"""Milestone 388 E5: which Patreon post announced which Discord drop.

The failure this step must not have is a WRONG link. Telling the operator that
two different pieces are one is worse than telling them nothing — no link
leaves them where they already were, a wrong one actively misinforms. So most
of what follows pins refusals, and the central one is structural rather than
behavioural: the threshold sits above every single signal weight, which is what
makes "time proximity alone is never sufficient" arithmetic instead of a hope.
"""
from datetime import UTC, datetime, timedelta

import pytest
from sqlalchemy import select

from backend.app.models import (
    Artist,
    ImageRecord,
    ImportSettings,
    Post,
    PostAssociation,
    Source,
)
from backend.app.services.discord_grouping import DROP_GROUPER
from backend.app.services.post_association_service import (
    WEIGHTS,
    PostAssociationService,
    declared_signal,
    proximity_signal,
    rescan,
    weighted_score,
)
from backend.app.services.post_feed_service import PostFeedService

pytestmark = pytest.mark.integration

DEFAULT_THRESHOLD = 0.60
WINDOW = 24.0


# --- the structural guard -------------------------------------------------


def test_no_single_signal_can_reach_the_threshold():
    """THE load-bearing property of this matcher.

    On a busy day an artist posts several times, so a matcher that could pair
    on proximity alone would turn every busy day into false pairs and the
    review queue would be abandoned. Requiring two signals is what prevents
    that — and it is a fact about the WEIGHTS, not about any code path, so it
    survives every refactor of the scorer.

    If this fails, either a weight grew or the default threshold dropped. Do
    not "fix" it by lowering the assertion; the arithmetic IS the safeguard.
    """
    assert max(WEIGHTS.values()) < DEFAULT_THRESHOLD
    assert sum(WEIGHTS.values()) == pytest.approx(1.0)


def test_perfect_proximity_alone_does_not_propose():
    """The same property, expressed through the scorer."""
    score = weighted_score({"proximity": 1.0, "declared": 0.0})
    assert score < DEFAULT_THRESHOLD


def test_an_explicit_declaration_alone_does_not_propose():
    score = weighted_score({"proximity": 0.0, "declared": 1.0})
    assert score < DEFAULT_THRESHOLD


def test_both_signals_together_do_propose():
    assert weighted_score({"proximity": 1.0, "declared": 1.0}) >= DEFAULT_THRESHOLD


# --- the signals ----------------------------------------------------------


def test_proximity_decays_to_zero_at_the_window_edge():
    window = timedelta(hours=24)
    assert proximity_signal(timedelta(0), window) == 1.0
    assert proximity_signal(timedelta(hours=24), window) == 0.0
    assert proximity_signal(timedelta(hours=48), window) == 0.0
    assert 0.4 < proximity_signal(timedelta(hours=12), window) < 0.6


def test_proximity_is_symmetric_because_either_can_land_first():
    """The teaser usually goes up around the drop, not reliably before it."""
    window = timedelta(hours=24)
    assert proximity_signal(timedelta(hours=-2), window) == proximity_signal(
        timedelta(hours=2), window
    )


def test_an_invite_link_scores_higher_than_a_bare_mention():
    assert declared_signal("Full set on my discord.gg/abc123 now!") == 1.0
    assert 0 < declared_signal("Posted the rest on discord earlier") < 1.0
    assert declared_signal("New piece, hope you like it") == 0.0
    assert declared_signal(None) == 0.0


def test_the_declaration_signal_reads_through_html():
    """Post bodies are HTML; a link inside an anchor tag must still count."""
    assert declared_signal(
        '<p>Full set: <a href="https://discord.gg/xyz">here</a></p>'
    ) > 0


def test_a_word_containing_discord_is_not_a_mention():
    """\"discordant\" is not a declaration. Without the word boundary the
    signal fires on ordinary prose and drags pairs over the threshold."""
    assert declared_signal("a discordant palette, deliberately") == 0.0


# --- end to end -----------------------------------------------------------


async def _artist_with_channels(db, name: str):
    artist = Artist(name=name, slug=name.lower().replace(" ", "-"))
    db.add(artist)
    await db.flush()
    patreon = Source(
        artist_id=artist.id, platform="patreon",
        url=f"https://patreon.com/{name}", enabled=True,
    )
    discord = Source(
        artist_id=artist.id, platform="discord",
        url=f"https://discord.com/channels/1/{name}", enabled=True,
    )
    db.add_all([patreon, discord])
    await db.flush()
    return artist, patreon, discord


async def _teaser(db, artist, source, *, at, body, ext="teaser"):
    post = Post(
        source_id=source.id, artist_id=artist.id, external_post_id=ext,
        post_date=at, post_title="New piece", description=body,
    )
    db.add(post)
    await db.flush()
    db.add(ImageRecord(
        path=f"/images/{source.id}-{ext}.jpg", sha256=f"{ext:0>64}"[:64],
        size_bytes=10, mime="image/jpeg", width=10, height=10,
        origin="downloaded", primary_post_id=post.id, artist_id=artist.id,
    ))
    await db.flush()
    return post


async def _drop(db, artist, source, *, at, ext="fc-drop:1"):
    post = Post(
        source_id=source.id, artist_id=artist.id, external_post_id=ext,
        post_date=at, synthesized_by=DROP_GROUPER,
        synthesis_details={"message_count": 4, "images_since_surface": 0},
    )
    db.add(post)
    await db.flush()
    return post


@pytest.mark.asyncio
async def test_a_teaser_and_its_drop_an_hour_apart_are_proposed(db):
    artist, patreon, discord = await _artist_with_channels(db, "pairartist")
    now = datetime.now(UTC)
    teaser = await _teaser(
        db, artist, patreon, at=now - timedelta(hours=3),
        body="Full set is up on discord.gg/abc now",
    )
    drop = await _drop(db, artist, discord, at=now - timedelta(hours=2))
    await db.commit()

    made = await PostAssociationService(db).match_post(
        teaser.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW,
    )
    await db.commit()
    assert made == 1

    assoc = (await db.execute(select(PostAssociation))).scalar_one()
    assert assoc.announcement_post_id == teaser.id
    assert assoc.payload_post_id == drop.id
    assert assoc.status == "pending", "nothing is linked without the operator"
    # The per-signal breakdown survives, so the proposal stays explicable
    # after the weights or threshold move.
    assert assoc.signals["declared"] == 1.0
    assert assoc.signals["proximity"] > 0.9


@pytest.mark.asyncio
async def test_two_unrelated_posts_the_same_day_are_not_proposed(db):
    """Time proximity alone must not be sufficient, or every busy day becomes
    a false pair. The teaser here says nothing about Discord."""
    artist, patreon, discord = await _artist_with_channels(db, "busyartist")
    now = datetime.now(UTC)
    teaser = await _teaser(
        db, artist, patreon, at=now - timedelta(hours=3),
        body="Just a sketch I liked",
    )
    await _drop(db, artist, discord, at=now - timedelta(hours=2))
    await db.commit()

    made = await PostAssociationService(db).match_post(
        teaser.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW,
    )
    await db.commit()
    assert made == 0
    assert (await db.execute(select(PostAssociation))).scalars().all() == []


@pytest.mark.asyncio
async def test_a_drop_outside_the_window_is_not_proposed(db):
    artist, patreon, discord = await _artist_with_channels(db, "farapartartist")
    now = datetime.now(UTC)
    teaser = await _teaser(
        db, artist, patreon, at=now - timedelta(days=10),
        body="Everything is on discord.gg/abc",
    )
    await _drop(db, artist, discord, at=now)
    await db.commit()

    assert await PostAssociationService(db).match_post(
        teaser.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW,
    ) == 0


@pytest.mark.asyncio
async def test_another_artists_drop_is_never_proposed(db):
    """Same-artist is a HARD filter, not a scored signal: two different
    creators posting minutes apart is a coincidence, not evidence."""
    artist_a, patreon_a, _ = await _artist_with_channels(db, "artista")
    _artist_b, _patreon_b, discord_b = await _artist_with_channels(db, "artistb")
    now = datetime.now(UTC)
    teaser = await _teaser(
        db, artist_a, patreon_a, at=now - timedelta(hours=1),
        body="new drop on discord.gg/abc",
    )
    await _drop(db, _artist_b, discord_b, at=now)
    await db.commit()

    assert await PostAssociationService(db).match_post(
        teaser.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW,
    ) == 0


@pytest.mark.asyncio
async def test_an_artist_with_no_discord_source_produces_nothing_and_no_error(db):
    artist = Artist(name="soloartist", slug="soloartist")
    db.add(artist)
    await db.flush()
    patreon = Source(
        artist_id=artist.id, platform="patreon",
        url="https://patreon.com/solo", enabled=True,
    )
    db.add(patreon)
    await db.flush()
    teaser = await _teaser(
        db, artist, patreon, at=datetime.now(UTC),
        body="on discord.gg/abc", ext="solo",
    )
    await db.commit()

    assert await PostAssociationService(db).match_post(
        teaser.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW,
    ) == 0


@pytest.mark.asyncio
async def test_a_synthetic_post_cannot_announce_anything(db):
    """FC wrote it, so it announces nothing — and a grouping proposing itself
    as the teaser for another grouping would be pure noise."""
    artist, _patreon, discord = await _artist_with_channels(db, "noselfannounce")
    now = datetime.now(UTC)
    drop_a = await _drop(db, artist, discord, at=now - timedelta(hours=1), ext="fc-drop:a")
    await _drop(db, artist, discord, at=now, ext="fc-drop:b")
    await db.commit()

    assert await PostAssociationService(db).match_post(
        drop_a.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW,
    ) == 0


@pytest.mark.asyncio
async def test_a_dismissed_pair_is_never_proposed_again(db):
    """The row is what remembers the rejection. Re-proposing a rejected pair on
    every scan is the single behaviour that makes a review queue get ignored."""
    artist, patreon, discord = await _artist_with_channels(db, "dismissartist")
    now = datetime.now(UTC)
    teaser = await _teaser(
        db, artist, patreon, at=now - timedelta(hours=2),
        body="discord.gg/abc has the rest",
    )
    await _drop(db, artist, discord, at=now - timedelta(hours=1))
    await db.commit()

    svc = PostAssociationService(db)
    assert await svc.match_post(
        teaser.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW,
    ) == 1
    await db.commit()

    assoc = (await db.execute(select(PostAssociation))).scalar_one()
    await svc.dismiss(assoc.id)
    await db.commit()

    assert await svc.match_post(
        teaser.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW,
    ) == 0
    await db.commit()
    assert len((await db.execute(select(PostAssociation))).scalars().all()) == 1


@pytest.mark.asyncio
async def test_only_an_accepted_link_reaches_the_post_payload(db):
    """A pending proposal is a question for the review queue, not a claim to
    render beside the artwork."""
    artist, patreon, discord = await _artist_with_channels(db, "payloadartist")
    now = datetime.now(UTC)
    teaser = await _teaser(
        db, artist, patreon, at=now - timedelta(hours=2),
        body="rest is on discord.gg/abc",
    )
    drop = await _drop(db, artist, discord, at=now - timedelta(hours=1))
    await db.commit()

    svc = PostAssociationService(db)
    await svc.match_post(teaser.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW)
    await db.commit()

    feed = PostFeedService(db)
    assert (await feed.get_post(teaser.id))["associations"] == []

    assoc = (await db.execute(select(PostAssociation))).scalar_one()
    await svc.accept(assoc.id)
    await db.commit()

    # Both ends see it, and each sees the OTHER post with its own role.
    teaser_item = await feed.get_post(teaser.id)
    assert teaser_item["associations"] == [
        {"role": "announces", "post_id": drop.id, "id": assoc.id}
    ]
    drop_item = await feed.get_post(drop.id)
    assert drop_item["associations"] == [
        {"role": "announced_by", "post_id": teaser.id, "id": assoc.id}
    ]


@pytest.mark.asyncio
async def test_deleting_the_grouping_takes_its_proposals_with_it(db):
    """E3's reversal path is one DELETE; it must not leave a dangling proposal
    pointing at a post that no longer exists."""
    artist, patreon, discord = await _artist_with_channels(db, "cascadeartist")
    now = datetime.now(UTC)
    teaser = await _teaser(
        db, artist, patreon, at=now - timedelta(hours=2),
        body="discord.gg/abc",
    )
    drop = await _drop(db, artist, discord, at=now - timedelta(hours=1))
    await db.commit()

    await PostAssociationService(db).match_post(
        teaser.id, threshold=DEFAULT_THRESHOLD, window_hours=WINDOW,
    )
    await db.commit()
    assert len((await db.execute(select(PostAssociation))).scalars().all()) == 1

    await db.delete(drop)
    await db.commit()
    assert (await db.execute(select(PostAssociation))).scalars().all() == []


@pytest.mark.asyncio
async def test_the_rescan_is_a_no_op_when_the_switch_is_off(db):
    settings = await ImportSettings.load(db)
    settings.discord_link_enabled = False
    await db.commit()
    assert await rescan(db) == {"enabled": False, "scanned": 0, "proposed": 0}