package reportbuf_test

import (
	"os"
	"strings"
	"testing"

	"sneak.berlin/go/netwatch/internal/config"
	"sneak.berlin/go/netwatch/internal/globals"
	"sneak.berlin/go/netwatch/internal/logger"
	"sneak.berlin/go/netwatch/internal/reportbuf"

	"go.uber.org/fx"
	"go.uber.org/fx/fxtest"
)

// TestFlushOnShutdown proves the flush-on-shutdown path: a
// report appended after start but before the periodic flush
// window must reach disk when the fx lifecycle stops. This is
// the exact case that silent data loss on restart used to
// destroy.
func TestFlushOnShutdown(t *testing.T) {
	dir := t.TempDir()
	t.Setenv("DATA_DIR", dir)

	var buf *reportbuf.Buffer

	app := fxtest.New(t,
		fx.Provide(
			globals.New,
			logger.New,
			config.New,
			reportbuf.New,
		),
		fx.Populate(&buf),
	)

	app.RequireStart()

	err := buf.Append(map[string]string{"probe": "shutdown"})
	if err != nil {
		t.Fatalf("append report: %v", err)
	}

	// RequireStop runs the reportbuf OnStop hook, which is the
	// only code path that flushes buffered reports on shutdown.
	app.RequireStop()

	if !hasReportFile(t, dir) {
		t.Fatal("no report file on disk after shutdown; " +
			"the buffered report was lost")
	}
}

func hasReportFile(t *testing.T, dir string) bool {
	t.Helper()

	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatalf("read data dir: %v", err)
	}

	for _, e := range entries {
		if strings.HasSuffix(e.Name(), ".jsonl.zst") {
			info, statErr := e.Info()
			if statErr != nil {
				t.Fatalf("stat %s: %v", e.Name(), statErr)
			}

			if info.Size() > 0 {
				return true
			}
		}
	}

	return false
}