package server_test

import (
	"testing"
	"time"

	"github.com/stretchr/testify/require"
	"sneak.berlin/go/webhooker/internal/server"
)

// TestSentryFlushBudget covers the clamp that keeps the Sentry flush
// from spending the tail hooks' share of the fx stop budget.
// sentry.Flush ignores the stop context, so without the clamp a
// stalled flush adds its whole timeout on top of the HTTP drain.
func TestSentryFlushBudget(t *testing.T) {
	t.Parallel()

	tests := []struct {
		name      string
		remaining time.Duration
		want      time.Duration
	}{
		{
			name:      "full drain leaves only the reserve",
			remaining: server.TailHookReserve,
			want:      0,
		},
		{
			name:      "expired budget",
			remaining: -time.Second,
			want:      0,
		},
		{
			name:      "sliver above the reserve is not worth it",
			remaining: server.TailHookReserve + 10*time.Millisecond,
			want:      0,
		},
		{
			name:      "partial flush when some room is left",
			remaining: server.TailHookReserve + time.Second,
			want:      time.Second,
		},
		{
			name:      "capped at the nominal timeout",
			remaining: time.Hour,
			want:      2 * time.Second,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			require.Equal(
				t, tt.want, server.SentryFlushBudget(tt.remaining),
			)
		})
	}
}