"""Memory embedding service boundary."""

from __future__ import annotations

from sqlalchemy.ext.asyncio import AsyncSession

from app.core.logging import get_logger
from app.features.memory.repo import (
    list_chunks_for_source,
    set_chunk_embedding_status,
    set_source_embedding_status,
    update_chunk_embedding,
)
from app.ports.embedding import EmbeddingProvider

logger = get_logger(__name__)


def _short_error(exc: BaseException | str, *, max_chars: int = 500) -> str:
    text = str(exc)
    if len(text) > max_chars:
        return text[: max_chars - 3] + "..."
    return text


async def _commit_if_available(db: AsyncSession) -> None:
    commit = getattr(db, "commit", None)
    if commit is not None:
        await commit()


class MemoryEmbeddingService:
    """Embeds persisted memory chunks and records source/chunk status."""

    def __init__(
        self,
        db: AsyncSession,
        *,
        embedding_provider: EmbeddingProvider | None = None,
    ) -> None:
        self._db = db
        self._embedding = embedding_provider

    async def embed_source(
        self,
        user_id: str,
        source_id: str,
        *,
        raise_on_failure: bool = False,
    ) -> dict:
        chunks = await list_chunks_for_source(
            self._db,
            user_id=user_id,
            source_id=source_id,
            include_excluded=True,
        )
        if not chunks:
            await set_source_embedding_status(
                self._db,
                source_id=source_id,
                user_id=user_id,
                status="skipped",
                error="no_chunks",
            )
            await _commit_if_available(self._db)
            return {"status": "skipped", "reason": "no_chunks", "chunks": 0}

        if self._embedding is None:
            err = "embedding_provider_missing"
            await self._mark_failed(user_id, source_id, [c.id for c in chunks], err)
            if raise_on_failure:
                raise RuntimeError(err)
            return {"status": "failed", "error": err, "chunks": len(chunks)}

        await set_source_embedding_status(
            self._db,
            source_id=source_id,
            user_id=user_id,
            status="running",
            error=None,
        )
        await _commit_if_available(self._db)

        try:
            texts = [c.content for c in chunks]
            raw_embeddings = await self._embedding.embed_texts(texts)
            embeddings = list(raw_embeddings or [])
        except Exception as e:
            err = _short_error(e)
            await self._mark_failed(user_id, source_id, [c.id for c in chunks], err)
            logger.warning(
                "event=memory_embedding_failed user_id={} source_id={} chunks={} exc_type={} exc={}",
                user_id,
                source_id,
                len(chunks),
                type(e).__name__,
                err,
            )
            if raise_on_failure:
                raise
            return {"status": "failed", "error": err, "chunks": len(chunks)}

        vectors_written = 0
        failed_chunk_ids: list[str] = []
        for chunk, emb in zip(chunks, embeddings, strict=False):
            if emb:
                vectors_written += 1
                await update_chunk_embedding(self._db, chunk.id, emb)
            else:
                failed_chunk_ids.append(chunk.id)
                await set_chunk_embedding_status(
                    self._db,
                    chunk.id,
                    status="failed",
                    error="empty_embedding",
                )

        if len(embeddings) != len(chunks):
            missing = chunks[len(embeddings) :]
            failed_chunk_ids.extend(c.id for c in missing)
            for chunk in missing:
                await set_chunk_embedding_status(
                    self._db,
                    chunk.id,
                    status="failed",
                    error="embedding_count_mismatch",
                )
            logger.warning(
                "event=memory_embedding_count_mismatch user_id={} source_id={} chunks={} embeddings={}",
                user_id,
                source_id,
                len(chunks),
                len(embeddings),
            )

        status = "success"
        error = None
        if failed_chunk_ids:
            status = "partial" if vectors_written else "failed"
            error = f"failed_chunks={len(failed_chunk_ids)}"
        await set_source_embedding_status(
            self._db,
            source_id=source_id,
            user_id=user_id,
            status=status,
            error=error,
        )
        await _commit_if_available(self._db)
        if status == "failed" and raise_on_failure:
            raise RuntimeError(error or "embedding_failed")
        return {
            "status": status,
            "chunks": len(chunks),
            "vectors_written": vectors_written,
            "failed_chunks": failed_chunk_ids,
        }

    async def _mark_failed(
        self,
        user_id: str,
        source_id: str,
        chunk_ids: list[str],
        error: str,
    ) -> None:
        await set_source_embedding_status(
            self._db,
            source_id=source_id,
            user_id=user_id,
            status="failed",
            error=error,
        )
        for chunk_id in chunk_ids:
            await set_chunk_embedding_status(
                self._db,
                chunk_id,
                status="failed",
                error=error,
            )
        await _commit_if_available(self._db)


__all__ = ["MemoryEmbeddingService"]