"""Discord file naming, checked against the metadata gallery-dl really emitted.

Discord moved from gallery-dl to the native downloader in milestone 428. Every
file gallery-dl wrote is on disk under gallery-dl's naming, and the native
downloader finds it there — skips it instead of fetching it again — only if it
builds the SAME name. This file used to pin gallery-dl's patterns (#3999: they
named keys the extractor never set, and every file landed as
`None/<date>_None_<name>`); it now pins the native downloader to what those
patterns produced from the same real metadata.

The fixture keeps the key set and value types of a real attachment sidecar
from the operator's instance (2026-09-13), with every value invented.
"""

import json
from pathlib import Path

from backend.app.services.discord_client import DiscordClient
from backend.app.services.discord_downloader import channel_dir, media_stem
from backend.app.utils.sidecar import find_sidecar

_FIXTURE = Path(__file__).parent / "fixtures" / "discord_attachment_sidecar.json"


def _message_from_the_fixture():
    """The API message that produced the fixture's sidecar."""
    gdl = json.loads(_FIXTURE.read_text())
    date, time = gdl["date"].split(" ")
    return {
        "id": gdl["message_id"],
        "type": 0,
        "timestamp": f"{date}T{time}.000000+00:00",
        "content": gdl["message"],
        "attachments": [{"id": "500000000000000005", "url": gdl["url"]}],
        "embeds": [],
        "_meta": {"channel": gdl["channel"], "channel_id": gdl["channel_id"],
                  "server": gdl["server"], "server_id": gdl["server_id"]},
    }


def test_the_native_name_is_the_name_gallery_dl_wrote(tmp_path):
    """gallery-dl's `{date:%Y%m%d}_{message_id}_{num:>02}_{filename}.{extension}`
    in directory `{channel}`, rendered from the fixture."""
    msg = _message_from_the_fixture()
    [media] = DiscordClient.extract_media(msg)
    assert media_stem(msg, media) + "." + media.extension == (
        "20240716_300000000000000003_01_image.png"
    )
    assert channel_dir(tmp_path, "a", msg) == tmp_path / "a" / "discord" / "nsfw-drops"


def test_a_gallery_dl_sidecar_on_disk_still_pairs_with_its_file(tmp_path):
    """Files gallery-dl wrote keep their full sidecars beside them; the native
    name must be the stem those sidecars were named after."""
    msg = _message_from_the_fixture()
    [media] = DiscordClient.extract_media(msg)
    stem = media_stem(msg, media)
    (tmp_path / f"{stem}.png").write_bytes(b"x")
    (tmp_path / f"{stem}.json").write_text(_FIXTURE.read_text())
    assert find_sidecar(tmp_path / f"{stem}.png") == tmp_path / f"{stem}.json"


def test_two_files_with_the_same_original_name_get_distinct_names():
    """`image.png` is Discord's default name; two messages must not collide."""
    one = _message_from_the_fixture()
    two = {**one, "id": "300000000000000099"}
    [m1] = DiscordClient.extract_media(one)
    [m2] = DiscordClient.extract_media(two)
    assert media_stem(one, m1) != media_stem(two, m2)