package modules

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"slices"
	"strings"
	"testing"

	"github.com/novox/mesh-control/internal/catalogue"
	"github.com/novox/mesh-control/internal/overlay"
)

// The examples are manifests, so the thing to check is that the catalogue accepts them.
//
// A manifest that only ever appears in a document is a manifest nobody has run through the parser,
// and the parser refuses unknown keys — so a typo here would be discovered by whoever first tried
// to use one, which is the opposite of what an example is for.
func read(t *testing.T, name string) catalogue.Manifest {
	t.Helper()
	raw, err := os.ReadFile(filepath.Join(".", name))
	if err != nil {
		t.Fatal(err)
	}
	m, err := catalogue.ParseManifest(raw)
	if err != nil {
		t.Fatalf("%s is not a manifest this mesh accepts: %v", name, err)
	}
	return m
}

func TestEveryExampleIsAManifestTheMeshAccepts(t *testing.T) {
	found, err := filepath.Glob("*.json")
	if err != nil {
		t.Fatal(err)
	}
	if len(found) == 0 {
		t.Fatal("no examples, so this test proves nothing")
	}
	for _, name := range found {
		read(t, name)
	}
}

// The serving module reads what the mesh writes, and restarts when the mesh rewrites it.
//
// Without the second it would serve the names it started with for ever — every machine that
// joined afterwards unreachable by name, and every check passing.
func TestTheResolverReadsTheMeshsNamesAndFollowsThem(t *testing.T) {
	m := read(t, "dnsmasq.json")

	var config, service map[string]any
	for _, r := range m.Resources {
		switch r["id"] {
		case "config":
			config = r
		case "service":
			service = r
		}
	}
	if config == nil || service == nil {
		t.Fatal("the module has no configuration or no service")
	}
	if !strings.Contains(config["content"].(string), overlay.ResolverPath) {
		t.Fatalf("it does not read what the mesh writes at %s", overlay.ResolverPath)
	}

	var follows bool
	for _, id := range service["restart-on"].([]any) {
		if id.(string) == overlay.Resolver+".nodes" {
			follows = true
		}
	}
	if !follows {
		t.Fatalf("it does not restart when the mesh rewrites the names: %v", service["restart-on"])
	}
}

// It binds names the mesh chose, so it needs to know nothing about the machine it is on.
//
// That is the whole reason these can be static manifests: a resolver must bind somewhere and a
// stub must be pointed somewhere, and neither address is knowable in advance — unless the mesh
// named it.
func TestTheResolverNeedsToKnowNothingAboutItsMachine(t *testing.T) {
	config := read(t, "dnsmasq.json").Resources[1]["content"].(string)
	// The directive, not the word: the comment above it names the interface too, so a plain
	// Contains passes whatever the module actually binds. It did.
	if !strings.Contains(config, "interface="+overlay.Interface+"\n") {
		t.Fatalf("it does not bind the private network's interface %q:\n%s",
			overlay.Interface, config)
	}
	// That it binds one, not which. Which address it is belongs in the manifests, where the
	// asking modules can be checked against it — naming it here too would be a fourth place to
	// keep in step, and the one nobody would think to change.
	if !strings.Contains(config, "\nlisten-address=127.0.0.") {
		t.Fatalf("it answers on no address for the machine's own use:\n%s", config)
	}
	// Not an address that belongs to something else.
	//
	// **systemd-resolved holds .53 AND .54** — the stub and the proxy stub. This module asserted
	// .54 was free, in a comment that read as reasoned, and a machine said otherwise: dnsmasq
	// could not start at all. A unit test cannot know which addresses a machine has spare, but it
	// can hold on to what one has already told us.
	for _, taken := range []string{"127.0.0.1", "127.0.0.53", "127.0.0.54"} {
		if strings.Contains(config, "listen-address="+taken) {
			t.Fatalf("it takes %s, which belongs to something else:\n%s", taken, config)
		}
	}
}

// Everything that points resolution at the mesh points at the same place.
//
// Three files name this address — one binds it and two send queries to it — and a change to one
// of them alone is a resolver answering where nobody asks.
func TestTheAskingModulesPointAtWhereTheResolverAnswers(t *testing.T) {
	serving := read(t, "dnsmasq.json").Resources[1]["content"].(string)
	var at string
	for _, line := range strings.Split(serving, "\n") {
		if rest, found := strings.CutPrefix(strings.TrimSpace(line), "listen-address="); found {
			at = rest
		}
	}
	if at == "" {
		t.Fatal("the resolver binds no address for the machine's own use")
	}
	for _, asking := range []string{"resolved-split-dns.json", "resolv-conf.json"} {
		m := read(t, asking)
		var mentions bool
		for _, r := range m.Resources {
			if content, ok := r["content"].(string); ok && strings.Contains(content, at) {
				mentions = true
			}
		}
		if !mentions {
			t.Fatalf("%s does not point at %s, where the resolver answers", asking, at)
		}
	}
}

// The two ways of deciding what a machine asks claim the same thing, so the mesh refuses the pair.
func TestTwoWaysOfOwningTheResolverCannotBothBeAssigned(t *testing.T) {
	shelf := map[string]catalogue.Manifest{}
	for _, name := range []string{"resolved-split-dns.json", "resolv-conf.json", "dnsmasq.json"} {
		m := read(t, name)
		shelf[m.Module] = m
	}
	// Something has to answer `wildcard-resolution`, or they are refused for that instead and the
	// test would pass without ever reaching the claim.
	shelf["dnsmasq"] = read(t, "dnsmasq.json")

	_, err := catalogue.Resolve(shelf,
		[]string{"dnsmasq", "resolved-split-dns", "resolv-conf"},
		catalogue.Node{Name: "anchor", Capabilities: map[string]bool{}},
		catalogue.World{Unchecked: true})
	if err == nil {
		t.Fatal("both ways of owning the resolver were assigned to one machine")
	}
	said := err.Error()
	if !strings.Contains(said, "the-resolver-configuration") {
		t.Fatalf("the refusal does not name what they both want: %v", said)
	}
}

// And the two roles are not the same claim: a machine runs one resolver AND one thing deciding
// what it asks, so serving and asking must be assignable together.
func TestServingAndAskingAreAssignableTogether(t *testing.T) {
	shelf := map[string]catalogue.Manifest{}
	for _, name := range []string{"dnsmasq.json", "resolved-split-dns.json"} {
		m := read(t, name)
		shelf[m.Module] = m
	}
	if _, err := catalogue.Resolve(shelf,
		[]string{"dnsmasq", "resolved-split-dns"},
		catalogue.Node{Name: "anchor", Capabilities: map[string]bool{}},
		catalogue.World{Unchecked: true}); err != nil {
		t.Fatalf("a resolver and the thing pointing at it cannot both be assigned: %v", err)
	}
}

// The examples are JSON a person edits, so a stray comma is worth catching here rather than on a
// machine.
func TestTheExamplesAreWellFormed(t *testing.T) {
	found, _ := filepath.Glob("*.json")
	for _, name := range found {
		raw, err := os.ReadFile(name)
		if err != nil {
			t.Fatal(err)
		}
		var any map[string]any
		if err := json.Unmarshal(raw, &any); err != nil {
			t.Fatalf("%s is not JSON: %v", name, err)
		}
	}
}

// The resolver must not look up its own upstreams.
//
// Whatever points a machine at the mesh writes that address into resolv.conf, so a resolver that
// read it would find itself — and every query it could not answer locally would loop until its
// receive queue filled. It did: 15KB of queries backed up and every lookup on the machine hung.
//
// It needs no upstream because it is never asked for anything else: the asking module routes only
// the mesh's suffix here and leaves the rest where the machine already sent it.
func TestTheResolverDoesNotAskItselfForUpstreams(t *testing.T) {
	config := read(t, "dnsmasq.json").Resources[1]["content"].(string)
	if !strings.Contains(config, "\nno-resolv\n") {
		t.Fatalf("it reads resolv.conf for upstreams, which now points at itself:\n%s", config)
	}
	// And names no upstream of its own: choosing one would send every query this machine cannot
	// answer somewhere nobody agreed to.
	for _, line := range strings.Split(config, "\n") {
		if strings.HasPrefix(strings.TrimSpace(line), "server=") {
			t.Fatalf("it forwards to %q, which is not the mesh's to choose", line)
		}
	}
}

// The two halves of an object-store edge, as a pair.
//
// `minio.json` is the provider. There were two manifests describing the same object store — the
// other named `object-store.json` — which is not a choice between implementations but one module
// written twice: same image, same provision, same scope. Assigning both to a node would have
// collided on `s3-bucket`.
//
// A provider and a consumer that only ever appear separately are two manifests nobody has checked
// against each other: the name one provides has to be the name the other requires, and the key a
// consumer contributes has to be the one the provisioner reads. Both were got wrong while writing
// them, and neither would have been caught by parsing either file alone.
func TestTheObjectStoreEdgeFitsTogether(t *testing.T) {
	provider := read(t, "minio.json")
	consumer := read(t, "photos.json")

	const provision = "s3-bucket"

	var provides bool
	for _, offer := range provider.Provides {
		if offer.Name == provision {
			provides = true
		}
	}
	if !provides {
		t.Fatalf("the provider does not offer %q", provision)
	}
	if !strings.Contains(strings.Join(consumer.Requires, ","), provision) {
		t.Fatalf("the consumer does not require %q", provision)
	}

	// Where each side wants to be told. A provider that receives nowhere is a provider the mesh
	// writes nothing for, and a provisioner with nothing to read.
	if provider.Receives[provision] == "" {
		t.Error("the provider says nowhere to write what its consumers asked for")
	}
	if provider.Grants[provision] == "" {
		t.Error("the provider says nowhere to write its consumers' credentials")
	}
	if consumer.Binds[provision] == "" {
		t.Error("the consumer says nowhere to be told where its bucket is")
	}
	if consumer.Secrets[provision] == "" {
		t.Error("the consumer says nowhere to be given its key")
	}

	// The key the provisioner reads out of `values`. It looks for `bucket`, so a consumer
	// contributing `name` — which is what the database one contributes — resolves cleanly and
	// then fails on the machine with "asked for a bucket and did not name it".
	if _, named := consumer.Contributes[provision]["bucket"]; !named {
		t.Errorf("the consumer contributes %v, and the provisioner reads \"bucket\"",
			consumer.Contributes[provision])
	}
}

// Every hole an example leaves for a credential can be filled from what that module declared.
//
// **A manifest that parses is not a manifest that works.** These say `${secret:x}` in a file and
// declare `x` under `own-secrets`; if the two ever disagree the mesh refuses the whole declaration
// at push time, on the machine, with the module's name and nothing else to go on. Checking it here
// costs nothing and moves the answer to whoever edited the file.
//
// This is also the shape that was missing entirely until 2026-09-01: an own secret arrives as a
// file whose whole content is the password, and every one of these programs reads `KEY=value`. The
// manifests said `own-secrets` pointed at a `.env` and it did not — it pointed at a password.
func TestEveryCredentialHoleCanBeFilledByTheModuleThatLeftIt(t *testing.T) {
	found, err := filepath.Glob("*.json")
	if err != nil {
		t.Fatal(err)
	}
	var checked int
	for _, name := range found {
		m := read(t, name)
		has := map[string]bool{}
		for own := range m.OwnSecrets {
			has[own] = true
		}
		for required := range m.Secrets {
			has[required] = true
		}
		for _, r := range m.Resources {
			content, ok := r["content"].(string)
			if !ok {
				continue
			}
			for _, wanted := range secretsUsedForTest(content) {
				checked++
				if !has[wanted] {
					t.Errorf(
						"%s: %v says ${secret:%s}, and %s neither owns a secret by that name "+
							"nor requires anything that grants one",
						name, r["id"], wanted, m.Module)
				}
			}
		}
	}
	if checked == 0 {
		t.Fatal("no example puts a credential into a file, so this test proves nothing")
	}
}

// A secret file is a password and nothing else, so nothing may read one as an env file.
//
// The fault this catches is the one these manifests shipped with: `own-secrets` pointing at a
// path called `.env`, mounted as `env-file`, holding a bare password. Docker reads that as a
// malformed line and the container starts with no password at all.
func TestNoContainerReadsABarePasswordAsAnEnvFile(t *testing.T) {
	found, _ := filepath.Glob("*.json")
	for _, name := range found {
		m := read(t, name)
		bare := map[string]bool{}
		for _, where := range m.OwnSecrets {
			bare[where] = true
		}
		for _, where := range m.Secrets {
			bare[where] = true
		}
		for _, r := range m.Resources {
			files, ok := r["env-file"].([]any)
			if !ok {
				continue
			}
			for _, f := range files {
				if bare[fmt.Sprint(f)] {
					t.Errorf(
						"%s: %v reads %s as an env file, and that path holds a bare password — "+
							"declare a file whose content says ${secret:...} and read that instead",
						name, r["id"], f)
				}
			}
		}
	}
}

// The same expression the control plane and the host both match.
var placeholder = regexp.MustCompile(`\$\{secret:([a-z0-9][a-z0-9-]*)\}`)

func secretsUsedForTest(content string) []string {
	var used []string
	seen := map[string]bool{}
	for _, m := range placeholder.FindAllStringSubmatch(content, -1) {
		if !seen[m[1]] {
			seen[m[1]] = true
			used = append(used, m[1])
		}
	}
	return used
}

// Every module that requires something produces configuration a program could use.
//
// **Parsing is not working, and this file has now learned that twice.** These modules parsed and
// resolved for a day while their credentials went into files nothing could read; they would parse
// and resolve just as happily with a connection string naming no user, or with a placeholder
// written through as a hostname. What has to be true is that the bytes reaching the machine are
// usable, so that is what this asks — of every consumer, not of the one that was being worked on.
func TestEveryConsumerGetsConfigurationAProgramCouldUse(t *testing.T) {
	found, err := filepath.Glob("*.json")
	if err != nil {
		t.Fatal(err)
	}
	shelf := map[string]catalogue.Manifest{}
	for _, name := range found {
		m := read(t, name)
		shelf[m.Module] = m
	}

	var checked int
	for _, m := range shelf {
		if len(m.Requires) == 0 {
			continue
		}
		out := declareOnItsOwn(t, shelf, m)
		if out == nil {
			continue
		}
		checked++
		for _, r := range out {
			content, ok := r["content"].(string)
			if !ok {
				continue
			}
			// A placeholder written through is read as a value by whatever parses the file — a
			// connection to a host literally called "${bound:postgres-database:at}", failing
			// somewhere that names neither the module nor the mesh.
			if strings.Contains(content, "${bound:") {
				t.Errorf("%s: %v reached the machine with a placeholder in it:\n%s",
					m.Module, r["id"], content)
			}
			// The password is the one that must survive: only the host may fill it, and only on
			// the machine. If it is gone, something composed it here.
			for _, line := range strings.Split(content, "\n") {
				if strings.Contains(line, "PASSWORD") || strings.Contains(line, "PASSWD") {
					if !strings.Contains(line, "${secret:") {
						t.Errorf("%s: %v carries %q, which is not a hole the host fills",
							m.Module, r["id"], line)
					}
				}
			}
		}
	}
	if checked == 0 {
		t.Fatal("no example requires anything, so this test proves nothing")
	}
}

// declareOnItsOwn resolves one consumer against a mesh that answers everything it requires, and
// returns what would reach the machine. Nil when its requirements cannot be answered from the
// examples, which is not this test's business to complain about.
func declareOnItsOwn(t *testing.T, shelf map[string]catalogue.Manifest,
	m catalogue.Manifest) []map[string]any {
	t.Helper()

	// Everything it requires, answered from somewhere else in the mesh, with whatever the
	// providing example says it serves.
	offered := map[string][]catalogue.Provider{}
	for _, want := range m.Requires {
		// Built the way the control plane builds it: what a provider tells a consumer includes
		// the port, and the module no longer writes that into `serves` by hand — it says it once
		// in `listens` and the mesh puts it there (novox/hq ADR 0038).
		serves := map[string]any{}
		for _, other := range shelf {
			if _, said := other.Serves[want]; said {
				serves = catalogue.ServedOn(other, want, nil)
			}
		}
		offered[want] = []catalogue.Provider{
			{Node: "anchor", At: "anchor.internal", Serves: serves}}
	}
	resolved, err := catalogue.Resolve(shelf, []string{m.Module},
		catalogue.Node{Name: "workstation", At: "workstation.internal",
			Capabilities: map[string]bool{"container-runtime": true}},
		catalogue.World{Offered: offered})
	if err != nil {
		t.Logf("%s does not resolve on its own: %v", m.Module, err)
		return nil
	}
	for i := range resolved.Needs {
		resolved.Needs[i].Sealed = "sealed"
	}
	own := map[string]map[string]string{}
	for name := range m.OwnSecrets {
		if own[m.Module] == nil {
			own[m.Module] = map[string]string{}
		}
		own[m.Module][name] = "sealed"
	}
	out, err := resolved.Declaration(catalogue.Rendering{Needed: own})
	if err != nil {
		t.Errorf("%s resolves and does not declare: %v", m.Module, err)
		return nil
	}
	return out
}

// Every image an example names is one this repository builds.
//
// A manifest naming an image nothing produces is a module that resolves, plans, pushes, and stops
// on the machine at `docker pull` — the fault arriving as far from its cause as it can get. Two of
// these were found by reading the manifests rather than by running them: the object store's
// provisioner had a Dockerfile and no target, and Keycloak's did not exist at all.
//
// Only the mesh's own images are checked. `postgres`, `redis` and the rest come from a registry
// and are somebody else's to build; what this bounds is the set this repository is responsible
// for and might forget.
func TestEveryImageTheExamplesNameIsOneThisRepositoryBuilds(t *testing.T) {
	makefile, err := os.ReadFile(filepath.Join("..", "..", "Makefile"))
	if err != nil {
		t.Fatal(err)
	}

	found, _ := filepath.Glob("*.json")
	var checked int
	for _, name := range found {
		for _, r := range read(t, name).Resources {
			image, ok := r["image"].(string)
			if !ok {
				continue
			}
			repository, _, _ := strings.Cut(image, "@")
			if !strings.HasPrefix(repository, "mesh-") {
				continue
			}
			checked++
			if !strings.Contains(string(makefile), repository+":") {
				t.Errorf(
					"%s names the image %q and nothing in this repository builds one. A module "+
						"naming an image that does not exist resolves, plans, pushes, and stops "+
						"on the machine at `docker pull`",
					name, repository)
			}
		}
	}
	if checked == 0 {
		t.Fatal("no example names an image this repository builds, so this proves nothing")
	}
}

// Every host path a container mounts is a directory the module declared.
//
// **The mesh owns a directory or it does not** (novox/hq 04-ISSUES/026). A bind mount whose source
// does not exist is created by the container runtime as root, with a mode nobody chose — so
// `owner` and `mode` go unapplied on exactly the directories that hold the data.
//
// Worse, the rule that a directory is *kept* rather than removed when it holds something the mesh
// did not put there (ADR 0030) is written in terms of declared directories. An undeclared one is
// not covered by it. So the single rule guarding against data loss reached the configuration and
// not the data.
//
// These manifests were written by carrying compose files across, and a container shape that can
// express a compose file gets filled in like one. This is the check that says so.
func TestEveryMountedPathIsADirectoryTheModuleDeclared(t *testing.T) {
	found, _ := filepath.Glob("*.json")
	var checked int
	for _, name := range found {
		m := read(t, name)
		declared := map[string]bool{}
		for _, r := range m.Resources {
			if fmt.Sprint(r["type"]) == "directory" {
				declared[fmt.Sprint(r["path"])] = true
			}
		}
		for _, r := range m.Resources {
			for _, v := range stringsOfTest(r["volumes"]) {
				host, _, _ := strings.Cut(v, ":")
				if !strings.HasPrefix(host, "/") {
					continue // a named volume, which the runtime owns and the mesh does not
				}
				checked++
				// A machine facility is not the module's data, and the manifest cannot yet say
				// so (novox/hq 04-ISSUES/026, reopened on exactly this): the runtime's socket
				// exists, the machine owns it, and declaring it as the module's directory would
				// be a lie the host acts on. Named here one by one rather than waved through by
				// pattern, so each new facility is a deliberate addition beside the issue that
				// owns the vocabulary.
				if host == "/var/run/docker.sock" {
					continue
				}
				var covered bool
				for d := range declared {
					if host == d || strings.HasPrefix(host, strings.TrimRight(d, "/")+"/") {
						covered = true
					}
				}
				if !covered {
					t.Errorf(
						"%s: %v mounts %s and no resource declares it. The runtime will create it "+
							"as root, and the rule that keeps a directory holding data does not "+
							"reach a directory the mesh never declared",
						name, r["id"], host)
				}
			}
		}
	}
	if checked == 0 {
		t.Fatal("no example mounts a host path, so this test proves nothing")
	}
}

func stringsOfTest(v any) []string {
	list, ok := v.([]any)
	if !ok {
		return nil
	}
	out := make([]string, 0, len(list))
	for _, item := range list {
		out = append(out, fmt.Sprint(item))
	}
	return out
}

// A resource uses only the keys its shape has.
//
// **The host is the only thing that knew, and it is five steps downstream.** A container carrying
// `restart-on` — which belongs to a service — composed into a declaration without complaint, was
// pushed, and was refused on the machine. The host refused *the whole declaration*, correctly,
// because applying the parts it understood would leave a machine that looks configured and is
// not. So one misplaced key stopped a module dead, and the only place that said so was a log on a
// lab machine after a seventeen-minute run.
//
// Nine of them had shipped across seven modules.
//
// The lists are written out rather than imported: the host is another repository and this is its
// wire format, like the shape of a grant file. Duplicated deliberately, and checked — a contract
// with two copies and no check is a contract until somebody edits one.
func TestAResourceUsesOnlyTheKeysItsShapeHas(t *testing.T) {
	common := []string{"id", "type"}
	shapes := map[string][]string{
		"file":      {"path", "content", "bytes", "sealed", "secrets", "mode", "owner"},
		"directory": {"path", "mode", "owner"},
		"container": {"name", "image", "env", "env-file", "ports", "volumes", "args", "hosts", "network", "artifact"},
		"service":   {"unit", "state", "boot", "restart-on"},
		"package":   {"package", "state"},
		"network":   {"name"},
		"archive":   {"path", "artifact", "digest", "owner", "mode"},
		"user":      {"name", "shell", "groups", "home"},
		"action":    {"command", "verify", "in"},
	}

	found, _ := filepath.Glob("*.json")
	var checked int
	for _, name := range found {
		for _, r := range read(t, name).Resources {
			kind := fmt.Sprint(r["type"])
			allowed, known := shapes[kind]
			if !known {
				t.Errorf("%s: %v is a %q, which is not a shape the mesh has", name, r["id"], kind)
				continue
			}
			for key := range r {
				checked++
				// `merge` and `protected` are read by the control plane and removed before a
				// machine sees them, so they are legal here and unknown to the host.
				if key == "merge" || key == "protected" {
					continue
				}
				if !slices.Contains(common, key) && !slices.Contains(allowed, key) {
					t.Errorf(
						"%s: %v is a %s and carries %q, which that shape does not have. It would "+
							"compose cleanly and be refused on the machine — and the host refuses "+
							"the whole declaration, so this stops the module entirely",
						name, r["id"], kind, key)
				}
			}
		}
	}
	if checked == 0 {
		t.Fatal("no example declares a resource, so this test proves nothing")
	}
}