package git

import (
	"context"
	"runtime"
	"testing"
)

func BenchmarkPerformanceBlobReader(b *testing.B) {
	fixture := newRemoteFixture(b)
	objectID := gitText(b, fixture.work, "rev-parse", "HEAD:source.txt")
	const expectedBytes = int64(len("candidate"))

	b.Run("new-session-per-read", func(b *testing.B) {
		b.ReportAllocs()
		b.SetBytes(expectedBytes)
		b.ResetTimer()
		b.ReportMetric(float64(expectedBytes), "bytes/op")
		b.ReportMetric(1, "blobs/op")
		for i := 0; i < b.N; i++ {
			reader := NewBlobReader(context.Background(), fixture.work)
			contents, err := reader.Read(context.Background(), objectID)
			if err != nil {
				b.Fatal(err)
			}
			if int64(len(contents)) != expectedBytes {
				b.Fatalf("read %d bytes, want %d", len(contents), expectedBytes)
			}
			if err := reader.Close(); err != nil {
				b.Fatal(err)
			}
			runtime.KeepAlive(contents)
		}
	})

	b.Run("shared-session", func(b *testing.B) {
		reader := NewBlobReader(context.Background(), fixture.work)
		b.Cleanup(func() {
			if err := reader.Close(); err != nil {
				b.Error(err)
			}
		})
		b.ReportAllocs()
		b.SetBytes(expectedBytes)
		b.ResetTimer()
		b.ReportMetric(float64(expectedBytes), "bytes/op")
		b.ReportMetric(1, "blobs/op")
		for i := 0; i < b.N; i++ {
			contents, err := reader.Read(context.Background(), objectID)
			if err != nil {
				b.Fatal(err)
			}
			if int64(len(contents)) != expectedBytes {
				b.Fatalf("read %d bytes, want %d", len(contents), expectedBytes)
			}
			runtime.KeepAlive(contents)
		}
	})
}