"""
Deep behavioral tests for error handling patterns.
Tests error categorization, retry logic, circuit breakers,
and graceful degradation patterns.
"""

from datetime import datetime, timezone
import random


# --- Error categorization patterns ---


class TestErrorCategorization:
    """Tests for error categorization patterns."""

    def _categorize_error(self, error):
        """Categorize an error for handling."""
        error_str = str(error).lower()

        if any(w in error_str for w in ["timeout", "timed out"]):
            return "timeout"
        if any(w in error_str for w in ["connection", "network", "refused"]):
            return "network"
        if any(
            w in error_str
            for w in ["auth", "permission", "forbidden", "unauthorized"]
        ):
            return "auth"
        if any(w in error_str for w in ["not found", "404"]):
            return "not_found"
        if any(w in error_str for w in ["rate limit", "429", "too many"]):
            return "rate_limit"
        if any(
            w in error_str for w in ["invalid", "validation", "bad request"]
        ):
            return "validation"
        return "unknown"

    def test_timeout_categorized(self):
        assert self._categorize_error("Connection timed out") == "timeout"
        assert self._categorize_error("Request timeout") == "timeout"

    def test_network_categorized(self):
        assert self._categorize_error("Connection refused") == "network"
        assert self._categorize_error("Network error") == "network"

    def test_auth_categorized(self):
        assert self._categorize_error("Unauthorized access") == "auth"
        assert self._categorize_error("Permission denied") == "auth"

    def test_not_found_categorized(self):
        assert self._categorize_error("Resource not found") == "not_found"
        assert self._categorize_error("404 error") == "not_found"

    def test_rate_limit_categorized(self):
        assert self._categorize_error("Rate limit exceeded") == "rate_limit"
        assert self._categorize_error("429 Too Many Requests") == "rate_limit"

    def test_validation_categorized(self):
        assert self._categorize_error("Invalid input") == "validation"
        assert self._categorize_error("Bad request") == "validation"

    def test_unknown_categorized(self):
        assert self._categorize_error("Something went wrong") == "unknown"


class TestErrorSeverity:
    """Tests for error severity determination."""

    def _get_severity(self, error_category):
        """Get severity level for error category."""
        severities = {
            "validation": "low",
            "not_found": "low",
            "auth": "medium",
            "timeout": "medium",
            "network": "high",
            "rate_limit": "medium",
            "unknown": "high",
        }
        return severities.get(error_category, "high")

    def test_validation_low_severity(self):
        assert self._get_severity("validation") == "low"

    def test_network_high_severity(self):
        assert self._get_severity("network") == "high"

    def test_unknown_high_severity(self):
        assert self._get_severity("unknown") == "high"


# --- Retry logic patterns ---


class TestRetryDecision:
    """Tests for retry decision patterns."""

    def _should_retry(self, error_category, attempt, max_attempts=3):
        """Decide if error should be retried."""
        if attempt >= max_attempts:
            return False
        retryable = ["timeout", "network", "rate_limit"]
        return error_category in retryable

    def test_retryable_on_first_attempt(self):
        assert self._should_retry("timeout", 0) is True
        assert self._should_retry("network", 0) is True

    def test_not_retryable_categories(self):
        assert self._should_retry("auth", 0) is False
        assert self._should_retry("validation", 0) is False
        assert self._should_retry("not_found", 0) is False

    def test_no_retry_after_max_attempts(self):
        assert self._should_retry("timeout", 3) is False

    def test_retry_before_max_attempts(self):
        assert self._should_retry("timeout", 2) is True


class TestExponentialBackoff:
    """Tests for exponential backoff patterns."""

    def _calculate_backoff(
        self, attempt, base_delay=1.0, max_delay=60.0, jitter=True
    ):
        """Calculate exponential backoff delay."""
        delay = base_delay * (2**attempt)
        delay = min(delay, max_delay)
        if jitter:
            delay = delay * (0.5 + random.random() * 0.5)
        return delay

    def _calculate_backoff_no_jitter(
        self, attempt, base_delay=1.0, max_delay=60.0
    ):
        """Calculate backoff without jitter."""
        delay = base_delay * (2**attempt)
        return min(delay, max_delay)

    def test_first_attempt_base_delay(self):
        delay = self._calculate_backoff_no_jitter(0)
        assert delay == 1.0

    def test_exponential_increase(self):
        delay0 = self._calculate_backoff_no_jitter(0)
        delay1 = self._calculate_backoff_no_jitter(1)
        delay2 = self._calculate_backoff_no_jitter(2)
        assert delay1 == delay0 * 2
        assert delay2 == delay1 * 2

    def test_capped_at_max(self):
        delay = self._calculate_backoff_no_jitter(100, max_delay=60.0)
        assert delay == 60.0

    def test_jitter_varies_delay(self):
        delays = [self._calculate_backoff(1, jitter=True) for _ in range(10)]
        # With jitter, delays should vary
        assert len(set(delays)) > 1


# --- Circuit breaker patterns ---


class TestCircuitBreaker:
    """Tests for circuit breaker patterns."""

    def _create_circuit_breaker(self, failure_threshold=5, recovery_timeout=30):
        """Create a circuit breaker."""
        return {
            "state": "closed",  # closed, open, half_open
            "failure_count": 0,
            "failure_threshold": failure_threshold,
            "recovery_timeout": recovery_timeout,
            "last_failure_time": None,
        }

    def _record_failure(self, breaker):
        """Record a failure in the circuit breaker."""
        breaker["failure_count"] += 1
        breaker["last_failure_time"] = datetime.now(timezone.utc)
        if breaker["failure_count"] >= breaker["failure_threshold"]:
            breaker["state"] = "open"

    def _record_success(self, breaker):
        """Record a success in the circuit breaker."""
        breaker["failure_count"] = 0
        breaker["state"] = "closed"

    def _is_call_allowed(self, breaker):
        """Check if call is allowed through circuit breaker."""
        if breaker["state"] == "closed":
            return True
        if breaker["state"] == "open":
            # Check if recovery timeout has passed
            if breaker["last_failure_time"]:
                elapsed = (
                    datetime.now(timezone.utc) - breaker["last_failure_time"]
                ).total_seconds()
                if elapsed >= breaker["recovery_timeout"]:
                    breaker["state"] = "half_open"
                    return True
            return False
        if breaker["state"] == "half_open":
            return True
        return False

    def test_starts_closed(self):
        breaker = self._create_circuit_breaker()
        assert breaker["state"] == "closed"

    def test_allows_calls_when_closed(self):
        breaker = self._create_circuit_breaker()
        assert self._is_call_allowed(breaker) is True

    def test_opens_after_threshold(self):
        breaker = self._create_circuit_breaker(failure_threshold=3)
        for _ in range(3):
            self._record_failure(breaker)
        assert breaker["state"] == "open"

    def test_blocks_when_open(self):
        breaker = self._create_circuit_breaker()
        breaker["state"] = "open"
        breaker["last_failure_time"] = datetime.now(timezone.utc)
        assert self._is_call_allowed(breaker) is False

    def test_success_resets(self):
        breaker = self._create_circuit_breaker()
        breaker["failure_count"] = 3
        self._record_success(breaker)
        assert breaker["failure_count"] == 0
        assert breaker["state"] == "closed"


class TestCircuitBreakerHalfOpen:
    """Tests for circuit breaker half-open state."""

    def _transition_to_half_open(self, breaker):
        """Transition breaker to half-open state."""
        breaker["state"] = "half_open"
        return breaker

    def _handle_half_open_result(self, breaker, success):
        """Handle result in half-open state."""
        if success:
            breaker["state"] = "closed"
            breaker["failure_count"] = 0
        else:
            breaker["state"] = "open"
            breaker["last_failure_time"] = datetime.now(timezone.utc)

    def test_success_closes_breaker(self):
        breaker = {"state": "half_open", "failure_count": 0}
        self._handle_half_open_result(breaker, True)
        assert breaker["state"] == "closed"

    def test_failure_opens_breaker(self):
        breaker = {
            "state": "half_open",
            "failure_count": 0,
            "last_failure_time": None,
        }
        self._handle_half_open_result(breaker, False)
        assert breaker["state"] == "open"


# --- Graceful degradation patterns ---


class TestGracefulDegradation:
    """Tests for graceful degradation patterns."""

    def _get_with_fallback(self, primary_func, fallback_value):
        """Get value with fallback on error."""
        try:
            return primary_func()
        except Exception:
            return fallback_value

    def _get_with_cache_fallback(self, fetch_func, cache, key):
        """Get fresh value or use cached value on error."""
        try:
            value = fetch_func()
            cache[key] = value
            return value, True  # value, is_fresh
        except Exception:
            if key in cache:
                return cache[key], False  # Stale cache
            raise

    def test_primary_succeeds(self):
        result = self._get_with_fallback(lambda: "primary", "fallback")
        assert result == "primary"

    def test_fallback_on_error(self):
        def failing():
            raise Exception("Error")

        result = self._get_with_fallback(failing, "fallback")
        assert result == "fallback"

    def test_fresh_value_returned(self):
        cache = {}
        value, is_fresh = self._get_with_cache_fallback(
            lambda: "fresh", cache, "key"
        )
        assert value == "fresh"
        assert is_fresh is True

    def test_stale_cache_on_error(self):
        cache = {"key": "stale"}

        def failing():
            raise Exception("Error")

        value, is_fresh = self._get_with_cache_fallback(failing, cache, "key")
        assert value == "stale"
        assert is_fresh is False


class TestPartialResults:
    """Tests for partial result handling patterns."""

    def _collect_partial_results(self, sources, fetch_func):
        """Collect results from multiple sources, tolerating failures."""
        results = []
        errors = []
        for source in sources:
            try:
                result = fetch_func(source)
                results.append({"source": source, "data": result})
            except Exception as e:
                errors.append({"source": source, "error": str(e)})
        return {"results": results, "errors": errors}

    def test_all_succeed(self):
        sources = ["a", "b", "c"]
        outcome = self._collect_partial_results(sources, lambda s: f"data-{s}")
        assert len(outcome["results"]) == 3
        assert len(outcome["errors"]) == 0

    def test_partial_failure(self):
        def fetch(source):
            if source == "b":
                raise Exception("Failed")
            return f"data-{source}"

        outcome = self._collect_partial_results(["a", "b", "c"], fetch)
        assert len(outcome["results"]) == 2
        assert len(outcome["errors"]) == 1

    def test_all_fail(self):
        def failing(source):
            raise Exception("Failed")

        outcome = self._collect_partial_results(["a", "b"], failing)
        assert len(outcome["results"]) == 0
        assert len(outcome["errors"]) == 2


# --- Error response patterns ---


class TestErrorResponse:
    """Tests for error response building patterns."""

    def _build_error_response(
        self, error, status_code=500, include_details=False
    ):
        """Build error response."""
        response = {
            "success": False,
            "error": {
                "code": status_code,
                "message": self._get_user_message(error),
            },
        }
        if include_details:
            response["error"]["details"] = str(error)
        return response

    def _get_user_message(self, error):
        """Get user-friendly error message."""
        error_str = str(error).lower()
        if "not found" in error_str:
            return "The requested resource was not found."
        if "unauthorized" in error_str or "auth" in error_str:
            return "Authentication required."
        if "forbidden" in error_str:
            return "You don't have permission to access this resource."
        if "timeout" in error_str:
            return "The request timed out. Please try again."
        return "An unexpected error occurred. Please try again later."

    def test_has_success_false(self):
        response = self._build_error_response("Error")
        assert response["success"] is False

    def test_has_status_code(self):
        response = self._build_error_response("Error", status_code=404)
        assert response["error"]["code"] == 404

    def test_friendly_not_found_message(self):
        response = self._build_error_response("Resource not found")
        assert "not found" in response["error"]["message"].lower()

    def test_includes_details_when_requested(self):
        response = self._build_error_response(
            "Specific error", include_details=True
        )
        assert "Specific error" in response["error"]["details"]


# --- Error logging patterns ---


class TestErrorLogging:
    """Tests for error logging patterns."""

    def _format_error_log(self, error, context=None):
        """Format error for logging."""
        log = {
            "timestamp": datetime.now(timezone.utc).isoformat(),
            "error_type": type(error).__name__
            if hasattr(error, "__class__")
            else "Unknown",
            "message": str(error),
        }
        if context:
            log["context"] = context
        return log

    def _should_alert(self, error_category, count_in_window):
        """Check if error should trigger alert."""
        alert_thresholds = {
            "auth": 10,
            "network": 5,
            "timeout": 10,
            "unknown": 3,
        }
        threshold = alert_thresholds.get(error_category, 5)
        return count_in_window >= threshold

    def test_log_has_timestamp(self):
        log = self._format_error_log(Exception("Test"))
        assert "timestamp" in log

    def test_log_has_message(self):
        log = self._format_error_log(Exception("Test error"))
        assert log["message"] == "Test error"

    def test_log_includes_context(self):
        log = self._format_error_log(Exception("Error"), {"user_id": "123"})
        assert log["context"]["user_id"] == "123"

    def test_alert_threshold(self):
        assert self._should_alert("network", 5) is True
        assert self._should_alert("network", 4) is False


# --- Timeout handling patterns ---


class TestTimeoutHandling:
    """Tests for timeout handling patterns."""

    def _with_timeout(self, func, timeout_seconds, default=None):
        """Execute function with timeout (simulated)."""
        # In real code, this would use threading or asyncio
        # Here we just test the pattern
        try:
            return func()
        except TimeoutError:
            return default

    def _calculate_dynamic_timeout(self, operation_type, payload_size=0):
        """Calculate dynamic timeout based on operation."""
        base_timeouts = {
            "search": 10,
            "research": 60,
            "download": 30,
            "api_call": 5,
        }
        base = base_timeouts.get(operation_type, 10)
        # Add time for larger payloads
        size_factor = payload_size / 1000000  # MB
        return base + (size_factor * 5)

    def test_returns_result_on_success(self):
        result = self._with_timeout(lambda: "success", 10)
        assert result == "success"

    def test_returns_default_on_timeout(self):
        def timeout_func():
            raise TimeoutError()

        result = self._with_timeout(timeout_func, 10, default="fallback")
        assert result == "fallback"

    def test_research_has_longer_timeout(self):
        search_timeout = self._calculate_dynamic_timeout("search")
        research_timeout = self._calculate_dynamic_timeout("research")
        assert research_timeout > search_timeout

    def test_timeout_scales_with_size(self):
        small = self._calculate_dynamic_timeout("download", payload_size=100000)
        large = self._calculate_dynamic_timeout(
            "download", payload_size=10000000
        )
        assert large > small


# --- Error recovery patterns ---


class TestErrorRecovery:
    """Tests for error recovery patterns."""

    def _attempt_recovery(self, error_category):
        """Determine recovery action for error."""
        recovery_actions = {
            "timeout": "retry_with_backoff",
            "network": "retry_with_backoff",
            "rate_limit": "wait_and_retry",
            "auth": "refresh_credentials",
            "not_found": "return_empty",
            "validation": "return_error",
        }
        return recovery_actions.get(error_category, "log_and_fail")

    def test_timeout_retries(self):
        action = self._attempt_recovery("timeout")
        assert action == "retry_with_backoff"

    def test_rate_limit_waits(self):
        action = self._attempt_recovery("rate_limit")
        assert action == "wait_and_retry"

    def test_auth_refreshes(self):
        action = self._attempt_recovery("auth")
        assert action == "refresh_credentials"

    def test_validation_returns_error(self):
        action = self._attempt_recovery("validation")
        assert action == "return_error"


class TestStateRecovery:
    """Tests for state recovery patterns."""

    def _save_checkpoint(self, state, checkpoints, max_checkpoints=5):
        """Save state checkpoint."""
        checkpoint = {
            "timestamp": datetime.now(timezone.utc),
            "state": state.copy(),
        }
        checkpoints.append(checkpoint)
        while len(checkpoints) > max_checkpoints:
            checkpoints.pop(0)
        return len(checkpoints)

    def _restore_checkpoint(self, checkpoints, index=-1):
        """Restore from checkpoint."""
        if not checkpoints:
            return None
        return checkpoints[index]["state"]

    def test_saves_checkpoint(self):
        checkpoints = []
        self._save_checkpoint({"progress": 50}, checkpoints)
        assert len(checkpoints) == 1

    def test_limits_checkpoints(self):
        checkpoints = []
        for i in range(10):
            self._save_checkpoint(
                {"progress": i}, checkpoints, max_checkpoints=3
            )
        assert len(checkpoints) == 3

    def test_restores_latest(self):
        checkpoints = []
        self._save_checkpoint({"v": 1}, checkpoints)
        self._save_checkpoint({"v": 2}, checkpoints)
        restored = self._restore_checkpoint(checkpoints)
        assert restored["v"] == 2

    def test_restores_specific(self):
        checkpoints = []
        self._save_checkpoint({"v": 1}, checkpoints)
        self._save_checkpoint({"v": 2}, checkpoints)
        restored = self._restore_checkpoint(checkpoints, index=0)
        assert restored["v"] == 1


# --- Health check patterns ---


class TestHealthCheckPatterns:
    """Tests for health check patterns."""

    def _check_component_health(self, component, check_func):
        """Check health of a component."""
        try:
            start = datetime.now(timezone.utc)
            result = check_func()
            elapsed = (datetime.now(timezone.utc) - start).total_seconds()
            return {
                "component": component,
                "healthy": result,
                "latency_ms": elapsed * 1000,
            }
        except Exception as e:
            return {
                "component": component,
                "healthy": False,
                "error": str(e),
            }

    def _aggregate_health(self, checks):
        """Aggregate health checks."""
        all_healthy = all(c.get("healthy", False) for c in checks)
        unhealthy = [
            c["component"] for c in checks if not c.get("healthy", False)
        ]
        return {
            "status": "healthy" if all_healthy else "unhealthy",
            "unhealthy_components": unhealthy,
        }

    def test_healthy_component(self):
        result = self._check_component_health("db", lambda: True)
        assert result["healthy"] is True

    def test_unhealthy_component(self):
        result = self._check_component_health("db", lambda: False)
        assert result["healthy"] is False

    def test_failed_check(self):
        def failing():
            raise Exception("Connection failed")

        result = self._check_component_health("db", failing)
        assert result["healthy"] is False
        assert "error" in result

    def test_aggregate_all_healthy(self):
        checks = [
            {"component": "db", "healthy": True},
            {"component": "cache", "healthy": True},
        ]
        result = self._aggregate_health(checks)
        assert result["status"] == "healthy"

    def test_aggregate_some_unhealthy(self):
        checks = [
            {"component": "db", "healthy": True},
            {"component": "cache", "healthy": False},
        ]
        result = self._aggregate_health(checks)
        assert result["status"] == "unhealthy"
        assert "cache" in result["unhealthy_components"]
