"""Tests for Phase 3 — relational tier (Mem0g-light).

Coverage:
  1. upsert_relation inserts a row and query_relations returns it
  2. upsert_relation updates existing row on duplicate (subject/predicate/object)
  3. tier gating: Free user gets empty list from query_relations + enrich_context
  4. enrich_context includes relational_memory key for Pro user
  5. decay_relations decays confidence and prunes rows below threshold
"""

from __future__ import annotations

import uuid
from datetime import datetime, timedelta, timezone
from unittest.mock import patch

import pytest
import pytest_asyncio
from cryptography.fernet import Fernet
from sqlalchemy import select

from app.core.memory_maintenance import decay_relations
from app.core.memory_middleware import MemoryMiddleware
from app.db import get_session
from app.main import app
from app.models import MemoryRelation, User
from tests.conftest import TEST_USER_IDS

PRO_USER_ID = TEST_USER_IDS["pro"]
FREE_USER_ID = TEST_USER_IDS["free"]
_FERNET_KEY = Fernet.generate_key().decode()


# ── DB override ───────────────────────────────────────────────────────────────

@pytest.fixture(autouse=True)
def _override_db(db_session):
    async def _gen():
        yield db_session

    app.dependency_overrides[get_session] = _gen
    yield
    app.dependency_overrides.pop(get_session, None)


@pytest_asyncio.fixture
async def pro_user_with_key(db_session):
    """Set encryption_key on the pro test user so Fernet works."""
    result = await db_session.execute(select(User).where(User.id == PRO_USER_ID))
    user = result.scalar_one()
    user.encryption_key = _FERNET_KEY
    await db_session.commit()
    return user


@pytest_asyncio.fixture
async def free_user_with_key(db_session):
    """Set encryption_key on the free test user."""
    result = await db_session.execute(select(User).where(User.id == FREE_USER_ID))
    user = result.scalar_one()
    user.encryption_key = _FERNET_KEY
    await db_session.commit()
    return user


# ── Tests ─────────────────────────────────────────────────────────────────────

@pytest.mark.asyncio
async def test_upsert_relation_inserts_and_queries(db_session, pro_user_with_key):
    """upsert_relation inserts a row; query_relations returns it."""
    mm = MemoryMiddleware(db_session)
    await mm.upsert_relation(
        PRO_USER_ID,
        subject="Giulia",
        subject_type="person",
        predicate="works_at",
        object_="Acme Corp",
        object_type="company",
        confidence=0.9,
    )
    rows = await mm.query_relations(PRO_USER_ID, subject="Giulia")
    assert len(rows) == 1
    assert rows[0].subject_label == "Giulia"
    assert rows[0].predicate == "works_at"
    assert rows[0].object_label == "Acme Corp"
    assert abs(rows[0].confidence - 0.9) < 0.001


@pytest.mark.asyncio
async def test_upsert_relation_updates_on_duplicate(db_session, pro_user_with_key):
    """Second upsert on same triple updates confidence and last_confirmed_at."""
    mm = MemoryMiddleware(db_session)
    await mm.upsert_relation(
        PRO_USER_ID,
        subject="Marco",
        subject_type="person",
        predicate="stakeholder_of",
        object_="Project Nexus",
        object_type="project",
        confidence=0.7,
    )
    await mm.upsert_relation(
        PRO_USER_ID,
        subject="Marco",
        subject_type="person",
        predicate="stakeholder_of",
        object_="Project Nexus",
        object_type="project",
        confidence=0.95,
    )
    rows = await mm.query_relations(PRO_USER_ID, subject="Marco")
    # Only one row despite two upserts
    assert len(rows) == 1
    assert abs(rows[0].confidence - 0.95) < 0.001
    assert rows[0].last_confirmed_at is not None


@pytest.mark.asyncio
async def test_free_tier_relation_skipped(db_session, free_user_with_key):
    """Free user: upsert_relation is silently skipped (no row created)."""
    mm = MemoryMiddleware(db_session)
    await mm.upsert_relation(
        FREE_USER_ID,
        subject="Alice",
        subject_type="person",
        predicate="reports_to",
        object_="Bob",
        object_type="person",
        confidence=0.8,
    )
    rows = await mm.query_relations(FREE_USER_ID, subject="Alice")
    assert rows == []


@pytest.mark.asyncio
async def test_enrich_context_includes_relational_memory(db_session, pro_user_with_key):
    """enrich_context includes relational_memory key for Pro user."""
    mm = MemoryMiddleware(db_session)
    await mm.upsert_relation(
        PRO_USER_ID,
        subject="Elena",
        subject_type="person",
        predicate="cfo_of",
        object_="StartupXYZ",
        object_type="company",
        confidence=0.85,
    )

    with patch("app.core.memory_middleware.MemoryMiddleware._load_associative", return_value=[]):
        ctx = await mm.enrich_context(PRO_USER_ID, "who is Elena?")

    assert "relational_memory" in ctx
    assert any("Elena" in r for r in ctx["relational_memory"])


@pytest.mark.asyncio
async def test_enrich_context_relational_empty_for_free(db_session, free_user_with_key):
    """Free user: relational_memory is empty list in enrich_context."""
    mm = MemoryMiddleware(db_session)

    with patch("app.core.memory_middleware.MemoryMiddleware._load_associative", return_value=[]):
        ctx = await mm.enrich_context(FREE_USER_ID, "test message")

    assert ctx.get("relational_memory") == []


@pytest.mark.asyncio
async def test_decay_relations_reduces_confidence(db_session, pro_user_with_key):
    """decay_relations reduces confidence on stale rows."""
    old_date = datetime.now(timezone.utc) - timedelta(days=35)
    row = MemoryRelation(
        id=str(uuid.uuid4()),
        user_id=PRO_USER_ID,
        subject_label="OldContact",
        subject_type="person",
        predicate="knows",
        object_label="SomeProject",
        object_type="project",
        confidence=0.8,
        last_confirmed_at=old_date,
    )
    db_session.add(row)
    await db_session.commit()

    await decay_relations(db_session, PRO_USER_ID)

    result = await db_session.execute(
        select(MemoryRelation).where(MemoryRelation.subject_label == "OldContact")
    )
    updated = result.scalar_one_or_none()
    assert updated is not None
    assert updated.confidence < 0.8


@pytest.mark.asyncio
async def test_decay_relations_prunes_low_confidence(db_session, pro_user_with_key):
    """decay_relations deletes rows whose confidence drops below 0.2 threshold."""
    # Start at 0.21 with 60-day-old last_confirmed_at → two decay periods → 0.21 * 0.95^2 ≈ 0.19 → pruned
    old_date = datetime.now(timezone.utc) - timedelta(days=65)
    row = MemoryRelation(
        id=str(uuid.uuid4()),
        user_id=PRO_USER_ID,
        subject_label="ExpiredContact",
        subject_type="person",
        predicate="used_to_work_with",
        object_label="OldCorp",
        object_type="company",
        confidence=0.21,
        last_confirmed_at=old_date,
    )
    db_session.add(row)
    await db_session.commit()

    await decay_relations(db_session, PRO_USER_ID)

    result = await db_session.execute(
        select(MemoryRelation).where(MemoryRelation.subject_label == "ExpiredContact")
    )
    pruned = result.scalar_one_or_none()
    assert pruned is None