"""Tests for :class:`app.services.media.MediaService`.

Uses real bytes produced by Pillow in-test so the magic-byte check
exercises real image data. Does NOT mock the filesystem — writes go
to a per-test temp dir so we can assert the stored JPEG is a valid
JPEG after the re-encode pipeline.
"""

from __future__ import annotations

import io
from pathlib import Path

import pytest
from PIL import Image
from sqlalchemy import Engine

from app.services.audit import AuditService
from app.services.media import (
    MAX_UPLOAD_BYTES,
    MediaRejectedError,
    MediaService,
)


# ---------------------------------------------------------------------------
# helpers
# ---------------------------------------------------------------------------
def _jpeg_bytes(size: tuple[int, int] = (64, 48), color: str = "red") -> bytes:
    """Return valid JPEG bytes produced by Pillow."""
    img = Image.new("RGB", size, color)
    buf = io.BytesIO()
    img.save(buf, format="JPEG", quality=85)
    return buf.getvalue()


def _rgba_png_bytes(size: tuple[int, int] = (32, 32)) -> bytes:
    """Return valid RGBA-transparent PNG bytes."""
    img = Image.new("RGBA", size, (0, 128, 0, 128))
    buf = io.BytesIO()
    img.save(buf, format="PNG")
    return buf.getvalue()


@pytest.fixture
def media_root(tmp_path: Path) -> Path:
    """Return a per-test directory rooted under the pytest tmpdir."""
    root = tmp_path / "media"
    root.mkdir()
    return root


@pytest.fixture
def service(db_engine: Engine, media_root: Path) -> MediaService:
    """Return a :class:`MediaService` wired to a real engine + temp dir."""
    return MediaService(
        engine=db_engine,
        media_root=str(media_root),
        audit=AuditService(db_engine),
    )


# ---------------------------------------------------------------------------
# happy path
# ---------------------------------------------------------------------------
def test_save_upload_stores_jpeg_and_returns_media(
    service: MediaService, media_root: Path
) -> None:
    """A valid JPEG is re-encoded and written under a random filename."""
    data = _jpeg_bytes()
    media = service.save_upload(
        original_filename="cute-chick.jpg",
        data=data,
        uploaded_by=1,
    )

    assert media.id > 0
    assert media.content_type == "image/jpeg"
    assert media.filename.endswith(".jpg")
    assert media.original_filename == "cute-chick.jpg"
    assert media.size_bytes > 0

    stored = Path(media.stored_path)
    assert stored.exists()
    assert stored.parent.parent.parent == media_root
    # Verify the written file is a real JPEG RGB image.
    with Image.open(stored) as img:
        assert img.format == "JPEG"
        assert img.mode == "RGB"


def test_save_upload_assigns_random_filename_not_original(
    service: MediaService,
) -> None:
    """The stored filename is a random token — not the client-supplied name."""
    data = _jpeg_bytes()
    media = service.save_upload(
        original_filename="secret.jpg",
        data=data,
        uploaded_by=1,
    )
    assert media.filename != "secret.jpg"
    # Random component is 16 bytes url-safe (~22 chars) + ".jpg".
    name, _, ext = media.filename.rpartition(".")
    assert ext == "jpg"
    assert len(name) >= 16


def test_public_url_is_under_media_prefix(service: MediaService) -> None:
    """``public_url`` starts with ``/media/`` and a year partition."""
    media = service.save_upload(
        original_filename="ok.jpg",
        data=_jpeg_bytes(),
        uploaded_by=1,
    )
    url = service.public_url(media)
    assert url.startswith("/media/")
    assert url.endswith(media.filename)


def test_save_upload_flattens_rgba_onto_white(service: MediaService) -> None:
    """An RGBA PNG upload is flattened and stored as RGB JPEG."""
    data = _rgba_png_bytes()
    media = service.save_upload(
        original_filename="transparent.png",
        data=data,
        uploaded_by=1,
    )
    stored = Path(media.stored_path)
    with Image.open(stored) as img:
        assert img.format == "JPEG"
        assert img.mode == "RGB"


# ---------------------------------------------------------------------------
# rejection paths
# ---------------------------------------------------------------------------
def test_reject_empty_upload(service: MediaService) -> None:
    """Empty uploads are rejected before any decode runs."""
    with pytest.raises(MediaRejectedError):
        service.save_upload(
            original_filename="empty.jpg",
            data=b"",
            uploaded_by=1,
        )


def test_reject_non_image_bytes(service: MediaService) -> None:
    """A plain-text payload fails the magic-byte sniff."""
    with pytest.raises(MediaRejectedError):
        service.save_upload(
            original_filename="totally.jpg",
            data=b"this is definitely not an image payload" * 10,
            uploaded_by=1,
        )


def test_reject_gif_upload(service: MediaService) -> None:
    """Animated-GIF hazard — GIFs are explicitly not on the allowlist."""
    img = Image.new("RGB", (16, 16), "green")
    buf = io.BytesIO()
    img.save(buf, format="GIF")
    with pytest.raises(MediaRejectedError):
        service.save_upload(
            original_filename="animated.gif",
            data=buf.getvalue(),
            uploaded_by=1,
        )


def test_reject_oversize_upload(service: MediaService) -> None:
    """Payloads over the 8 MB cap are rejected."""
    huge = b"\xff" * (MAX_UPLOAD_BYTES + 1)
    with pytest.raises(MediaRejectedError):
        service.save_upload(
            original_filename="huge.jpg",
            data=huge,
            uploaded_by=1,
        )