import { context, ROOT_CONTEXT, trace, TraceFlags } from "@opentelemetry/api"
import { NodeTracerProvider } from "@opentelemetry/sdk-trace-node"
import { SimpleSpanProcessor } from "@opentelemetry/sdk-trace-base"
import { OTLPTraceExporter } from "@opentelemetry/exporter-trace-otlp-http"

process.on("unhandledRejection", (err) => console.error("[child] export error:", err?.message ?? err))

function parentContextFromEnv() {
  const tp = process.env.TRACEPARENT
  if (!tp) return ROOT_CONTEXT
  const [, traceId, spanId, flags] = tp.split("-")
  return trace.setSpanContext(ROOT_CONTEXT, {
    traceId, spanId,
    traceFlags: Number.parseInt(flags, 16) || TraceFlags.NONE,
    isRemote: true,
  })
}

const provider = new NodeTracerProvider({
  spanProcessors: [new SimpleSpanProcessor(new OTLPTraceExporter())],
  const [, traceId, spanId, flags] = tp.split("-")
  return trace.setSpanContext(ROOT_CONTEXT, {
    traceId, spanId,
    traceFlags: Number.parseInt(flags, 16) || TraceFlags.NONE,
    isRemote: true,
  })
}

const provider = new NodeTracerProvider({
  spanProcessors: [new SimpleSpanProcessor(new OTLPTraceExporter())],
})
provider.register()

await context.with(parentContextFromEnv(), async () => {
  await new Promise((resolve) => {
    trace.getTracer("otel-subprocess-test").startActiveSpan("subprocess-work", (span) => {
      span.setAttribute("test.tag", "subprocess-propagation")
      setTimeout(() => { span.end(); resolve() }, 50)
    })
  })
})
try { await provider.shutdown() } catch {}