Initial DDC release

internal/preferences/preferences.go

@@ -0,0 +1,41 @@
+package preferences
+
+import (
+	"errors"
+	"fmt"
+)
+
+const (
+	gigabyte             = int64(1) << 30
+	maxConcurrentLimit   = 10
+	maxReservedGigabytes = 100000
+)
+
+var ErrInvalid = errors.New("invalid settings")
+
+type Preferences struct {
+	MaxConcurrentDownloads int      `json:"maxConcurrentDownloads"`
+	MinFreeGB              int      `json:"minFreeGB"`
+	AllowedPorts           []uint16 `json:"allowedPorts"`
+	AutoExtract            bool     `json:"autoExtract"`
+	CleanupAfterMove       bool     `json:"cleanupAfterMove"`
+}
+
+func (preferences Preferences) MinFreeBytes() int64 {
+	return int64(preferences.MinFreeGB) * gigabyte
+}
+
+func (preferences Preferences) Validate() error {
+	if preferences.MaxConcurrentDownloads < 1 || preferences.MaxConcurrentDownloads > maxConcurrentLimit {
+		return fmt.Errorf("%w: parallel downloads must be between 1 and %d", ErrInvalid, maxConcurrentLimit)
+	}
+	if preferences.MinFreeGB < 0 || preferences.MinFreeGB > maxReservedGigabytes {
+		return fmt.Errorf("%w: free space to keep must be between 0 and %d GB", ErrInvalid, maxReservedGigabytes)
+	}
+	for _, port := range preferences.AllowedPorts {
+		if port == 0 {
+			return fmt.Errorf("%w: port 0 is not allowed", ErrInvalid)
+		}
+	}
+	return nil
+}