chore: Refactor Enterprise code to layer on top of AGPL (#4034)

* chore: Refactor Enterprise code to layer on top of AGPL

This is an experiment to invert the import order of the Enterprise
code to layer on top of AGPL.

* Fix Garrett's comments

* Add pointer.Handle to atomically obtain references

This uses a context to ensure the same value persists through
multiple executions to `Load()`.

* Remove entitlements API from AGPL coderd

* Remove AGPL Coder entitlements endpoint test

* Fix warnings output

* Add command-line flag to toggle audit logging

* Fix hasLicense being set

* Remove features interface

* Fix audit logging default

* Add bash as a dependency

* Add comment

* Add tests for resync and pubsub, and add back previous exp backoff retry

* Separate authz code again

* Add pointer loading example from comment

* Fix duplicate test, remove pointer.Handle

* Fix expired license

* Add entitlements struct

* Fix context passing

enterprise/coderd/coderdenttest/coderdenttest.go

@@ -0,0 +1,133 @@
+package coderdenttest
+
+import (
+	"context"
+	"crypto/ed25519"
+	"crypto/rand"
+	"io"
+	"testing"
+	"time"
+
+	"github.com/golang-jwt/jwt/v4"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/coder/coder/coderd/coderdtest"
+	"github.com/coder/coder/codersdk"
+	"github.com/coder/coder/enterprise/coderd"
+)
+
+const (
+	testKeyID = "enterprise-test"
+)
+
+var (
+	testPrivateKey ed25519.PrivateKey
+	testPublicKey  ed25519.PublicKey
+)
+
+func init() {
+	var err error
+	testPublicKey, testPrivateKey, err = ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		panic(err)
+	}
+}
+
+type Options struct {
+	*coderdtest.Options
+	EntitlementsUpdateInterval time.Duration
+}
+
+// New constructs a codersdk client connected to an in-memory Enterprise API instance.
+func New(t *testing.T, options *Options) *codersdk.Client {
+	client, _, _ := NewWithAPI(t, options)
+	return client
+}
+
+func NewWithAPI(t *testing.T, options *Options) (*codersdk.Client, io.Closer, *coderd.API) {
+	if options == nil {
+		options = &Options{}
+	}
+	if options.Options == nil {
+		options.Options = &coderdtest.Options{}
+	}
+	srv, cancelFunc, oop := coderdtest.NewOptions(t, options.Options)
+	coderAPI, err := coderd.New(context.Background(), &coderd.Options{
+		AuditLogging:               true,
+		Options:                    oop,
+		EntitlementsUpdateInterval: options.EntitlementsUpdateInterval,
+		Keys: map[string]ed25519.PublicKey{
+			testKeyID: testPublicKey,
+		},
+	})
+	assert.NoError(t, err)
+	srv.Config.Handler = coderAPI.AGPL.RootHandler
+	var provisionerCloser io.Closer = nopcloser{}
+	if options.IncludeProvisionerDaemon {
+		provisionerCloser = coderdtest.NewProvisionerDaemon(t, coderAPI.AGPL)
+	}
+	t.Cleanup(func() {
+		cancelFunc()
+		_ = provisionerCloser.Close()
+		_ = coderAPI.Close()
+	})
+	return codersdk.New(coderAPI.AccessURL), provisionerCloser, coderAPI
+}
+
+type LicenseOptions struct {
+	AccountType string
+	AccountID   string
+	GraceAt     time.Time
+	ExpiresAt   time.Time
+	UserLimit   int64
+	AuditLog    bool
+}
+
+// AddLicense generates a new license with the options provided and inserts it.
+func AddLicense(t *testing.T, client *codersdk.Client, options LicenseOptions) codersdk.License {
+	license, err := client.AddLicense(context.Background(), codersdk.AddLicenseRequest{
+		License: GenerateLicense(t, options),
+	})
+	require.NoError(t, err)
+	return license
+}
+
+// GenerateLicense returns a signed JWT using the test key.
+func GenerateLicense(t *testing.T, options LicenseOptions) string {
+	if options.ExpiresAt.IsZero() {
+		options.ExpiresAt = time.Now().Add(time.Hour)
+	}
+	if options.GraceAt.IsZero() {
+		options.GraceAt = time.Now().Add(time.Hour)
+	}
+	auditLog := int64(0)
+	if options.AuditLog {
+		auditLog = 1
+	}
+	c := &coderd.Claims{
+		RegisteredClaims: jwt.RegisteredClaims{
+			Issuer:    "test@testing.test",
+			ExpiresAt: jwt.NewNumericDate(options.ExpiresAt),
+			NotBefore: jwt.NewNumericDate(time.Now().Add(-time.Minute)),
+			IssuedAt:  jwt.NewNumericDate(time.Now().Add(-time.Minute)),
+		},
+		LicenseExpires: jwt.NewNumericDate(options.GraceAt),
+		AccountType:    options.AccountType,
+		AccountID:      options.AccountID,
+		Version:        coderd.CurrentVersion,
+		Features: coderd.Features{
+			UserLimit: options.UserLimit,
+			AuditLog:  auditLog,
+		},
+	}
+	tok := jwt.NewWithClaims(jwt.SigningMethodEdDSA, c)
+	tok.Header[coderd.HeaderKeyID] = testKeyID
+	signedTok, err := tok.SignedString(testPrivateKey)
+	require.NoError(t, err)
+	return signedTok
+}
+
+type nopcloser struct{}
+
+func (nopcloser) Close() error { return nil }