"""Tests for goal-aware retrieval integration in the gateway.

Tests the Session attributes for goal tracking, cosine similarity-based
topic shift detection, and graceful degradation when helper_llm is absent.
"""

from __future__ import annotations

from pathlib import Path
from tempfile import TemporaryDirectory
from unittest.mock import AsyncMock, MagicMock, patch

import pytest

from mnemosyne.gateway import Session
from mnemosyne.helper_llm import GoalClassification
from mnemosyne.object_store import DummyEmbedder, _cosine_similarity


# ── Fixtures ─────────────────────────────────────────────────────────────


@pytest.fixture
def tmp_log_dir():
    with TemporaryDirectory() as d:
        yield Path(d)


@pytest.fixture
def session(tmp_log_dir):
    return Session("goal01", tmp_log_dir)


# ── Session attributes ───────────────────────────────────────────────────


class TestGoalSessionAttributes:
    """Verify Session.__init__ creates goal-tracking attributes."""

    def test_goal_session_attributes_exist(self, session):
        """Session has _last_user_embedding and _current_goal attributes."""
        assert hasattr(session, "_last_user_embedding")
        assert session._last_user_embedding is None
        assert hasattr(session, "_current_goal")
        assert session._current_goal is None
        assert hasattr(session, "entropy_detector")
        assert session.entropy_detector is not None


# ── Cosine similarity topic shift ────────────────────────────────────────


class TestCosineTopicShift:
    """Test topic shift detection via cosine similarity."""

    def test_goal_cosine_similarity_topic_shift(self):
        """Different topics produce low cosine similarity (< 0.5)."""
        embedder = DummyEmbedder()
        # Two very different texts should produce different embeddings
        emb_a = embedder.embed("How do I configure the database connection pool?")
        emb_b = embedder.embed("What color should the login button be?")
        sim = _cosine_similarity(emb_a, emb_b)
        # DummyEmbedder uses hash-based vectors, so different texts
        # produce essentially random vectors with low expected similarity
        # For 384-dim random unit vectors, expected |cos| ≈ 0.05
        assert sim < 0.5

    def test_goal_cosine_similarity_same_topic(self):
        """Identical text produces cosine similarity of 1.0."""
        embedder = DummyEmbedder()
        text = "How do I configure the database connection pool?"
        emb_a = embedder.embed(text)
        emb_b = embedder.embed(text)
        sim = _cosine_similarity(emb_a, emb_b)
        assert sim > 0.99  # Same text → same hash → same embedding

    def test_goal_first_message_always_classifies(self, session):
        """First message (no prior embedding) should always trigger classification."""
        # _last_user_embedding is None → goal_changed should be True
        assert session._last_user_embedding is None
        # This is the logic from gateway._preprocess step 1c:
        # if session._last_user_embedding is not None: check sim
        # else: goal_changed = True
        goal_changed = session._last_user_embedding is None
        assert goal_changed is True

    def test_goal_classification_fallback_no_helper(self, session):
        """Goal detection is skipped gracefully when helper_llm is None.

        The gateway code wraps goal detection in try/except and checks
        `if goal_changed and helper_llm is not None`. When helper_llm
        is None, no classification occurs and _current_goal stays None.
        """
        # Simulate the gateway logic: helper_llm is None
        helper_llm = None
        goal_changed = True  # First message

        # This mirrors the gateway code path
        if goal_changed and helper_llm is not None:
            # Would call helper_llm.classify_goal(...)
            session._current_goal = GoalClassification(goal="test")

        # Goal should remain None since helper_llm is None
        assert session._current_goal is None

    def test_goal_embedding_updated_after_message(self, session):
        """_last_user_embedding is updated after processing a message."""
        embedder = DummyEmbedder()
        user_text = "Tell me about the authentication system"
        current_embedding = embedder.embed(user_text)

        # Simulate the gateway update
        session._last_user_embedding = current_embedding

        assert session._last_user_embedding is not None
        assert len(session._last_user_embedding) == 384

    def test_goal_classification_stored_on_session(self, session):
        """GoalClassification is stored on session._current_goal."""
        goal = GoalClassification(
            goal="Implement authentication",
            relevant_types=["file_context", "design_decision"],
            relevant_tags=["auth", "security"],
            predicted_needs=["auth.py", "middleware.py"],
        )
        session._current_goal = goal

        assert session._current_goal.goal == "Implement authentication"
        assert "file_context" in session._current_goal.relevant_types
        assert "auth" in session._current_goal.relevant_tags