"""The native Discord downloader lands files where gallery-dl did (#4414).

A cutover that names one file differently re-downloads it and imports a
duplicate, so these pin the path, the name cleaning and the sidecar pairing
against what gallery-dl's config produces — and that the records it writes read
back through `parse_sidecar` as the same post the gallery-dl sidecars made.
"""

from __future__ import annotations

import json

from backend.app.services.discord_client import DiscordClient
from backend.app.services.discord_downloader import (
    DiscordDownloader,
    channel_dir,
    gdl_clean,
    media_stem,
)
from backend.app.utils.sidecar import find_sidecar, parse_sidecar

_PNG = b"\x89PNG\r\n\x1a\n" + b"\x00" * 16 + b"\x00\x00\x00\x00IEND\xaeB`\x82"


class _Resp:
    status_code = 200
    headers: dict = {}

    def raise_for_status(self):
        pass

    def iter_content(self, chunk_size=None):
        yield _PNG


class _Media:
    def __init__(self):
        self.calls = []

    def get(self, url, stream=None, timeout=None, headers=None):
        self.calls.append(url)
        return _Resp()


def _message(**extra):
    return {
        "id": "1234", "type": 0, "timestamp": "2026-09-20T23:30:00.000000+00:00",
        "content": "new set!", "channel_id": "22",
        "author": {"id": "7", "username": "artist"},
        "attachments": [{"url": "https://cdn.discordapp.com/attachments/2/3/Red%3AAlt.PNG?ex=1"}],
        "embeds": [],
        "_meta": {"server": "Studio", "server_id": "11", "channel": "drops/nsfw",
                  "channel_id": "22", "is_thread": False},
        **extra,
    }


def _downloader(tmp_path, session=None):
    return DiscordDownloader(tmp_path, validate=False, session=session or _Media())


def test_names_follow_gallery_dls_pattern_and_linux_cleaning(tmp_path):
    msg = _message()
    [media] = DiscordClient.extract_media(msg)
    assert channel_dir(tmp_path, "art", msg) == tmp_path / "art" / "discord" / "drops_nsfw"
    # `:` survives: gallery-dl on Linux only replaces `/`.
    assert media_stem(msg, media) == "20260920_1234_01_Red:Alt"
    assert gdl_clean("a\x07b/c") == "ab_c"


def test_a_channel_with_no_name_adds_no_directory(tmp_path):
    msg = _message(_meta={"channel": "  "})
    assert channel_dir(tmp_path, "art", msg) == tmp_path / "art" / "discord"


def test_a_file_gallery_dl_already_wrote_is_not_fetched_again(tmp_path):
    msg = _message()
    media = DiscordClient.extract_media(msg)
    existing = tmp_path / "art" / "discord" / "drops_nsfw" / "20260920_1234_01_Red:Alt.png"
    existing.parent.mkdir(parents=True)
    existing.write_bytes(_PNG)
    session = _Media()
    [out] = _downloader(tmp_path, session).download_post(msg, media, "art")
    assert out.status == "skipped_disk" and out.path == existing
    assert session.calls == []


def test_a_new_file_gets_a_sidecar_the_importer_pairs_to_its_message(tmp_path):
    msg = _message()
    [out] = _downloader(tmp_path).download_post(msg, DiscordClient.extract_media(msg), "art")
    assert out.status == "downloaded"
    assert out.path.name == "20260920_1234_01_Red:Alt.png"
    sidecar = find_sidecar(out.path)
    assert sidecar is not None
    data = json.loads(sidecar.read_text())
    # No `id`/`post_id`: either would outrank message_id as the post id.
    assert "id" not in data and "post_id" not in data
    sd = parse_sidecar(data)
    assert sd.external_post_id == "1234"
    assert sd.source_url.startswith("https://cdn.discordapp.com/")


def test_a_seen_file_is_skipped_without_a_request(tmp_path):
    msg = _message()
    session = _Media()
    [out] = _downloader(tmp_path, session).download_post(
        msg, DiscordClient.extract_media(msg), "art", is_seen=lambda m: True,
    )
    assert out.status == "skipped_seen" and session.calls == []


def test_the_message_record_reads_back_as_the_gallery_dl_post(tmp_path):
    rec = _downloader(tmp_path).write_post_record(_message(), "art")
    assert rec.path.name == "20260920_1234_post.json"
    assert rec.body_chars == len("new set!")
    sd = parse_sidecar(json.loads(rec.path.read_text()))
    assert sd.platform == "discord"
    assert sd.external_post_id == "1234"
    assert sd.post_url == "https://discord.com/channels/11/22/1234"
    assert sd.description == "new set!"
    assert sd.post_date.isoformat().startswith("2026-09-20T23:30")


def test_the_record_is_not_a_media_sidecar(tmp_path):
    """It must not pair with any file of the message."""
    msg = _message()
    dl = _downloader(tmp_path)
    [out] = dl.download_post(msg, DiscordClient.extract_media(msg), "art")
    rec = dl.write_post_record(msg, "art")
    assert find_sidecar(out.path) != rec.path


def test_an_empty_re_read_never_blanks_a_stored_body(tmp_path):
    rec = _downloader(tmp_path).write_post_record(_message(content=""), "art", revisit=True)
    assert rec.path is None