package flydetector

import (
	"context"
	"os"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/sdk/resource"
	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
)

var _ resource.Detector = &FlyDetector{}

type FlyDetector struct{}

func NewDetector() resource.Detector {
	return &FlyDetector{}
}

func (d *FlyDetector) Detect(_ context.Context) (*resource.Resource, error) {
	a := []attribute.KeyValue{semconv.CloudProviderKey.String("fly")}

	if an, ok := os.LookupEnv("FLY_APP_NAME"); ok {
		a = append(a, attribute.String("fly.app_name", an))
	} else {
		return resource.Empty(), nil
	}

	if mid, ok := os.LookupEnv("FLY_MACHINE_ID"); ok {
		a = append(a, attribute.String("fly.machine_id", mid))
	}

	if aid, ok := os.LookupEnv("FLY_ALLOC_ID"); ok {
		a = append(a, attribute.String("fly.alloc_id", aid))
	}

	if pg, ok := os.LookupEnv("FLY_PROCESS_GROUP"); ok {
		a = append(a, attribute.String("fly.process_group", pg))
	}

	if mv, ok := os.LookupEnv("FLY_MACHINE_VERSION"); ok {
		a = append(a, attribute.String("fly.machine_version", mv), semconv.CloudResourceID(mv))
	}

	if reg, ok := os.LookupEnv("FLY_REGION"); ok {
		a = append(a, attribute.String("fly.region", reg), semconv.CloudRegionKey.String(reg))
	}

	if ir, ok := os.LookupEnv("FLY_IMAGE_REF"); ok {
		a = append(a, attribute.String("fly.image_ref", ir))
	}

	return resource.NewWithAttributes(semconv.SchemaURL, a...), nil
}