"""Capture-bound Needs review items for ambiguous files (#249 E2).

The output scan and the live monitor hand every file the ingestion resolver
finds ``ambiguous`` to :func:`record_ambiguous_file`. It captures the file
(the bounded private copy of ``utils.media_capture``, hashed while copied),
reads the metadata again from the capture, resolves it with the default
(ingestion) profile and stores only an ``ambiguous`` result, bound to the
capture's byte record. The evidence a reviewer chooses from is therefore the
evidence of exactly those bytes. An ambiguous result is stored only when it
is ``reviewable``: at least two candidates carry a resolved prompt text. With
none the file could not be traced; with exactly one, the untraced branches
may still have made the file, so that text is not certain and the file stays
unresolved (the resolver never flattens unknown semantics into a guess).
Nothing here links a file, loads a model or decodes pixels; the capture is
released before the database write.

Evidence is small on purpose (startup validates every row): the resolver's
reason and, per candidate sampler, ``{sampler_id, state, reason, positive,
negative}`` where each side is ``{text, storage_text, provenance}``. A
candidate's ``hash`` is the SHA-256 of its canonical JSON without the hash.
More than ``MAX_CANDIDATES`` candidates or evidence over the 8 MiB bound make
a ``limited`` item without candidates (a result without any candidate is not
``reviewable`` and is never stored).
"""

from __future__ import annotations

import hashlib
import json
import logging
import os
from pathlib import Path
from typing import Any

try:
    from ..database.library_commands import LibraryCommandError
    from ..database.review_schema import (
        MAX_CANDIDATES,
        MIN_CHOOSABLE,
        canonical_evidence,
        choosable,
    )
    from .media_capture import CaptureCapacity, CaptureError
    from .prompt_inspector import MetadataReadError, read_inspection_file
    from .prompt_pair_resolver import RESOLVER_VERSION, resolve_prompt_pair
except ImportError:  # imported with the repo root on sys.path
    from database.library_commands import LibraryCommandError
    from database.review_schema import (
        MAX_CANDIDATES,
        MIN_CHOOSABLE,
        canonical_evidence,
        choosable,
    )
    from utils.media_capture import CaptureCapacity, CaptureError
    from utils.prompt_inspector import MetadataReadError, read_inspection_file
    from utils.prompt_pair_resolver import RESOLVER_VERSION, resolve_prompt_pair

logger = logging.getLogger("prompt_manager.review_capture")

# Capture scope label: review captures are never handed to a client.
REVIEW_SCOPE = "needs-review"
# Nested ambiguous stages are flattened at most this deep.
MAX_CANDIDATE_DEPTH = 8


def record_ambiguous_file(db, store, root, root_index: int, relative: str) -> str:
    """Persist the ambiguous evidence of one rooted file.

    Returns ``recorded`` (new item with candidates), ``limited`` (new item
    without candidates), ``duplicate`` (these bytes already carry this
    evidence, or the file's current stat is the verified fingerprint of
    bytes an item cites, so it is not even copied, and that item is still
    pending), ``decided`` (as ``duplicate``, but the item carries a decision,
    so the file is not in the queue), ``untraced`` (ambiguous in its captured
    bytes, but not ``reviewable``: nothing to choose, nothing stored) or
    ``skipped`` (the file
    changed, vanished, is not ambiguous in its captured bytes, or storage was
    restored meanwhile).
    ``CaptureCapacity`` and database errors propagate to the caller, which
    logs and counts them.
    """
    spelled_path, queued = _queued_spelling(db, root, relative)
    if queued is not None:
        return _already_queued(db, *queued)
    epoch = db.get_execution_epoch()
    try:
        # Background: the last worker stays free for an interactive request.
        capture = store.capture(
            root,
            relative,
            epoch=epoch,
            scope=REVIEW_SCOPE,
            root_index=root_index,
            background=True,
        )
    except CaptureCapacity:
        raise
    except CaptureError as error:
        logger.debug("Review capture skipped (%s): %s", error.code, error)
        return "skipped"
    try:
        captured = captured_review(store, capture)
    finally:
        store.release(capture.token)
    resolution = captured[1] if captured is not None else None
    if resolution is None or resolution.get("state") != "ambiguous":
        return "skipped"
    if not reviewable(resolution):
        return "untraced"
    evidence, count, limited = review_evidence(resolution)
    try:
        inserted = db.record_review_item(
            locator=capture.locator,
            spelled_path=spelled_path,
            sha256=capture.sha256,
            size=capture.size,
            mtime_ns=capture.mtime_ns,
            epoch=capture.epoch,
            resolver_version=RESOLVER_VERSION,
            evidence=evidence,
            candidate_count=count,
            limited=limited,
        )
    except LibraryCommandError:
        return "skipped"
    if not inserted:
        return _already_queued(db, capture.locator, capture.size, capture.mtime_ns)
    return "limited" if limited else "recorded"


def _already_queued(db, locator: str, size: int, mtime_ns: int) -> str:
    """``duplicate`` while the existing item is pending, else ``decided``."""
    if db.review_pending_at(locator, size, mtime_ns, RESOLVER_VERSION):
        return "duplicate"
    return "decided"


def _queued_spelling(db, root, relative: str) -> tuple[str, tuple | None]:
    """The file's spelling, and ``(locator, size, mtime_ns)`` when queued.

    The second value is None unless the file's current stat is already
    queued.

    The spelling is the capture's own candidate path (the real root joined
    with the listed relative path), so it folds to the capture's locator. A
    file whose size and ``mtime_ns`` equal the verified fingerprint of bytes
    an item already cites is not copied or hashed again (maintainer ruling:
    the rescan stays cheap and the file stays in the default scope); its
    items take the current spelling. A stat failure leaves the decision to
    the capture.
    """
    spelled = os.path.join(os.path.realpath(os.fspath(root)), *relative.split("/"))
    try:
        facts = os.lstat(spelled)
    except OSError:
        return spelled, None
    locator = os.path.normcase(spelled)
    if db.review_fingerprint_queued(
        locator, facts.st_size, facts.st_mtime_ns, RESOLVER_VERSION
    ):
        # Not copied again, but a case-only rename keeps the stat: record
        # the current spelling so the item's target still opens.
        db.refresh_review_spelling(locator, spelled)
        return spelled, (locator, facts.st_size, facts.st_mtime_ns)
    return spelled, None


def captured_review(store, capture) -> tuple[dict, dict] | None:
    """``(metadata, resolution)`` of the capture's own bytes, else None.

    ``metadata`` is what the scan hands the ingester: prompt and workflow
    JSON-decoded and ``file_info`` (size, dimensions, format) from the
    capture. None when the capture is gone or carries no prompt metadata.
    """
    if store.acquire(capture.token) is None:
        return None
    try:
        try:
            read = read_inspection_file(Path(capture.path))
        except MetadataReadError:
            return None
    finally:
        store.release_use(capture.token)
    canonical = dict(read.metadata)
    for key in ("prompt", "workflow"):
        if isinstance(canonical.get(key), str):
            try:
                canonical[key] = json.loads(canonical[key])
            except (ValueError, TypeError, RecursionError):
                # Malformed metadata stays as text for the resolver to reject.
                pass
    if not canonical.get("prompt") and not canonical.get("parameters"):
        return None
    info = {"size": capture.size}
    if read.width is not None and read.height is not None:
        info["dimensions"] = [read.width, read.height]
    if read.format is not None:
        info["format"] = read.format
    canonical["file_info"] = info
    return canonical, resolve_prompt_pair(canonical)


def reviewable(resolution: Any) -> bool:
    """True when an ambiguous result offers a choice: ``MIN_CHOOSABLE`` of its
    selectable candidates (nested ambiguous stages flattened) are choosable.

    Counted before the evidence is bounded, so a ``limited`` item (more than
    ``MAX_CANDIDATES`` candidates) with prompts to choose is still queued.
    """
    if not isinstance(resolution, dict) or resolution.get("state") != "ambiguous":
        return False
    count = 0
    for candidate in _flattened(resolution.get("candidates"), 0):
        if choosable(candidate):
            count += 1
            if count >= MIN_CHOOSABLE:
                return True
    return False


def review_evidence(resolution: dict) -> tuple[dict, int, bool]:
    """``(evidence, candidate_count, limited)`` for one ambiguous result."""
    base = {
        "resolver_version": RESOLVER_VERSION,
        "reason": _text(resolution.get("reason")),
    }
    candidates: list[dict] = []
    seen: set[str] = set()
    total = 0
    for candidate in _flattened(resolution.get("candidates"), 0):
        total += 1
        try:
            projected = _projection(candidate)
            digest = hashlib.sha256(
                canonical_evidence(projected).encode("utf-8")
            ).hexdigest()
        except (ValueError, TypeError, KeyError):
            return _limited(base, total), 0, True
        if digest in seen:
            total -= 1
            continue
        seen.add(digest)
        candidates.append({**projected, "hash": digest})
    if not candidates or len(candidates) > MAX_CANDIDATES:
        return _limited(base, total), 0, True
    evidence = {**base, "candidates": candidates}
    try:
        canonical_evidence(evidence)
    except ValueError:
        return _limited(base, total), 0, True
    return evidence, len(candidates), False


def _limited(base: dict, total: int) -> dict:
    return {**base, "limited": True, "candidate_total": total, "candidates": []}


def _flattened(candidates: Any, depth: int):
    """Selectable candidates; a nested ambiguous stage yields its own."""
    if not isinstance(candidates, list):
        return
    for candidate in candidates:
        if not isinstance(candidate, dict):
            continue
        nested = candidate.get("candidates")
        if (
            candidate.get("state") == "ambiguous"
            and isinstance(nested, list)
            and nested
            and depth < MAX_CANDIDATE_DEPTH
        ):
            yield from _flattened(nested, depth + 1)
        else:
            yield candidate


def _projection(candidate: dict) -> dict:
    return {
        "sampler_id": candidate.get("sampler_id"),
        "state": _text(candidate.get("state")),
        "reason": _text(candidate.get("reason")),
        "positive": _side(candidate.get("positive")),
        "negative": _side(candidate.get("negative")),
    }


def _side(side: Any) -> dict | None:
    if not isinstance(side, dict):
        return None
    text = side["text"]
    return {
        "text": text,
        "storage_text": side.get("storage_text", text),
        "provenance": side.get("provenance"),
    }


def _text(value: Any) -> str:
    return value if isinstance(value, str) else ""