imagefetcher -> fetcher (#1514)

fetcher/config.go

@@ -0,0 +1,49 @@
+package fetcher
+
+import (
+	"errors"
+	"time"
+
+	"github.com/imgproxy/imgproxy/v3/config"
+	"github.com/imgproxy/imgproxy/v3/version"
+)
+
+// Config holds the configuration for the image fetcher.
+type Config struct {
+	// UserAgent is the User-Agent header to use when fetching images.
+	UserAgent string
+	// DownloadTimeout is the timeout for downloading an image, in seconds.
+	DownloadTimeout time.Duration
+	// MaxRedirects is the maximum number of redirects to follow when fetching an image.
+	MaxRedirects int
+}
+
+// NewDefaultConfig returns a new Config instance with default values.
+func NewDefaultConfig() *Config {
+	return &Config{
+		UserAgent:       "imgproxy/" + version.Version,
+		DownloadTimeout: 5 * time.Second,
+		MaxRedirects:    10,
+	}
+}
+
+// LoadFromEnv loads config variables from env
+func LoadFromEnv(c *Config) (*Config, error) {
+	c.UserAgent = config.UserAgent
+	c.DownloadTimeout = time.Duration(config.DownloadTimeout) * time.Second
+	c.MaxRedirects = config.MaxRedirects
+	return c, nil
+}
+
+// Validate checks config for errors
+func (c *Config) Validate() error {
+	if len(c.UserAgent) == 0 {
+		return errors.New("user agent cannot be empty")
+	}
+
+	if c.DownloadTimeout <= 0 {
+		return errors.New("download timeout must be greater than 0")
+	}
+
+	return nil
+}