"""Prove a freshly built image can still do the things its OS packages provide.

Run INSIDE the image, not against the source tree. That distinction is the
entire reason this file exists.

`ci.yml`'s lanes run on `ci-python:3.14` and install `requirements.txt`. A base
refresh changes neither, so all five lanes stay green through a base bump that
breaks the product. What a refresh actually re-resolves is this, from the
Dockerfile:

    RUN apt-get update && apt-get install -y --no-install-recommends \
            ffmpeg unar libpq5 postgresql-client zstd megatools \
            libjpeg62-turbo libwebp7 libpng16-16 ca-certificates

Unpinned, every build. Nothing else in this repo looks at it.

So the checks below run the APPLICATION'S OWN code — `Thumbnailer`, which needs
no database and no app context — against whatever Pillow and ffmpeg have
become. `ffmpeg -version` exiting 0 would pass while a codec removal or an
soname bump broke every thumbnail in the library; producing a thumbnail would
not.

Every failure names the package it implicates. This fires on a Sunday,
unattended, about a change nobody made deliberately — "assertion failed" a week
later teaches nobody anything.

Usage:  docker run --rm -i <image> shell -c 'python3 -' < scripts/smoke_image.py
"""

from __future__ import annotations

import shutil
import subprocess
import tempfile
from pathlib import Path

try:
    from PIL import Image

    from backend.app.services.thumbnailer import Thumbnailer
except Exception as exc:  # noqa: BLE001 — a smoke test reports, it never raises
    print(f"smoke: FAILED — could not import the thumbnail path at all: {exc}")
    print("  Implicates Pillow or its shared libraries (libjpeg62-turbo,")
    print("  libpng16-16, libwebp7), or the python base image itself.")
    raise SystemExit(1) from exc


# Binary → what stops working without it. Listed individually because
# `--no-install-recommends` means any one of them can vanish on its own when a
# dependency chain higher up changes.
REQUIRED_BINARIES = {
    "ffmpeg": "video thumbnails and transcoding (Dockerfile: ffmpeg)",
    "unar": "archive import — cbz/zip/rar members (Dockerfile: unar)",
    "pg_dump": "database backup (Dockerfile: postgresql-client)",
    "zstd": "backup compression, pg_dump | tar --zstd (Dockerfile: zstd)",
    "megatools": "mega.nz public-link downloads, #830 (Dockerfile: megatools)",
}


def check_jpeg(thumbs: Thumbnailer, src: Path) -> None:
    path = src / "flat.jpg"
    Image.new("RGB", (900, 400), (30, 90, 160)).save(path, "JPEG")
    result = thumbs.generate_image_thumbnail(path, "a" * 64)
    assert result.mime == "image/jpeg", f"mime was {result.mime}"
    assert result.path.stat().st_size > 0, "no bytes written"
    # Re-open it. A file that writes but cannot be read back is the shape a
    # half-broken codec produces, and size alone would not catch it.
    with Image.open(result.path) as im:
        im.load()


def check_png_alpha(thumbs: Thumbnailer, src: Path) -> None:
    path = src / "alpha.png"
    Image.new("RGBA", (400, 900), (200, 40, 40, 128)).save(path, "PNG")
    result = thumbs.generate_image_thumbnail(path, "b" * 64)
    assert result.mime == "image/png", f"mime was {result.mime}"
    with Image.open(result.path) as im:
        im.load()
        assert im.mode in ("RGBA", "LA", "P"), f"alpha lost, mode={im.mode}"


def check_webp(thumbs: Thumbnailer, src: Path) -> None:
    path = src / "sample.webp"
    Image.new("RGB", (500, 500), (10, 140, 70)).save(path, "WEBP")
    result = thumbs.generate_image_thumbnail(path, "c" * 64)
    assert result.path.stat().st_size > 0, "no bytes written"


def check_video(thumbs: Thumbnailer, src: Path) -> None:
    # Synthesised rather than committed as a fixture: a checked-in video is a
    # binary blob nobody can review, and lavfi ships with every ffmpeg build.
    #
    # 3 seconds, not 2. The seek lands at max(1.0, duration * 0.05) = 1.0s, and
    # a clip barely longer than its own seek is how #1231 produced zero frames.
    # This check exists to exercise ffmpeg, not to re-litigate that edge.
    clip = src / "clip.mp4"
    subprocess.run(
        ["ffmpeg", "-nostdin", "-f", "lavfi", "-i", "testsrc=size=640x360:rate=10",
         "-t", "3", "-pix_fmt", "yuv420p", "-y", str(clip)],
        check=True, capture_output=True, timeout=120,
    )
    result = thumbs.generate_video_thumbnail(clip, "d" * 64, duration_seconds=3.0)
    assert result.path.stat().st_size > 0, "no bytes written"
    with Image.open(result.path) as im:
        im.load()


CHECKS = (
    ("JPEG thumbnail", "libjpeg62-turbo / Pillow", check_jpeg),
    ("PNG thumbnail (alpha)", "libpng16-16 / Pillow", check_png_alpha),
    ("WebP decode", "libwebp7 / Pillow", check_webp),
    ("video thumbnail", "ffmpeg", check_video),
)


def main() -> int:
    failures: list[str] = []

    print("smoke: binaries the apt layer provides")
    for binary, purpose in REQUIRED_BINARIES.items():
        if shutil.which(binary) is None:
            print(f"  FAIL  {binary}: not on PATH")
            failures.append(f"{binary} — {purpose}")
        else:
            print(f"  ok    {binary}")

    print("smoke: the application's own thumbnail path, against this image's libraries")
    with tempfile.TemporaryDirectory() as tmp:
        root = Path(tmp)
        src = root / "src"
        src.mkdir()
        thumbs = Thumbnailer(root)
        for name, implicates, fn in CHECKS:
            try:
                fn(thumbs, src)
                print(f"  ok    {name}")
            except Exception as exc:  # noqa: BLE001 — report every check, then fail once
                print(f"  FAIL  {name}: {exc}")
                failures.append(f"{name} — {implicates}")

    if failures:
        print(f"\nsmoke: FAILED — {len(failures)} check(s)")
        for failure in failures:
            print(f"  - {failure}")
        print("\nThis image was built against freshly resolved base layers. The")
        print("named packages are where to look: compare this build's apt versions")
        print("against the previous :latest before assuming the app changed.")
        return 1

    print("\nsmoke: all checks passed")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())