Adds implementation for init command

campaign/campaign.go

@@ -0,0 +1,21 @@
+package campaign
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+
+	"git.ctrlz.es/mgdelacroix/campaigner/model"
+)
+
+func Save(campaign *model.Campaign) error {
+	marshaledCampaign, err := json.MarshalIndent(campaign, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	if err := ioutil.WriteFile("./campaign.json", marshaledCampaign, 0600); err != nil {
+		return fmt.Errorf("cannot save campaign: %w", err)
+	}
+	return nil
+}