package main

// A rollback to a record (novox/hq ADR 0508 §7; acceptance 1841/AC8): the plan says each package now -> record with
// its source, the packages added and no foreign package; apply is an ask the node's keeper runs as one
// transaction, emitting rollback.started and rollback.finished and ending with the after-upgrade check.

import (
	"context"
	"encoding/json"
	"strings"
	"testing"
	"time"

	stdio "git.novox.be/novox/mesh-sdk/go"
)

var recordAt = time.Date(2026, 10, 3, 4, 0, 12, 0, time.UTC)

// rollbackRecord is node-a's record of run 20261003T040012Z; rollbackNow its packages since.
var (
	rollbackRecord = Record{Node: "node-a", Run: "20261003T040012Z", At: recordAt, Installed: InstalledValue{At: recordAt, Packages: []InstalledPackage{
		{"bash", "5.3.15-1", true, "core"}, {"glibc", "2.42-1", false, "core"}, {"linux", "7.2.8.arch1-2", true, "core"},
		{"made-up-old-library", "1.0-1", false, "extra"}, {"made-up-foreign", "1-1", true, RepoForeign},
	}}}
	rollbackNow = InstalledValue{At: recordAt.Add(time.Hour), Packages: []InstalledPackage{
		{"bash", "5.3.20-1", true, "core"}, {"glibc", "2.42-1", false, "core"}, {"linux", "7.3.1.arch1-1", true, "core"},
		{"made-up-foreign", "2-1", true, RepoForeign}, {"made-up-library", "1.0-1", false, "extra"},
	}}
)

// rollbackCache is the node's package cache: bash's recorded version, and linux at its new version only.
const rollbackCache = "bash-5.3.15-1-x86_64.pkg.tar.zst\nbash-5.3.20-1-x86_64.pkg.tar.zst\nlinux-7.3.1.arch1-1-x86_64.pkg.tar.zst\n" +
	"not-a-package-file\n"

func rollbackStates(t *testing.T) (*fakeStates, *Machine, *[]call) {
	t.Helper()
	states := &fakeStates{}
	states.store(StateRecords).Put(NodeKey("node-a", rollbackRecord.Run), rollbackRecord)
	states.store(StateInstalled).Put("node-a", rollbackNow)
	var calls []call
	m := machine(byLine(map[string]Ran{
		"find " + CacheDir + " -mindepth 1 -maxdepth 1 -name *.pkg.tar.* -printf %f\n": {Stdout: rollbackCache},
	}, &calls), 1000)
	m.Node, m.States = "node-a", readerOf(states)
	return states, m, &calls
}

func TestThePlanSaysEachPackageNowToTheRecordWithItsSourceTheAddedAndNoForeign(t *testing.T) {
	_, m, calls := rollbackStates(t)
	p, err := PlanRollback(m, m.States(StateInstalled), m.States(StateRecords), "node-a", rollbackRecord.Run, false, true)
	if err != nil {
		t.Fatal(err)
	}
	want := []RollbackItem{
		{"bash", "5.3.20-1", "5.3.15-1", SourceCache, CacheDir + "/bash-5.3.15-1-x86_64.pkg.tar.zst"},
		{"linux", "7.3.1.arch1-1", "7.2.8.arch1-2", SourceArchive, "https://archive.archlinux.org/packages/l/linux/linux-7.2.8.arch1-2-x86_64.pkg.tar.zst"},
		{"made-up-old-library", "", "1.0-1", SourceRepository, "https://archive.archlinux.org/repos/2026/10/03/extra/os/$arch"},
	}
	if len(p.Items) != len(want) {
		t.Fatalf("items: %+v", p.Items)
	}
	for i := range want {
		if p.Items[i] != want[i] {
			t.Errorf("item %d: %+v, want %+v", i, p.Items[i], want[i])
		}
	}
	if len(p.Added) != 1 || p.Added[0] != (PackageVersion{"made-up-library", "1.0-1"}) || p.Foreign != 1 || !p.CacheRead {
		t.Errorf("added %+v, foreign %d, cache %v", p.Added, p.Foreign, p.CacheRead)
	}
	for _, c := range *calls {
		if strings.Contains(c.String(), "made-up-foreign") {
			t.Errorf("a command named the foreign package: %s", c)
		}
	}
	// asked to remove what was added: the added package is removed too.
	p, _ = PlanRollback(m, m.States(StateInstalled), m.States(StateRecords), "node-a", rollbackRecord.Run, true, true)
	if len(p.Items) != 4 || p.Items[2] != (RollbackItem{Name: "made-up-library", From: "1.0-1", Source: SourceRemoved}) {
		t.Errorf("with remove_added: %+v", p.Items)
	}
}

func TestAnotherNodesPlanReadsNoCacheAndTakesUnknownArchitecturesFromTheDatedRepository(t *testing.T) {
	_, m, calls := rollbackStates(t)
	m.Node = "node-b"
	r, err := m.Rollback("node-a", rollbackRecord.Run, false, false)
	if err != nil {
		t.Fatal(err)
	}
	p := r["plan"].(RollbackPlan)
	if p.CacheRead || len(*calls) != 0 {
		t.Errorf("another node's cache was read: %v", *calls)
	}
	for _, i := range p.Items {
		if i.Source != SourceRepository || !strings.HasPrefix(i.Location, "https://archive.archlinux.org/repos/2026/10/03/") {
			t.Errorf("%+v", i)
		}
	}
}

func TestNoPlanFromPackagesNotCurrentOrWithoutARecord(t *testing.T) {
	states, m, _ := rollbackStates(t)
	if _, err := m.Rollback("node-a", "20250101T000000Z", false, false); err == nil || !strings.Contains(err.Error(), "no record") {
		t.Errorf("no record: %v", err)
	}
	states.store(StateInstalled).Put(NotCurrentKey("node-a"), NotCurrent{Bytes: 300000, Since: recordAt})
	if _, err := m.Rollback("node-a", rollbackRecord.Run, false, false); err == nil || !strings.Contains(err.Error(), "not current") {
		t.Errorf("not current: %v", err)
	}
}

func TestApplyWritesAnAskForTheNodesKeeper(t *testing.T) {
	_, m, _ := rollbackStates(t)
	asks := newBucket()
	saved := upgradeState
	upgradeState = func(name string) Bucket { return asks }
	t.Cleanup(func() { upgradeState = saved })
	r, err := m.Rollback("", rollbackRecord.Run, true, true)
	if err != nil {
		t.Fatal(err)
	}
	a := r["asked"].(Ask)
	var got Ask
	if !asks.value(NodeKey("node-a", a.ID), &got) || got.Act != ActRollback || got.Of != rollbackRecord.Run || !got.RemoveAdded {
		t.Errorf("the ask: %+v", got)
	}
}

func TestAnAskedRollbackIsOneTransactionWithItsEventsAndTheCheck(t *testing.T) {
	k := newKeeperBed(t)
	k.records.Put(NodeKey("node-a", rollbackRecord.Run), rollbackRecord)
	k.installed.Put("node-a", rollbackNow)
	inner := k.u.Machine.Run
	k.u.Machine.Run = func(ctx context.Context, name string, args ...string) Ran {
		if name == "find" {
			return Ran{Stdout: rollbackCache}
		}
		return inner(ctx, name, args...)
	}
	a := Ask{ID: "20261004T120000Z-abc123", Node: "node-a", Act: ActRollback, At: k.now, Of: rollbackRecord.Run}
	if err := k.takeAsk(t, a); err != nil {
		t.Fatal(err)
	}
	var r Run
	keys, _ := k.runs.Keys()
	for _, key := range keys {
		var x Run
		k.runs.value(key, &x)
		if x.Kind == RunRollback {
			r = x
		}
	}
	if r.Of != rollbackRecord.Run || r.Ask != a.ID || steps(r) != "started" || len(r.Steps[0].Plan) != 3 {
		t.Fatalf("the rollback run: %+v", r)
	}
	if strings.Join(k.root.started, ";") != "rollback "+r.Run+" plan=bash:5.3.15-1:cache,linux:7.2.8.arch1-2:archive,made-up-old-library:1.0-1:repository" {
		t.Errorf("the root helper was asked: %v", k.root.started)
	}
	if _, there := k.asks.values[NodeKey("node-a", a.ID)]; there {
		t.Error("the ask is deleted once the run names it")
	}
	k.unitState, k.now = "LoadState=not-found\n", k.now.Add(time.Minute)
	if err := k.u.Follow(); err != nil {
		t.Fatal(err)
	}
	k.runs.value(NodeKey("node-a", r.Run), &r)
	if steps(r) != "started finished checked-after" || r.Steps[2].Check == nil {
		t.Errorf("steps: %s", steps(r))
	}
	if got := strings.Join(k.events.names(), " "); got != "rollback.started rollback.finished upgrade.checked" {
		t.Errorf("events: %s", got)
	}
	// the same record again: nothing to bring back once the packages are the record's.
	k.installed.Put("node-a", rollbackRecord.Installed)
	k.now = k.now.Add(time.Minute)
	if err := k.takeAsk(t, Ask{ID: "20261004T120200Z-def456", Node: "node-a", Act: ActRollback, At: k.now, Of: rollbackRecord.Run}); err != nil {
		t.Fatal(err)
	}
	var again Run
	k.runs.value(NodeKey("node-a", "20261004T120200Z"), &again)
	if steps(again) != "refused" || !strings.Contains(again.Steps[0].Why, "nothing to bring back") {
		t.Errorf("a rollback with nothing to do: %+v", again)
	}
}

// takeAsk writes an ask and hands its change to the keeper, as the watch of `asks` would.
func (k *keeperBed) takeAsk(t *testing.T, a Ask) error {
	t.Helper()
	key := NodeKey(a.Node, a.ID)
	rev, err := k.asks.Create(key, a)
	if err != nil {
		t.Fatal(err)
	}
	raw, _ := json.Marshal(a)
	return k.u.TakeAsk(stdio.StateChange{State: StateAsks, Key: key, Op: "put", Value: raw, Revision: rev})
}