refactor(installer): externalize installer

Move installation-related code out of `main.go` and into a new
`installer.Run` method.

internal/installer/clone.go

@@ -8,8 +8,8 @@ import (
 
 const cloneURL = "https://github.com/cheat/cheatsheets.git"
 
-// Clone clones the community cheatsheets
-func Clone(path string) error {
+// clone clones the community cheatsheets
+func clone(path string) error {
 
 	// perform the clone in a shell
 	cmd := exec.Command("git", "clone", cloneURL, path)

internal/installer/run.go

@@ -0,0 +1,55 @@
+package installer
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"strings"
+
+	"github.com/cheat/cheat/internal/config"
+)
+
+// Run runs the installer
+func Run(configs string, confpath string) error {
+
+	// determine the appropriate paths for config data and (optional) community
+	// cheatsheets based on the user's platform
+	confdir := path.Dir(confpath)
+
+	// create paths for community and personal cheatsheets
+	community := path.Join(confdir, "/cheatsheets/community")
+	personal := path.Join(confdir, "/cheatsheets/personal")
+
+	// template the above paths into the default configs
+	configs = strings.Replace(configs, "COMMUNITY_PATH", community, -1)
+	configs = strings.Replace(configs, "PERSONAL_PATH", personal, -1)
+
+	// prompt the user to download the community cheatsheets
+	yes, err := Prompt(
+		"Would you like to download the community cheatsheets? [Y/n]",
+		true,
+	)
+	if err != nil {
+		return fmt.Errorf("failed to prompt: %v", err)
+	}
+
+	// clone the community cheatsheets if so instructed
+	if yes {
+		// clone the community cheatsheets
+		if err := clone(community); err != nil {
+			return fmt.Errorf("failed to clone cheatsheets: %v", err)
+		}
+
+		// also create a directory for personal cheatsheets
+		if err := os.MkdirAll(personal, os.ModePerm); err != nil {
+			return fmt.Errorf("failed to create directory: %v", err)
+		}
+	}
+
+	// the config file does not exist, so we'll try to create one
+	if err = config.Init(confpath, configs); err != nil {
+		return fmt.Errorf("failed to create config file: %v", err)
+	}
+
+	return nil
+}