"""
OpenTelemetry setup for tracing and metrics.

Supports both gRPC and HTTP exporters, with optional HyperDX integration.
"""

import logging
import os
from typing import Optional, Tuple

from opentelemetry import metrics, trace
from opentelemetry.exporter.otlp.proto.grpc.metric_exporter import OTLPMetricExporter
from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter
from opentelemetry.exporter.otlp.proto.http.metric_exporter import (
    OTLPMetricExporter as OTLPMetricExporterHTTP,
)
from opentelemetry.exporter.otlp.proto.http.trace_exporter import (
    OTLPSpanExporter as OTLPSpanExporterHTTP,
)
from opentelemetry.instrumentation.httpx import HTTPXClientInstrumentor
from opentelemetry.instrumentation.logging import LoggingInstrumentor
from opentelemetry.sdk.metrics import MeterProvider
from opentelemetry.sdk.metrics.export import PeriodicExportingMetricReader
from opentelemetry.sdk.resources import SERVICE_NAME, SERVICE_NAMESPACE, SERVICE_VERSION, Resource
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import BatchSpanProcessor

from handler_base.config import Settings

logger = logging.getLogger(__name__)

# Global references
_tracer: Optional[trace.Tracer] = None
_meter: Optional[metrics.Meter] = None
_initialized = False


def setup_telemetry(
    settings: Optional[Settings] = None,
) -> Tuple[Optional[trace.Tracer], Optional[metrics.Meter]]:
    """
    Initialize OpenTelemetry tracing and metrics.

    Args:
        settings: Configuration settings. If None, loads from environment.

    Returns:
        Tuple of (tracer, meter) or (None, None) if disabled.
    """
    global _tracer, _meter, _initialized

    if _initialized:
        return _tracer, _meter

    if settings is None:
        settings = Settings()

    if not settings.otel_enabled:
        logger.info("OpenTelemetry disabled")
        _initialized = True
        return None, None

    # Create resource with service information
    resource = Resource.create(
        {
            SERVICE_NAME: settings.service_name,
            SERVICE_VERSION: settings.service_version,
            SERVICE_NAMESPACE: settings.service_namespace,
            "deployment.environment": settings.deployment_env,
            "host.name": os.environ.get("HOSTNAME", "unknown"),
        }
    )

    # Determine endpoint and exporter type
    if settings.hyperdx_enabled and settings.hyperdx_api_key:
        # HyperDX uses HTTP with API key header
        endpoint = settings.hyperdx_endpoint
        headers = {"authorization": settings.hyperdx_api_key}
        use_http = True
        logger.info(f"Using HyperDX endpoint: {endpoint}")
    else:
        endpoint = settings.otel_endpoint
        headers = None
        use_http = settings.otel_use_http
        logger.info(f"Using OTEL endpoint: {endpoint} (HTTP: {use_http})")

    # Setup tracing
    if use_http:
        trace_exporter = OTLPSpanExporterHTTP(
            endpoint=f"{endpoint}/v1/traces",
            headers=headers,
        )
    else:
        trace_exporter = OTLPSpanExporter(
            endpoint=endpoint,
        )

    tracer_provider = TracerProvider(resource=resource)
    tracer_provider.add_span_processor(BatchSpanProcessor(trace_exporter))
    trace.set_tracer_provider(tracer_provider)

    # Setup metrics
    if use_http:
        metric_exporter = OTLPMetricExporterHTTP(
            endpoint=f"{endpoint}/v1/metrics",
            headers=headers,
        )
    else:
        metric_exporter = OTLPMetricExporter(
            endpoint=endpoint,
        )

    metric_reader = PeriodicExportingMetricReader(
        metric_exporter,
        export_interval_millis=60000,
    )
    meter_provider = MeterProvider(resource=resource, metric_readers=[metric_reader])
    metrics.set_meter_provider(meter_provider)

    # Instrument libraries
    HTTPXClientInstrumentor().instrument()
    LoggingInstrumentor().instrument(set_logging_format=True)

    # Create tracer and meter for this service
    _tracer = trace.get_tracer(settings.service_name, settings.service_version)
    _meter = metrics.get_meter(settings.service_name, settings.service_version)

    logger.info(f"OpenTelemetry initialized for {settings.service_name}")
    _initialized = True

    return _tracer, _meter


def get_tracer() -> Optional[trace.Tracer]:
    """Get the global tracer instance."""
    return _tracer


def get_meter() -> Optional[metrics.Meter]:
    """Get the global meter instance."""
    return _meter


def create_span(name: str, **kwargs):
    """
    Create a new span.

    Usage:
        with create_span("my_operation") as span:
            span.set_attribute("key", "value")
            # do work
    """
    if _tracer is None:
        # Return a no-op context manager
        from contextlib import nullcontext

        return nullcontext()
    return _tracer.start_as_current_span(name, **kwargs)