in enumerate(chunk_ids)}
    return sorted(chunks, key=lambda c: order.get(c.id, 999))


async def get_facts_for_user(
    db: AsyncSession, user_id: str, limit: int = 20
) -> list[MemoryFact]:
    """Fetch recent facts for user."""
    stmt = (
        select(MemoryFact)
        .where(MemoryFact.user_id == user_id, MemoryFact.status == "confirmed")
        .order_by(MemoryFact.created_at.desc())
        .limit(limit)
    )
    result = await db.execute(stmt)
    return list(result.unique().scalars().all())


async def search_chunks_vector(
    db: AsyncSession, user_id: str, query_embedding: list[float], limit: int = 20
) -> list[dict]:
    """Vector similarity search. Returns list of {id, content, chunk_index, distance}."""
    if not query_embedding:
        return []
    # pgvector cosine distance: 1 - cosine_similarity, lower is better
    stmt = text("""
        SELECT id, content, chunk_index,
               (embedding <=> :emb::vector) AS distance
        FROM memory_chunks
        WHERE user_id = :user_id AND (is_excluded IS NOT TRUE OR is_excluded = false)
          AND embedding IS NOT NULL
        ORDER BY embedding <=> :emb2::vector
        LIMIT :lim
    """)
    emb_str = "[" + ",".join(str(x) for x in query_embedding) + "]"
    result = await db.execute(
        stmt,
        {"user_id": user_id, "emb": emb_str, "emb2": emb_str, "lim": limit},
    )
    rows = result.mappings().all()
    return [
        {
            "id": r["id"],
            "content": r["content"],
            "chunk_index": r["chunk_index"],
            "distance": float(r["distance"]),
        }
        for r in rows
    ]


def retrieve_evidence_sync(
    session: Session, user_id: str, query: str, *, top_k: int = 10
) -> dict:
    """
    Sync evidence retrieval for Celery tasks.

    能力：**仅 FTS** 检索 chunks（与 `HybridRetriever` 的 FTS+向量 RRF 不同，见
    `api/docs/memory-retrieval.md`）；confirmed facts；timeline。
    ingest 在 Celery 任务内先于 story 流水线执行并已 commit，故本检索可见刚写入的 chunk。
    """
    if not query or not query.strip():
        return {
            "relevant_chunks": [],
            "relevant_summaries": [],
            "relevant_facts": [],
            "timeline_hints": [],
            "relevant_stories": [],
        }
    q = query.strip()
    # FTS chunks
    stmt = text("""
        SELECT id, content, chunk_index
        FROM memory_chunks
        WHERE user_id = :user_id AND (is_excluded IS NOT TRUE OR is_excluded = false)
          AND content_tsv IS NOT NULL AND content_tsv @@ plainto_tsquery('simple', :q)
        ORDER BY ts_rank_cd(content_tsv, plainto_tsquery('simple', :q2)) DESC
        LIMIT :lim
    """)
    result = session.execute(stmt, {"user_id": user_id, "q": q, "q2": q, "lim": top_k})
    rows = result.mappings().all()
    relevant_chunks = [
        {"id": r["id"], "content": r["content"], "chunk_index": r["chunk_index"]}
        for r in rows
    ]
    # Facts
    facts_stmt = (
        select(MemoryFact)
        .where(MemoryFact.user_id == user_id, MemoryFact.status == "confirmed")
        .order_by(MemoryFact.created_at.desc())
        .limit(top_k)
    )
    facts = list(session.execute(facts_stmt).unique().scalars().all())
    relevant_facts = [
        {
            "id": f.id,
            "fact_type": f.fact_type,
            "subject": f.subject,
            "predicate": f.predicate,
            "object_json": f.object_json,
        }
        for f in facts
    ]
    # Timeline
    events_stmt = (
        select(TimelineEvent)
        .where(TimelineEvent.user_id == user_id)
        .order_by(TimelineEvent.event_year.desc().nullslast())
        .limit(top_k)
    )
    events = list(session.execute(events_stmt).unique().scalars().all())
    timeline_hints = [
        {
            "id": e.id,
            "event_year": e.event_year,
            "event_date": e.event_date,
            "title": e.title,
            "description": e.description,
        }
        for e in events
    ]
    return {
        "relevant_chunks": relevant_chunks,
        "relevant_summaries": [],
        "relevant_facts": relevant_facts,
        "timeline_hints": timeline_hints,
        "relevant_stories": [],
    }


async def get_timeline_events_for_user(
    db: AsyncSession, user_id: str, limit: int = 20
) -> list[TimelineEvent]:
    """Fetch timeline events for user."""
    stmt = (
        select(TimelineEvent)
        .where(TimelineEvent.user_id == user_id)
        .order_by(
            TimelineEvent.event_year.desc().nullslast(), TimelineEvent.created_at.desc()
        )
        .limit(limit)
    )
    result = await db.execute(stmt)
    return list(result.unique().scalars().all())


async def list_storage_keys_for_conversation(
    db: AsyncSession, conversation_id: str
) -> list[str]:
    """对话关联的 memory_sources 上记录的 COS object key（若有）。"""
    stmt = select(MemorySource.storage_key).where(
        MemorySource.conversation_id == conversation_id,
        MemorySource.storage_key.isnot(None),
    )
    result = await db.execute(stmt)
    return sorted({r for r in result.scalars().all() if r})