from datetime import UTC, datetime, timedelta

import pytest

from backend.app.models import ImageRecord, Tag, TagKind
from backend.app.models.tag import image_tag
from backend.app.services.gallery_service import (
    GalleryService,
    decode_cursor,
    encode_cursor,
)

pytestmark = pytest.mark.integration


def _now():
    return datetime.now(UTC)


async def _seed_images(db, count: int, sha_prefix: str = "0") -> list[ImageRecord]:
    base = _now()
    records = []
    for i in range(count):
        r = ImageRecord(
            path=f"/images/test/{i}.jpg",
            sha256=f"{sha_prefix}{i:063d}",
            size_bytes=1000,
            mime="image/jpeg",
            width=100,
            height=100,
            origin="imported_filesystem",
            integrity_status="unknown",
        )
        r.created_at = base - timedelta(minutes=i)
        db.add(r)
        records.append(r)
    await db.flush()
    return records


def test_cursor_roundtrip():
    ts = datetime(2026, 5, 14, 12, 30, 0, tzinfo=UTC)
    encoded = encode_cursor(ts, 42)
    back_ts, back_id = decode_cursor(encoded)
    assert back_ts == ts
    assert back_id == 42


def test_decode_invalid_cursor_raises():
    with pytest.raises(ValueError):
        decode_cursor("not-base64!!!")


@pytest.mark.asyncio
async def test_scroll_returns_newest_first(db):
    await _seed_images(db, 5)
    svc = GalleryService(db)
    page = await svc.scroll(cursor=None, limit=10)
    assert len(page.images) == 5
    assert page.images[0].created_at > page.images[-1].created_at


@pytest.mark.asyncio
async def test_scroll_pagination(db):
    await _seed_images(db, 5)
    svc = GalleryService(db)
    first = await svc.scroll(cursor=None, limit=2)
    assert len(first.images) == 2
    assert first.next_cursor is not None
    second = await svc.scroll(cursor=first.next_cursor, limit=2)
    assert len(second.images) == 2
    assert {i.id for i in first.images}.isdisjoint({i.id for i in second.images})


@pytest.mark.asyncio
async def test_scroll_with_tag_filter(db):
    images = await _seed_images(db, 5)
    tag = Tag(name="filterme", kind=TagKind.general)
    db.add(tag)
    await db.flush()
    await db.execute(
        image_tag.insert().values(
            image_record_id=images[0].id, tag_id=tag.id, source="manual"
        )
    )

    svc = GalleryService(db)
    page = await svc.scroll(cursor=None, limit=10, tag_id=tag.id)
    assert len(page.images) == 1
    assert page.images[0].id == images[0].id


@pytest.mark.asyncio
async def test_timeline_groups_by_month(db):
    await _seed_images(db, 3)
    svc = GalleryService(db)
    buckets = await svc.timeline()
    assert sum(b.count for b in buckets) == 3


@pytest.mark.asyncio
async def test_date_groups_in_page(db):
    await _seed_images(db, 3)
    svc = GalleryService(db)
    page = await svc.scroll(cursor=None, limit=10)
    assert len(page.date_groups) == 1
    y, m, ids = page.date_groups[0]
    assert len(ids) == 3


@pytest.mark.asyncio
async def test_neighbors(db):
    images = await _seed_images(db, 3)
    svc = GalleryService(db)
    middle = images[1]
    payload = await svc.get_image_with_tags(middle.id)
    assert payload["neighbors"]["prev_id"] == images[0].id
    assert payload["neighbors"]["next_id"] == images[2].id


@pytest.mark.asyncio
async def test_get_image_with_tags_returns_none_for_missing(db):
    svc = GalleryService(db)
    assert await svc.get_image_with_tags(99999) is None


@pytest.mark.asyncio
async def test_get_image_with_tags_includes_integrity_status(db):
    images = await _seed_images(db, 1)
    img = images[0]
    img.integrity_status = "ok"
    await db.flush()
    svc = GalleryService(db)
    payload = await svc.get_image_with_tags(img.id)
    assert payload["integrity_status"] == "ok"


async def _seed_image_with_post(
    db, *, sha: str, image_created_at, post_date, artist_name="test-artist",
    platform="patreon", external_post_id="42",
):
    """Helper: seed an Artist + Source + Post and one ImageRecord whose
    primary_post_id points at that Post. Used for date-coalesce tests."""
    from backend.app.models import Artist, Post, Source
    artist = Artist(name=artist_name, slug=artist_name.lower().replace(" ", "-"))
    db.add(artist)
    await db.flush()
    source = Source(
        artist_id=artist.id, platform=platform,
        url=f"https://www.{platform}.com/{artist.slug}",
    )
    db.add(source)
    await db.flush()
    post = Post(
        source_id=source.id, artist_id=artist.id,
        external_post_id=external_post_id,
        post_title="A Post", post_date=post_date,
    )
    db.add(post)
    await db.flush()
    img = ImageRecord(
        path=f"/images/test/{sha[:8]}.jpg",
        sha256=sha, size_bytes=1000, mime="image/jpeg",
        width=100, height=100,
        origin="imported_filesystem", integrity_status="unknown",
        primary_post_id=post.id,
    )
    img.created_at = image_created_at
    db.add(img)
    await db.flush()
    return img, post


@pytest.mark.asyncio
async def test_scroll_sorts_by_post_date_when_available(db):
    """Operator-flagged 2026-05-25: ~57k IR images all imported in the
    same week sort by image.created_at and pile up in one month bucket.
    Once primary_post_id is wired (via tag_apply phase 4), the gallery
    should sort by Post.post_date instead, spreading them across the
    actual publish years."""
    base_import = _now()
    # Image A: imported NOW, but post was made 2 years ago.
    img_a, _ = await _seed_image_with_post(
        db, sha="a" * 64,
        image_created_at=base_import,
        post_date=base_import - timedelta(days=730),
        artist_name="Aria", external_post_id="A-1",
    )
    # Image B: imported NOW (1 min later), post made YESTERDAY.
    img_b, _ = await _seed_image_with_post(
        db, sha="b" * 64,
        image_created_at=base_import - timedelta(minutes=1),
        post_date=base_import - timedelta(days=1),
        artist_name="Bea", external_post_id="B-1",
    )
    # Image C: filesystem-imported, no primary_post_id, created 5 days ago.
    img_c = ImageRecord(
        path="/images/test/c.jpg", sha256="c" * 64,
        size_bytes=1000, mime="image/jpeg",
        width=100, height=100,
        origin="imported_filesystem", integrity_status="unknown",
    )
    img_c.created_at = base_import - timedelta(days=5)
    db.add(img_c)
    await db.flush()

    svc = GalleryService(db)
    page = await svc.scroll(cursor=None, limit=10)
    # Effective-date order: B (yesterday) > C (5 days ago) > A (2 years ago)
    assert [i.id for i in page.images] == [img_b.id, img_c.id, img_a.id]

    # API exposes both fields explicitly so the UI can show "Posted X / Imported Y".
    a_payload = next(i for i in page.images if i.id == img_a.id)
    assert a_payload.posted_at is not None
    assert a_payload.posted_at < a_payload.created_at
    c_payload = next(i for i in page.images if i.id == img_c.id)
    assert c_payload.posted_at is None
    assert c_payload.effective_date == c_payload.created_at


@pytest.mark.asyncio
async def test_timeline_buckets_use_post_date_when_available(db):
    """Timeline group-by must follow the same effective_date rule so the
    UI's year/month navigation surfaces publish-date buckets, not the
    single FC-scan bucket all migrated images share."""
    base = datetime(2026, 6, 15, 12, 0, tzinfo=UTC)
    await _seed_image_with_post(
        db, sha="1" * 64,
        image_created_at=base,
        post_date=datetime(2024, 3, 10, tzinfo=UTC),
        artist_name="Carl", external_post_id="C-1",
    )
    await _seed_image_with_post(
        db, sha="2" * 64,
        image_created_at=base,
        post_date=datetime(2024, 3, 11, tzinfo=UTC),
        artist_name="Dee", external_post_id="D-1",
    )
    await _seed_image_with_post(
        db, sha="3" * 64,
        image_created_at=base,
        post_date=datetime(2025, 9, 1, tzinfo=UTC),
        artist_name="Eli", external_post_id="E-1",
    )
    svc = GalleryService(db)
    buckets = await svc.timeline()
    bucket_keys = {(b.year, b.month, b.count) for b in buckets}
    # Two posts in 2024-03, one in 2025-09 — even though all imported in 2026-06.
    assert (2024, 3, 2) in bucket_keys
    assert (2025, 9, 1) in bucket_keys
    # The FC-import bucket should NOT appear since all 3 images have post_date.
    assert not any(b.year == 2026 and b.month == 6 for b in buckets)


@pytest.mark.asyncio
async def test_get_image_with_tags_includes_posted_at_when_present(db):
    base = _now()
    img, _ = await _seed_image_with_post(
        db, sha="f" * 64,
        image_created_at=base,
        post_date=base - timedelta(days=365),
        artist_name="Fred", external_post_id="F-1",
    )
    svc = GalleryService(db)
    payload = await svc.get_image_with_tags(img.id)
    assert payload["posted_at"] is not None
    # Image's own created_at is still surfaced separately.
    assert payload["created_at"] != payload["posted_at"]