feat: cli client with spec schema validation

internal/command/client/agent/flag/flag.go

@@ -0,0 +1,34 @@
+package flag
+
+import (
+	"errors"
+
+	clientFlag "forge.cadoles.com/Cadoles/emissary/internal/command/client/flag"
+	"forge.cadoles.com/Cadoles/emissary/internal/datastore"
+	"github.com/urfave/cli/v2"
+)
+
+func WithAgentFlags(flags ...cli.Flag) []cli.Flag {
+	baseFlags := clientFlag.ComposeFlags(
+		&cli.Int64Flag{
+			Name:    "agent-id",
+			Aliases: []string{"a"},
+			Usage:   "use `AGENT_ID` as selected agent",
+			Value:   -1,
+		},
+	)
+
+	flags = append(flags, baseFlags...)
+
+	return flags
+}
+
+func AssertAgentID(ctx *cli.Context) (datastore.AgentID, error) {
+	rawAgentID := ctx.Int64("agent-id")
+
+	if rawAgentID == -1 {
+		return -1, errors.New("flag 'agent-id' is required")
+	}
+
+	return datastore.AgentID(rawAgentID), nil
+}