feat: allow external services to be authable (#9996)

* feat: allow external services to be authable

* Refactor external auth config structure for defaults

* Add support for new config properties

* Change the name of external auth

* Move externalauth -> external-auth

* Run gen

* Fix tests

* Fix MW tests

* Fix git auth redirect

* Fix lint

* Fix name

* Allow any ID

* Fix invalid type test

* Fix e2e tests

* Fix comments

* Fix colors

* Allow accepting any type as string

* Run gen

* Fix href

cli/cliui/externalauth.go

@@ -0,0 +1,72 @@
+package cliui
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"time"
+
+	"github.com/briandowns/spinner"
+
+	"github.com/coder/coder/v2/codersdk"
+)
+
+type ExternalAuthOptions struct {
+	Fetch         func(context.Context) ([]codersdk.TemplateVersionExternalAuth, error)
+	FetchInterval time.Duration
+}
+
+func ExternalAuth(ctx context.Context, writer io.Writer, opts ExternalAuthOptions) error {
+	if opts.FetchInterval == 0 {
+		opts.FetchInterval = 500 * time.Millisecond
+	}
+	gitAuth, err := opts.Fetch(ctx)
+	if err != nil {
+		return err
+	}
+
+	spin := spinner.New(spinner.CharSets[78], 100*time.Millisecond, spinner.WithColor("fgHiGreen"))
+	spin.Writer = writer
+	spin.ForceOutput = true
+	spin.Suffix = " Waiting for Git authentication..."
+	defer spin.Stop()
+
+	ticker := time.NewTicker(opts.FetchInterval)
+	defer ticker.Stop()
+	for _, auth := range gitAuth {
+		if auth.Authenticated {
+			return nil
+		}
+
+		_, _ = fmt.Fprintf(writer, "You must authenticate with %s to create a workspace with this template. Visit:\n\n\t%s\n\n", auth.DisplayName, auth.AuthenticateURL)
+
+		ticker.Reset(opts.FetchInterval)
+		spin.Start()
+		for {
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			case <-ticker.C:
+			}
+			gitAuth, err := opts.Fetch(ctx)
+			if err != nil {
+				return err
+			}
+			var authed bool
+			for _, a := range gitAuth {
+				if !a.Authenticated || a.ID != auth.ID {
+					continue
+				}
+				authed = true
+				break
+			}
+			// The user authenticated with the provider!
+			if authed {
+				break
+			}
+		}
+		spin.Stop()
+		_, _ = fmt.Fprintf(writer, "Successfully authenticated with %s!\n\n", auth.DisplayName)
+	}
+	return nil
+}