from __future__ import annotations

from pathlib import Path

from alembic.config import Config
from alembic.script import ScriptDirectory


def test_migration_graph_has_unique_revisions_and_one_head() -> None:
    migrations = Path(__file__).parents[1] / "packages" / "harness" / "deerflow" / "persistence" / "migrations"
    config = Config()
    config.set_main_option("script_location", str(migrations))
    scripts = ScriptDirectory.from_config(config)

    revisions = list(scripts.walk_revisions())
    assert len({revision.revision for revision in revisions}) == len(revisions)
    assert scripts.get_heads() == ["20261102_02"]
    assert scripts.get_revision("20261026_02").down_revision == ("20261026_01", "20261022_01")
    assert scripts.get_revision("20261026_01").down_revision == "20261025_03"
    assert scripts.get_revision("20261023_03").down_revision == "20261023_02"
    assert scripts.get_revision("20261023_02").down_revision == (
        "20261024_02",
        "20261022_02",
    )
    assert scripts.get_revision("20261024_02").down_revision == "20261024_01"
    assert scripts.get_revision("20261022_02").down_revision == "20261024_01"
    assert scripts.get_revision("20261024_01").down_revision == "20261023_01"
    assert scripts.get_revision("20261023_01").down_revision == "20261022_03"
    assert scripts.get_revision("20261022_03").down_revision == "20261021_01"
    assert scripts.get_revision("20261022_01").down_revision == "20261014_02"
    assert scripts.get_revision("20261021_01").down_revision == "20261020_01"
    assert scripts.get_revision("20261020_01").down_revision == (
        "20261019_01",
        "20261014_02",
    )
    assert scripts.get_revision("20261019_01").down_revision == "20261015_01"
    assert scripts.get_revision("20261014_02").down_revision == "20261014_01"
    assert scripts.get_revision("20261014_01").down_revision == "20261009_01"
    assert scripts.get_revision("20261009_01").down_revision == "20261006_01"

    assert scripts.get_revision("20260916_02").down_revision == "20260916_01"
    assert scripts.get_revision("20260916_03").down_revision == (
        "20260916_02",
        "20260909_01",
        "20260914_01",
    )
    assert scripts.get_revision("20260920_02").down_revision == (
        "20260920_01",
        "20260916_03",
    )
    assert scripts.get_revision("20261015_01").down_revision == "20260920_02"