feat: basic metadata extractor

2 files changed, 96 insertions, 0 deletions

diff --git a/config/config.go b/config/config.go
new file mode 100644
index 0000000..63c1e0c
--- /dev/null
+++ b/config/config.go
@@ -0,0 +1,83 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"os"
+
+	"github.com/go-playground/validator/v10"
+)
+
+type Config struct {
+	LogLevel slog.Level    `json:"LogLevel" validate:"required"`
+	Storage  StorageConfig `json:"Storage" validate:"required"`
+}
+
+type StorageConfig struct {
+	Type   string `json:"Type" validate:"required,oneof=b2"`
+	Config any    `json:"Config" validate:"required"`
+}
+
+func (sc *StorageConfig) UnmarshalJSON(data []byte) error {
+	var tmp struct {
+		Type   string          `json:"Type"`
+		Config json.RawMessage `json:"Config"`
+	}
+
+	if err := json.Unmarshal(data, &tmp); err != nil {
+		return err
+	}
+
+	sc.Type = tmp.Type
+
+	switch tmp.Type {
+	case "b2":
+		var b2Config B2Config
+		if err := json.Unmarshal(tmp.Config, &b2Config); err != nil {
+			return fmt.Errorf("unmarshal B2Config: %w", err)
+		}
+		sc.Config = &b2Config
+	default:
+		return fmt.Errorf("unsupported storage type: %s", tmp.Type)
+	}
+
+	return nil
+}
+
+type B2Config struct {
+	BucketName     string `json:"BucketName" validate:"required,min=1"`
+	Region         string `json:"Region" validate:"required,min=1"`
+	Prefix         string `json:"Prefix"`
+	KeyID          string `json:"KeyID"`
+	ApplicationKey string `json:"ApplicationKey"`
+}
+
+func LoadConfig(path string, config *Config) error {
+	fileBytes, err := os.ReadFile(path)
+	if err != nil {
+		return err
+	}
+
+	expandedFileBytes := []byte(os.ExpandEnv(string(fileBytes)))
+
+	if err = json.Unmarshal(expandedFileBytes, config); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func InitConfig(path string) (*Config, error) {
+	config := &Config{}
+	if err := LoadConfig(path, config); err != nil {
+		return nil, err
+	}
+
+	validate := validator.New(validator.WithRequiredStructEnabled())
+	if err := validate.Struct(config); err != nil {
+		return nil, err
+	}
+
+	return config, nil
+}
diff --git a/config/config.json b/config/config.json
new file mode 100644
index 0000000..9a49b76
--- /dev/null
+++ b/config/config.json
@@ -0,0 +1,13 @@
+{
+    "LogLevel": "debug",
+    "Storage": {
+        "Type": "b2",
+        "Config": {
+            "BucketName": "sayana-pages",
+            "Region": "eu-central-003",
+            "Prefix": "",
+            "KeyID": "${B2_KEY_ID}",
+            "ApplicationKey": "${B2_APPLICATION_KEY}"
+        }
+    }
+}
\ No newline at end of file