"""
OpenTelemetry distributed tracing integration
Provides end-to-end request tracking across all services
"""

import structlog
from typing import Optional
from opentelemetry import trace
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import BatchSpanProcessor
from opentelemetry.sdk.resources import Resource, SERVICE_NAME, SERVICE_VERSION
from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter
from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor
from opentelemetry.instrumentation.httpx import HTTPXClientInstrumentor
from opentelemetry.instrumentation.redis import RedisInstrumentor
from opentelemetry.instrumentation.sqlalchemy import SQLAlchemyInstrumentor

logger = structlog.get_logger()


def setup_tracing(
    app,
    service_name: str,
    service_version: str = "1.0.0",
    otel_endpoint: str = "http://signoz-otel-collector.signoz:4318"
):
    """
    Setup OpenTelemetry distributed tracing for a FastAPI service.

    Automatically instruments:
    - FastAPI endpoints
    - HTTPX client requests (inter-service calls)
    - Redis operations
    - PostgreSQL/SQLAlchemy queries

    Args:
        app: FastAPI application instance
        service_name: Name of the service (e.g., "auth-service")
        service_version: Version of the service
        otel_endpoint: OpenTelemetry collector endpoint (SigNoz)

    Example:
        from shared.monitoring.tracing import setup_tracing

        app = FastAPI(title="Auth Service")
        setup_tracing(app, "auth-service")
    """

    try:
        # Create resource with service information
        resource = Resource(attributes={
            SERVICE_NAME: service_name,
            SERVICE_VERSION: service_version,
            "deployment.environment": "production"
        })

        # Configure tracer provider
        tracer_provider = TracerProvider(resource=resource)
        trace.set_tracer_provider(tracer_provider)

        # Configure OTLP exporter to send to SigNoz
        otlp_exporter = OTLPSpanExporter(
            endpoint=otel_endpoint,
            insecure=True  # Use TLS in production
        )

        # Add span processor with batching for performance
        span_processor = BatchSpanProcessor(otlp_exporter)
        tracer_provider.add_span_processor(span_processor)

        # Auto-instrument FastAPI
        FastAPIInstrumentor.instrument_app(
            app,
            tracer_provider=tracer_provider,
            excluded_urls="health,metrics"  # Don't trace health/metrics endpoints
        )

        # Auto-instrument HTTPX (inter-service communication)
        HTTPXClientInstrumentor().instrument(tracer_provider=tracer_provider)

        # Auto-instrument Redis
        try:
            RedisInstrumentor().instrument(tracer_provider=tracer_provider)
        except Exception as e:
            logger.warning(f"Failed to instrument Redis: {e}")

        # Auto-instrument PostgreSQL (psycopg2) - skip if not available
        # Most services use asyncpg instead of psycopg2
        # try:
        #     Psycopg2Instrumentor().instrument(tracer_provider=tracer_provider)
        # except Exception as e:
        #     logger.warning(f"Failed to instrument Psycopg2: {e}")

        # Auto-instrument SQLAlchemy
        try:
            SQLAlchemyInstrumentor().instrument(tracer_provider=tracer_provider)
        except Exception as e:
            logger.warning(f"Failed to instrument SQLAlchemy: {e}")

        logger.info(
            "Distributed tracing configured",
            service=service_name,
            otel_endpoint=otel_endpoint
        )

    except Exception as e:
        logger.error(
            "Failed to setup tracing - continuing without it",
            service=service_name,
            error=str(e)
        )


def get_current_trace_id() -> Optional[str]:
    """
    Get the current trace ID for correlation with logs.

    Returns:
        Trace ID as hex string, or None if no active trace
    """
    span = trace.get_current_span()
    if span and span.get_span_context().is_valid:
        return format(span.get_span_context().trace_id, '032x')
    return None


def get_current_span_id() -> Optional[str]:
    """
    Get the current span ID.

    Returns:
        Span ID as hex string, or None if no active span
    """
    span = trace.get_current_span()
    if span and span.get_span_context().is_valid:
        return format(span.get_span_context().span_id, '016x')
    return None


def add_trace_attributes(**attributes):
    """
    Add custom attributes to the current span.

    Example:
        add_trace_attributes(
            user_id="123",
            tenant_id="abc",
            operation="user_registration"
        )
    """
    span = trace.get_current_span()
    if span and span.get_span_context().is_valid:
        for key, value in attributes.items():
            span.set_attribute(key, str(value))


def add_trace_event(name: str, **attributes):
    """
    Add an event to the current span (for important operations).

    Example:
        add_trace_event("user_authenticated", user_id="123", method="jwt")
    """
    span = trace.get_current_span()
    if span and span.get_span_context().is_valid:
        span.add_event(name, attributes)


def record_exception(exception: Exception):
    """
    Record an exception in the current span.

    Args:
        exception: The exception to record
    """
    span = trace.get_current_span()
    if span and span.get_span_context().is_valid:
        span.record_exception(exception)
        span.set_status(trace.Status(trace.StatusCode.ERROR, str(exception)))