feat: 'init' command generate configuration file

.gazer.toml

@@ -0,0 +1,6 @@
+current_version = "0.0.0"
+
+[[files]]
+path = "Cargo.toml"
+search = "version = \"{current_version}\""
+replace = "version = \"{new_version}\""

src/commands/init.rs

@@ -1,6 +1,16 @@
-use std::{env::current_dir, path::Path, result::Result};
+use std::{env::current_dir, fs::File, path::Path, result::Result};
+
+use std::io::prelude::*;
 
 const DEFAULT_CONFIG_FILE: &'static str = ".gazer.toml";
+const DEFAULT_CONFIG_VALUE: &'static str = r#"
+current_version = "0.0.0"
+
+[[files]]
+path = "Cargo.toml"
+search = "version = \"{current_version}\""
+replace = "version = \"{new_version}\""
+"#;
 
 pub fn run() -> Result<(), &'static str> {
     // TODO: Right way?
@@ -11,13 +21,17 @@ pub fn run() -> Result<(), &'static str> {
     {
         // TODO: Right way?
         let target = target.as_os_str().to_str().expect("Failure");
-        println!("{target}");
+        println!("Config file is {target}");
     }
 
     if target.exists() {
-        println!("Config file is already exists.");
+        println!("Already exists.");
     } else {
+        println!("Creating file.");
         // Generate config file.
+        let mut out = File::create(target).expect("File-creating is failed");
+        let conf = DEFAULT_CONFIG_VALUE.as_bytes();
+        let _ = out.write(conf);
     }
 
     Ok(())