package main

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"reflect"
	"strings"
	"testing"
	"time"

	"github.com/novox/mesh-controller/internal/catalogue"
	"github.com/novox/mesh-controller/internal/inventory"
	"github.com/novox/mesh-controller/internal/link"
	"github.com/novox/mesh-controller/internal/overlay"
)

// novox/hq ADR 0100: taking a module is its cutover; converging a node is one act, previewed, and
// refused while a found container is held; returning to adopted keeps what was taken.

// anAdoptedAnchor is aMesh with the anchor adopted, running a served module the predecessor also
// runs and a module with only a file, and a filter module in the catalogue.
func anAdoptedAnchor(t *testing.T) (*stores, *[]string) {
	t.Helper()
	open := aMesh(t)
	ctx := t.Context()
	register(t, open, catalogue.Manifest{Module: "hello-web", Version: "1",
		Listens: []catalogue.Listening{{Port: 8080, From: catalogue.FromEverywhere}},
		Resources: []map[string]any{
			{"id": "page", "type": "file", "path": "/var/lib/hello-web/index.html", "content": "hi"},
			{"id": "server", "type": "container", "name": "hello-web", "ports": []any{"8080:80"},
				"image": "registry.example/hello@sha256:" + strings.Repeat("a", 64)},
		}})
	register(t, open, catalogue.Manifest{Module: "notes", Version: "1",
		Resources: []map[string]any{
			{"id": "conf", "type": "file", "path": "/etc/notes.conf", "content": "x"},
		}})
	register(t, open, catalogue.Manifest{Module: "nftables", Version: "1",
		Filtering: &catalogue.Filtering{Into: "/etc/nftables.conf"},
		Resources: []map[string]any{{"id": "load", "type": "service", "unit": "mesh-filter.service",
			"state": "running", "restart-on": []any{"filtering"}}}})
	if err := open.inventory.SetAdopted(ctx, "anchor", true); err != nil {
		t.Fatal(err)
	}
	for _, m := range []string{"hello-web", "notes"} {
		if _, err := assign(ctx, open, "anchor", m); err != nil {
			t.Fatal(err)
		}
	}
	sent := &[]string{}
	saved := sendNodes
	sendNodes = func(_ context.Context, _ *stores, names []string) error {
		*sent = append(*sent, names...)
		return nil
	}
	t.Cleanup(func() { sendNodes = saved })
	return open, sent
}

// reportsHolding has the anchor report, on what it was last sent, holding what is given.
func reportsHolding(t *testing.T, open *stores, held ...link.Held) {
	t.Helper()
	reportsReaching(t, open, []link.Reach{
		{Protocol: "tcp", Address: "0.0.0.0", Port: 22, By: "sshd"},
		{Protocol: "tcp", Address: "0.0.0.0", Port: 8080, By: "hello-web", Published: true,
			ContainerPort: 80},
		{Protocol: "tcp", Address: "0.0.0.0", Port: 5000, By: "predecessor-registry",
			Published: true, ContainerPort: 5000},
		{Protocol: "tcp", Address: "127.0.0.1", Port: 15672, By: "mesh-broker",
			Published: true, ContainerPort: 15672},
	}, held...)
}

// reportsReaching has the anchor report, on what it was last sent, what is reachable on it and
// holding what is given.
func reportsReaching(t *testing.T, open *stores, reachable []link.Reach, held ...link.Held) {
	t.Helper()
	ctx := t.Context()
	body, err := composed(t, open, "anchor").Body()
	if err != nil {
		t.Fatal(err)
	}
	record, err := open.inventory.NodeByName(ctx, "anchor")
	if err != nil {
		t.Fatal(err)
	}
	if err := open.inventory.RecordSent(ctx, record.ID, digestOf(body)); err != nil {
		t.Fatal(err)
	}
	if err := (link.Enrolment{Inventory: open.inventory}).Heard(ctx, link.Report{
		Node: "anchor", Applied: []string{"hello-web.x"}, Declared: digestOf(body),
		Firewall: "ufw", Held: held, Reachable: reachable,
	}); err != nil {
		t.Fatal(err)
	}
}

var (
	heldContainer = link.Held{ID: "hello-web.server", Module: "hello-web", Kind: "container",
		Target: "hello-web", Since: time.Now()}
	heldFile = link.Held{ID: "notes.conf", Module: "notes", Kind: "file",
		Target: "/etc/notes.conf", Since: time.Now(), Kept: "/var/lib/mesh-host/kept/abc-notes.conf"}
)

func TestTakingAModuleNotOnTheNodeIsRefused(t *testing.T) {
	open, _ := anAdoptedAnchor(t)
	if _, err := take(t.Context(), open, "anchor", "nftables"); !errors.Is(err, inventory.ErrNotAssigned) {
		t.Fatalf("taking an unassigned module gave %v", err)
	}
	if _, err := take(t.Context(), open, "laptop", "network"); !errors.Is(err, inventory.ErrNotAdopted) {
		t.Fatalf("taking on a converged node gave %v", err)
	}
}

func TestConvergingIsRefusedOnAPreviewThatWouldBeStale(t *testing.T) {
	open, sent := anAdoptedAnchor(t)
	_, err := converge(t.Context(), open, "anchor", false, "", "")
	if err == nil || !strings.Contains(err.Error(), "has not reported") {
		t.Fatalf("a node that never reported was previewed: %v", err)
	}
	if len(*sent) != 0 {
		t.Fatal("a refused converge sent something")
	}
}

func TestTheFlipIsRefusedWhileAFoundContainerIsHeld(t *testing.T) {
	open, sent := anAdoptedAnchor(t)
	reportsHolding(t, open, heldContainer, heldFile)
	_, err := converge(t.Context(), open, "anchor", true, "", "")
	if err == nil || !strings.Contains(err.Error(), "take anchor hello-web once its data has moved") {
		t.Fatalf("the flip was not refused while hello-web holds its found container: %v", err)
	}
	if n, _ := open.inventory.NodeByName(t.Context(), "anchor"); !n.Adopted || len(*sent) != 0 {
		t.Fatal("a refused flip changed something")
	}
}

func TestTakingNamesWhatItReplaces(t *testing.T) {
	open, _ := anAdoptedAnchor(t)
	reportsHolding(t, open, heldContainer, heldFile)
	said, err := take(t.Context(), open, "anchor", "hello-web")
	if err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(said, "container hello-web (hello-web.server)") ||
		!strings.Contains(said, "push anchor") {
		t.Fatalf("taking did not say what it replaces and what to run:\n%s", said)
	}
}

func TestConvergingPreviewsThenChangesAndAdoptingKeepsWhatWasTaken(t *testing.T) {
	open, sent := anAdoptedAnchor(t)
	ctx := t.Context()
	if _, err := take(ctx, open, "anchor", "hello-web"); err != nil {
		t.Fatal(err)
	}
	reportsHolding(t, open, heldFile)

	preview, err := converge(ctx, open, "anchor", false, "", "")
	if err != nil {
		t.Fatal(err)
	}
	for _, want := range []string{
		"tcp/8080 hello-web (published, container port 80)",
		"declared by hello-web (from anywhere)",
		"WILL CLOSE — no module assigned here declares it",
		// The anchor faces inward and is on the private network: the derived filter admits ssh
		// from the mesh only.
		"WILL CLOSE to everything outside the private network — ssh stays open from the mesh",
		"notes\n      replacing the found file /etc/notes.conf (notes.conf), original kept at",
		"assigns nftables",
		"the found firewall (ufw) is disabled, never flushed",
		// What it routes is not a listener: said not to be previewed, and to be dropped.
		"not previewed: traffic the machine routes that is not a published port",
		"the derived filter drops it unless a module declares it",
	} {
		if !strings.Contains(preview, want) {
			t.Errorf("the preview does not say %q:\n%s", want, preview)
		}
	}
	if strings.Contains(preview, "15672") {
		t.Errorf("a loopback listener is in the preview:\n%s", preview)
	}
	for _, line := range strings.Split(preview, "\n") {
		if strings.Contains(line, "5000") && !strings.Contains(line, "WILL CLOSE") {
			t.Errorf("an undeclared published port is not said to close: %s", line)
		}
	}
	if n, _ := open.inventory.NodeByName(ctx, "anchor"); !n.Adopted || len(*sent) != 0 {
		t.Fatal("the preview changed something")
	}

	if _, err := converge(ctx, open, "anchor", true, digestIn(t, preview), ""); err != nil {
		t.Fatal(err)
	}
	n, _ := open.inventory.NodeByName(ctx, "anchor")
	if n.Adopted {
		t.Fatal("converge --yes left the node adopted")
	}
	taken, _ := open.inventory.Taken(ctx, "anchor")
	if !reflect.DeepEqual(taken, []string{"hello-web", overlay.Name, "nftables", "notes"}) {
		t.Fatalf("the flip took %v", taken)
	}
	if !reflect.DeepEqual(*sent, []string{"anchor"}) {
		t.Fatalf("the flip sent %v", *sent)
	}
	declared := composed(t, open, "anchor")
	if declared.Adoption != nil {
		t.Fatal("a converged node is still sent an adoption envelope")
	}
	if !hasID(declared.Resources, "nftables.filtering") {
		t.Fatal("the converged node is not declared the mesh's filter")
	}

	if _, err := adopt(ctx, open, "anchor"); err != nil {
		t.Fatal(err)
	}
	if _, err := adopt(ctx, open, "anchor"); err == nil {
		t.Fatal("adopting an adopted node was not refused")
	}
	again, _ := open.inventory.Taken(ctx, "anchor")
	if !reflect.DeepEqual(again, taken) {
		t.Fatalf("returning to adopted lost what was taken: %v", again)
	}
	declared = composed(t, open, "anchor")
	if declared.Adoption == nil || len(declared.Adoption.Untaken) != 0 {
		t.Fatalf("returned to adopted, the envelope is %+v", declared.Adoption)
	}
	if hasID(declared.Resources, "nftables.filtering") || hasID(declared.Resources, "nftables.load") {
		t.Fatal("returned to adopted, the mesh's filter is still declared")
	}
}

func hasID(resources []map[string]any, id string) bool {
	for _, r := range resources {
		if r["id"] == id {
			return true
		}
	}
	return false
}

// The command API refuses a flip exactly as the command line does, in the same words.
func TestTheApiRefusesTheFlipInTheCommandLinesWords(t *testing.T) {
	open, _ := anAdoptedAnchor(t)
	reportsHolding(t, open, heldContainer)
	_, direct := converge(t.Context(), open, "anchor", true, "", "")
	if direct == nil {
		t.Fatal("the flip was not refused")
	}
	got := asking(t, letIn{}, "POST", "/converge", `{"node":"anchor","yes":true}`)
	if got.Code != http.StatusConflict {
		t.Fatalf("got %d: %s", got.Code, got.Body.String())
	}
	var said map[string]any
	if err := json.Unmarshal(got.Body.Bytes(), &said); err != nil {
		t.Fatal(err)
	}
	if said["refused"] != direct.Error() {
		t.Fatalf("the API said %q and the command line %q", said["refused"], direct.Error())
	}
	if got := asking(t, letIn{}, "POST", "/take", `{"node":"anchor"}`); got.Code != http.StatusBadRequest {
		t.Fatalf("a take naming no module got %d", got.Code)
	}
}

// novox/hq ADR 0100: the preview says what the derived filter does, rendered as it is rendered. On
// a machine that faces inward, ssh is admitted from the private network only, and a port a module
// admits from the mesh only closes to everything outside it: both are said to close.
func TestThePreviewSaysWhatNarrowsToTheMeshCloses(t *testing.T) {
	open, _ := anAdoptedAnchor(t)
	ctx := t.Context()
	register(t, open, catalogue.Manifest{Module: "store", Version: "1",
		Listens: []catalogue.Listening{{Port: 5432, From: catalogue.FromMesh}}})
	if _, err := assign(ctx, open, "anchor", "store"); err != nil {
		t.Fatal(err)
	}
	reportsReaching(t, open, []link.Reach{
		{Protocol: "tcp", Address: "0.0.0.0", Port: 22, By: "sshd"},
		{Protocol: "tcp", Address: "0.0.0.0", Port: 5432, By: "postgres"},
		{Protocol: "tcp", Address: "10.77.0.1", Port: 5432, By: "postgres"},
		{Protocol: "tcp", Address: "0.0.0.0", Port: 8080, By: "hello-web", Published: true,
			ContainerPort: 80},
	})
	preview, err := converge(ctx, open, "anchor", false, "", "")
	if err != nil {
		t.Fatal(err)
	}
	lines := map[string]string{}
	for _, line := range strings.Split(preview, "\n") {
		fields := strings.Fields(line)
		if len(fields) > 1 && strings.HasPrefix(fields[0], "tcp/") {
			lines[fields[0]+" "+fields[1]] += line + "\n"
		}
	}
	if got := lines["tcp/22 sshd"]; !strings.Contains(got, "WILL CLOSE to everything outside "+
		"the private network") {
		t.Errorf("ssh on an inward machine is not said to close outside the mesh:\n%s", preview)
	}
	store := lines["tcp/5432 postgres"]
	if strings.Count(store, "WILL CLOSE to everything outside the private network") != 1 ||
		!strings.Contains(store, "declared by store (from mesh)") {
		t.Errorf("the store's narrowing is not said to close, or its mesh address is:\n%s", preview)
	}
	if got := lines["tcp/8080 hello-web"]; !strings.Contains(got, "declared by hello-web (from anywhere)") {
		t.Errorf("a port open to everywhere is not said to stay:\n%s", preview)
	}
}

// digestIn is the digest a converge preview printed.
func digestIn(t *testing.T, preview string) string {
	t.Helper()
	for _, line := range strings.Split(preview, "\n") {
		if fields := strings.Fields(line); len(fields) == 2 && fields[0] == "preview" {
			return fields[1]
		}
	}
	t.Fatalf("the preview printed no digest:\n%s", preview)
	return ""
}

// The flip acts on the preview the operator saw: it names that preview's digest, and it is refused
// when the digest is missing, when anything the preview says has changed since, or when the node's
// account of itself is too old to be the machine as it is.
func TestTheFlipActsOnlyOnThePreviewTheOperatorSaw(t *testing.T) {
	open, sent := anAdoptedAnchor(t)
	ctx := t.Context()
	if _, err := take(ctx, open, "anchor", "hello-web"); err != nil {
		t.Fatal(err)
	}
	reportsHolding(t, open, heldFile)
	preview, err := converge(ctx, open, "anchor", false, "", "")
	if err != nil {
		t.Fatal(err)
	}
	saw := digestIn(t, preview)
	if !strings.Contains(preview, "converge anchor --yes "+saw) {
		t.Fatalf("the preview does not say how to act on it:\n%s", preview)
	}
	unchanged := func() {
		t.Helper()
		if n, _ := open.inventory.NodeByName(ctx, "anchor"); !n.Adopted || len(*sent) != 0 {
			t.Fatal("a refused flip changed something")
		}
	}

	if _, err := converge(ctx, open, "anchor", true, "", ""); err == nil ||
		!strings.Contains(err.Error(), "--yes "+saw) {
		t.Fatalf("a flip naming no preview was not refused: %v", err)
	}
	unchanged()

	// Something new is reachable: the preview the operator saw is not what would happen.
	reportsReaching(t, open, []link.Reach{
		{Protocol: "tcp", Address: "0.0.0.0", Port: 22, By: "sshd"},
		{Protocol: "tcp", Address: "0.0.0.0", Port: 8080, By: "hello-web", Published: true,
			ContainerPort: 80},
		{Protocol: "tcp", Address: "0.0.0.0", Port: 6000, By: "something-new"},
	}, heldFile)
	_, err = converge(ctx, open, "anchor", true, saw, "")
	if err == nil || !strings.Contains(err.Error(), "has changed since preview "+saw) {
		t.Fatalf("a flip on a changed preview was not refused: %v", err)
	}
	unchanged()

	// An account older than the flip trusts is refused, whatever digest is named.
	again, err := converge(ctx, open, "anchor", false, "", "")
	if err != nil {
		t.Fatal(err)
	}
	saved := reportFreshFor
	reportFreshFor = time.Nanosecond
	_, err = converge(ctx, open, "anchor", true, digestIn(t, again), "")
	reportFreshFor = saved
	if err == nil || !strings.Contains(err.Error(), "wait for its next report") {
		t.Fatalf("a flip on an old account was not refused: %v", err)
	}
	unchanged()

	if _, err := converge(ctx, open, "anchor", true, digestIn(t, again), ""); err != nil {
		t.Fatalf("the flip on the preview just seen was refused: %v", err)
	}
	if n, _ := open.inventory.NodeByName(ctx, "anchor"); n.Adopted {
		t.Fatal("the flip did not converge the node")
	}
}

// The flip holds the node from its checks to its send, so a push composed meanwhile waits and is
// composed after it — never sent after it with the node still adopted. And the send inside the
// flip is not made to wait on the flip's own hold.
func TestTheFlipHoldsTheNodeWhileItSends(t *testing.T) {
	open, _ := anAdoptedAnchor(t)
	ctx := t.Context()
	if _, err := take(ctx, open, "anchor", "hello-web"); err != nil {
		t.Fatal(err)
	}
	reportsHolding(t, open, heldFile)
	preview, err := converge(ctx, open, "anchor", false, "", "")
	if err != nil {
		t.Fatal(err)
	}
	var heldElsewhere, heldHere error
	sendNodes = func(inner context.Context, open *stores, names []string) error {
		// Another caller cannot hold the node while the flip sends it.
		waiting, cancel := context.WithTimeout(ctx, 300*time.Millisecond)
		defer cancel()
		if release, err := open.inventory.HoldNodes(waiting, names); err == nil {
			release()
			heldElsewhere = errors.New("another caller held the node while the flip sent it")
		}
		// The flip's own send holds it without waiting on itself.
		_, release, err := holdNodes(inner, open, names)
		if err != nil {
			heldHere = err
			return err
		}
		release()
		return nil
	}
	if _, err := converge(ctx, open, "anchor", true, digestIn(t, preview), ""); err != nil {
		t.Fatal(err)
	}
	if heldElsewhere != nil || heldHere != nil {
		t.Fatalf("%v %v", heldElsewhere, heldHere)
	}
	// And given back once it is done.
	release, err := open.inventory.HoldNodes(ctx, []string{"anchor"})
	if err != nil {
		t.Fatal(err)
	}
	release()
}

// novox/hq ADR 0103: the preview names every kind of thing a module the flip takes holds as found,
// not only its files, and the digest changes when any of them does.
func TestThePreviewNamesEveryHeldKind(t *testing.T) {
	open, _ := anAdoptedAnchor(t)
	ctx := t.Context()
	if _, err := take(ctx, open, "anchor", "hello-web"); err != nil {
		t.Fatal(err)
	}
	since := time.Now()
	held := []link.Held{heldFile,
		{ID: "notes.data", Module: "notes", Kind: "directory", Target: "/var/lib/notes", Since: since},
		{ID: "notes.daemon", Module: "notes", Kind: "service", Target: "notes.service", Since: since},
		{ID: "notes.seed", Module: "notes", Kind: "archive", Target: "/srv/notes", Since: since},
		{ID: "notes.worker", Module: "notes", Kind: "process", Target: "notes-worker", Since: since},
		{ID: "notes.account", Module: "notes", Kind: "user", Target: "notes", Since: since},
	}
	reportsHolding(t, open, held...)
	preview, err := converge(ctx, open, "anchor", false, "", "")
	if err != nil {
		t.Fatal(err)
	}
	for _, want := range []string{
		"replacing the found directory /var/lib/notes (notes.data)",
		"replacing the found service notes.service (notes.daemon)",
		"replacing the found archive /srv/notes (notes.seed)",
		"replacing the found process notes-worker (notes.worker)",
		"replacing the found user notes (notes.account)",
	} {
		if !strings.Contains(preview, want) {
			t.Errorf("the preview does not say %q:\n%s", want, preview)
		}
	}
	reportsHolding(t, open, held[:len(held)-1]...)
	fewer, err := converge(ctx, open, "anchor", false, "", "")
	if err != nil {
		t.Fatal(err)
	}
	if digestIn(t, fewer) == digestIn(t, preview) {
		t.Fatal("the digest does not change with what is held")
	}
}

// novox/hq ADR 0100: the flip acts on what the node said is reachable, so an account naming nothing
// is refused. Every machine that is up answers on ssh; nothing reported means the host's collectors
// did not, and flipping would close ports the preview never named.
func TestTheFlipIsRefusedOnAnAccountNamingNothingReachable(t *testing.T) {
	open, sent := anAdoptedAnchor(t)
	ctx := t.Context()
	if _, err := take(ctx, open, "anchor", "hello-web"); err != nil {
		t.Fatal(err)
	}
	// Only a loopback listener: nothing off the machine, which is the same silence.
	reportsReaching(t, open, []link.Reach{
		{Protocol: "tcp", Address: "127.0.0.1", Port: 15672, By: "mesh-broker"},
	}, heldFile)
	preview, err := converge(ctx, open, "anchor", false, "", "")
	if err != nil {
		t.Fatal(err)
	}
	if !strings.Contains(preview, "this account looks partial") {
		t.Errorf("the preview does not mark a partial account:\n%s", preview)
	}
	_, err = converge(ctx, open, "anchor", true, digestIn(t, preview), "")
	if err == nil || !strings.Contains(err.Error(), "says nothing is reachable on it") {
		t.Fatalf("the flip was not refused on an account naming nothing: %v", err)
	}
	if n, _ := open.inventory.NodeByName(ctx, "anchor"); !n.Adopted || len(*sent) != 0 {
		t.Fatal("a refused flip changed something")
	}
}

// An assignment cannot land between a preview and the flip that takes every module: assigning
// holds the node, so it waits for whatever is converging it.
func TestAssigningWaitsForWhateverIsConvergingTheNode(t *testing.T) {
	open, _ := anAdoptedAnchor(t)
	ctx := t.Context()
	if _, err := take(ctx, open, "anchor", "hello-web"); err != nil {
		t.Fatal(err)
	}
	reportsHolding(t, open, heldFile)
	preview, err := converge(ctx, open, "anchor", false, "", "")
	if err != nil {
		t.Fatal(err)
	}
	saved, savedPoll := inventory.HoldWaitFor, inventory.HoldPoll
	inventory.HoldWaitFor, inventory.HoldPoll = time.Second, 50*time.Millisecond
	defer func() { inventory.HoldWaitFor, inventory.HoldPoll = saved, savedPoll }()

	var whileFlipping error
	sendNodes = func(context.Context, *stores, []string) error {
		_, whileFlipping = assign(ctx, open, "anchor", "notes")
		return nil
	}
	if _, err := converge(ctx, open, "anchor", true, digestIn(t, preview), ""); err != nil {
		t.Fatal(err)
	}
	if !errors.Is(whileFlipping, inventory.ErrNodeBusy) {
		t.Fatalf("an assignment landed while the node was being converged: %v", whileFlipping)
	}
}