From 924c717ed86c9f6fa23973d8b36cc2b3904ebb4c Mon Sep 17 00:00:00 2001
From: SayaAndy <montferrat@tuta.io>
Date: Wed, 30 Jul 2025 20:58:44 +0700
Subject: feat: basic metadata extractor

---
 internal/storage/b2.go                | 140 ++++++++++++++++++++++++++++++++++
 internal/storage/storage_interface.go |  19 +++++
 2 files changed, 159 insertions(+)
 create mode 100644 internal/storage/b2.go
 create mode 100644 internal/storage/storage_interface.go

(limited to 'internal/storage')

diff --git a/internal/storage/b2.go b/internal/storage/b2.go
new file mode 100644
index 0000000..168690a
--- /dev/null
+++ b/internal/storage/b2.go
@@ -0,0 +1,140 @@
+package storage
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"strings"
+	"time"
+
+	"github.com/Backblaze/blazer/b2"
+	"github.com/SayaAndy/saya-today-article-metadata-add/config"
+	"github.com/SayaAndy/saya-today-article-metadata-add/internal/frontmatter"
+)
+
+var _ StorageClient = &B2StorageClient{}
+
+type B2StorageClient struct {
+	prefix string
+	bucket *b2.Bucket
+	b2cl   *b2.Client
+}
+
+func NewB2StorageClient(cfg *config.StorageConfig) (StorageClient, error) {
+	if cfg.Type != "b2" {
+		return nil, fmt.Errorf("invalid storage type for B2InputClient")
+	}
+	b2cfg := cfg.Config.(*config.B2Config)
+
+	b2cl, err := b2.NewClient(context.Background(), b2cfg.KeyID, b2cfg.ApplicationKey)
+	if err != nil {
+		return nil, err
+	}
+
+	bucket, err := b2cl.Bucket(context.Background(), b2cfg.BucketName)
+	if err != nil {
+		return nil, err
+	}
+
+	return &B2StorageClient{b2cl: b2cl, bucket: bucket, prefix: b2cfg.Prefix}, nil
+}
+
+func (sc *B2StorageClient) Scan() ([]string, error) {
+	filePaths := []string{}
+
+	iter := sc.bucket.List(context.Background(), b2.ListPrefix(sc.prefix))
+
+	for iter.Next() {
+		obj := iter.Object()
+		if obj == nil {
+			return nil, fmt.Errorf("failed to reference object in B2 bucket")
+		}
+
+		attrs, err := obj.Attrs(context.Background())
+		if err != nil {
+			return nil, fmt.Errorf("get attributes for object: %w", err)
+		}
+
+		if attrs.Status != b2.Uploaded {
+			continue
+		}
+
+		name := obj.Name()
+
+		nameParts := strings.Split(name, ".")
+		if len(nameParts) < 2 {
+			continue
+		}
+
+		ext := strings.ToLower(nameParts[len(nameParts)-1])
+		if ext != "md" {
+			continue
+		}
+
+		filePaths = append(filePaths, strings.TrimPrefix(name, sc.prefix))
+	}
+
+	if err := iter.Err(); err != nil {
+		return nil, fmt.Errorf("iterate over B2 objects: %w", err)
+	}
+
+	return filePaths, nil
+}
+
+func (sc *B2StorageClient) GetReader(path string) (io.ReadCloser, int64, error) {
+	obj := sc.bucket.Object(sc.prefix + path)
+	if obj == nil {
+		return nil, 0, fmt.Errorf("failed to reference object in B2 bucket")
+	}
+	attrs, err := obj.Attrs(context.Background())
+	if err != nil {
+		return nil, 0, fmt.Errorf("error getting attributes of an object: %w", err)
+	}
+
+	return obj.NewReader(context.Background()), attrs.Size, nil
+}
+
+func (sc *B2StorageClient) WriteMetadata(path string, metadata *frontmatter.Metadata) error {
+	obj := sc.bucket.Object(sc.prefix + path)
+	if obj == nil {
+		return fmt.Errorf("failed to reference object in B2 bucket")
+	}
+	oldAttrs, err := obj.Attrs(context.Background())
+	if err != nil {
+		return fmt.Errorf("error getting attributes of an object: %w", err)
+	}
+
+	attrs := &b2.Attrs{Info: map[string]string{
+		"title":                     metadata.Title,
+		"short-description":         metadata.ShortDescription,
+		"action-date":               metadata.ActionDate,
+		"published-time":            metadata.PublishedTime.Format(time.RFC3339),
+		"thumbnail":                 metadata.Thumbnail,
+		"tags":                      strings.Join(metadata.Tags, ","),
+		"metadata-last-update-sha1": oldAttrs.SHA1,
+	}}
+
+	writer := obj.NewWriter(context.Background(), b2.WithAttrsOption(attrs))
+	writer.Close()
+
+	return nil
+}
+
+func (sc *B2StorageClient) FileHasChanged(path string) bool {
+	obj := sc.bucket.Object(sc.prefix + path)
+	if obj == nil {
+		return true
+	}
+
+	attrs, err := obj.Attrs(context.Background())
+	if err != nil {
+		return true
+	}
+
+	lastUpdateSha1, ok := attrs.Info["metadata-last-update-sha1"]
+	if !ok {
+		return true
+	}
+
+	return attrs.SHA1 == lastUpdateSha1
+}
diff --git a/internal/storage/storage_interface.go b/internal/storage/storage_interface.go
new file mode 100644
index 0000000..91eeedb
--- /dev/null
+++ b/internal/storage/storage_interface.go
@@ -0,0 +1,19 @@
+package storage
+
+import (
+	"io"
+
+	"github.com/SayaAndy/saya-today-article-metadata-add/config"
+	"github.com/SayaAndy/saya-today-article-metadata-add/internal/frontmatter"
+)
+
+type StorageClient interface {
+	Scan() (paths []string, err error)
+	GetReader(path string) (reader io.ReadCloser, sz int64, err error)
+	WriteMetadata(path string, metadata *frontmatter.Metadata) error
+	FileHasChanged(path string) bool
+}
+
+var NewStorageClientMap = map[string]func(cfg *config.StorageConfig) (StorageClient, error){
+	"b2": NewB2StorageClient,
+}
-- 
cgit v1.3.1+13