/**
 * Test-environment setup for @suaveplan/api-migrations.
 *
 * Wires a real in-memory OpenTelemetry MeterProvider BEFORE any source
 * module is imported, so the meter resolved at module load is the real
 * provider's meter — not the noop fallback. Tests that inspect emitted
 * metrics (counter `migrations.applied_total`, histogram
 * `migrations.apply_duration_ms`) read them out of
 * `testInMemoryMetricExporter`.
 *
 * Node ≥18 exposes `crypto.subtle` globally, so no crypto polyfill is
 * required. Server-tier: `node:fs/promises` is available natively.
 */
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() {
    await testMeterProvider.forceFlush();
    const collected = testInMemoryMetricExporter.getMetrics();
    testInMemoryMetricExporter.reset();
    return collected;
}