package telemetry

import (
	"context"
	"errors"
	"time"

	"gitea.nik4nao.com/nik/home-services/discord-bot/internal/logger"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
	"go.opentelemetry.io/otel/metric/noop"
	"go.opentelemetry.io/otel/propagation"
	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/resource"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
	tracenoop "go.opentelemetry.io/otel/trace/noop"

	"gitea.nik4nao.com/nik/home-services/discord-bot/internal/config"
)

func Setup(ctx context.Context, serviceName, version string, cfg *config.Config) (shutdown func(context.Context) error, err error) {
	if cfg.OTELEndpoint == "" {
		otel.SetTracerProvider(tracenoop.NewTracerProvider())
		otel.SetMeterProvider(noop.NewMeterProvider())
		logger.FromContext(ctx).Debug("otel disabled — OTEL_ENDPOINT not set")
		return func(context.Context) error { return nil }, nil
	}

	res := resource.NewWithAttributes(
		semconv.SchemaURL,
		semconv.ServiceNameKey.String(serviceName),
		semconv.ServiceVersionKey.String(version),
	)

	traceExp, err := otlptracegrpc.New(ctx,
		otlptracegrpc.WithEndpoint(cfg.OTELEndpoint),
		otlptracegrpc.WithInsecure(),
	)
	if err != nil {
		return nil, err
	}
	tp := sdktrace.NewTracerProvider(
		sdktrace.WithBatcher(traceExp),
		sdktrace.WithResource(res),
		sdktrace.WithSampler(sdktrace.AlwaysSample()),
	)
	otel.SetTracerProvider(tp)
	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(
		propagation.TraceContext{},
		propagation.Baggage{},
	))

	metricExp, err := otlpmetricgrpc.New(ctx,
		otlpmetricgrpc.WithEndpoint(cfg.OTELEndpoint),
		otlpmetricgrpc.WithInsecure(),
	)
	if err != nil {
		_ = tp.Shutdown(ctx)
		return nil, err
	}
	mp := sdkmetric.NewMeterProvider(
		sdkmetric.WithReader(sdkmetric.NewPeriodicReader(metricExp,
			sdkmetric.WithInterval(30*time.Second))),
		sdkmetric.WithResource(res),
	)
	otel.SetMeterProvider(mp)

	return func(ctx context.Context) error {
		shutdownCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
		defer cancel()
		var shutdownErr error
		if err := tp.Shutdown(shutdownCtx); err != nil {
			shutdownErr = errors.Join(shutdownErr, err)
		}
		if err := mp.Shutdown(shutdownCtx); err != nil {
			shutdownErr = errors.Join(shutdownErr, err)
		}
		return shutdownErr
	}, nil
}