package channelhealth

import (
	"errors"
	"io"
	"log"
	"os"
	"path/filepath"
	"testing"
)

// R-271: the 401 alert's remedy is a re-bootstrap (a controller restart), and an unseeded→up first
// observation is silent — so following the instruction guaranteed no recovery event. The consequence
// asserted across a simulated restart: a NEW checker over the same marker file notifies recovery on
// its first UP; a restart with no alert outstanding stays silent (the seeding rule is unchanged).
func TestR271_RecoveryAfterRestartIsNotified(t *testing.T) {
	marker := filepath.Join(t.TempDir(), "channelhealth-down-alerted")
	lg := log.New(io.Discard, "", 0)

	// Process 1: the channel goes down with a 401 and the alert is sent.
	s1 := &fakeSink{}
	c1 := New(nil, s1, lg).WithAlertMarker(marker)
	run(c1, &scriptedProbe{steps: []struct {
		cons bool
		err  error
	}{step(false, nil), step(false, errors.New("agentapi: GET /storage: HTTP 401"))}})
	if len(s1.downs) != 1 {
		t.Fatalf("setup: want one down alert, got %d", len(s1.downs))
	}

	// Restart (the remedy). Process 2 sees the channel UP on its first probe.
	s2 := &fakeSink{}
	c2 := New(nil, s2, lg).WithAlertMarker(marker)
	run(c2, &scriptedProbe{steps: []struct {
		cons bool
		err  error
	}{step(false, nil), step(false, nil)}})
	if s2.recovered != 1 {
		t.Fatalf("R-271: the recovery after a restart must be notified exactly once, got %d", s2.recovered)
	}
	if _, err := os.Stat(marker); !os.IsNotExist(err) {
		t.Errorf("the marker must be cleared once the recovery is sent (stat err=%v)", err)
	}

	// Process 3: a restart with nothing outstanding stays silent (first observation seeds).
	s3 := &fakeSink{}
	c3 := New(nil, s3, lg).WithAlertMarker(marker)
	run(c3, &scriptedProbe{steps: []struct {
		cons bool
		err  error
	}{step(false, nil)}})
	if s3.recovered != 0 {
		t.Errorf("a restart with no alert outstanding must not send a recovery, got %d", s3.recovered)
	}

	// A live recovery (no restart) clears the marker too, so a later restart is silent.
	s4 := &fakeSink{}
	c4 := New(nil, s4, lg).WithAlertMarker(marker)
	run(c4, &scriptedProbe{steps: []struct {
		cons bool
		err  error
	}{step(false, nil), step(false, errors.New("agentapi: GET /storage: HTTP 401")), step(false, nil)}})
	if s4.recovered != 1 {
		t.Fatalf("live recovery: want 1, got %d", s4.recovered)
	}
	if _, err := os.Stat(marker); !os.IsNotExist(err) {
		t.Errorf("a live recovery must clear the marker (stat err=%v)", err)
	}
}