Re-structure packages

Overhaul of package structure and other cleanup.

config/config.go

@@ -0,0 +1,83 @@
+package config
+
+import (
+	"errors"
+	"io/ioutil"
+	"log"
+	"os"
+	"runtime"
+
+	"github.com/davegallant/srv/file"
+	"gopkg.in/yaml.v2"
+)
+
+// Configuration stores the global config
+type Configuration struct {
+	Feeds          []string `yaml:"feeds"`
+	ExternalViewer string   `yaml:"externalViewer,omitempty"`
+}
+
+// DefaultConfiguration can be used if a config is missing
+var DefaultConfiguration = Configuration{
+	Feeds: []string{
+		"https://news.ycombinator.com/rss",
+		"https://www.reddit.com/r/golang/.rss",
+		"https://www.zdnet.com/topic/security/rss.xml",
+	},
+}
+
+// DetermineExternalViewer checks the OS to decide the default viewer
+func DetermineExternalViewer() (string, error) {
+	switch os := runtime.GOOS; os {
+	case "linux":
+		return "xdg-open", nil
+	case "darwin":
+		return "open", nil
+	}
+
+	return "", errors.New("Unable to determine a default external viewer")
+}
+
+// LoadConfiguration takes a filename (configuration) and loads it.
+func LoadConfiguration(f string) Configuration {
+	var config Configuration
+
+	if !file.Exists(f) {
+		WriteConfig(DefaultConfiguration, f)
+	}
+
+	data, err := ioutil.ReadFile(f)
+
+	if err != nil {
+		log.Println(err)
+		os.Exit(1)
+	}
+
+	if config.ExternalViewer == "" {
+		config.ExternalViewer, err = DetermineExternalViewer()
+		if err != nil {
+			log.Println(err)
+			os.Exit(1)
+		}
+	}
+
+	err = yaml.Unmarshal(data, &config)
+	if err != nil {
+		log.Panicln(err)
+	}
+	return config
+}
+
+// WriteConfig writes a config to disk
+func WriteConfig(config Configuration, file string) error {
+	c, err := yaml.Marshal(&config)
+	if err != nil {
+		log.Fatalf("Unable to marshal default config: %v", err)
+	}
+
+	err = ioutil.WriteFile(file, c, 0600)
+	if err != nil {
+		log.Fatalf("Unable to write default config: %v", err)
+	}
+	return nil
+}