src/checkout.rs: add pre-checkout fonctionality

src/checkout.rs

+use crate::commit;
+use std::{
+    path::PathBuf,
+    process::{exit, Command},
+};
+
+/// Check if two commits are differents
+pub fn is_diff(commit1: &str, commit2: &str, borg_folder: &PathBuf) -> bool {
+    let archive1 = format!("{}::{}", borg_folder.to_str().unwrap(), commit1);
+    let cmd = format!("borg diff {} {} | wc -l", archive1, commit2);
+    let output = Command::new("sh").arg("-c").arg(cmd).output().unwrap();
+    match output.status.code().unwrap() {
+        0 => (),
+        num => {
+            eprintln!("{}", String::from_utf8(output.stderr).unwrap());
+            exit(num);
+        }
+    }
+    let mut strcode = String::from_utf8(output.stdout).unwrap();
+    if strcode.ends_with('\n') {
+        strcode.pop();
+    }
+    let res: i32 = strcode.parse().unwrap();
+    res > 0
+}
+
+/// Function that checks if the archive with the name of the current commit id
+/// exits in borg repository
+pub fn check_if_current_commit_exits(borg_path: &PathBuf, commit_id: &str) {
+    // Trying to create an archive with the current git commit id
+    let output = Command::new("borg")
+        .arg("list")
+        .arg(format!("{}::{}", borg_path.to_str().unwrap(), commit_id))
+        .output()
+        .unwrap();
+    match output.status.code().unwrap() {
+        0 => (),
+        num => {
+            let msg = format!("Archive {} does not exist", commit_id);
+            let mut output_msg = String::from_utf8(output.stderr).unwrap();
+            if output_msg.ends_with("\n") {
+                output_msg.pop();
+            }
+            if output_msg == msg {
+                eprintln!(
+                    "No archive with the current commit id found !\n You should commit it first !"
+                );
+                exit(3);
+            } else {
+                eprintln!("{}", output_msg);
+                exit(num);
+            }
+        }
+    }
+}
+
+/// Function that prepare checkout. **This function should be used before a
+/// git checkout !**
+///
+/// # Description:
+/// This function will check if the archive named as the current commit exits.
+/// If it doesn't exists, it will create one. If it exists, it will create a
+/// temporary archive of the current result respository and compare it with
+/// the archive with the current git commit id.
+/// If it is the same as the temporary achive then you can make a
+/// checkout without losing data. If not, then you might.
+pub fn prepare_checkout() {
+    let (borg_path, _) = commit::check_path();
+    let commit_id = commit::get_current_commit();
+    check_if_current_commit_exits(&borg_path, &commit_id);
+    // Create an archive with the content of the current commit
+    let tmp_name = format!("{}-tmp", commit_id);
+    commit::commit(String::from("none"), tmp_name.clone());
+    let res = is_diff(&commit_id, &tmp_name, &borg_path);
+    let output = Command::new("borg")
+        .arg("delete")
+        .arg(format!("{}::{}", borg_path.to_str().unwrap(), tmp_name))
+        .output()
+        .unwrap();
+    match output.status.code().unwrap() {
+        0 => (),
+        num => {
+            eprintln!("{}", String::from_utf8(output.stderr).unwrap());
+            exit(num);
+        }
+    }
+    if res {
+        eprintln!("Your results folder contains unsaved changes!\nPlease update your current commit with:  gbl commit --update");
+        exit(4);
+    }
+}