import uuid
from dataclasses import dataclass
from typing import Any

from qdrant_client import QdrantClient
from qdrant_client.http import models as qm


@dataclass(frozen=True)
class ChunkPoint:
    vector: list[float]
    payload: dict[str, Any]


def ensure_collection(client: QdrantClient, name: str, vector_size: int) -> None:
    """Create the collection if missing. Crash if it exists with wrong dim.

    Note: payload indexes are created only on initial collection creation;
    they are not reconciled on subsequent runs.
    """
    if not client.collection_exists(name):
        client.create_collection(
            collection_name=name,
            vectors_config=qm.VectorParams(size=vector_size, distance=qm.Distance.COSINE),
        )
        for field in ("file_path", "semester", "fach"):
            client.create_payload_index(
                collection_name=name,
                field_name=field,
                field_schema=qm.PayloadSchemaType.KEYWORD,
            )
        return

    info = client.get_collection(name)
    existing = info.config.params.vectors.size
    if existing != vector_size:
        raise RuntimeError(
            f"qdrant collection '{name}' dimension mismatch: "
            f"existing={existing}, model={vector_size}. "
            "Drop the collection manually and run a bulk import."
        )


def upsert_chunks(client: QdrantClient, name: str, chunks: list[ChunkPoint]) -> None:
    """Insert chunks with fresh UUID ids.

    Caller is responsible for deduplication: call ``delete_by_path`` for the
    file before re-ingesting, otherwise duplicates accumulate.
    """
    points = [
        qm.PointStruct(id=str(uuid.uuid4()), vector=c.vector, payload=c.payload)
        for c in chunks
    ]
    client.upsert(collection_name=name, points=points)


def delete_by_path(client: QdrantClient, name: str, file_path: str) -> None:
    selector = qm.FilterSelector(
        filter=qm.Filter(
            must=[qm.FieldCondition(key="file_path", match=qm.MatchValue(value=file_path))]
        )
    )
    client.delete(collection_name=name, points_selector=selector)