"""Join graph nodes to their stored embeddings — the plumbing behind the semantic map.

``visualize_graph()`` forwards only nodes/links; no embeddings ride along. This
module fetches the embedding for each node by looking it up in the vector store,
reusing the fact that a graph node id is stored verbatim as the vector-row id
(both sides use ``str(data_point.id)``).

Strategy per node type:
  * Group node ids by type and derive the collection ``f"{Type}_{field}"`` from
    the type's indexed field.
  * One batched ``retrieve(..., include_vector=True)`` per collection — never per
    node. On adapters that don't support ``include_vector`` (everything except
    LanceDB), fall back to re-embedding the indexed field in one batch (the stored
    vector is ``embed(indexed_field)``, so the re-embedded vector matches).

Bounding lives in :func:`select_nodes`: the orchestrator samples the graph down
to ``SEMANTIC_NODE_CAP`` once, and the fetch, projection, clustering, and
de-overlap passes all operate on that same subset.

Any vector-engine failure is logged and yields a partial/empty dict — the classic
render must never break because the semantic tab couldn't fetch vectors.
"""

import inspect
import random
from collections import defaultdict
from typing import Any, Dict, List, Optional

from cognee.shared.logging_utils import get_logger

logger = get_logger("embedding_join")

# type_name -> indexed field. The vector collection is ``f"{type_name}_{field}"``.
# Mirrors each DataPoint subclass's ``metadata["index_fields"]``; this fallback
# covers the node types the graph visualization actually surfaces.
DEFAULT_INDEX_FIELDS: Dict[str, str] = {
    "Entity": "name",
    "EntityType": "name",
    "TextSummary": "text",
    "DocumentChunk": "text",
    "TextDocument": "name",
}

# Max nodes the semantic map renders. Bounds the vector fetch AND the O(n²)
# layout/neighbor passes downstream — everything runs on the same sample.
SEMANTIC_NODE_CAP = 2000

# Seed for the deterministic over-cap sample. Fixed so a given graph always
# samples the same nodes across runs (snapshot tests depend on this).
SAMPLE_SEED = 42


def select_nodes(nodes: List[Dict[str, Any]], cap: int = SEMANTIC_NODE_CAP) -> List[Dict[str, Any]]:
    """Sort nodes by id and, if over ``cap``, take a deterministic seeded sample.

    The single bounding step for the semantic map: the embedding fetch and every
    downstream pass (projection, clustering, de-overlap) run on this subset only.
    """
    ordered = sorted(nodes, key=lambda n: str(n["id"]))
    if len(ordered) <= cap:
        return ordered
    rng = random.Random(SAMPLE_SEED)
    picked = sorted(rng.sample(range(len(ordered)), cap))
    logger.warning(
        "select_nodes: %d nodes exceeds cap %d; the semantic map shows a deterministic sample",
        len(ordered),
        cap,
    )
    return [ordered[i] for i in picked]


async def _reembed(
    vector_engine, type_nodes: List[Dict[str, Any]], field: str
) -> Dict[str, List[float]]:
    """Fallback: re-embed each node's indexed field in one batch."""
    texts: List[str] = []
    ids: List[str] = []
    for node in type_nodes:
        value = node.get(field)
        if value is None:
            value = node.get("name")
        if value is None:
            continue
        texts.append(str(value))
        ids.append(str(node["id"]))
    if not texts:
        return {}
    vectors = await vector_engine.embedding_engine.embed_text(texts)
    return {nid: list(vec) for nid, vec in zip(ids, vectors)}


async def _fetch_for_collection(
    vector_engine, collection: str, type_nodes: List[Dict[str, Any]], field: str
) -> Dict[str, List[float]]:
    """One batched retrieve for a collection, with re-embed fallback."""
    ids = [str(node["id"]) for node in type_nodes]
    # Capability detection (not error handling): only LanceDB's retrieve() declares
    # ``include_vector``. Probe the signature — the same idiom run_async / Task use
    # for optional params — so a genuine TypeError raised *inside* a supporting
    # retrieve() surfaces via fetch_node_embeddings' ``except Exception`` instead of
    # being silently reinterpreted as "unsupported" and masked behind a re-embed.
    try:
        supports_vector = "include_vector" in inspect.signature(vector_engine.retrieve).parameters
    except (ValueError, TypeError):
        supports_vector = False
    if not supports_vector:
        return await _reembed(vector_engine, type_nodes, field)

    results = await vector_engine.retrieve(collection, ids, include_vector=True)

    found: Dict[str, List[float]] = {}
    for result in results:
        payload = result.payload if isinstance(result.payload, dict) else None
        vector = payload.get("vector") if payload else None
        if vector is not None:
            found[str(result.id)] = list(vector)

    if not found and results:
        # Adapter accepted the flag but returned no vectors -> re-embed.
        return await _reembed(vector_engine, type_nodes, field)
    return found


async def fetch_node_embeddings(
    nodes: List[Dict[str, Any]],
    vector_engine=None,
    index_fields: Optional[Dict[str, str]] = None,
) -> Dict[str, List[float]]:
    """Return ``{node_id: vector}`` for as many nodes as the vector store can supply.

    Args:
        nodes: renderer-facing node dicts (each carries ``id`` and ``type``),
            already bounded by :func:`select_nodes`.
        vector_engine: injected engine (defaults to ``await get_vector_engine_async()``).
            This is the single mocking seam for tests.
        index_fields: type -> indexed-field override (defaults to
            ``DEFAULT_INDEX_FIELDS``).

    Missing vectors are simply absent from the dict; the layout handles them.
    """
    fields = index_fields or DEFAULT_INDEX_FIELDS

    if vector_engine is None:
        from cognee.infrastructure.databases.vector import get_vector_engine_async

        vector_engine = await get_vector_engine_async()

    by_type: Dict[Optional[str], List[Dict[str, Any]]] = defaultdict(list)
    for node in nodes:
        by_type[node.get("type")].append(node)

    embeddings: Dict[str, List[float]] = {}
    hit_collections = 0
    missing_collections: List[str] = []
    unmapped_types: List[str] = []
    for type_name, type_nodes in by_type.items():
        field = fields.get(type_name)
        if not field:
            if type_name is not None:
                unmapped_types.append(type_name)
            continue
        collection = f"{type_name}_{field}"
        try:
            if not await vector_engine.has_collection(collection):
                missing_collections.append(collection)
                continue
            found = await _fetch_for_collection(vector_engine, collection, type_nodes, field)
        except Exception as exc:  # never let a vector-store failure break the render
            logger.warning("fetch_node_embeddings: fetch failed for %s: %s", collection, exc)
            continue
        if found:
            hit_collections += 1
        embeddings.update(found)

    # Join hit-rate: turn a silent empty map into a diagnosable one. A zero
    # resolution over non-empty input almost always means an id/collection-name
    # mismatch — surface which collections were missing and which types were
    # unmapped instead of rendering blank with no signal.
    total = len(nodes)
    logger.info(
        "fetch_node_embeddings: resolved %d/%d node embeddings across %d collection(s)",
        len(embeddings),
        total,
        hit_collections,
    )
    if total and not embeddings:
        logger.warning(
            "fetch_node_embeddings: no embeddings resolved — the semantic map will be empty. "
            "Missing collections: %s. Unmapped node types: %s.",
            missing_collections or "none",
            unmapped_types or "none",
        )

    return embeddings