feat: Check if project directory exists before creating it

BREAKING CHANGE: We now abort the process if it turns out the directory
already exists

src/main.rs

@@ -1,4 +1,6 @@
 extern crate clap;
+use std::process;
+
 use clap::{Arg, App};
 
 extern crate serde;
@@ -11,6 +13,11 @@ mod inbox_file;
 
 const VERSION: &'static str = env!("CARGO_PKG_VERSION");
 
+fn fatal(message: &str) {
+    println!("{}", message);
+    process::exit(1);
+}
+
 fn main() {
     let matches = App::new("foam-up")
                           .version(VERSION)
@@ -28,7 +35,15 @@ fn main() {
     let path = matches.value_of("path").expect("Expected a Path");
     println!("Generating project at {}", path);
     let project = project::Project::new(path);
-    project.create_directories().expect("FATAL: Could not create project directory");
-    project.create_files().expect("FATAL: Could not create project files");
-    println!("[x] Project created.");
+
+    match project.is_dirty() {
+        Some(project::Error::DirectoryExists) => {
+            fatal("Cannot create project -- Directory already exists");
+        }
+        None => {
+            project.create_directories().expect("FATAL: Could not create project directory");
+            project.create_files().expect("FATAL: Could not create project files");
+            println!("[x] Project created.");
+        }
+    }
 }

src/project.rs

@@ -5,6 +5,10 @@ use crate::inbox_file::InboxFile;
 use crate::todo_file::TodoFile;
 use crate::vscode_templates;
 
+pub enum Error {
+    DirectoryExists
+}
+
 pub struct Project {
     path: String
 }
@@ -42,4 +46,12 @@ impl Project {
         blog_post_template.write_file(Path::new(&self.path))?;
         Ok(())
     }
+
+    pub fn is_dirty(&self) -> Option<Error> {
+        let local_dir = Path::new(&self.path);
+        if local_dir.exists() {
+            return Some(Error::DirectoryExists);
+        }
+        return None;
+    }
 }