"""Offline index builder — run once on ZeroGPU, commit the output.

Embeds the full corpus (EU Directive articles + IDA salary rows) with the
pinned embedding model and persists a FAISS index under
``data/processed/index/``. The embedding step is wrapped in ``@spaces.GPU`` so,
when run on the ZeroGPU Space, it uses the GPU. Commit the resulting
``index.faiss`` + ``chunks.jsonl`` so the live app only *loads* them — runtime
never re-embeds the corpus (keeps generation smooth).

Usage (on the ZeroGPU Space / any GPU machine)::

    uv run python scripts/build_index.py

Requires ``embeddings.repo`` set in ``configs/models.yaml``.
"""

from __future__ import annotations

import sys
from pathlib import Path

import spaces

# Allow running as a plain script (`python scripts/build_index.py`).
sys.path.insert(0, str(Path(__file__).resolve().parents[1]))

from src.backend.indexing.embedder import Embedder  # noqa: E402
from src.backend.indexing.ingest import (  # noqa: E402
    build_corpus,
    load_directive_chunks,
    load_ida_chunks,
)
from src.backend.indexing.store import DEFAULT_INDEX_DIR, VectorStore  # noqa: E402


@spaces.GPU(duration=300)
def _embed_corpus(texts: list[str]):
    """Embed all passages on ZeroGPU (model loads here, in GPU context)."""
    embedder = Embedder.get()
    print(f"embedding with {embedder.repo} (loader={embedder.loader}) …")
    return embedder.embed_passages(texts)


def main() -> None:
    n_dir = len(load_directive_chunks())
    n_ida = len(load_ida_chunks())
    chunks = build_corpus()
    print(f"ingested: directive={n_dir} ida={n_ida} total={len(chunks)}")

    vectors = _embed_corpus([c.text for c in chunks])
    dim = vectors.shape[1] if vectors.size else 0

    store = VectorStore()
    store.add(chunks, vectors)
    store.persist()
    print(f"persisted {len(store)} vectors (dim={dim}) → {DEFAULT_INDEX_DIR}")


if __name__ == "__main__":
    main()