"""Post-run filesystem read of the FDR archive.

The FDR archive is a line-delimited JSON record stream per AZ-272 / AZ-273.
Each line is an `FdrRecord` envelope (producer_id, type, monotonic_ms,
payload). The runner image must NEVER import the SUT's FdrRecord schema
directly — it parses the JSON bytes and validates against a duplicate
record-type allowlist baked into this module.

Public surface only; concrete parser + assertion helpers are owned by
AZ-441 (NFT-LIM-02 — FDR size budget) and the resilience scenario tasks
that need to crawl the archive (AZ-432, AZ-433, AZ-435).
"""

from __future__ import annotations

from dataclasses import dataclass
from pathlib import Path
from typing import Iterator


@dataclass(frozen=True)
class FdrRecord:
    """Mirror of `gps_denied_onboard.fdr_client.records.FdrRecord` — public-boundary copy.

    The schema is duplicated intentionally; if the SUT's FDR schema evolves
    in a breaking way, this duplicate file fails to parse (visible drift)
    rather than silently following along.
    """

    producer_id: str
    monotonic_ms: int
    record_type: str
    payload: dict[str, object]


def iter_records(fdr_archive_root: Path) -> Iterator[FdrRecord]:
    """Iterate every FDR record in the archive root (ordered by monotonic_ms).

    Raises NotImplementedError until AZ-441 supplies the orjson-backed parser.
    """
    raise NotImplementedError(
        "fdr_reader.iter_records is owned by AZ-441 — AZ-406 supplies only "
        "the public surface."
    )


def archive_size_bytes(fdr_archive_root: Path) -> int:
    """Sum the size of every file under ``fdr_archive_root``.

    Concrete implementation here — it's a thin os.walk + stat loop that
    NFT-LIM-02 needs as soon as a real archive lands.
    """
    if not fdr_archive_root.exists():
        return 0
    total = 0
    for p in fdr_archive_root.rglob("*"):
        if p.is_file():
            total += p.stat().st_size
    return total