From 4289e4961b6ba48a58e3719206d80b9cc9e795be Mon Sep 17 00:00:00 2001
From: Santo Cariotti <santo@dcariotti.me>
Date: Thu, 18 Mar 2021 12:13:58 +0100
Subject: feat: add 'git' module

---
 src/git.rs | 142 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 src/git.rs

diff --git a/src/git.rs b/src/git.rs
new file mode 100644
index 0000000..76f9a4e
--- /dev/null
+++ b/src/git.rs
@@ -0,0 +1,142 @@
+use crate::commit::models::Commit;
+use chrono::{DateTime, Local};
+use git2::{BranchType, Error, Repository, Time};
+
+use std::fs::remove_dir_all;
+
+/// Return the temporary folder of the git repository
+fn get_tmp_dir(repo_name: &String) -> String {
+    format!("/tmp/{}", &repo_name)
+}
+
+/// Clone a repository `repo` in a temporary folder. It uses only GitHub at
+/// this moment.
+pub fn clone_repo(repo_name: &String) -> Result<Repository, Error> {
+    let url: &str =
+        &format!("https://github.com/{}", &repo_name).to_owned()[..];
+    let tmp_dir: String = get_tmp_dir(&repo_name);
+
+    let cloned = Repository::clone(url, tmp_dir)?;
+
+    Ok(cloned)
+}
+
+/// Check if a `branch` exists inside the repository and then set the head of
+/// `repo` to that branch
+pub fn get_branch(repo: &Repository, branch: &str) -> Result<(), Error> {
+    if let Err(e) = repo.find_branch(&branch, BranchType::Local) {
+        return Err(e);
+    }
+
+    repo.set_head(&format!("refs/heads/{}", branch).to_owned()[..])
+}
+
+/// Get a `git2::Commit` and returns a date in RFC2822 format
+pub fn get_date(commit: &git2::Commit) -> String {
+    let t: Time = commit.time();
+    let (offset, sign) = match t.offset_minutes() {
+        n if n < 0 => (-n, '-'),
+        n => (n, '+'),
+    };
+    let (hours, minutes) = (offset / 60, offset % 60);
+    let ts =
+        time::Timespec::new(t.seconds() + (t.offset_minutes() as i64) * 60, 0);
+    let time = time::at(ts);
+
+    let result = format!(
+        "{} {}{:02}{:02}",
+        time.strftime("%a, %e %b %Y %T").unwrap(),
+        sign,
+        hours,
+        minutes
+    );
+
+    result
+}
+
+/// Get a `git2::Commit` and returns a valid `Commit` to upload to the database
+fn get_commit(gcommit: &git2::Commit, repo_name: &String) -> Commit {
+    let hash = gcommit.id().to_string();
+    let tree = match gcommit.parent_id(0) {
+        Ok(parent) => Some(parent.to_string()),
+        Err(_) => None,
+    };
+
+    let mut text = "".to_string();
+    for line in String::from_utf8_lossy(gcommit.message_bytes()).lines() {
+        text += line;
+        text += "\n";
+    }
+
+    // Remove the last "\n"
+    let _ = text.pop();
+
+    let date: DateTime<Local> =
+        match DateTime::parse_from_rfc2822(&get_date(&gcommit)) {
+            Ok(date) => date.into(),
+            Err(e) => {
+                // This is a real problem!
+                // TODO: manage this error
+                panic!(e)
+            }
+        };
+    let author_email = gcommit.author().email().unwrap().to_string();
+    let author_name = gcommit.author().name().unwrap().to_string();
+    let committer_email = gcommit.committer().email().unwrap().to_string();
+    let committer_name = gcommit.committer().name().unwrap().to_string();
+
+    Commit {
+        hash,
+        tree,
+        text,
+        date,
+        author_email,
+        author_name,
+        committer_email,
+        committer_name,
+        repository_url: repo_name.clone(),
+    }
+}
+
+/// Get all commits from a Git repository. Returns an array of `Commit`.
+/// First, clone the repo into a temporary folder.
+/// Then, open the repository.
+/// Then, get commits
+/// Finally, remove the temporary folder
+pub fn repo_commits(repo_name: &String) -> Result<Vec<Commit>, Error> {
+    // Try to clone the repo. If it returns an error, it's useless to go ahead:
+    // raises an error.
+    let repo = match clone_repo(&repo_name) {
+        Ok(r) => r,
+        Err(e) => {
+            return Err(e);
+        }
+    };
+
+    if let Err(e) = get_branch(&repo, "main") {
+        return Err(e);
+    }
+
+    let mut revwalk = repo.revwalk()?;
+    let head = repo.head().unwrap().target().unwrap();
+
+    if let Err(e) = revwalk.push(head) {
+        return Err(e);
+    }
+
+    let mut commits: Vec<Commit> = vec![];
+    for commit in revwalk {
+        let hash = repo.find_commit(commit?)?;
+        commits.push(get_commit(&hash, &repo_name));
+    }
+
+    if let Err(_) = remove_dir_all(get_tmp_dir(&repo_name)) {
+        return Err(git2::Error::new(
+            git2::ErrorCode::GenericError,
+            git2::ErrorClass::Os,
+            "Temporary clone not deleted",
+        ));
+    }
+
+    Ok(commits)
+}
-- 
cgit v1.2.3-18-g5258