"""Operator pre-flight cache assembly driver (AZ-839 / Epic AZ-835 C3).

Replaces the placeholder ``operator_pre_flight_setup`` fixture stub at
``conftest.py`` lines 293-310 with a real driver that wires together
the four operator-side production components:

1. **C1 / AZ-836 RouteSpec** — already extracted by the caller via
   :func:`gps_denied_onboard.replay_input.tlog_route.extract_route_from_tlog`
   and handed in as :paramref:`populate_c6_from_route.route_spec`.
2. **C2 / AZ-838 SatelliteProviderRouteClient** — POSTs the route to
   satellite-provider, polls ``mapsReady``.
3. **C11 / AZ-316 + AZ-777 Phase 1 HttpTileDownloader** — pulls the
   seeded tiles from satellite-provider into C6 over a bbox derived
   from the route waypoints.
4. **C10 / AZ-322 DescriptorBatcher** — rebuilds the FAISS HNSW
   descriptor index over the populated C6 cache (NetVLAD backbone per
   ``c2_vpr/config.py:67``).

The descriptor index sidecar coherence (AZ-306 triple-consistency:
``.index`` + ``.sha256`` + ``.meta.json``) is verified by re-loading
the index after rebuild via the caller-supplied
``descriptor_index_factory``; any tampering surfaces as
:class:`IndexUnavailableError`.

Public surface — re-exported from this module:

* :class:`PopulatedC6Cache` — frozen dataclass returned on success.
* :func:`populate_c6_from_route` — the driver function.

Cleanup-on-failure removes any FAISS sidecar files produced inside the
driver if any later step raises. Tile-store rows written by C11 are
NOT deleted (the C6 store owns its own rollback semantics — leaving
those rows enables idempotent re-runs via the C11 download journal).
"""

from __future__ import annotations

import logging
import time
from collections.abc import Callable
from dataclasses import dataclass
from pathlib import Path
from typing import Any
from uuid import UUID, uuid4

from gps_denied_onboard.components.c10_provisioning.descriptor_batcher import (
    BatcherOutcome,
    CorpusFilter,
    DescriptorBatcher,
)
from gps_denied_onboard.components.c11_tile_manager import (
    DownloadOutcome,
    DownloadRequest,
    HttpTileDownloader,
    SectorClassification,
)
from gps_denied_onboard.components.c11_tile_manager.errors import (
    RouteTerminalFailureError,
    RouteTransientError,
    RouteValidationError,
)
from gps_denied_onboard.components.c11_tile_manager.route_client import (
    SatelliteProviderRouteClient,
)
from gps_denied_onboard.components.c6_tile_cache.errors import (
    IndexUnavailableError,
)
from gps_denied_onboard.components.c6_tile_cache.faiss_descriptor_index import (
    META_SUFFIX,
)
from gps_denied_onboard.helpers.sha256_sidecar import SIDECAR_SUFFIX
from gps_denied_onboard._types.route import RouteSpec

__all__ = [
    "PopulatedC6Cache",
    "populate_c6_from_route",
]


# Mirror C11's existing schedule so the fixture does not introduce a
# parallel retry budget. AC-5 ties our per-attempt cap (3) to the
# documented pause cadence; the schedule itself lives in the
# downloader module and is re-exported here so tests can override.
_DEFAULT_RETRY_SCHEDULE_S: tuple[float, ...] = (1.0, 2.0, 4.0, 8.0)
_DEFAULT_MAX_RETRY_ATTEMPTS: int = 3
_DEFAULT_ZOOM_LEVEL: int = 18
_DEFAULT_SECTOR_CLASS: SectorClassification = SectorClassification.ACTIVE_CONFLICT
# Per-degree-of-latitude metres at WGS84 mean radius — reused from C11
# route-coverage enumeration (route_client._enumerate_route_tile_coords).
# Re-stated here so the driver does not depend on a private constant.
_METERS_PER_DEGREE_LAT: float = 111_320.0

_LOGGER = logging.getLogger(
    "tests.e2e.replay.operator_pre_flight"
)


@dataclass(frozen=True, slots=True)
class PopulatedC6Cache:
    """Output of :func:`populate_c6_from_route`.

    Mirrors the public-surface dataclass documented in the AZ-839 spec.
    All paths point at on-disk artifacts that survive the fixture's
    ``session`` scope (when mounted on the named docker volume the
    e2e-runner declares); ``elapsed_seconds`` powers the AC-1 / AC-2
    perf budget assertions.
    """

    cache_root: Path
    tile_store_path: Path
    faiss_index_path: Path
    faiss_sidecar_sha256_path: Path
    faiss_sidecar_meta_path: Path
    route_spec: RouteSpec
    tile_count: int
    elapsed_seconds: float


def populate_c6_from_route(
    *,
    route_spec: RouteSpec,
    route_client: SatelliteProviderRouteClient,
    tile_downloader: HttpTileDownloader,
    descriptor_batcher: DescriptorBatcher,
    descriptor_index_factory: Callable[[], Any],
    cache_root: Path,
    tile_store_path: Path,
    faiss_index_path: Path,
    flight_id: UUID | None = None,
    sector_class: SectorClassification = _DEFAULT_SECTOR_CLASS,
    zoom_level: int = _DEFAULT_ZOOM_LEVEL,
    region_size_meters: float | None = None,
    retry_schedule_s: tuple[float, ...] = _DEFAULT_RETRY_SCHEDULE_S,
    max_retry_attempts: int = _DEFAULT_MAX_RETRY_ATTEMPTS,
    sleep: Callable[[float], None] = time.sleep,
    monotonic: Callable[[], float] = time.monotonic,
    logger: logging.Logger | None = None,
) -> PopulatedC6Cache:
    """Drive the full C1+C2+C11+C10 pipeline end-to-end.

    Args:
        route_spec: Coarsened route from AZ-836's
            :func:`extract_route_from_tlog`. The caller chooses the
            tlog (typically a session-scoped fixture); this driver is
            tlog-agnostic.
        route_client: Configured C2 client. Built from env vars by the
            production fixture; injected as a stub by unit tests.
        tile_downloader: Configured C11 downloader. Same wiring rules.
        descriptor_batcher: Configured C10 batcher; its rebuild path
            owns the on-disk FAISS write (atomic via
            :class:`Sha256Sidecar`).
        descriptor_index_factory: Zero-arg callable that constructs a
            FRESH descriptor index pointed at ``faiss_index_path``.
            Production passes
            ``lambda: FaissDescriptorIndex.from_config(config)``; the
            constructor auto-loads via
            :meth:`FaissDescriptorIndex._load`, raising
            :class:`IndexUnavailableError` on triple-consistency
            failure (AC-3 / AC-6 verification).
        cache_root: Root directory mounted on the named docker volume
            that survives across pytest sessions.
        tile_store_path: Where C6's :class:`TileStore` writes JPEG
            blobs. Carried on the result for downstream tests.
        faiss_index_path: Final ``.index`` blob path. Sidecars live at
            ``<faiss_index_path>.sha256`` + ``<faiss_index_path>.meta.json``.
        flight_id: C11 download-journal key; defaults to a fresh UUID
            so two fixture sessions never collide their journals.
        sector_class: C11 / C6 sector classification. Defaults to
            ``ACTIVE_CONFLICT`` — Derkachi is an active-conflict
            corridor; ``STABLE_REAR`` is for non-Ukraine clips.
        zoom_level: Single Web-Mercator zoom level the fixture
            populates. AZ-839 spec defaults to 18 to match
            ``seed_route.py`` ergonomics; tests override for speed.
        region_size_meters: Per-waypoint coverage radius in metres.
            ``None`` falls back to
            :attr:`RouteSpec.suggested_region_size_meters`.
        retry_schedule_s: Pause cadence between transient retries.
            Defaults to C11's documented ``_DEFAULT_BACKOFF_SCHEDULE_S``.
        max_retry_attempts: Total :meth:`seed_route` attempts on
            transient error before propagating (AC-5 — final
            attempt's exception is propagated unchanged).
        sleep: Test override for the retry pause; production passes
            :func:`time.sleep`.
        monotonic: Test override for elapsed-time measurement.
        logger: Optional logger. Defaults to the module logger.

    Returns:
        :class:`PopulatedC6Cache` on success.

    Raises:
        RouteValidationError: Pre-emptive validation or HTTP 4xx —
            propagated unchanged with original cause (AC-4).
        RouteTerminalFailureError: ``mapsReady`` never reached or
            terminal failure status — propagated unchanged (AC-4).
        RouteTransientError: 5xx / network / timeout AFTER all retry
            attempts have been exhausted (AC-5).
        IndexUnavailableError: Triple-consistency check failed after
            rebuild — sidecars are corrupt / mismatched (AC-3 / AC-6).
        RuntimeError: C11 ``download_tiles_for_area`` returned a
            non-success outcome OR C10 ``populate_descriptors``
            returned :attr:`BatcherOutcome.FAILURE`.

    Notes:
        Cleanup behaviour (AC-7) — if any step raises after the
        rebuild has begun writing sidecar files, the partial files
        (.index, .sha256, .meta.json) are removed before the
        exception propagates so a re-run starts from a clean slate.
        Tile-store rows are NOT deleted on cleanup; the C11 download
        journal owns idempotent re-run semantics.
    """

    log = logger or _LOGGER
    if max_retry_attempts < 1:
        raise ValueError(
            f"max_retry_attempts must be >= 1; got {max_retry_attempts}"
        )

    started_monotonic = monotonic()
    effective_flight_id = flight_id or uuid4()
    effective_region_size = float(
        region_size_meters
        if region_size_meters is not None
        else route_spec.suggested_region_size_meters
    )
    if effective_region_size <= 0:
        raise ValueError(
            f"region_size_meters must be > 0; got {effective_region_size}"
        )
    if not route_spec.waypoints:
        raise ValueError("route_spec.waypoints must be non-empty")

    sidecar_paths = (
        faiss_index_path,
        Path(str(faiss_index_path) + SIDECAR_SUFFIX),
        Path(str(faiss_index_path) + META_SUFFIX),
    )
    pre_existing_sidecar = {p: p.is_file() for p in sidecar_paths}

    try:
        seed_result = _seed_route_with_retry(
            route_client=route_client,
            spec=route_spec,
            region_size_meters=effective_region_size,
            zoom_level=zoom_level,
            retry_schedule_s=retry_schedule_s,
            max_retry_attempts=max_retry_attempts,
            sleep=sleep,
            logger=log,
        )

        bbox = _route_bbox(
            waypoints=route_spec.waypoints,
            region_size_meters=effective_region_size,
        )
        download_request = DownloadRequest(
            flight_id=effective_flight_id,
            bbox_min_lat=bbox[0],
            bbox_min_lon=bbox[1],
            bbox_max_lat=bbox[2],
            bbox_max_lon=bbox[3],
            zoom_levels=(int(zoom_level),),
            sector_class=sector_class,
            cache_root=cache_root,
        )
        download_report = tile_downloader.download_tiles_for_area(download_request)
        if download_report.outcome not in {
            DownloadOutcome.SUCCESS,
            DownloadOutcome.IDEMPOTENT_NO_OP,
        }:
            raise RuntimeError(
                "C11 download_tiles_for_area returned non-success outcome "
                f"{download_report.outcome.value!r}; "
                f"requested={download_report.tiles_requested} "
                f"downloaded={download_report.tiles_downloaded} "
                f"rejected_resolution={download_report.tiles_rejected_resolution} "
                f"rejected_freshness={download_report.tiles_rejected_freshness}"
            )

        log.info(
            "operator_pre_flight: tiles populated",
            extra={
                "kind": "operator_pre_flight.tiles_populated",
                "kv": {
                    "route_id": str(seed_result.route_id),
                    "seeded_tile_count": seed_result.tile_count,
                    "downloaded_tiles": download_report.tiles_downloaded,
                    "request_hash": download_report.request_hash,
                },
            },
        )

        corpus_filter = CorpusFilter(
            bbox=bbox,
            zoom_levels=(int(zoom_level),),
            sector_class=sector_class.value,
        )
        batcher_report = descriptor_batcher.populate_descriptors(corpus_filter)
        if batcher_report.outcome is not BatcherOutcome.SUCCESS:
            raise RuntimeError(
                "C10 populate_descriptors returned FAILURE: "
                f"{batcher_report.failure_reason}"
            )

        verifier_index = descriptor_index_factory()
        log.debug(
            "operator_pre_flight: sidecar coherence verified",
            extra={
                "kind": "operator_pre_flight.sidecar_verified",
                "kv": {
                    "faiss_index_path": str(faiss_index_path),
                    "verifier_type": type(verifier_index).__name__,
                },
            },
        )

        elapsed_seconds = max(0.0, monotonic() - started_monotonic)
        return PopulatedC6Cache(
            cache_root=cache_root,
            tile_store_path=tile_store_path,
            faiss_index_path=faiss_index_path,
            faiss_sidecar_sha256_path=sidecar_paths[1],
            faiss_sidecar_meta_path=sidecar_paths[2],
            route_spec=route_spec,
            tile_count=batcher_report.tiles_consumed,
            elapsed_seconds=elapsed_seconds,
        )
    except BaseException:
        _cleanup_partial_sidecars(
            sidecar_paths=sidecar_paths,
            pre_existing=pre_existing_sidecar,
            logger=log,
        )
        raise


def _seed_route_with_retry(
    *,
    route_client: SatelliteProviderRouteClient,
    spec: RouteSpec,
    region_size_meters: float,
    zoom_level: int,
    retry_schedule_s: tuple[float, ...],
    max_retry_attempts: int,
    sleep: Callable[[float], None],
    logger: logging.Logger,
) -> Any:
    """Call ``seed_route`` with bounded transient retries (AC-5).

    Validation / terminal-failure errors propagate IMMEDIATELY with
    their original cause (AC-4 — no silent swallow). Only
    :class:`RouteTransientError` triggers the retry ladder; the final
    attempt's exception is re-raised unchanged so the caller sees
    the actual transient signal that exhausted the budget.
    """
    last_transient: RouteTransientError | None = None
    for attempt in range(1, max_retry_attempts + 1):
        try:
            return route_client.seed_route(
                spec,
                region_size_meters=region_size_meters,
                zoom_level=zoom_level,
            )
        except (RouteValidationError, RouteTerminalFailureError):
            raise
        except RouteTransientError as exc:
            last_transient = exc
            logger.warning(
                "operator_pre_flight: route seed transient failure",
                extra={
                    "kind": "operator_pre_flight.route_seed.transient",
                    "kv": {
                        "attempt": attempt,
                        "max_attempts": max_retry_attempts,
                        "exc": repr(exc),
                    },
                },
            )
            if attempt >= max_retry_attempts:
                raise
            pause_s = retry_schedule_s[
                min(attempt - 1, len(retry_schedule_s) - 1)
            ]
            sleep(pause_s)
    # Defensive — the loop body always returns or raises before this.
    if last_transient is not None:
        raise last_transient
    raise RuntimeError(
        "operator_pre_flight: seed_route loop exited without result"
    )


def _route_bbox(
    *,
    waypoints: tuple[tuple[float, float], ...],
    region_size_meters: float,
) -> tuple[float, float, float, float]:
    """Bounding box of every waypoint's coverage square.

    Mirrors the local enumeration in
    :func:`gps_denied_onboard.components.c11_tile_manager.route_client._enumerate_route_tile_coords`
    by taking ``region_size_meters`` as the per-waypoint square edge
    and unioning the lat/lon extents. The result is a single bbox
    that the C11 :meth:`HttpTileDownloader.download_tiles_for_area`
    Protocol consumes; C11 then runs the standard slippy-map
    enumeration over that bbox at the requested zoom level.

    Returns:
        ``(min_lat, min_lon, max_lat, max_lon)`` — matching
        :class:`DownloadRequest`'s field order.
    """

    import math

    half = region_size_meters / 2.0
    min_lat = float("inf")
    max_lat = float("-inf")
    min_lon = float("inf")
    max_lon = float("-inf")
    for lat_deg, lon_deg in waypoints:
        lat_delta_deg = half / _METERS_PER_DEGREE_LAT
        cos_lat = math.cos(math.radians(lat_deg))
        if cos_lat <= 1e-9:
            cos_lat = 1e-9
        lon_delta_deg = half / (_METERS_PER_DEGREE_LAT * cos_lat)
        min_lat = min(min_lat, lat_deg - lat_delta_deg)
        max_lat = max(max_lat, lat_deg + lat_delta_deg)
        min_lon = min(min_lon, lon_deg - lon_delta_deg)
        max_lon = max(max_lon, lon_deg + lon_delta_deg)

    if min_lat >= max_lat or min_lon >= max_lon:
        raise ValueError(
            "operator_pre_flight: degenerate bbox from route waypoints "
            f"(min_lat={min_lat}, max_lat={max_lat}, "
            f"min_lon={min_lon}, max_lon={max_lon})"
        )
    return (min_lat, min_lon, max_lat, max_lon)


def _cleanup_partial_sidecars(
    *,
    sidecar_paths: tuple[Path, ...],
    pre_existing: dict[Path, bool],
    logger: logging.Logger,
) -> None:
    """Remove sidecar files this driver may have produced.

    Only files that did NOT exist when the driver started AND now
    exist are removed — pre-existing files (a warm cache from a prior
    run) are preserved. OS errors during cleanup are logged but do
    not mask the original exception.
    """

    for path in sidecar_paths:
        if pre_existing.get(path, False):
            continue
        if not path.exists():
            continue
        try:
            path.unlink()
            logger.warning(
                "operator_pre_flight: cleaned up partial sidecar",
                extra={
                    "kind": "operator_pre_flight.cleanup.removed",
                    "kv": {"path": str(path)},
                },
            )
        except OSError as exc:
            logger.error(
                "operator_pre_flight: cleanup unlink failed",
                extra={
                    "kind": "operator_pre_flight.cleanup.failed",
                    "kv": {"path": str(path), "exc": repr(exc)},
                },
            )