"""Decision-log immutability & dedup contract (Gitea issue #6 / T8).

Pins the desired behaviour: a decision log is append-only and not silently
overwritten or duplicated. The current router writes through directly; once
it moves into a service (P3), these guards must continue to pass.
"""
import uuid

import pytest
from fastapi.testclient import TestClient
from sqlmodel import Session, SQLModel, create_engine, select

from agenteval.intelligent_eval.models import IntelligentEvalStatus
from agenteval.storage.db import (
    IntelligentEvalDB,
    IntelligentEvalDecisionLogDB,
    utc_now,
)
from agenteval.web.app import app
from agenteval.web.deps import get_db


@pytest.fixture()
def client(tmp_path):
    from agenteval.storage.db import (  # noqa: F401
        IntelligentEvalDB,
        IntelligentEvalSessionDB,
        IntelligentEvalTaskQueueDB,
    )

    engine = create_engine(
        f"sqlite:///{tmp_path / 'test.db'}",
        connect_args={"check_same_thread": False},
    )
    SQLModel.metadata.create_all(engine)
    session = Session(engine)

    def override_get_db():
        try:
            yield session
        finally:
            pass

    app.dependency_overrides[get_db] = override_get_db
    yield TestClient(app)
    app.dependency_overrides.clear()
    session.close()
    engine.dispose()


@pytest.fixture()
def db_session(client):
    return next(app.dependency_overrides[get_db]())


def _make_eval(db_session: Session) -> IntelligentEvalDB:
    eval_db = IntelligentEvalDB(
        id=str(uuid.uuid4()),
        name="eval-dl-immut",
        target_id="t1",
        status=IntelligentEvalStatus.EXECUTING.value,
    )
    db_session.add(eval_db)
    db_session.commit()
    return eval_db


def _post_log(client: TestClient, eval_id: str, **overrides) -> dict:
    body = {
        "decision_type": "execute_session",
        "reason": "slot_due",
        "context": {"slot": "8-10h", "deficit": 2},
        "cron_id": "cron-1",
    }
    body.update(overrides)
    response = client.post(
        f"/api/intelligent-evals/{eval_id}/decision-logs",
        json=body,
    )
    assert response.status_code == 200, response.text
    return response.json()


def test_decision_log_is_append_only_on_context_change(
    client: TestClient, db_session: Session
):
    """Modifying context must append, never overwrite, an existing log row."""
    eval_db = _make_eval(db_session)

    first = _post_log(
        client, eval_db.id, context={"slot": "8-10h", "deficit": 2}
    )
    second = _post_log(
        client, eval_db.id, context={"slot": "10-12h", "deficit": 1}
    )

    assert first["id"] != second["id"]

    rows = db_session.exec(
        select(IntelligentEvalDecisionLogDB)
        .where(IntelligentEvalDecisionLogDB.eval_id == eval_db.id)
        .order_by(IntelligentEvalDecisionLogDB.created_at)
    ).all()
    assert len(rows) == 2
    # The first row's context is preserved (not overwritten by the second).
    assert rows[0].get_context() == {"slot": "8-10h", "deficit": 2}
    assert rows[1].get_context() == {"slot": "10-12h", "deficit": 1}


def test_decision_log_dedupes_identical_entries(
    client: TestClient, db_session: Session
):
    """Identical (decision_type, context) must not insert a second row."""
    eval_db = _make_eval(db_session)

    body = {
        "decision_type": "execute_session",
        "reason": "slot_due",
        "context": {"slot": "8-10h", "deficit": 2},
        "cron_id": "cron-1",
    }
    for _ in range(3):
        r = client.post(
            f"/api/intelligent-evals/{eval_db.id}/decision-logs",
            json=body,
        )
        assert r.status_code == 200

    rows = db_session.exec(
        select(IntelligentEvalDecisionLogDB).where(
            IntelligentEvalDecisionLogDB.eval_id == eval_db.id
        )
    ).all()
    assert len(rows) == 1, f"expected dedup, got {len(rows)} rows"