"""Migration + wiring of the git coordination backend (SHARD-WP-0009 T4)."""

from shard_wiki.coordination import (
    DecisionLog,
    EventType,
    GitEventStore,
    InMemoryEventStore,
    export_jsonl,
    import_jsonl,
    migrate_space,
)
from shard_wiki.space import InformationSpace


def test_information_space_git_backed_uses_git_log(tmp_path):
    space = InformationSpace.git_backed("space-1", tmp_path / "coord")
    assert isinstance(space.log._store, GitEventStore)
    space.alias("Home", "shardA:Index")
    # Read-your-writes through the orchestrator's git-backed log.
    assert space.log.fold("space-1").resolve_alias("Home") == "shardA:Index"


def test_default_information_space_stays_in_memory():
    space = InformationSpace("space-1")
    assert isinstance(space.log._store, InMemoryEventStore)


def test_migrate_space_preserves_order_and_provenance(tmp_path):
    source = InMemoryEventStore()
    e0 = source.append("s", EventType.ALIAS_SET, {"alias": "Home", "target": "x:1"}, actor="ana")
    source.append("s", EventType.BINDING_MADE, {"members": ["a", "b"]}, actor="ben")

    dest = GitEventStore(tmp_path / "coord")
    n = migrate_space(source, "s", dest)
    assert n == 2

    migrated = dest.events("s")
    assert [e.seq for e in migrated] == [0, 1]
    # Provenance preserved verbatim — actor and timestamp survive the move (no restamping).
    assert migrated[0].actor == "ana"
    assert migrated[1].actor == "ben"
    assert migrated[0].timestamp == e0.timestamp


def test_migration_yields_identical_fold(tmp_path):
    source = DecisionLog(InMemoryEventStore())
    for typ, payload in [
        (EventType.ALIAS_SET, {"alias": "Home", "target": "x:1"}),
        (EventType.BINDING_MADE, {"members": ["a", "b"]}),
        (EventType.BINDING_MADE, {"members": ["b", "c"]}),
        (EventType.ALIAS_SET, {"alias": "Home", "target": "x:2"}),
    ]:
        source.append("s", typ, payload)

    dest = GitEventStore(tmp_path / "coord")
    migrate_space(source._store, "s", dest)
    after = DecisionLog(dest)
    assert after.fold("s").aliases == source.fold("s").aliases
    assert after.fold("s").equivalence_groups == source.fold("s").equivalence_groups


def test_jsonl_round_trip_into_git(tmp_path):
    source = InMemoryEventStore()
    source.append("s", EventType.ALIAS_SET, {"alias": "Home", "target": "x:1"})
    source.append("s", EventType.PAGE_FORKED, {"source": "p", "fork": "q"})

    path = tmp_path / "log.jsonl"
    assert export_jsonl(source.events("s"), path) == 2

    dest = GitEventStore(tmp_path / "coord")
    assert import_jsonl(path, dest) == 2
    state = DecisionLog(dest).fold("s")
    assert state.resolve_alias("Home") == "x:1"
    assert state.equivalent_to("p") == frozenset({"p", "q"})