"""Migration 0112's data step, DB-lane: a user who already has two Watch later lists keeps the oldest,
with the other's videos moved in after its own (one it already held is not added twice) and a Home
pin of the other moved onto it, and the one-per-user index then refuses a second list.

The schema half is checked by test_migrations.py; a video or a pin lost on the way is invisible there.
"""

from datetime import datetime, timezone

import pytest
from alembic import command
from alembic.config import Config
from sqlalchemy import text
from sqlalchemy.exc import IntegrityError

from app.catalog.models import Channel, Video
from app.db import engine


def _lists(conn, user_id: int, n: int) -> list[int]:
    values = ", ".join(f"(:u, 'Watch later', 'watch_later', {i})" for i in range(n))
    return list(
        conn.execute(
            text(
                f"INSERT INTO playlists (user_id, name, kind, position) VALUES {values} RETURNING id"
            ),
            {"u": user_id},
        ).scalars()
    )


def _pin(conn, user_id: int, playlist_id: int, position: int) -> None:
    conn.execute(
        text("INSERT INTO comfort_pins (user_id, playlist_id, position) VALUES (:u, :p, :pos)"),
        {"u": user_id, "p": playlist_id, "pos": position},
    )


def test_a_second_watch_later_is_folded_into_the_first(db, make_user):
    user, other = make_user(), make_user()
    db.add(Channel(id="UCm", title="M"))
    now = datetime.now(timezone.utc)
    for v in ("v1", "v2", "v3"):
        db.add(Video(id=v, channel_id="UCm", published_at=now, duration_seconds=60))
    db.commit()
    cfg = Config("alembic.ini")
    command.downgrade(cfg, "0111_audit_request_id")
    try:
        with engine.begin() as conn:
            first, second, third = _lists(conn, user.id, 3)
            theirs, their_second = _lists(conn, other.id, 2)
            conn.execute(
                text(
                    "INSERT INTO playlist_items (playlist_id, video_id, position) VALUES"
                    " (:a, 'v1', 0), (:b, 'v2', 0), (:b, 'v1', 1), (:c, 'v3', 0)"
                ),
                {"a": first, "b": second, "c": theirs},
            )
            # The user pinned two of the copies, the kept one neither: the first on the shelf moves.
            _pin(conn, user.id, third, 0)
            _pin(conn, user.id, second, 1)
            # The other pinned both: the kept one's pin stays, and is the only one.
            _pin(conn, other.id, their_second, 0)
            _pin(conn, other.id, theirs, 1)
    finally:
        command.upgrade(cfg, "head")

    with engine.connect() as conn:
        lists = conn.execute(
            text("SELECT id, user_id FROM playlists WHERE kind = 'watch_later' ORDER BY id")
        ).all()
        assert [tuple(r) for r in lists] == [(first, user.id), (theirs, other.id)]
        items = conn.execute(
            text(
                "SELECT playlist_id, video_id, position FROM playlist_items ORDER BY playlist_id, position"
            )
        ).all()
        assert [tuple(r) for r in items] == [(first, "v1", 0), (first, "v2", 1), (theirs, "v3", 0)]
        pins = conn.execute(
            text("SELECT user_id, playlist_id, position FROM comfort_pins ORDER BY user_id")
        ).all()
        assert [tuple(r) for r in pins] == [(user.id, first, 0), (other.id, theirs, 1)]
    with pytest.raises(IntegrityError), engine.begin() as conn:
        conn.execute(
            text(
                "INSERT INTO playlists (user_id, name, kind, position)"
                " VALUES (:u, 'Watch later', 'watch_later', 2)"
            ),
            {"u": user.id},
        )