package stacks

import (
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"testing"
)

// R-736 (decision 53): the box keeps each app service's running image and the one before it; it deletes older
// images of that app; it never deletes an image a container or an installed compose names. Docker is the
// imageDocker seam — nothing here reaches a daemon (and dockerexec refuses one under go test anyway, R-650).

type fakeImages struct {
	imgs       []localImage
	containers map[string]string // container id -> image id
	rmi        []string
}

func (f *fakeImages) run(args ...string) (string, error) {
	switch {
	case args[0] == "image" && args[1] == "ls":
		var b strings.Builder
		for _, im := range f.imgs {
			fmt.Fprintf(&b, "%s\t%s\t%s\t%s\t%s\n", im.ID, im.Repo, im.Tag, im.Digest, im.Size)
		}
		return b.String(), nil
	case args[0] == "ps":
		var ids []string
		for c := range f.containers {
			ids = append(ids, c)
		}
		sort.Strings(ids)
		return strings.Join(ids, "\n"), nil
	case args[0] == "inspect":
		var out []string
		for _, c := range args[3:] {
			out = append(out, f.containers[c])
		}
		return strings.Join(out, "\n"), nil
	case args[0] == "rmi":
		f.rmi = append(f.rmi, args[1])
		var keep []localImage
		for _, im := range f.imgs {
			if im.ID != args[1] {
				keep = append(keep, im)
			}
		}
		f.imgs = keep
		return "Deleted", nil
	case args[0] == "system":
		return "Images 1GB 0B", nil
	}
	return "", fmt.Errorf("unexpected docker %v", args)
}

func withFakeImages(t *testing.T, f *fakeImages) {
	t.Helper()
	prev := imageDocker
	imageDocker = f.run
	t.Cleanup(func() { imageDocker = prev })
}

// retentionManager: two installed apps sharing postgres:18-alpine; app "web" at web:3 (previous web:2), web:1 older.
func retentionManager(t *testing.T) *Manager {
	t.Helper()
	m := gateManager(t, "display_name: G\n")
	m.cfg.Paths.DataDir = filepath.Join(t.TempDir(), "data") // never the package folder
	root := m.cfg.Paths.StacksDir
	write := func(app, compose, appYaml string) {
		d := filepath.Join(root, app)
		must(t, os.MkdirAll(d, 0o755))
		must(t, os.WriteFile(filepath.Join(d, "docker-compose.yml"), []byte(compose), 0o644))
		must(t, os.WriteFile(filepath.Join(d, "app.yaml"), []byte(appYaml), 0o644))
	}
	write("web", "services:\n  web:\n    image: acme/web:3\n  web-db:\n    image: postgres:18-alpine\n",
		"deployed: true\nenv: {}\ninstalled_images:\n    web:\n        ref: acme/web:3\n        digest: sha256:w3\n        at: \"2026-09-30T00:00:00Z\"\n    web-db:\n        ref: postgres:18-alpine\n        digest: sha256:p18\n        at: \"2026-09-30T00:00:00Z\"\nprevious_images:\n    web:\n        ref: acme/web:2\n        digest: sha256:w2\n        at: \"2026-09-20T00:00:00Z\"\n")
	write("docs", "services:\n  docs:\n    image: acme/docs:1\n  docs-db:\n    image: postgres:18-alpine\n",
		"deployed: true\nenv: {}\ninstalled_images:\n    docs:\n        ref: acme/docs:1\n        digest: sha256:d1\n        at: \"2026-09-30T00:00:00Z\"\n")
	must(t, m.ScanStacks())
	return m
}

func baseImages() *fakeImages {
	return &fakeImages{
		imgs: []localImage{
			{ID: "sha256:W3", Repo: "acme/web", Tag: "3", Digest: "sha256:w3", Size: "100MB"},
			{ID: "sha256:W2", Repo: "acme/web", Tag: "2", Digest: "sha256:w2", Size: "100MB"},
			{ID: "sha256:W1", Repo: "acme/web", Tag: "1", Digest: "sha256:w1", Size: "100MB"},
			{ID: "sha256:P18", Repo: "postgres", Tag: "18-alpine", Digest: "sha256:p18", Size: "300MB"},
			{ID: "sha256:P16", Repo: "postgres", Tag: "16-alpine", Digest: "sha256:p16", Size: "290MB"},
			{ID: "sha256:D1", Repo: "acme/docs", Tag: "1", Digest: "sha256:d1", Size: "50MB"},
			{ID: "sha256:CTL", Repo: "gitea.dooplex.hu/admin/felhom-controller", Tag: "0.283.0", Digest: "", Size: "400MB"},
		},
		containers: map[string]string{"c-web": "sha256:W3", "c-webdb": "sha256:P18", "c-docs": "sha256:D1", "c-docsdb": "sha256:P18"},
	}
}

// After an update: the running image and the one before it stay; the older one goes; the shared engine stays.
// COMPANION RED-PROOF: drop previous_images from imageKeepSet → "the undo's image (web:2) was deleted".
func TestImageRetention_KeepsRunningAndPreviousDeletesOlder(t *testing.T) {
	m := retentionManager(t)
	f := baseImages()
	withFakeImages(t, f)
	st, _ := m.GetStack("web")
	if _, err := m.deleteUnkeptImages("test", appImageRepos(filepath.Dir(st.ComposePath), st.AppConfig), ""); err != nil {
		t.Fatal(err)
	}
	got := strings.Join(f.rmi, ",")
	if strings.Contains(got, "sha256:W2") {
		t.Fatal("the undo's image (web:2) was deleted")
	}
	if strings.Contains(got, "sha256:W3") || strings.Contains(got, "sha256:P18") {
		t.Fatalf("a running image was deleted: %s", got)
	}
	if !strings.Contains(got, "sha256:W1") {
		t.Fatalf("the older web:1 was not deleted: %s", got)
	}
	if !strings.Contains(got, "sha256:P16") {
		t.Fatalf("postgres:16-alpine is this app's repo and nothing keeps it — expected deleted: %s", got)
	}
	if strings.Contains(got, "sha256:CTL") || strings.Contains(got, "sha256:D1") {
		t.Fatalf("another app's or the controller's image was touched: %s", got)
	}
}

// A shared image survives the remove of one of its apps (another app's container and compose name it).
// COMPANION RED-PROOF: drop the container half of the keep set (return an empty map from imagesUsedByContainers)
// AND the compose half → "the shared postgres:18-alpine was deleted".
func TestImageRetention_ASharedImageSurvivesTheRemoveOfOneApp(t *testing.T) {
	m := retentionManager(t)
	f := baseImages()
	withFakeImages(t, f)
	st, _ := m.GetStack("web")
	repos := appImageRepos(filepath.Dir(st.ComposePath), st.AppConfig)
	// the remove took web's containers away
	delete(f.containers, "c-web")
	delete(f.containers, "c-webdb")
	m.mu.Lock()
	m.stacks["web"].Deployed = false
	m.mu.Unlock()
	m.RetainImagesAfterRemove("web", repos)
	got := strings.Join(f.rmi, ",")
	if strings.Contains(got, "sha256:P18") {
		t.Fatal("the shared postgres:18-alpine was deleted while docs still runs it")
	}
	for _, id := range []string{"sha256:W3", "sha256:W2", "sha256:W1"} {
		if !strings.Contains(got, id) {
			t.Fatalf("the removed app's image %s was kept: %s", id, got)
		}
	}
}

// The keep set is checked from the compose too, not only containers: an installed app whose containers are down
// (stopped by the household, or mid-restart) keeps its images.
// COMPANION RED-PROOF: drop the ParseComposeImages loop from imageKeepSet → docs' image goes.
func TestImageRetention_AStoppedAppsComposeKeepsItsImage(t *testing.T) {
	m := retentionManager(t)
	f := baseImages()
	f.containers = map[string]string{} // nothing running anywhere
	withFakeImages(t, f)
	m.RunImageRetentionOnce() // catalog-cache is absent → skipped, no marker
	if len(f.rmi) != 0 {
		t.Fatalf("the one-time sweep ran without a catalog: %v", f.rmi)
	}
	st, _ := m.GetStack("docs")
	m.mu.Lock()
	m.stacks["docs"].AppConfig.InstalledImages = nil // only the compose names it now
	m.mu.Unlock()
	if _, err := m.deleteUnkeptImages("test", appImageRepos(filepath.Dir(st.ComposePath), nil), ""); err != nil {
		t.Fatal(err)
	}
	if strings.Contains(strings.Join(f.rmi, ","), "sha256:D1") {
		t.Fatal("a stopped app's image was deleted although its compose names it")
	}
}

// A keep set that cannot be read deletes NOTHING (fail closed).
func TestImageRetention_UnreadableKeepSetDeletesNothing(t *testing.T) {
	m := retentionManager(t)
	f := baseImages()
	withFakeImages(t, f)
	prev := imageDocker
	imageDocker = func(args ...string) (string, error) {
		if args[0] == "ps" {
			return "", fmt.Errorf("daemon hiccup")
		}
		return f.run(args...)
	}
	t.Cleanup(func() { imageDocker = prev })
	if _, err := m.deleteUnkeptImages("test", map[string]bool{"acme/web": true, "postgres": true}, ""); err == nil {
		t.Fatal("no error from an unreadable keep set")
	}
	if len(f.rmi) != 0 {
		t.Fatalf("deleted with no keep set: %v", f.rmi)
	}
}

// The one-time sweep reaches only images the catalog names (app images) — never the controller's.
func TestImageRetention_OneTimeSweepOnlyCatalogRepos(t *testing.T) {
	m := retentionManager(t)
	f := baseImages()
	f.imgs = append(f.imgs, localImage{ID: "sha256:OLD", Repo: "acme/gone", Tag: "5", Digest: "sha256:g5", Size: "70MB"})
	withFakeImages(t, f)
	cat := filepath.Join(m.cfg.Paths.DataDir, "catalog-cache", "templates", "gone")
	must(t, os.MkdirAll(cat, 0o755))
	must(t, os.WriteFile(filepath.Join(cat, "docker-compose.yml"), []byte("services:\n  gone:\n    image: acme/gone:6\n"), 0o644))
	deleted := m.RunImageRetentionOnce()
	got := strings.Join(f.rmi, ",")
	if !strings.Contains(got, "sha256:OLD") {
		t.Fatalf("an earlier-removed app's image was not swept: %v", deleted)
	}
	if strings.Contains(got, "sha256:CTL") || strings.Contains(got, "sha256:W1") {
		t.Fatalf("the sweep reached beyond the catalog's repos: %s", got)
	}
	if _, err := os.Stat(m.imageRetentionMarker()); err != nil {
		t.Fatal("no marker — the sweep would run at every start")
	}
	f.rmi = nil
	m.RunImageRetentionOnce()
	if len(f.rmi) != 0 {
		t.Fatal("the one-time sweep ran twice")
	}
}

// An update in flight pauses every pass: its undo's image is named by nothing the keep set reads.
// COMPANION RED-PROOF: drop the busy check in deleteUnkeptImages → "a pass ran while docs was updating".
func TestImageRetention_NoPassWhileAnUpdateRuns(t *testing.T) {
	m := retentionManager(t)
	f := baseImages()
	withFakeImages(t, f)
	m.mu.Lock()
	m.stacks["docs"].Updating = true
	m.mu.Unlock()
	st, _ := m.GetStack("web")
	if _, err := m.deleteUnkeptImages("test", appImageRepos(filepath.Dir(st.ComposePath), st.AppConfig), ""); err != nil {
		t.Fatal(err)
	}
	if len(f.rmi) != 0 {
		t.Fatalf("a pass ran while docs was updating: %v", f.rmi)
	}
}