"""Unit tests for services/listing_cache.py."""
import json
from unittest import mock

import pytest
import redis

from models.listing import ListingType, QueryParameters
from services.listing_cache import (
    CACHE_PREFIX,
    CACHE_TTL_SECONDS,
    STALE_AFTER_SECONDS,
    _get_redis_client,
    acquire_repopulation_lock,
    cache_features_batch,
    get_cache_age,
    get_cached_count,
    get_cached_features,
    invalidate_cache,
    is_cache_stale,
    make_cache_key,
)


def _make_query(**overrides) -> QueryParameters:
    """Create a QueryParameters with defaults for testing."""
    defaults = {"listing_type": ListingType.RENT, "min_price": 1000, "max_price": 3000}
    defaults.update(overrides)
    return QueryParameters(**defaults)


class TestMakeCacheKey:
    """Tests for make_cache_key()."""

    def test_deterministic_for_same_params(self):
        """Same parameters produce the same cache key."""
        qp = _make_query()
        assert make_cache_key(qp) == make_cache_key(qp)

    def test_different_for_different_params(self):
        """Different parameters produce different cache keys."""
        qp1 = _make_query(min_price=1000)
        qp2 = _make_query(min_price=2000)
        assert make_cache_key(qp1) != make_cache_key(qp2)

    def test_key_starts_with_prefix(self):
        """Cache key starts with CACHE_PREFIX."""
        qp = _make_query()
        assert make_cache_key(qp).startswith(CACHE_PREFIX)


class TestGetRedisClient:
    """Tests for _get_redis_client() URL parsing."""

    @mock.patch("services.listing_cache.redis")
    def test_default_broker_url(self, mock_redis):
        """Uses default localhost URL when env var is not set."""
        with mock.patch.dict("os.environ", {}, clear=True):
            _get_redis_client()

        mock_redis.from_url.assert_called_once_with(
            "redis://localhost:6379/2", decode_responses=True
        )

    @mock.patch("services.listing_cache.redis")
    def test_custom_broker_url(self, mock_redis):
        """Replaces db number from custom broker URL."""
        with mock.patch.dict(
            "os.environ", {"CELERY_BROKER_URL": "redis://myhost:1234/5"}
        ):
            _get_redis_client()

        mock_redis.from_url.assert_called_once_with(
            "redis://myhost:1234/2", decode_responses=True
        )

    @mock.patch("services.listing_cache.redis")
    def test_broker_url_with_password(self, mock_redis):
        """Preserves auth info in broker URL."""
        with mock.patch.dict(
            "os.environ",
            {"CELERY_BROKER_URL": "redis://:secret@myhost:6379/0"},
        ):
            _get_redis_client()

        mock_redis.from_url.assert_called_once_with(
            "redis://:secret@myhost:6379/2", decode_responses=True
        )

    @mock.patch("services.listing_cache.redis")
    def test_broker_url_with_query_params(self, mock_redis):
        """Preserves query parameters in broker URL."""
        with mock.patch.dict(
            "os.environ",
            {"CELERY_BROKER_URL": "redis://myhost:6379/0?timeout=5"},
        ):
            _get_redis_client()

        mock_redis.from_url.assert_called_once_with(
            "redis://myhost:6379/2?timeout=5", decode_responses=True
        )


class TestGetCachedCount:
    """Tests for get_cached_count()."""

    @mock.patch("services.listing_cache._get_redis_client")
    def test_returns_none_on_redis_error(self, mock_get_client):
        """Returns None when Redis raises an error."""
        mock_get_client.side_effect = redis.RedisError("connection refused")

        result = get_cached_count(_make_query())
        assert result is None

    @mock.patch("services.listing_cache._get_redis_client")
    def test_returns_none_when_key_not_exists(self, mock_get_client):
        """Returns None when the cache key does not exist."""
        mock_client = mock.MagicMock()
        mock_client.exists.return_value = False
        mock_get_client.return_value = mock_client

        result = get_cached_count(_make_query())
        assert result is None

    @mock.patch("services.listing_cache._get_redis_client")
    def test_returns_count_when_key_exists(self, mock_get_client):
        """Returns list length when key exists."""
        mock_client = mock.MagicMock()
        mock_client.exists.return_value = True
        mock_client.llen.return_value = 42
        mock_get_client.return_value = mock_client

        result = get_cached_count(_make_query())
        assert result == 42


class TestGetCachedFeatures:
    """Tests for get_cached_features()."""

    @mock.patch("services.listing_cache._get_redis_client")
    def test_yields_empty_on_redis_error(self, mock_get_client):
        """Yields nothing when Redis raises an error."""
        mock_get_client.side_effect = redis.RedisError("connection refused")

        batches = list(get_cached_features(_make_query()))
        assert batches == []

    @mock.patch("services.listing_cache._get_redis_client")
    def test_yields_batches(self, mock_get_client):
        """Yields features in batches."""
        features = [{"type": "Feature", "id": i} for i in range(3)]
        mock_client = mock.MagicMock()
        mock_client.llen.return_value = 3
        mock_client.lrange.return_value = [json.dumps(f) for f in features]
        mock_get_client.return_value = mock_client

        batches = list(get_cached_features(_make_query(), batch_size=50))
        assert len(batches) == 1
        assert batches[0] == features


class TestCacheFeaturesBatch:
    """Tests for cache_features_batch()."""

    @mock.patch("services.listing_cache._get_redis_client")
    def test_empty_features_returns_early(self, mock_get_client):
        """Does not call Redis when features list is empty."""
        cache_features_batch(_make_query(), [])
        mock_get_client.assert_not_called()

    @mock.patch("services.listing_cache._get_redis_client")
    def test_writes_features_via_pipeline(self, mock_get_client):
        """Writes features and sets TTL through pipeline."""
        mock_client = mock.MagicMock()
        mock_pipeline = mock.MagicMock()
        mock_client.pipeline.return_value = mock_pipeline
        mock_get_client.return_value = mock_client

        features = [{"type": "Feature", "id": 1}]
        cache_features_batch(_make_query(), features)

        mock_pipeline.rpush.assert_called_once()
        mock_pipeline.expire.assert_called_once()
        mock_pipeline.execute.assert_called_once()

    @mock.patch("services.listing_cache._get_redis_client")
    def test_handles_redis_error(self, mock_get_client):
        """Handles Redis error gracefully during write."""
        mock_get_client.side_effect = redis.RedisError("write error")

        # Should not raise
        cache_features_batch(_make_query(), [{"id": 1}])


class TestInvalidateCache:
    """Tests for invalidate_cache()."""

    @mock.patch("services.listing_cache._get_redis_client")
    def test_handles_redis_error(self, mock_get_client):
        """Handles Redis error gracefully during invalidation."""
        mock_get_client.side_effect = redis.RedisError("connection refused")

        # Should not raise
        invalidate_cache()

    @mock.patch("services.listing_cache._get_redis_client")
    def test_deletes_matching_keys_via_pipeline(self, mock_get_client):
        """Deletes keys matching the cache prefix using pipeline."""
        mock_client = mock.MagicMock()
        mock_pipeline = mock.MagicMock()
        mock_client.pipeline.return_value = mock_pipeline
        # invalidate_cache scans two patterns (CACHE_PREFIX*, STAGING_PREFIX*)
        # First scan returns matching keys, second returns none
        mock_client.scan.side_effect = [
            (0, ["listings:geojson:abc", "listings:geojson:def"]),
            (0, []),
        ]
        mock_get_client.return_value = mock_client

        invalidate_cache()

        assert mock_pipeline.delete.call_count == 2
        mock_pipeline.execute.assert_called_once()

    @mock.patch("services.listing_cache._get_redis_client")
    def test_no_keys_to_delete(self, mock_get_client):
        """Does nothing when no cache keys exist."""
        mock_client = mock.MagicMock()
        mock_client.scan.return_value = (0, [])
        mock_get_client.return_value = mock_client

        invalidate_cache()

        mock_client.pipeline.assert_not_called()


class TestCacheTTLConstants:
    """Tests for cache TTL constants."""

    def test_cache_ttl_is_24_hours(self):
        """CACHE_TTL_SECONDS should be 24 hours."""
        assert CACHE_TTL_SECONDS == 24 * 60 * 60

    def test_stale_after_is_4_hours(self):
        """STALE_AFTER_SECONDS should be 4 hours."""
        assert STALE_AFTER_SECONDS == 4 * 60 * 60

    def test_stale_after_less_than_ttl(self):
        """Stale threshold must be less than the hard TTL."""
        assert STALE_AFTER_SECONDS < CACHE_TTL_SECONDS


class TestGetCacheAge:
    """Tests for get_cache_age()."""

    @mock.patch("services.listing_cache._get_redis_client")
    def test_returns_none_when_key_missing(self, mock_get_client):
        """Returns None when key does not exist (ttl returns -2)."""
        mock_client = mock.MagicMock()
        mock_client.ttl.return_value = -2
        mock_get_client.return_value = mock_client

        result = get_cache_age(_make_query())
        assert result is None

    @mock.patch("services.listing_cache._get_redis_client")
    def test_returns_none_when_no_expiry(self, mock_get_client):
        """Returns None when key has no TTL set (ttl returns -1)."""
        mock_client = mock.MagicMock()
        mock_client.ttl.return_value = -1
        mock_get_client.return_value = mock_client

        result = get_cache_age(_make_query())
        assert result is None

    @mock.patch("services.listing_cache._get_redis_client")
    def test_computes_age_from_ttl(self, mock_get_client):
        """Age = CACHE_TTL_SECONDS - remaining TTL."""
        mock_client = mock.MagicMock()
        remaining = CACHE_TTL_SECONDS - 3600  # 1 hour old
        mock_client.ttl.return_value = remaining
        mock_get_client.return_value = mock_client

        result = get_cache_age(_make_query())
        assert result == 3600

    @mock.patch("services.listing_cache._get_redis_client")
    def test_returns_none_on_redis_error(self, mock_get_client):
        """Returns None when Redis raises an error."""
        mock_get_client.side_effect = redis.RedisError("connection refused")

        result = get_cache_age(_make_query())
        assert result is None


class TestIsCacheStale:
    """Tests for is_cache_stale()."""

    @mock.patch("services.listing_cache.get_cache_age")
    def test_not_stale_when_young(self, mock_age):
        """Returns False when cache is younger than STALE_AFTER_SECONDS."""
        mock_age.return_value = 100  # 100 seconds old
        assert is_cache_stale(_make_query()) is False

    @mock.patch("services.listing_cache.get_cache_age")
    def test_stale_when_old(self, mock_age):
        """Returns True when cache is older than STALE_AFTER_SECONDS."""
        mock_age.return_value = STALE_AFTER_SECONDS + 1
        assert is_cache_stale(_make_query()) is True

    @mock.patch("services.listing_cache.get_cache_age")
    def test_not_stale_when_missing(self, mock_age):
        """Returns False when cache does not exist."""
        mock_age.return_value = None
        assert is_cache_stale(_make_query()) is False

    @mock.patch("services.listing_cache.get_cache_age")
    def test_not_stale_at_exact_threshold(self, mock_age):
        """Returns False when cache age equals STALE_AFTER_SECONDS exactly."""
        mock_age.return_value = STALE_AFTER_SECONDS
        assert is_cache_stale(_make_query()) is False


class TestAcquireRepopulationLock:
    """Tests for acquire_repopulation_lock()."""

    @mock.patch("services.listing_cache._get_redis_client")
    def test_acquires_lock_successfully(self, mock_get_client):
        """Returns True when lock is acquired (SETNX succeeds)."""
        mock_client = mock.MagicMock()
        mock_client.set.return_value = True
        mock_get_client.return_value = mock_client

        result = acquire_repopulation_lock(_make_query())
        assert result is True
        mock_client.set.assert_called_once()
        # Verify nx=True and ex=60 were passed
        call_kwargs = mock_client.set.call_args[1]
        assert call_kwargs["nx"] is True
        assert call_kwargs["ex"] == 60

    @mock.patch("services.listing_cache._get_redis_client")
    def test_returns_false_when_locked(self, mock_get_client):
        """Returns False when lock already held (SETNX returns None)."""
        mock_client = mock.MagicMock()
        mock_client.set.return_value = None
        mock_get_client.return_value = mock_client

        result = acquire_repopulation_lock(_make_query())
        assert result is False

    @mock.patch("services.listing_cache._get_redis_client")
    def test_returns_false_on_redis_error(self, mock_get_client):
        """Returns False when Redis raises an error."""
        mock_get_client.side_effect = redis.RedisError("connection refused")

        result = acquire_repopulation_lock(_make_query())
        assert result is False