update all usage of user.name to user.accountId for privacy migration:

https://developer.atlassian.com/cloud/jira/platform/deprecation-notice-user-privacy-api-migration-guide/

jiracmd/assign.go

@@ -2,6 +2,7 @@ package jiracmd
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/coryb/figtree"
 	"github.com/coryb/oreo"
@@ -48,7 +49,33 @@ func CmdAssignUsage(cmd *kingpin.CmdClause, opts *AssignOptions) error {
 
 // CmdAssign will assign an issue to a user
 func CmdAssign(o *oreo.Client, globals *jiracli.GlobalOptions, opts *AssignOptions) error {
-	err := jira.IssueAssign(o, globals.Endpoint.Value, opts.Issue, opts.Assignee)
+	if globals.JiraDeploymentType.Value == "" {
+		serverInfo, err := jira.ServerInfo(o, globals.Endpoint.Value)
+		if err != nil {
+			return err
+		}
+		globals.JiraDeploymentType.Value = strings.ToLower(serverInfo.DeploymentType)
+	}
+
+	assignFunc := jira.IssueAssign
+	if globals.JiraDeploymentType.Value == jiracli.CloudDeploymentType {
+		if opts.Assignee != "" && opts.Assignee != "-1" {
+			users, err := jira.UserSearch(o, globals.Endpoint.Value, &jira.UserSearchOptions{
+				Username: opts.Assignee,
+			})
+			if err != nil {
+				return err
+			}
+			if len(users) > 1 {
+				return fmt.Errorf("Found %d accounts for users with username %q", len(users), opts.Assignee)
+			} else if len(users) == 1 {
+				opts.Assignee = users[0].AccountID
+			}
+		}
+		assignFunc = jira.IssueAssignAccountID
+	}
+
+	err := assignFunc(o, globals.Endpoint.Value, opts.Issue, opts.Assignee)
 	if err != nil {
 		return err
 	}