package stacks

import (
	"bytes"
	"context"
	"log"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

// R-670 (v0.272.0) — every undo logged `[ERROR] .felhom.yml backup block rejected … docker-compose.yml
// unreadable`, because the undo read the previous version's `.felhom.yml` from `pre-update-meta/`, which has
// no compose beside it, through the validating loader. The consequence asserted: a REAL undo of an app whose
// `.felhom.yml` carries a backup block writes no such line to the process log.
//
// COMPANION RED-PROOF (REPORT.md): read PrevMeta with LoadMetadata again — this test fails at "the undo logged
// a false backup-block ERROR".
func TestR670_ProbeLoaderLogsNoFalseError(t *testing.T) {
	var buf bytes.Buffer
	prev := log.Writer()
	log.SetOutput(&buf)
	defer log.SetOutput(prev)

	m, dir, _, _, _ := ladderManager(t, true)
	withBlock := "display_name: Nextcloud\nbackup:\n  userdata:\n    - path: data\n      class: excluded\n"
	mustWrite(t, filepath.Join(dir, ".felhom.yml"), withBlock)
	if err := os.MkdirAll(filepath.Join(dir, appliedMetaDir), 0o755); err != nil {
		t.Fatal(err)
	}
	mustWrite(t, filepath.Join(dir, appliedMetaDir, ".felhom.yml"), withBlock)
	m.undoCopier = newFakeCopier(map[string]string{undoVol: "OLD"})
	m.updateHealthFn = func(context.Context, string, time.Duration) (bool, string) { return false, "B unhealthy" }
	m.updateUndoHealthFn = func(context.Context, string, time.Duration, *Metadata) (bool, string) { return true, "A answers" }
	if err := m.StartGuardedUpdate("nextcloud"); err != nil {
		t.Fatal(err)
	}
	if st := waitUpdateDone(t, m, "nextcloud"); st.UpdatePhase != UpdatePhaseUndone {
		t.Fatalf("the scenario must reach an undo; ended %q", st.UpdatePhase)
	}
	if strings.Contains(buf.String(), "docker-compose.yml unreadable") {
		t.Fatalf("the undo logged a false backup-block ERROR:\n%s", buf.String())
	}
	// control: the validating loader on the same compose-less copy DOES log it (the line is real elsewhere)
	buf.Reset()
	LoadMetadata(filepath.Join(dir, preUpdateMetaDirForTest(t, dir, withBlock)))
	if !strings.Contains(buf.String(), "docker-compose.yml unreadable") {
		t.Fatal("control failed: LoadMetadata on a compose-less copy must still reject the block")
	}
	if pm := LoadProbeMetadata(filepath.Join(dir, "probe-copy")); pm.Backup != nil || pm.DataPaths != nil {
		t.Fatal("the probe loader must never hand out a backup block")
	}
}

// preUpdateMetaDirForTest writes a compose-less copy and returns its dir name (relative to dir).
func preUpdateMetaDirForTest(t *testing.T, dir, body string) string {
	t.Helper()
	d := filepath.Join(dir, "probe-copy")
	if err := os.MkdirAll(d, 0o755); err != nil {
		t.Fatal(err)
	}
	mustWrite(t, filepath.Join(d, ".felhom.yml"), body)
	return "probe-copy"
}