package engine

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"log/slog"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"jarl/internal/auth"
	"jarl/internal/bind"
	"jarl/internal/model"
	"jarl/internal/render"
	"jarl/internal/store"
	"jarl/internal/testutil"
)

func freePort(t *testing.T) int {
	l, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	defer l.Close()
	return l.Addr().(*net.TCPAddr).Port
}

// namedEnv runs a real named on high ports, loading Jarl's configuration.
type namedEnv struct {
	*testEnv
	bins    *testutil.BindBinaries
	dnsPort int
	cmd     *exec.Cmd
	log     *bytes.Buffer
}

func newNamedEnv(t *testing.T) *namedEnv {
	bins := testutil.FindBind()
	if bins == nil || bins.Named == "" || bins.RNDC == "" || bins.Dig == "" {
		t.Skip("named, rndc and dig are needed (install bind9 or set JARL_BIND_ROOT)")
	}
	dir := t.TempDir()
	st, err := store.Open(filepath.Join(dir, "jarl.db"))
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { st.Close() })
	keyFile := filepath.Join(dir, "rndc.key")
	out, err := runEnv(bins.Env, bins.TSIGKeygen, "-a", "hmac-sha256", "rndc-key")
	if err != nil {
		t.Fatal(err)
	}
	os.WriteFile(keyFile, []byte(out), 0o600)
	dnsPort, ctlPort := freePort(t), freePort(t)
	paths := render.Paths{ConfigDir: filepath.Join(dir, "etc"), ZoneDir: filepath.Join(dir, "zones"), CacheDir: filepath.Join(dir, "cache")}
	tools := &bind.Tools{NamedCheckConf: bins.CheckConf, NamedCheckZone: bins.CheckZone, RNDC: bins.RNDC, Env: bins.Env,
		RNDCArgs: []string{"-k", keyFile, "-s", "127.0.0.1", "-p", fmt.Sprint(ctlPort)}}
	cfg := Config{Paths: paths, StagingDir: filepath.Join(dir, "staging"), ReloadTimeout: 10 * time.Second, NoReload: true}
	quiet := slog.New(slog.NewTextHandler(io.Discard, nil))
	e := New(st, tools, cfg, quiet)
	admin := &model.User{Username: "admin", Admin: true}
	st.CreateUser(context.Background(), admin)
	env := &namedEnv{testEnv: &testEnv{t: t, ctx: context.Background(), e: e, st: st, admin: &auth.Principal{User: admin, Method: "local"}, dir: dir}, bins: bins, dnsPort: dnsPort}
	run := filepath.Join(dir, "run")
	os.MkdirAll(run, 0o755)
	opt := func(scope, name, value string) Request {
		return NewRequest(OpOptionCreate, 0, OptionInput{Scope: &scope, Name: &name, Value: &value})
	}
	// Bootstrap the configuration without named running.
	env.submit(env.admin,
		NewRequest(OpSettingsUpdate, 0, SettingsInput{Nameservers: &[]string{"ns1.example.test."}}),
		opt(model.ScopeTopLevel, "include", `"`+keyFile+`"`),
		opt(model.ScopeTopLevel, "controls", fmt.Sprintf("{ inet 127.0.0.1 port %d allow { 127.0.0.1; } keys { rndc-key; }; }", ctlPort)),
		opt(model.ScopeOptions, "directory", `"`+run+`"`),
		opt(model.ScopeOptions, "pid-file", `"`+filepath.Join(run, "named.pid")+`"`),
		opt(model.ScopeOptions, "session-keyfile", `"`+filepath.Join(run, "session.key")+`"`),
		opt(model.ScopeOptions, "listen-on", fmt.Sprintf("port %d { 127.0.0.1; }", dnsPort)),
		opt(model.ScopeOptions, "listen-on-v6", "{ none; }"),
		opt(model.ScopeOptions, "recursion", "no"),
		NewRequest(OpZoneCreate, 0, ZoneInput{Name: model.Ptr("example.test")}),
		rec("example.test", "ns1", "A", "127.0.0.1"),
		rec("example.test", "www", "A", "192.0.2.10"),
	)
	env.log = &bytes.Buffer{}
	env.cmd = exec.Command(bins.Named, "-c", paths.MainConfig(), "-g", "-n", "1")
	env.cmd.Env = append(os.Environ(), bins.Env...)
	env.cmd.Stdout, env.cmd.Stderr = env.log, env.log
	if err := env.cmd.Start(); err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() {
		env.cmd.Process.Kill()
		env.cmd.Wait()
		if t.Failed() {
			t.Logf("named log:\n%s", env.log.String())
		}
	})
	deadline := time.Now().Add(10 * time.Second)
	for {
		if _, err := tools.Status(context.Background()); err == nil {
			break
		}
		if time.Now().After(deadline) {
			t.Fatalf("named did not start:\n%s", env.log.String())
		}
		time.Sleep(100 * time.Millisecond)
	}
	// From now on, reload named on every change.
	e.cfg.NoReload = false
	return env
}

func runEnv(env []string, bin string, args ...string) (string, error) {
	cmd := exec.Command(bin, args...)
	cmd.Env = append(os.Environ(), env...)
	out, err := cmd.CombinedOutput()
	return string(out), err
}

func (n *namedEnv) dig(name, typ string) string {
	out, err := runEnv(n.bins.Env, n.bins.Dig, "+short", "+norec", "-p", fmt.Sprint(n.dnsPort), "@127.0.0.1", name, typ)
	if err != nil {
		n.t.Fatalf("dig %s %s: %v %s", name, typ, err, out)
	}
	return strings.TrimSpace(out)
}

func TestWithRealNamed(t *testing.T) {
	n := newNamedEnv(t)
	if got := n.dig("www.example.test", "A"); got != "192.0.2.10" {
		t.Fatalf("initial www = %q", got)
	}
	// Change a record: named serves it as soon as Apply returns.
	r := findRec(n.state(), "www.example.test.", "A")
	res := n.submit(n.admin, NewRequest(OpRecordUpdate, r.ID, RecordInput{Data: model.Ptr("192.0.2.11")}))
	if got := n.dig("www.example.test", "A"); got != "192.0.2.11" {
		t.Errorf("www after update = %q (reloaded %v)", got, res.Reloaded)
	}
	if len(res.Serials) != 1 || res.Serials[0].New != res.Serials[0].Old+1 {
		t.Errorf("serials = %+v", res.Serials)
	}
	// A new zone is loaded via reconfig.
	n.submit(n.admin, NewRequest(OpZoneCreate, 0, ZoneInput{Name: model.Ptr("second.test"), Nameservers: []string{"ns1.example.test."}}),
		rec("second.test", "@", "TXT", "hello from jarl"))
	if got := n.dig("second.test", "TXT"); got != `"hello from jarl"` {
		t.Errorf("second.test TXT = %q", got)
	}
	// ACME-style challenge add and cleanup.
	n.submit(n.admin, rec("example.test", "_acme-challenge", "TXT", "abc-123"))
	if got := n.dig("_acme-challenge.example.test", "TXT"); got != `"abc-123"` {
		t.Errorf("challenge = %q", got)
	}
	n.submit(n.admin, NewRequest(OpRecordDelete, 0, RecordInput{Zone: "example.test", Name: model.Ptr("_acme-challenge"), Type: model.Ptr("TXT")}))
	if got := n.dig("_acme-challenge.example.test", "TXT"); got != "" {
		t.Errorf("challenge after cleanup = %q", got)
	}
	// Deleting a zone removes it from named and its file from disk.
	z := n.state().ZonesNamed("second.test")[0]
	n.submit(n.admin, NewRequest(OpZoneDelete, z.ID, nil))
	if got := n.dig("second.test", "TXT"); got != "" {
		t.Errorf("deleted zone still served: %q", got)
	}
	if _, err := os.Stat(filepath.Join(n.dir, "zones/_default/second.test.zone")); !os.IsNotExist(err) {
		t.Errorf("zone file of deleted zone still exists: %v", err)
	}
	st, err := n.e.Status(n.ctx)
	if err != nil || st.Named == nil || !st.Named.Running || len(st.Drift) != 0 {
		t.Errorf("status = %+v %v", st, err)
	}
}

func TestRollbackOnReloadFailure(t *testing.T) {
	n := newNamedEnv(t)
	// Make rndc fail for "reconfig" to simulate named rejecting the change.
	wrapper := filepath.Join(n.dir, "rndc-wrapper")
	os.WriteFile(wrapper, []byte(fmt.Sprintf("#!/bin/sh\nfor a in \"$@\"; do [ \"$a\" = reconfig ] && { echo 'rndc: reconfig failed: simulated' >&2; exit 1; }; done\nexec %s \"$@\"\n", n.bins.RNDC)), 0o755)
	n.e.tools.RNDC = wrapper
	confBefore, _ := os.ReadFile(n.e.cfg.Paths.MainConfig())
	_, err := n.e.Submit(n.ctx, []Request{NewRequest(OpZoneCreate, 0, ZoneInput{Name: model.Ptr("broken.test"), Nameservers: []string{"ns1.example.test."}})}, n.admin, "test", "", ApplyOptions{})
	ee, ok := AsError(err)
	if !ok || ee.Kind != KindBIND || !strings.Contains(ee.Message, "restored") {
		t.Fatalf("error = %v", err)
	}
	confAfter, _ := os.ReadFile(n.e.cfg.Paths.MainConfig())
	if !bytes.Equal(confBefore, confAfter) {
		t.Error("named.conf was not restored")
	}
	if _, err := os.Stat(filepath.Join(n.dir, "zones/_default/broken.test.zone")); !os.IsNotExist(err) {
		t.Error("zone file of failed change left behind")
	}
	if len(n.state().ZonesNamed("broken.test")) != 0 {
		t.Error("failed change recorded in the database")
	}
	// named keeps serving the old data and Jarl keeps working.
	n.e.tools.RNDC = n.bins.RNDC
	if got := n.dig("www.example.test", "A"); got != "192.0.2.10" {
		t.Errorf("www = %q", got)
	}
	n.submit(n.admin, rec("example.test", "after", "A", "192.0.2.99"))
	if got := n.dig("after.example.test", "A"); got != "192.0.2.99" {
		t.Errorf("after = %q", got)
	}
	evs, _ := n.st.ListAudit(n.ctx, store.AuditFilter{Outcome: "failure"})
	if len(evs) == 0 || !strings.Contains(evs[0].Message, "simulated") {
		t.Errorf("failure not audited: %+v", evs)
	}
}

func TestNamedCheckconfRejects(t *testing.T) {
	n := newNamedEnv(t)
	// An option value Jarl's quick checks accept but named rejects.
	name, value := "max-cache-size", "lots"
	scope := model.ScopeOptions
	_, err := n.e.Submit(n.ctx, []Request{NewRequest(OpOptionCreate, 0, OptionInput{Scope: &scope, Name: &name, Value: &value})}, n.admin, "test", "", ApplyOptions{})
	ee, ok := AsError(err)
	if !ok || ee.Kind != KindValidation || !strings.Contains(ee.Message, "named-checkconf") {
		t.Fatalf("error = %v", err)
	}
	found := false
	for _, m := range ee.Check {
		if m.Error && strings.Contains(m.Object, "server option max-cache-size") {
			found = true
		}
	}
	if !found {
		t.Errorf("checkconf message not mapped to the option: %+v", ee.Check)
	}
}