"""Pure offline catalog loader. No network."""
from __future__ import annotations
import json
import re
from dataclasses import dataclass, field
from pathlib import Path

from scripts.lib.term_extraction import build_regex


@dataclass
class Catalog:
    records: list[dict]
    term_to_docs: dict[str, list[str]]
    concept_graph: dict[str, dict]
    embedding_model: str
    embedding_dim: int
    term_regex: re.Pattern
    registry: dict = field(default_factory=dict)
    chunk_to_referencing_cards: dict[str, list[dict]] = field(default_factory=dict)


def load_catalog(derived_dir: Path, *, repo_root: Path | None = None) -> Catalog:
    """Load student-chat catalog and supporting layers from derived/ artifacts.

    repo_root defaults to derived_dir.parent.parent (assumes <repo>/derived/student-chat/
    layout); pass explicitly for non-standard paths.
    """
    if repo_root is None:
        repo_root = derived_dir.parent.parent

    catalog_path = derived_dir / "catalog.jsonl"
    if not catalog_path.is_file():
        raise FileNotFoundError(f"catalog.jsonl not found at {catalog_path}")
    records = [json.loads(line) for line in catalog_path.read_text(encoding="utf-8").splitlines() if line.strip()]
    if not records:
        raise ValueError(f"catalog.jsonl at {catalog_path} is empty")

    term_to_docs: dict[str, list[str]] = {}
    if (derived_dir / "term-to-docs.json").is_file():
        term_to_docs = json.loads((derived_dir / "term-to-docs.json").read_text(encoding="utf-8"))

    concept_graph: dict[str, dict] = {}
    if (derived_dir / "concept-graph.json").is_file():
        concept_graph = json.loads((derived_dir / "concept-graph.json").read_text(encoding="utf-8"))

    chunk_to_referencing_cards: dict[str, list[dict]] = {}
    rev_path = derived_dir / "chunk_to_referencing_cards.json"
    if rev_path.is_file():
        chunk_to_referencing_cards = json.loads(rev_path.read_text(encoding="utf-8"))

    cfg_path = derived_dir / "build-config.json"
    if not cfg_path.is_file():
        raise FileNotFoundError(f"build-config.json not found at {cfg_path}")
    cfg = json.loads(cfg_path.read_text(encoding="utf-8"))
    embedding_model = cfg["embedding_model"]
    embedding_dim = cfg["embedding_dimensions"]

    reg_path = repo_root / "content" / "syntopicon-mgrecon780" / "_registry.json"
    registry: dict = {}
    if reg_path.is_file():
        registry = json.loads(reg_path.read_text(encoding="utf-8"))
    term_regex = build_regex(registry) if registry else re.compile(r"$^")

    return Catalog(
        records=records, term_to_docs=term_to_docs, concept_graph=concept_graph,
        embedding_model=embedding_model, embedding_dim=embedding_dim,
        term_regex=term_regex, registry=registry,
        chunk_to_referencing_cards=chunk_to_referencing_cards,
    )