/**
 * Test-environment setup for @suaveplan/broadcast-channel.
 *
 * Wires a real in-memory OpenTelemetry `MeterProvider` BEFORE any source
 * module loads, so the meter resolved at module load is the real provider's
 * meter. Tests that inspect emitted instruments read them out of the in-memory
 * exporter via `flushTestMetrics()`.
 */
import { metrics } from "@opentelemetry/api";
import {
    AggregationTemporality,
    InMemoryMetricExporter,
    MeterProvider,
    PeriodicExportingMetricReader,
} from "@opentelemetry/sdk-metrics";

export const testInMemoryMetricExporter = new InMemoryMetricExporter(
    AggregationTemporality.CUMULATIVE
);

const reader = new PeriodicExportingMetricReader({
    exporter: testInMemoryMetricExporter,
    exportIntervalMillis: 60_000,
});

export const testMeterProvider = new MeterProvider({ readers: [reader] });
metrics.setGlobalMeterProvider(testMeterProvider);

export async function flushTestMetrics(): Promise<
    ReturnType<typeof testInMemoryMetricExporter.getMetrics>
> {
    await testMeterProvider.forceFlush();
    const collected = testInMemoryMetricExporter.getMetrics();
    testInMemoryMetricExporter.reset();
    return collected;
}