package apply

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

	"github.com/novox/mesh-host/internal/declaration"
	"github.com/novox/mesh-host/internal/store"
)

// Defends novox/hq ADR 0349 §4 (issue 668): the provisioner's client has the node-engine write a file it filled,
// and the node-engine writes it as an apply of the declared file with that content would — through applyFile,
// applyInto or applyBlock by who owns it at runtime — and makes what reads it take the change as an apply does.

// filledDecl is a declaration naming path as filled, with the file's fields after id, type and path, and more
// resources after it.
func filledDecl(t *testing.T, path, fields, more string) *declaration.Declaration {
	t.Helper()
	if more != "" {
		more = "," + more
	}
	return parseTrusted(t, fmt.Sprintf(`{"declaration":1,"provisioner_account":"mesh-node-provisioner",
	  "filled_files":[%q],"resources":[{"id":"m.conf","type":"file","path":%q,%s}%s]}`, path, path, fields, more))
}

func TestAWriteOfAPathNotFilledIsRefused(t *testing.T) {
	dir := t.TempDir()
	filled := filepath.Join(dir, "filled.conf")
	other := filepath.Join(dir, "other.conf")
	d := parseTrusted(t, fmt.Sprintf(`{"declaration":1,"filled_files":[%q],"resources":[
	  {"id":"m.conf","type":"file","path":%q,"content":"x\n","owner-at-runtime":"owned"},
	  {"id":"m.other","type":"file","path":%q,"content":"y\n"}
	]}`, filled, filled, other))
	for _, path := range []string{other, filepath.Join(dir, "nothing.conf")} {
		_, state, err := WriteFilled(context.Background(), archHost(t), d, store.State{}, path, []byte("evil\n"),
			noServices, nil, nil, nil)
		if err == nil || !strings.Contains(err.Error(), "does not name") {
			t.Errorf("%s: a write of a path the declaration does not fill was not refused: %v", path, err)
		}
		if _, err := os.Stat(path); err == nil && path != other {
			t.Errorf("%s was written", path)
		}
		if len(state.Resources) != 0 {
			t.Errorf("a refused write recorded something: %+v", state.Resources)
		}
	}
	if _, err := os.Stat(other); err == nil {
		t.Errorf("%s was written", other)
	}
}

// Each ownership is written by the write verb exactly as an apply of the declared file with the same content: the
// same action, the same bytes on disk, the same mode.
func TestAFilledFileIsWrittenAsItsOwnershipSays(t *testing.T) {
	for _, c := range []struct {
		name, fields, content, before, action string
	}{
		{"owned, absent", `"content":"","mode":"0640","owner-at-runtime":"owned"`, "port = 8080\n", "", "created"},
		{"owned, over what is there", `"content":"","mode":"0640","owner-at-runtime":"owned"`, "port = 8080\n",
			"port = 1\n", "updated"},
		{"seed, absent", `"content":"","mode":"0600","owner-at-runtime":"seed"`, "user default on\n", "", "created"},
		{"seed, present", `"content":"","mode":"0600","owner-at-runtime":"seed"`, "user default on\n",
			"user default on\nuser app-one on\n", "kept"},
		{"managed json", `"into":"json","content":"{}","owner-at-runtime":"managed"`,
			`{"insecure-registries":["10.42.0.1:5000"]}`, machinesOwn, "updated"},
		{"managed block", `"into":"block","content":"x\n","owner-at-runtime":"managed"`, "10.42.0.1 ace\n",
			workstationHosts, "updated"},
	} {
		t.Run(c.name, func(t *testing.T) {
			at := func() string {
				path := filepath.Join(t.TempDir(), "the-file")
				if c.before != "" {
					if err := os.WriteFile(path, []byte(c.before), 0o644); err != nil {
						t.Fatal(err)
					}
				}
				return path
			}
			written := at()
			report, state, err := WriteFilled(context.Background(), archHost(t), filledDecl(t, written, c.fields, ""),
				store.State{}, written, []byte(c.content), noServices, nil, nil, nil)
			if err != nil {
				t.Fatal(err)
			}
			applied := at()
			withContent := strings.Replace(c.fields, fmt.Sprintf(`"content":%q`, contentOf(t, c.fields)),
				fmt.Sprintf(`"content":%q`, c.content), 1)
			// The same file declared the old way: an apply writes a filled file only on the client's word (P7).
			plain := parseTrusted(t, fmt.Sprintf(`{"declaration":1,"resources":[{"id":"m.conf","type":"file",`+
				`"path":%q,%s}]}`, applied, withContent))
			want, _, err := Apply(context.Background(), archHost(t), plain, store.State{}, store.OriginDeclared,
				noServices, nil, nil)
			if err != nil {
				t.Fatal(err)
			}
			if got := report.Outcomes[0].Action; got != c.action || got != want.Outcomes[0].Action {
				t.Errorf("written %s; an apply of the same content %s; want %s", got, want.Outcomes[0].Action, c.action)
			}
			if got, apply := readText(t, written), readText(t, applied); got != apply {
				t.Errorf("written, the file holds\n%q\nan apply of the same content leaves\n%q", got, apply)
			}
			if a, b := modeAt(t, written), modeAt(t, applied); a != b {
				t.Errorf("written mode %o, an apply's %o", a, b)
			}
			if rec, ok := state.Find("m.conf"); !ok || rec.Target != written || rec.Origin != store.OriginDeclared {
				t.Errorf("the write is not recorded as the file's: %+v", rec)
			}
		})
	}
}

func contentOf(t *testing.T, fields string) string {
	t.Helper()
	var holder struct {
		Content string `json:"content"`
	}
	if err := json.Unmarshal([]byte("{"+fields+"}"), &holder); err != nil {
		t.Fatal(err)
	}
	return holder.Content
}

func modeAt(t *testing.T, path string) os.FileMode {
	t.Helper()
	info, err := os.Stat(path)
	if err != nil {
		t.Fatal(err)
	}
	return info.Mode().Perm()
}

// A file that carried a secret keeps the mode a secret is written with: the client filled the value, and the file
// is no more readable for it.
func TestAFilledFileThatCarriedASecretIsNotWorldReadable(t *testing.T) {
	path := filepath.Join(t.TempDir(), "token.env")
	d := filledDecl(t, path, `"content":"TOKEN=${secret:token}\n","secrets":{"token":"c2VhbGVk"},"owner-at-runtime":"owned"`, "")
	if _, _, err := WriteFilled(context.Background(), archHost(t), d, store.State{}, path, []byte("TOKEN=abc\n"),
		noServices, nil, nil, nil); err != nil {
		t.Fatal(err)
	}
	if m := modeAt(t, path); m != 0o600 {
		t.Errorf("a filled file that carried a secret is mode %o", m)
	}
}

func TestAWriteUnderReloadOnReloadsItsProgramOnce(t *testing.T) {
	path := filepath.Join(t.TempDir(), "daemon.conf")
	d := filledDecl(t, path, `"content":"","owner-at-runtime":"owned"`,
		`{"id":"m.daemon","type":"service","unit":"m.service","state":"running","reload-on":["m.conf"]},
		 {"id":"m.other","type":"service","unit":"other.service","state":"running"}`)
	var commands []string
	var said []string
	_, state, err := WriteFilled(context.Background(), archHost(t), d, store.State{}, path, []byte("level = 1\n"),
		recordingServices(&commands), func(line string) { said = append(said, line) }, nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	if n := count(commands, "systemctl reload m.service"); n != 1 {
		t.Errorf("the program was reloaded %d times; commands were %v", n, commands)
	}
	joined := strings.Join(commands, "\n")
	if strings.Contains(joined, "restart m.service") || strings.Contains(joined, "stop m.service") {
		t.Errorf("the program was restarted, not reloaded: %v", commands)
	}
	if strings.Contains(joined, "other.service") {
		t.Errorf("a service that does not read the file was touched: %v", commands)
	}
	if _, ok := state.Find("m.daemon"); !ok {
		t.Errorf("the reloaded service was not recorded")
	}
	// The log says the path and the digest, never the content.
	for _, line := range said {
		if strings.Contains(line, "level = 1") {
			t.Errorf("the content was said: %q", line)
		}
	}
	if !strings.Contains(strings.Join(said, "\n"), digestOf("level = 1\n")) {
		t.Errorf("the digest was not said: %q", said)
	}

	// The same content again moves nothing, and reloads nothing.
	commands = nil
	report, _, err := WriteFilled(context.Background(), archHost(t), d, state, path, []byte("level = 1\n"),
		recordingServices(&commands), nil, nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	if report.Outcomes[0].Action != "unchanged" || count(commands, "reload") != 0 {
		t.Errorf("an unchanged write reloaded: %v %+v", commands, report.Outcomes)
	}
}

func TestAWriteUnderRestartOnRestartsItsProgram(t *testing.T) {
	path := filepath.Join(t.TempDir(), "daemon.conf")
	d := filledDecl(t, path, `"content":"","owner-at-runtime":"owned"`,
		`{"id":"m.daemon","type":"service","unit":"m.service","state":"running","restart-on":["m.conf"]}`)
	var commands []string
	if _, _, err := WriteFilled(context.Background(), archHost(t), d, store.State{}, path, []byte("level = 1\n"),
		recordingServices(&commands), nil, nil, nil); err != nil {
		t.Fatal(err)
	}
	// A restart is a stop and a start, once.
	stops, starts := count(commands, "systemctl stop m.service"), count(commands, "systemctl start m.service")
	if stops != 1 || starts != 1 {
		t.Errorf("the program was stopped %d and started %d times; commands were %v", stops, starts, commands)
	}
}

// A running container that reads the file at creation is recreated, as an apply recreates it for a changed file.
func TestAWriteOfAFileAContainerReadsRecreatesIt(t *testing.T) {
	env := filepath.Join(t.TempDir(), "forge.env")
	d := filledDecl(t, env, `"content":"","mode":"0600","owner-at-runtime":"owned"`,
		`{"id":"forge.server","type":"container","name":"forge","image":"`+pinned+`","env-file":["`+env+`"]}`)
	m := &machine{containers: map[string]*fakeContainer{}}
	_, state, err := WriteFilled(context.Background(), archHost(t), d, store.State{}, env, []byte("PORT=5432\n"),
		m.run, nil, nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	if !m.did("docker run") {
		t.Fatalf("the container was not created: %v", m.asked)
	}
	m.asked = nil
	report, _, err := WriteFilled(context.Background(), archHost(t), d, state, env, []byte("PORT=5433\n"), m.run,
		nil, nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	if !m.removed("forge") || !m.did("docker run") {
		t.Fatalf("the container kept what it read before the write: %v", m.asked)
	}
	if o := outcomeOf(report, "forge.server"); o.Action != "updated" || !strings.Contains(o.Detail, env) {
		t.Errorf("the recreate did not say which file changed: %+v", o)
	}
}

func count(lines []string, prefix string) int {
	n := 0
	for _, l := range lines {
		if strings.Contains(l, prefix) {
			n++
		}
	}
	return n
}

// Two resources declaring one filled path — two modules' blocks in one file — are refused: the request carries the
// content only, so it cannot say whose block it is, and nothing is written.
func TestAFilledPathTwoResourcesDeclareIsRefused(t *testing.T) {
	path := filepath.Join(t.TempDir(), "hosts")
	if err := os.WriteFile(path, []byte(workstationHosts), 0o644); err != nil {
		t.Fatal(err)
	}
	d := parseTrusted(t, fmt.Sprintf(`{"declaration":1,"filled_files":[%q],"resources":[
	  {"id":"a.hosts","type":"file","path":%q,"into":"block","content":"10.42.0.1 ace\n","owner-at-runtime":"managed"},
	  {"id":"b.hosts","type":"file","path":%q,"into":"block","content":"10.42.0.2 g14\n","owner-at-runtime":"managed"}
	]}`, path, path, path))
	_, state, err := WriteFilled(context.Background(), archHost(t), d, store.State{}, path, []byte("6.6.6.6 evil\n"),
		noServices, nil, nil, nil)
	if err == nil || !strings.Contains(err.Error(), "2 resources declare") {
		t.Fatalf("a path two resources declare was not refused: %v", err)
	}
	if got := readText(t, path); got != workstationHosts || len(state.Resources) != 0 {
		t.Errorf("something was written or recorded: %q %+v", got, state.Resources)
	}
}