Add missing file

csaf/providermetaloader.go

@@ -0,0 +1,82 @@
+// This file is Free Software under the MIT License
+// without warranty, see README.md and LICENSES/MIT.txt for details.
+//
+// SPDX-License-Identifier: MIT
+//
+// SPDX-FileCopyrightText: 2023 German Federal Office for Information Security (BSI) <https://www.bsi.bund.de>
+// Software-Engineering: 2023 Intevation GmbH <https://intevation.de>
+
+package csaf
+
+import (
+	"errors"
+	"log"
+	"strings"
+
+	"github.com/csaf-poc/csaf_distribution/util"
+)
+
+// ProviderMetadataLoader helps load provider-metadata.json from
+// the various locations.
+type ProviderMetadataLoader struct {
+	client  *util.Client
+	logging func(string, ...any)
+}
+
+// LoadedProviderMetadata represents a loaded provider metadata.
+type LoadedProviderMetadata struct {
+	// URL is location where the document was found.
+	URL string
+	// Document is the de-serialized JSON document.
+	Document any
+	// Hash is a SHA256 sum over the document.
+	Hash []byte
+	// Messages are the error message happened while loading.
+	Messages []string
+}
+
+// Valid returns true if the loaded document is valid.
+func (lpm *LoadedProviderMetadata) Valid() bool {
+	return lpm != nil && lpm.Document != nil && lpm.Hash != nil
+}
+
+// NewProviderMetadataLoader create a new loader.
+func NewProviderMetadataLoader(
+	client *util.Client,
+	logging func(string, ...any),
+) *ProviderMetadataLoader {
+
+	// If no logging was given log to stdout.
+	if logging == nil {
+		logging = func(format string, args ...any) {
+			log.Printf("ProviderMetadataLoader: "+format+"\n", args...)
+		}
+	}
+	return &ProviderMetadataLoader{
+		client:  client,
+		logging: logging,
+	}
+}
+
+// Load loads a provider metadata for a given path.
+// If the domain starts with `https://` it only attemps to load
+// the data from that URL.
+func (pmdl *ProviderMetadataLoader) Load(path string) (*LoadedProviderMetadata, error) {
+
+	// check direct path
+	if strings.HasPrefix(path, "https://") {
+		return pmdl.loadFromURL(path)
+	}
+
+	// TODO: Implement me!
+	return nil, errors.New("not implemented, yet")
+}
+
+// loadFromURL loads a provider metadata from a given URL.
+func (pmdl *ProviderMetadataLoader) loadFromURL(path string) (*LoadedProviderMetadata, error) {
+
+	_ = path
+
+	// TODO: Implement me!
+	return nil, errors.New("not implemented, yet")
+}