"""Unit tests for the ``clean_duplicate_episodes`` CLI.

Exercises the core logic (find / delete) against an in-memory
SQLite engine so the test is hermetic. The CLI module reads the
global async session factory from ``src.server.database.connection``
— the test patches that factory with an in-memory engine.
"""
from __future__ import annotations

from typing import List

import pytest
from sqlalchemy import select, text
from sqlalchemy.ext.asyncio import (
    AsyncEngine,
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)
from sqlalchemy.pool import StaticPool

from src.cli import clean_duplicate_episodes as cli
from src.server.database import connection as conn_module
from src.server.database.base import Base
from src.server.database.models import AnimeSeries, Episode


@pytest.fixture
async def in_memory_engine():
    """Provide an in-memory async SQLite engine with the schema
    already created, and patch the connection module's session
    factory to use it for the duration of the test.

    The CLI test suite simulates the *pre-migration* state — a DB
    that predates the UNIQUE constraint on
    ``(series_id, season, episode_number)`` and has accumulated
    duplicate rows from historical scans. To create that state, we
    build the schema for everything except ``episodes``, then
    recreate ``episodes`` with raw DDL that omits the
    ``uq_episode_per_series_season`` constraint. SQLite ties
    UNIQUE constraints to an internal auto-named index that can't
    be dropped directly — table recreation is the only way to
    simulate the pre-migration schema.
    """
    engine: AsyncEngine = create_async_engine(
        "sqlite+aiosqlite:///:memory:",
        echo=False,
        poolclass=StaticPool,
    )
    async with engine.begin() as conn:
        # Create everything except episodes.
        await conn.run_sync(
            lambda sync_conn: [
                t.create(sync_conn)
                for t in Base.metadata.sorted_tables
                if t.name != "episodes"
            ]
        )
        # Recreate episodes without the UNIQUE constraint.
        await conn.execute(
            text(
                """
                CREATE TABLE episodes (
                    id INTEGER NOT NULL PRIMARY KEY,
                    series_id INTEGER NOT NULL
                        REFERENCES anime_series(id) ON DELETE CASCADE,
                    season INTEGER NOT NULL,
                    episode_number INTEGER NOT NULL,
                    title VARCHAR(500),
                    file_path VARCHAR(1000),
                    is_downloaded BOOLEAN NOT NULL DEFAULT 0,
                    created_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL,
                    updated_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL
                )
                """
            )
        )
        await conn.execute(
            text("CREATE INDEX ix_episodes_series_id ON episodes (series_id)")
        )

    factory = async_sessionmaker(
        bind=engine,
        class_=AsyncSession,
        expire_on_commit=False,
    )

    # Monkey-patch the global session factory.
    original_factory = conn_module._session_factory
    conn_module._session_factory = factory
    try:
        yield engine
    finally:
        conn_module._session_factory = original_factory
        await engine.dispose()


async def _add_series(session: AsyncSession, key: str) -> int:
    series = AnimeSeries(
        key=key,
        name=key.replace("-", " ").title(),
        site="https://aniworld.to",
        folder=f"/anime/{key}",
    )
    session.add(series)
    await session.commit()
    await session.refresh(series)
    return int(series.id)


async def _add_episode(
    session: AsyncSession,
    series_id: int,
    season: int,
    ep_num: int,
    is_downloaded: bool = False,
    title: str | None = None,
) -> int:
    """Insert an Episode row. The test fixture drops the UNIQUE
    constraint on the ``episodes`` table, so duplicate inserts
    succeed — the cleanup tool can then find them, mirroring the
    pre-migration pathology it's meant to repair."""
    ep = Episode(
        series_id=series_id,
        season=season,
        episode_number=ep_num,
        is_downloaded=is_downloaded,
        title=title,
    )
    session.add(ep)
    await session.commit()
    await session.refresh(ep)
    return int(ep.id)


def _tup(d):
    """Convert a SQLAlchemy row to the (sid, season, ep_num, count,
    keep_id, max_id) tuple shape the CLI uses."""
    return (
        int(d.series_id),
        int(d.season),
        int(d.episode_number),
        int(d.row_count),
        int(d.keep_id),
        int(d.max_id),
    )


@pytest.mark.asyncio
async def test_find_returns_empty_when_no_duplicates(in_memory_engine):
    """With one row per (series, season, ep_num), nothing is found."""
    async with AsyncSession(in_memory_engine) as session:
        sid = await _add_series(session, "no-dupes")
        await _add_episode(session, sid, 1, 1)
        await _add_episode(session, sid, 1, 2)
        await _add_episode(session, sid, 2, 1)

    duplicates = await cli.find_duplicate_episodes()
    assert duplicates == []


@pytest.mark.asyncio
async def test_find_groups_duplicates_per_tuple(in_memory_engine):
    """Three copies of (S1, E2) collapse to one DuplicateTuple with
    count=3 and keep_id = the lowest id."""
    async with AsyncSession(in_memory_engine) as session:
        sid = await _add_series(session, "triple")
        await _add_episode(session, sid, 1, 1)
        # Three rows for (S1, E2): the first via the normal path,
        # the next two via raw SQL to bypass the UNIQUE constraint.
        # Mirrors the pre-migration pathology the cleanup tool exists
        # to repair.
        e2 = await _add_episode(session, sid, 1, 2)
        e3 = await _add_episode(session, sid, 1, 2)
        e4 = await _add_episode(session, sid, 1, 2)
        await _add_episode(session, sid, 1, 3)

    duplicates = await cli.find_duplicate_episodes()

    # Only one duplicate tuple (S1, E2); (S1, E1) and (S1, E3) are
    # unique and must not appear.
    assert len(duplicates) == 1
    d = duplicates[0]
    assert (d[0], d[1], d[2]) == (sid, 1, 2)
    assert d[3] == 3
    assert d[4] == e2  # lowest id wins
    assert d[5] == e4  # max id (for the report)


@pytest.mark.asyncio
async def test_delete_keeps_lowest_id_per_tuple(in_memory_engine):
    """The DELETE call preserves the lowest-id row per duplicate
    tuple and removes the rest."""
    async with AsyncSession(in_memory_engine) as session:
        sid = await _add_series(session, "keep-lowest")
        e1 = await _add_episode(session, sid, 1, 1)  # unique
        e2 = await _add_episode(session, sid, 1, 2)  # lowest of dupes
        await _add_episode(
            session, sid, 1, 2
        )  # e3 - duplicate of e2
        await _add_episode(
            session, sid, 1, 2
        )  # e4 - duplicate of e2
        e5 = await _add_episode(session, sid, 1, 3)  # unique

    duplicates = await cli.find_duplicate_episodes()
    assert len(duplicates) == 1

    deleted = await cli.delete_duplicate_episodes(duplicates)
    assert deleted == 2  # two duplicate (S1, E2) rows removed

    # Verify the post-cleanup state directly via SQLAlchemy.
    async with AsyncSession(in_memory_engine) as session:
        rows = (
            await session.execute(
                select(Episode).order_by(Episode.id)
            )
        ).scalars().all()
        remaining_ids = [int(r.id) for r in rows]
        # e1, e2 (lowest of the dup group), and e5 survive; e3, e4
        # were the duplicates and are gone.
        assert remaining_ids == [e1, e2, e5]


@pytest.mark.asyncio
async def test_delete_keeps_lowest_even_with_title_metadata(in_memory_engine):
    """When a higher-id row has populated metadata but the lowest-id
    row is empty, the lowest-id row is still kept — that's the
    documented behavior (oldest insert wins)."""
    async with AsyncSession(in_memory_engine) as session:
        sid = await _add_series(session, "metadata")
        e1 = await _add_episode(session, sid, 1, 1)  # no title
        e2 = await _add_episode(
            session,
            sid,
            1,
            1,
            title="Better Episode 1",
        )

    duplicates = await cli.find_duplicate_episodes()
    assert len(duplicates) == 1

    await cli.delete_duplicate_episodes(duplicates)

    async with AsyncSession(in_memory_engine) as session:
        rows = (
            await session.execute(select(Episode))
        ).scalars().all()
        assert len(rows) == 1
        assert int(rows[0].id) == e1
        assert rows[0].title is None


@pytest.mark.asyncio
async def test_full_workflow_is_idempotent(in_memory_engine):
    """Running find -> delete -> find yields nothing the second
    time. Mirrors the production usage pattern."""
    async with AsyncSession(in_memory_engine) as session:
        sid = await _add_series(session, "idempotent")
        for ep_num in (1, 2, 3):
            await _add_episode(session, sid, 1, ep_num)
            await _add_episode(
                session, sid, 1, ep_num
            )
            await _add_episode(
                session, sid, 1, ep_num
            )

    first = await cli.find_duplicate_episodes()
    assert len(first) == 3

    await cli.delete_duplicate_episodes(first)
    second = await cli.find_duplicate_episodes()
    assert second == []


@pytest.mark.asyncio
async def test_max_series_filter_limits_report(in_memory_engine):
    """``--max-series`` caps which series appear in the report but
    the underlying find still returns every duplicate for those
    series."""
    async with AsyncSession(in_memory_engine) as session:
        s1 = await _add_series(session, "alpha")
        s2 = await _add_series(session, "beta")
        s3 = await _add_series(session, "gamma")
        for sid in (s1, s2, s3):
            for ep_num in (1, 2):
                await _add_episode(session, sid, 1, ep_num)
                await _add_episode(
                    session, sid, 1, ep_num
                )

    # Without filter: all three series have duplicates.
    full = await cli.find_duplicate_episodes()
    series_in_full = {t[0] for t in full}
    assert series_in_full == {s1, s2, s3}

    # With --max-series=2: only two series appear.
    limited = await cli.find_duplicate_episodes(max_series=2)
    series_in_limited = {t[0] for t in limited}
    assert len(series_in_limited) == 2


@pytest.mark.asyncio
async def test_format_report_human_readable(in_memory_engine):
    """The report includes the series name, season, episode, count
    and keep_id for each duplicate tuple."""
    async with AsyncSession(in_memory_engine) as session:
        sid = await _add_series(session, "attack-on-titan")
        await _add_episode(session, sid, 1, 1)
        await _add_episode(session, sid, 1, 1)

    duplicates = await cli.find_duplicate_episodes()
    names = await cli._load_series_names([sid])

    report = cli.format_report(duplicates, names)

    assert "Attack On Titan" in report or "Attack-on-Titan" in report
    # The row's keep_id column should appear, plus a count of "2".
    assert "2" in report
    assert "found" in report.lower()


@pytest.mark.asyncio
async def test_format_report_handles_no_duplicates():
    """Empty input yields a friendly 'nothing to do' message."""
    report = cli.format_report([], {})
    assert "no duplicate" in report.lower()


def test_argparse_defaults():
    """The CLI defaults to dry-run when --apply is not given."""
    import argparse

    parser = argparse.ArgumentParser()
    parser.add_argument("--apply", action="store_true")
    parser.add_argument("--max-series", type=int, default=None)

    # Simulate argv without --apply.
    args = parser.parse_args([])
    assert args.apply is False
    assert args.max_series is None