Add destination link metadata

internal/config/validate.go

@@ -2,6 +2,7 @@ package config
 
 import (
 	"fmt"
+	"net/url"
 	"regexp"
 	"strings"
 )
@@ -59,6 +60,7 @@ func Validate(cfg Config) error {
 			errs = validateDestinationBackend(errs, destinationContext, destination)
 			errs = validatePublishTransformPolicy(errs, destinationContext, destination.Publish, destination.Transform)
 			errs = validatePathMapping(errs, destinationContext+".path_mapping", destination.PathMap)
+			errs = validateLinks(errs, destinationContext+".links", destination.Links)
 			errs = validateTransferPolicy(errs, destinationContext+".transfer", destination.Transfer)
 		}
 	}
@@ -179,6 +181,43 @@ func validatePathMapping(errs ValidationErrors, context string, mapping PathMapp
 	return errs
 }
 
+func validateLinks(errs ValidationErrors, context string, links *Links) ValidationErrors {
+	if links == nil {
+		return errs
+	}
+	if links.BaseURL == "" {
+		errs = append(errs, context+".base_url is required")
+	} else if err := validateLinkBaseURL(links.BaseURL); err != nil {
+		errs = append(errs, context+".base_url "+err.Error())
+	}
+	switch links.Primary {
+	case LinkPrimaryAuto, LinkPrimaryHTML, LinkPrimarySource:
+	default:
+		errs = append(errs, context+".primary must be "+LinkPrimaryAuto+", "+LinkPrimaryHTML+", or "+LinkPrimarySource)
+	}
+	return errs
+}
+
+func validateLinkBaseURL(value string) error {
+	parsed, err := url.Parse(value)
+	if err != nil {
+		return fmt.Errorf("must be a valid URL")
+	}
+	if parsed.Scheme != "http" && parsed.Scheme != "https" {
+		return fmt.Errorf("must use http or https")
+	}
+	if parsed.Host == "" {
+		return fmt.Errorf("must include a host")
+	}
+	if parsed.RawQuery != "" {
+		return fmt.Errorf("must not include a query string")
+	}
+	if parsed.Fragment != "" {
+		return fmt.Errorf("must not include a fragment")
+	}
+	return nil
+}
+
 func validateTransferPolicy(errs ValidationErrors, context string, policy TransferPolicy) ValidationErrors {
 	if policy.OnDestinationSame != TransferActionSkip && policy.OnDestinationSame != TransferActionFail {
 		errs = append(errs, context+".on_destination_same must be skip or fail")