package main

import (
	"bytes"
	"encoding/json"
	"go/build"
	"os"
	"os/exec"
	"path/filepath"
	"reflect"
	"runtime"
	"sort"
	"strings"
	"testing"

	"git.novox.be/novox/mesh-sdk/go/catalogue"
	"git.novox.be/novox/mesh-sdk/go/compose"
	"git.novox.be/novox/mesh-sdk/go/composer"
	"git.novox.be/novox/mesh-sdk/go/internal/beside"
)

// captured is every manifest of the catalogue captured in testdata/beside (internal/beside), raw, by module name.
func captured(t *testing.T) map[string]composer.Manifest {
	t.Helper()
	read, err := readCatalogue(filepath.Dir(beside.Catalogue(t)))
	if err != nil {
		t.Fatal(err)
	}
	if len(read) < 100 {
		t.Fatalf("the captured catalogue holds %d manifests, fewer than the catalogue's", len(read))
	}
	return read
}

// meshOf is a mesh of three machines over the captured catalogue, each assigned real modules, the input the assigner
// composes with (nodes and their assignments, holdings from the claims): anchor runs the bus and the store, laptop a
// desktop's modules, ace a module whose requirement is provided elsewhere.
func meshOf() compose.Input {
	return compose.Input{Nodes: []compose.Node{
		{Name: "anchor", Assigned: []string{"nats", "postgres"}},
		{Name: "laptop", Assigned: []string{"sudo", "zsh"}},
		{Name: "ace", Assigned: []string{"mesh-reads", "nats"}},
	}}
}

func request(t *testing.T, depth string) composer.Request {
	t.Helper()
	return composer.Request{V: composer.Version, Input: meshOf(), Depth: depth, HoldingsFromClaims: true,
		Machines: []string{"anchor", "laptop", "ace"},
		Cases:    []composer.Case{{Name: "trunk", Manifests: captured(t)}}}
}

func runJSON(t *testing.T, args []string, in []byte) (int, composer.Verdict, string) {
	t.Helper()
	var out, errOut bytes.Buffer
	code := run(args, bytes.NewReader(in), &out, &errOut)
	var v composer.Verdict
	if code == 0 {
		if err := json.Unmarshal(out.Bytes(), &v); err != nil {
			t.Fatalf("the verdict is not JSON: %v\n%s", err, out.String())
		}
	}
	return code, v, errOut.String()
}

func encode(t *testing.T, r composer.Request) []byte {
	t.Helper()
	raw, err := json.Marshal(r)
	if err != nil {
		t.Fatal(err)
	}
	return raw
}

// 1621/AC1: the command reads the plain input and the manifests on standard input, validates every manifest, composes
// the machines named and writes one verdict: per machine composes or the reason, per manifest accepted or the field
// refused.
func TestTheCommandWritesOneVerdictPerManifestAndMachine(t *testing.T) {
	r := request(t, composer.DepthResolve)
	r.Cases[0].Manifests["broken"] = composer.Manifest{Raw: json.RawMessage(`{"module":"broken","version":"1","shares":["x"]}`)}
	code, v, stderr := runJSON(t, nil, encode(t, r))
	if code != 0 {
		t.Fatalf("exit %d: %s", code, stderr)
	}
	if len(v.Cases) != 1 || v.Cases[0].Name != "trunk" || v.SDK == "" {
		t.Fatalf("verdict = %+v", v)
	}
	c := v.Cases[0]
	if got := c.Manifests["broken"]; got.Accepted || !strings.Contains(got.Refused, `"shares"`) {
		t.Errorf("the manifest with an unknown field reads %+v, want refused naming the field", got)
	}
	if got := c.Manifests["nats"]; !got.Accepted {
		t.Errorf("nats reads %+v, want accepted", got)
	}
	if len(c.Machines) != 3 {
		t.Fatalf("machines = %v, want the three named", c.Machines)
	}
	for name, m := range c.Machines {
		if !m.Composes && m.Reason == "" {
			t.Errorf("%s does not compose and says no reason", name)
		}
	}
}

// 1621/AC3: over the captured catalogue and a mesh of three machines, the command's verdict equals, machine for
// machine and manifest for manifest, what the linked reader, resolution and composition answer, at both depths.
func TestTheCommandAnswersWhatTheLinkedCompositionAnswers(t *testing.T) {
	for _, depth := range []string{composer.DepthResolve, composer.DepthCompose} {
		r := request(t, depth)
		code, v, stderr := runJSON(t, nil, encode(t, r))
		if code != 0 {
			t.Fatalf("%s: exit %d: %s", depth, code, stderr)
		}
		in := meshOf()
		in.Catalogue = map[string]catalogue.Manifest{}
		for name, m := range r.Cases[0].Manifests {
			// A request without a list of predefined keys reads a fallback as the indexer does (Request.Predefined).
			parsed, err := catalogue.ParseManifestForInputs(m.Raw)
			got := v.Cases[0].Manifests[name]
			if (err == nil) != got.Accepted || (err != nil && err.Error() != got.Refused) {
				t.Errorf("%s: the manifest of %s: linked %v, command %+v", depth, name, err, got)
			}
			if err == nil {
				in.Catalogue[name] = parsed
			}
		}
		in.Holdings = composer.HoldingsOf(in.Catalogue, in.Nodes)
		composed := 0
		for _, node := range r.Machines {
			got := v.Cases[0].Machines[node]
			var want composer.Machine
			if depth == composer.DepthResolve {
				if _, err := compose.Resolve(in, node); err != nil {
					want = composer.Machine{Reason: err.Error()}
				} else {
					want = composer.Machine{Composes: true}
				}
			} else {
				d, problems, err := compose.Compose(in, node)
				switch {
				case err != nil:
					want = composer.Machine{Reason: err.Error()}
				default:
					want = composer.Machine{Composes: len(problems) == 0, Problems: problems, Refusals: d.Refusals()}
					if len(problems) > 0 {
						want.Reason = "the node-engine's validator refuses the declaration"
					}
				}
			}
			if !reflect.DeepEqual(got, want) {
				t.Errorf("%s: %s: command %+v, linked %+v", depth, node, got, want)
			}
			if got.Composes {
				composed++
			} else {
				t.Logf("%s: %s does not compose: %s %v", depth, node, got.Reason, got.Problems)
			}
		}
		t.Logf("%s: %d of %d machines compose", depth, composed, len(r.Machines))
	}
}

// 1621 note 6: a person composes a catalogue checkout (repository@ref checked out or archived: the command fetches
// nothing) for a node and reads its declaration: each path with its kind, owner and mode.
func TestACatalogueCheckoutIsComposedForANode(t *testing.T) {
	dir := t.TempDir()
	if err := os.MkdirAll(filepath.Join(dir, "modules", "demo"), 0o755); err != nil {
		t.Fatal(err)
	}
	manifest := `{"module": "demo", "version": "1", "resources": [{"id": "state", "type": "directory", ` +
		`"path": "/var/lib/demo", "mode": "0750", "owner": "root"}]}`
	if err := os.WriteFile(filepath.Join(dir, "modules", "demo", "module.json"), []byte(manifest), 0o644); err != nil {
		t.Fatal(err)
	}
	in := encode(t, composer.Request{V: composer.Version, Input: compose.Input{Nodes: []compose.Node{{Name: "laptop", Assigned: []string{"demo"}}}}})
	code, v, stderr := runJSON(t, []string{"-catalogue", dir, "-node", "laptop", "-declarations"}, in)
	if code != 0 {
		t.Fatalf("exit %d: %s", code, stderr)
	}
	m := v.Cases[0].Machines["laptop"]
	want := []composer.Path{{Path: "/var/lib/demo", Kind: "directory", Owner: "root", Mode: "0750", Module: ""}}
	if !m.Composes || len(m.Declared) != 1 || m.Declared[0].Path != want[0].Path || m.Declared[0].Mode != "0750" ||
		m.Declared[0].Owner != "root" || m.Declared[0].Kind != "directory" {
		t.Fatalf("laptop = %+v, want it composed declaring %+v", m, want)
	}
}

// A run step hands the command no standard input: the request is read from the file -request names, and a file that is
// not there is a request it cannot read.
func TestTheRequestIsReadFromAFile(t *testing.T) {
	file := filepath.Join(t.TempDir(), "request.json")
	r := composer.Request{V: composer.Version, Cases: []composer.Case{{Name: "only", Manifests: map[string]composer.Manifest{
		"demo": {Raw: json.RawMessage(`{"module":"demo","version":"1"}`)}}}}}
	if err := os.WriteFile(file, encode(t, r), 0o600); err != nil {
		t.Fatal(err)
	}
	code, v, stderr := runJSON(t, []string{"-request", file}, nil)
	if code != 0 || len(v.Cases) != 1 || !v.Cases[0].Manifests["demo"].Accepted {
		t.Fatalf("exit %d (%s), verdict %+v", code, stderr, v)
	}
	if code, _, stderr := runJSON(t, []string{"-request", file + ".gone"}, nil); code != 1 || !strings.Contains(stderr, "cannot be read") {
		t.Errorf("a request file that is not there: exit %d, %q", code, stderr)
	}
}

// The exit codes: 1 for a request that cannot be read or run, 2 for wrong flags, each said on standard error.
func TestTheExitCodesSayWhatFailed(t *testing.T) {
	unfilled := encode(t, composer.Request{V: composer.Version, Cases: []composer.Case{{Name: "c", Manifests: map[string]composer.Manifest{"x": {Digest: "abc"}}}}})
	for _, c := range []struct {
		name string
		args []string
		in   string
		code int
		says string
	}{
		{"not JSON", nil, "{", 1, "not JSON"},
		{"another version", nil, `{"v":2}`, 1, "version 2"},
		{"a digest left unfilled", nil, string(unfilled), 1, "digest"},
		{"an unknown depth", nil, `{"v":1,"depth":"deep"}`, 1, "depth"},
		{"nothing to read", nil, "", 1, "no request"},
		{"a wrong flag", []string{"-nope"}, "", 2, "nope"},
		{"an argument", []string{"extra"}, "", 2, "unexpected"},
	} {
		var out, errOut bytes.Buffer
		if got := run(c.args, strings.NewReader(c.in), &out, &errOut); got != c.code || !strings.Contains(errOut.String(), c.says) {
			t.Errorf("%s: exit %d saying %q, want %d saying %q", c.name, got, errOut.String(), c.code, c.says)
		}
	}
}

// sdkPackages is every package of this module the command imports, directly or not, with the packages each imports.
func sdkPackages(t *testing.T) map[string][]string {
	t.Helper()
	_, file, _, _ := runtime.Caller(0)
	root := filepath.Join(filepath.Dir(file), "..", "..")
	const module = "git.novox.be/novox/mesh-sdk/go"
	out := map[string][]string{}
	var walk func(path string)
	walk = func(path string) {
		if _, done := out[path]; done {
			return
		}
		rel := strings.TrimPrefix(strings.TrimPrefix(path, module), "/")
		pkg, err := build.Default.ImportDir(filepath.Join(root, rel), 0)
		if err != nil {
			t.Fatalf("%s: %v", path, err)
		}
		out[path] = pkg.Imports
		for _, imp := range pkg.Imports {
			if strings.HasPrefix(imp, module+"/") {
				walk(imp)
			}
		}
	}
	walk(composer.Package)
	return out
}

// 1621/AC2 and AC4: the command imports, through every package of mesh-sdk it reaches, only the standard library and
// mesh-sdk's own packages (so `go build` from mesh-sdk's module needs nothing beyond its lock), and none that reaches
// a bus, a store, a network service or another process.
func TestTheCommandImportsNoBusStoreNetworkOrProcess(t *testing.T) {
	forbidden := []string{"net/http", "net/rpc", "net/smtp", "os/exec", "database/sql", "plugin", "syscall"}
	for path, imports := range sdkPackages(t) {
		for _, imp := range imports {
			std := !strings.Contains(strings.SplitN(imp, "/", 2)[0], ".")
			if !std && !strings.HasPrefix(imp, "git.novox.be/novox/mesh-sdk/go/") {
				t.Errorf("%s imports %s, which is neither the standard library nor mesh-sdk", path, imp)
			}
			for _, f := range forbidden {
				if imp == f {
					t.Errorf("%s imports %s", path, imp)
				}
			}
		}
	}
}

// 1621/AC2: run with an empty network namespace, the command still writes its verdict: it needs no network. The test
// runs its own binary again under `unshare --net` as an unprivileged user's namespace; where the kernel or the sandbox
// allows no new namespace (a build module's run step is already one with no network), it says so and skips.
func TestTheCommandRunsWithNoNetwork(t *testing.T) {
	if os.Getenv("MESH_COMPOSE_HELPER") == "1" {
		os.Exit(run(nil, os.Stdin, os.Stdout, os.Stderr))
	}
	unshare, err := exec.LookPath("unshare")
	if err != nil {
		t.Skip("no unshare on this machine, so no empty network namespace can be made here")
	}
	if out, err := exec.Command(unshare, "--net", "--map-root-user", "true").CombinedOutput(); err != nil {
		t.Skipf("this machine makes no unprivileged network namespace (%v: %s); a run step's own has no network", err, out)
	}
	r := request(t, composer.DepthResolve)
	cmd := exec.Command(unshare, "--net", "--map-root-user", os.Args[0], "-test.run=^TestTheCommandRunsWithNoNetwork$")
	cmd.Env = []string{"MESH_COMPOSE_HELPER=1"}
	cmd.Stdin = bytes.NewReader(encode(t, r))
	var out, errOut bytes.Buffer
	cmd.Stdout, cmd.Stderr = &out, &errOut
	if err := cmd.Run(); err != nil {
		t.Fatalf("the command in an empty network namespace: %v: %s", err, errOut.String())
	}
	var v composer.Verdict
	if err := json.Unmarshal(out.Bytes(), &v); err != nil || len(v.Cases) != 1 || len(v.Cases[0].Machines) != 3 {
		t.Fatalf("no verdict from the command with no network: %v\n%s", err, out.String())
	}
	names := make([]string, 0, len(v.Cases[0].Machines))
	for n := range v.Cases[0].Machines {
		names = append(names, n)
	}
	sort.Strings(names)
	t.Logf("composed with no network: %v", names)
}

// -catalogue judges a fallback to a predefined key against the predefined.json at the checkout's root (ADR 0348 §7):
// xterm (mesh-catalog at 835bf22b) falls back to "font-size", accepted where the root lists it and refused where the
// root's list does not.
func TestACatalogueCheckoutJudgesFallbacksAgainstItsPredefinedKeys(t *testing.T) {
	raw, err := os.ReadFile("../../catalogue/testdata/catalogue-835bf22b-xterm.module.json")
	if err != nil {
		t.Fatal(err)
	}
	for _, c := range []struct {
		list string
		want bool
	}{
		{`{"font-size": {"type": "number", "description": "the desktop's font size"}}`, true},
		{`{"font-family": {"type": "string", "description": "the desktop's font"}}`, false},
	} {
		dir := t.TempDir()
		if err := os.MkdirAll(filepath.Join(dir, "modules", "xterm"), 0o700); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(filepath.Join(dir, "modules", "xterm", "module.json"), raw, 0o600); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(filepath.Join(dir, catalogue.PredefinedFile), []byte(c.list), 0o600); err != nil {
			t.Fatal(err)
		}
		code, v, stderr := runJSON(t, []string{"-catalogue", dir}, nil)
		if code != 0 {
			t.Fatalf("exit %d: %s", code, stderr)
		}
		if got := v.Cases[0].Manifests["xterm"]; got.Accepted != c.want {
			t.Errorf("predefined.json %s: xterm %+v, want accepted %v", c.list, got, c.want)
		}
	}
}