from django.apps import AppConfig
import os
import logging
import multiprocessing
from uuid import uuid4

from opentelemetry import trace, metrics
from opentelemetry._logs import set_logger_provider
from opentelemetry.sdk.resources import Resource, SERVICE_INSTANCE_ID

from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import BatchSpanProcessor
from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter

from opentelemetry.sdk.metrics import MeterProvider
from opentelemetry.sdk.metrics.export import PeriodicExportingMetricReader
from opentelemetry.exporter.otlp.proto.grpc.metric_exporter import OTLPMetricExporter

from opentelemetry.sdk._logs import LoggerProvider, LoggingHandler
from opentelemetry.sdk._logs.export import BatchLogRecordProcessor
from opentelemetry.exporter.otlp.proto.grpc._log_exporter import OTLPLogExporter
from opentelemetry.instrumentation.django import DjangoInstrumentor

class TelemetryConfig(AppConfig):
    name = "telemetry"

    def ready(self):
        # Resource Definition
        resource = Resource.create({
            "service.name": "development-kitchen",
            SERVICE_INSTANCE_ID: str(uuid4()),
            "worker": os.getpid(),  # os.getpid() works outside Gunicorn too
        })

        endpoint = os.environ.get("OTEL_EXPORTER_OTLP_ENDPOINT", "http://129.159.229.69:4317")

        # TRACE SETUP
        if not isinstance(trace.get_tracer_provider(), TracerProvider):
            tracer_provider = TracerProvider(resource=resource)
            span_exporter = OTLPSpanExporter(endpoint=endpoint)
            tracer_provider.add_span_processor(BatchSpanProcessor(span_exporter))
            trace.set_tracer_provider(tracer_provider)

        # METRIC SETUP
        if not isinstance(metrics.get_meter_provider(), MeterProvider):
            metric_reader = PeriodicExportingMetricReader(OTLPMetricExporter(endpoint=endpoint))
            meter_provider = MeterProvider(resource=resource, metric_readers=[metric_reader])
            metrics.set_meter_provider(meter_provider)

        # LOGGING SETUP
        # 1. Create and set the logger provider FIRST
        logger_provider = LoggerProvider(resource=resource)
        set_logger_provider(logger_provider)  # MUST be set before using LoggingHandler

        # 2. Add processor and exporter
        log_exporter = OTLPLogExporter(endpoint=endpoint)
        logger_provider.add_log_record_processor(BatchLogRecordProcessor(log_exporter))

        # 3. Now safely create the handler (uses global logger provider)
        otel_handler = LoggingHandler(level=logging.INFO)

        # 4. Attach to Django and root loggers
        logging.getLogger("django").addHandler(otel_handler)
        logging.getLogger("django").setLevel(logging.INFO)

        logging.getLogger().addHandler(otel_handler)
        logging.getLogger().setLevel(logging.INFO)
        
        
        from opentelemetry.instrumentation.django import DjangoInstrumentor
        DjangoInstrumentor().instrument()
        
        import sys
        from .utils import PrintLogger  # assuming PrintLogger is defined in telemetry/utils.py

        # Redirect print() and errors to logger so they appear in SigNoz
        sys.stdout = PrintLogger(logging.INFO)
        sys.stderr = PrintLogger(logging.ERROR)