"""Unit tests for api/rate_limiter.py."""
from unittest import mock

import pytest
from starlette.testclient import TestClient
from starlette.applications import Starlette
from starlette.requests import Request
from starlette.responses import JSONResponse
from starlette.routing import Route

from api.rate_limit_config import EndpointLimit, RateLimitConfig
from api.rate_limiter import (
    RateLimitMiddleware,
    _extract_user_email,
    _match_endpoint,
    EXEMPT_PATHS,
)


def _make_config(**overrides: object) -> RateLimitConfig:
    """Create a RateLimitConfig with defaults for testing."""
    defaults: dict[str, object] = {
        "endpoint_limits": {
            "/api/listing": EndpointLimit(3, 60),
            "/api/passkey": EndpointLimit(2, 60),
        },
        "listing_limit_cap": 100,
        "geojson_limit_cap": 5000,
        "geojson_stream_limit_cap": 10000,
        "geojson_stream_batch_size_cap": 200,
        "rate_limit_redis_db": 3,
        "metrics_allowed_ips": "127.0.0.1",
    }
    defaults.update(overrides)
    return RateLimitConfig(**defaults)  # type: ignore[arg-type]


async def _ok_endpoint(request: Request) -> JSONResponse:
    return JSONResponse({"ok": True})


def _build_app(config: RateLimitConfig) -> Starlette:
    """Build a minimal Starlette app with the rate limiter."""
    app = Starlette(routes=[
        Route("/api/listing", _ok_endpoint),
        Route("/api/passkey/login/begin", _ok_endpoint, methods=["POST"]),
        Route("/api/status", _ok_endpoint),
    ])
    app.add_middleware(RateLimitMiddleware, config=config)
    return app


class TestExtractUserEmail:
    """Tests for _extract_user_email."""

    def test_no_auth_header(self) -> None:
        scope = {"type": "http", "headers": []}
        request = Request(scope)
        assert _extract_user_email(request) is None

    def test_invalid_token(self) -> None:
        scope = {
            "type": "http",
            "headers": [(b"authorization", b"Bearer not-a-jwt")],
        }
        request = Request(scope)
        assert _extract_user_email(request) is None

    def test_valid_jwt(self) -> None:
        import jwt as pyjwt
        token = pyjwt.encode({"email": "test@example.com"}, "secret", algorithm="HS256")
        scope = {
            "type": "http",
            "headers": [(b"authorization", f"Bearer {token}".encode())],
        }
        request = Request(scope)
        assert _extract_user_email(request) == "test@example.com"


class TestMatchEndpoint:
    """Tests for _match_endpoint."""

    def test_exact_match(self) -> None:
        config = _make_config()
        limit = _match_endpoint("/api/listing", config)
        assert limit is not None
        assert limit.max_requests == 3

    def test_passkey_prefix_match(self) -> None:
        config = _make_config()
        limit = _match_endpoint("/api/passkey/login/begin", config)
        assert limit is not None
        assert limit.max_requests == 2

    def test_no_match(self) -> None:
        config = _make_config()
        assert _match_endpoint("/api/unknown", config) is None


class TestRateLimitMiddleware:
    """Integration tests for RateLimitMiddleware."""

    @mock.patch("api.rate_limiter._get_rate_limit_redis")
    def test_allows_requests_under_limit(self, mock_get_redis: mock.MagicMock) -> None:
        mock_redis = mock.MagicMock()
        mock_pipe = mock.MagicMock()
        mock_pipe.execute.return_value = [1, -1]  # first request, no TTL yet
        mock_redis.pipeline.return_value = mock_pipe
        mock_redis.ping.return_value = True
        mock_get_redis.return_value = mock_redis

        config = _make_config()
        app = _build_app(config)
        client = TestClient(app)

        resp = client.get("/api/listing")
        assert resp.status_code == 200
        assert "X-RateLimit-Limit" in resp.headers
        assert resp.headers["X-RateLimit-Limit"] == "3"
        assert resp.headers["X-RateLimit-Remaining"] == "2"

    @mock.patch("api.rate_limiter._get_rate_limit_redis")
    def test_returns_429_over_limit(self, mock_get_redis: mock.MagicMock) -> None:
        mock_redis = mock.MagicMock()
        mock_pipe = mock.MagicMock()
        # 4th request in window (limit=3), TTL=45s remaining
        mock_pipe.execute.return_value = [4, 45]
        mock_redis.pipeline.return_value = mock_pipe
        mock_redis.ping.return_value = True
        mock_get_redis.return_value = mock_redis

        config = _make_config()
        app = _build_app(config)
        client = TestClient(app)

        resp = client.get("/api/listing")
        assert resp.status_code == 429
        assert resp.headers["Retry-After"] == "45"
        assert resp.headers["X-RateLimit-Remaining"] == "0"

    @mock.patch("api.rate_limiter._get_rate_limit_redis")
    def test_exempt_paths_skip_rate_limiting(self, mock_get_redis: mock.MagicMock) -> None:
        mock_redis = mock.MagicMock()
        mock_redis.ping.return_value = True
        mock_get_redis.return_value = mock_redis

        config = _make_config()
        app = _build_app(config)
        client = TestClient(app)

        resp = client.get("/api/status")
        assert resp.status_code == 200
        assert "X-RateLimit-Limit" not in resp.headers
        # Redis pipeline should never be called for exempt paths
        mock_redis.pipeline.assert_not_called()

    @mock.patch("api.rate_limiter._get_rate_limit_redis")
    def test_fails_open_on_redis_error(self, mock_get_redis: mock.MagicMock) -> None:
        """When Redis raises an error, requests should be allowed through."""
        import redis

        mock_redis = mock.MagicMock()
        mock_pipe = mock.MagicMock()
        mock_pipe.execute.side_effect = redis.RedisError("connection lost")
        mock_redis.pipeline.return_value = mock_pipe
        mock_redis.ping.return_value = True
        mock_get_redis.return_value = mock_redis

        config = _make_config()
        app = _build_app(config)
        client = TestClient(app)

        resp = client.get("/api/listing")
        assert resp.status_code == 200

    @mock.patch("api.rate_limiter._get_rate_limit_redis")
    def test_fails_open_when_redis_unavailable_at_startup(self, mock_get_redis: mock.MagicMock) -> None:
        """When Redis is unavailable at startup, requests pass through."""
        import redis

        mock_get_redis.side_effect = redis.RedisError("connection refused")

        config = _make_config()
        app = _build_app(config)
        client = TestClient(app)

        resp = client.get("/api/listing")
        assert resp.status_code == 200

    @mock.patch("api.rate_limiter._get_rate_limit_redis")
    def test_unmatched_endpoint_skips_limiting(self, mock_get_redis: mock.MagicMock) -> None:
        """Endpoints not in the config are not rate limited."""
        mock_redis = mock.MagicMock()
        mock_redis.ping.return_value = True
        mock_get_redis.return_value = mock_redis

        config = _make_config()
        app = Starlette(routes=[Route("/api/unknown", _ok_endpoint)])
        app.add_middleware(RateLimitMiddleware, config=config)
        client = TestClient(app)

        resp = client.get("/api/unknown")
        assert resp.status_code == 200
        assert "X-RateLimit-Limit" not in resp.headers


class TestRateLimitConfig:
    """Tests for RateLimitConfig.from_env."""

    def test_defaults(self) -> None:
        with mock.patch.dict("os.environ", {}, clear=True):
            config = RateLimitConfig.from_env()
        assert config.listing_limit_cap == 100
        assert config.geojson_limit_cap == 5000
        assert config.rate_limit_redis_db == 3

    def test_custom_env_vars(self) -> None:
        env = {
            "RATE_LIMIT_LISTING": "50/120",
            "EXPORT_LISTING_LIMIT_CAP": "200",
            "RATE_LIMIT_REDIS_DB": "5",
            "METRICS_ALLOWED_IPS": "10.0.0.1",
        }
        with mock.patch.dict("os.environ", env, clear=True):
            config = RateLimitConfig.from_env()
        assert config.endpoint_limits["/api/listing"].max_requests == 50
        assert config.endpoint_limits["/api/listing"].window_seconds == 120
        assert config.listing_limit_cap == 200
        assert config.rate_limit_redis_db == 5
        assert config.metrics_allowed_ips == "10.0.0.1"

    def test_invalid_limit_format_uses_defaults(self) -> None:
        env = {"RATE_LIMIT_LISTING": "invalid"}
        with mock.patch.dict("os.environ", env, clear=True):
            config = RateLimitConfig.from_env()
        # Should fall back to default
        assert config.endpoint_limits["/api/listing"].max_requests == 30
        assert config.endpoint_limits["/api/listing"].window_seconds == 60