2 files changed, 164 insertions, 11 deletions

diff --git a/src/git.rs b/src/git.rs
index 0a06ab5..6edca0f 100644
--- a/src/git.rs
+++ b/src/git.rs
@@ -344,6 +344,12 @@ impl RepoActions for Repo {
     }
 
     fn create_branch_at_commit(&self, branch_name: &str, commit: &str) -> Result<()> {
+        let branch_checkedout = self.get_checked_out_branch_name()?.eq(branch_name);
+        if branch_checkedout {
+            let (name, _) = self.get_main_or_master_branch()?;
+            self.checkout(name)?;
+        }
+
         self.git_repo
             .branch(
                 branch_name,
@@ -351,6 +357,10 @@ impl RepoActions for Repo {
                 true,
             )
             .context("branch could not be created")?;
+
+        if branch_checkedout {
+            self.checkout(branch_name)?;
+        }
         Ok(())
     }
     /* returns patches applied */
@@ -1292,6 +1302,30 @@ mod tests {
                 assert_eq!(test_repo.checkout(branch_name)?, ahead_1_oid);
                 Ok(())
             }
+
+            #[test]
+            fn when_branch_is_checkedout_new_tip_specified_it_is_updated() -> Result<()> {
+                let test_repo = GitTestRepo::default();
+                test_repo.populate()?;
+                // create feature branch and add 2 commits
+                test_repo.create_branch("feature")?;
+                test_repo.checkout("feature")?;
+                std::fs::write(test_repo.dir.join("t3.md"), "some content")?;
+                let ahead_1_oid = test_repo.stage_and_commit("add t3.md")?;
+                std::fs::write(test_repo.dir.join("t4.md"), "some content")?;
+                let ahead_2_oid = test_repo.stage_and_commit("add t4.md")?;
+
+                let git_repo = Repo::from_path(&test_repo.dir)?;
+
+                let branch_name = "test-name-1";
+                git_repo.create_branch_at_commit(branch_name, &ahead_1_oid.to_string())?;
+                test_repo.checkout(branch_name)?;
+                git_repo.create_branch_at_commit(branch_name, &ahead_2_oid.to_string())?;
+                test_repo.checkout("main")?;
+
+                assert_eq!(test_repo.checkout(branch_name)?, ahead_2_oid);
+                Ok(())
+            }
         }
     }
 
diff --git a/src/sub_commands/pull.rs b/src/sub_commands/pull.rs
index de078e3..d832f6e 100644
--- a/src/sub_commands/pull.rs
+++ b/src/sub_commands/pull.rs
@@ -1,12 +1,13 @@
 use anyhow::{bail, Context, Result};
 
+use super::list::{get_commit_id_from_patch, tag_value};
 #[cfg(not(test))]
 use crate::client::Client;
 #[cfg(test)]
 use crate::client::MockConnect;
 use crate::{
     client::Connect,
-    git::{Repo, RepoActions},
+    git::{str_to_sha1, Repo, RepoActions},
     repo_ref,
     sub_commands::{
         list::get_most_recent_patch_with_ancestors,
@@ -14,6 +15,7 @@ use crate::{
     },
 };
 
+#[allow(clippy::too_many_lines)]
 pub async fn launch() -> Result<()> {
     let git_repo = Repo::discover().context("cannot find a git repository")?;
 
@@ -53,22 +55,139 @@ pub async fn launch() -> Result<()> {
     )
     .await?;
 
-    if git_repo.has_outstanding_changes()? {
-        bail!("cannot pull changes when repository is not clean. discard changes and try again.");
-    }
+    let most_recent_proposal_patch_chain =
+        get_most_recent_patch_with_ancestors(commit_events.clone())
+            .context("cannot get most recent patch for proposal")?;
+
+    let local_branch_tip = git_repo.get_tip_of_local_branch(&branch_name)?;
+
+    let (main_branch_name, master_tip) = git_repo.get_main_or_master_branch()?;
+
+    let (local_ahead_of_main, local_beind_main) =
+        git_repo.get_commits_ahead_behind(&master_tip, &local_branch_tip)?;
 
-    let most_recent_proposal_patch_chain = get_most_recent_patch_with_ancestors(commit_events)
-        .context("cannot get most recent patch for proposal")?;
+    let proposal_base_commit = str_to_sha1(&tag_value(
+        most_recent_proposal_patch_chain
+            .last()
+            .context("there should be at least one patch as we have already checked for this")?,
+        "parent-commit",
+    )?)
+    .context("cannot get valid parent commit id from patch")?;
 
-    let applied = git_repo
-        .apply_patch_chain(&branch_name, most_recent_proposal_patch_chain)
-        .context("cannot apply patch chain")?;
+    let (_, proposal_behind_main) =
+        git_repo.get_commits_ahead_behind(&master_tip, &proposal_base_commit)?;
 
-    if applied.is_empty() {
+    let proposal_tip =
+        str_to_sha1(
+            &get_commit_id_from_patch(most_recent_proposal_patch_chain.first().context(
+                "there should be at least one patch as we have already checked for this",
+            )?)
+            .context("cannot get valid commit_id from patch")?,
+        )
+        .context("cannot get valid commit_id from patch")?;
+
+    // if uptodate
+    if proposal_tip.eq(&local_branch_tip) {
         println!("branch already up-to-date");
-    } else {
+    }
+    // if new appendments
+    else if most_recent_proposal_patch_chain.iter().any(|patch| {
+        get_commit_id_from_patch(patch)
+            .unwrap_or_default()
+            .eq(&local_branch_tip.to_string())
+    }) {
+        check_clean(&git_repo)?;
+        let applied = git_repo
+            .apply_patch_chain(&branch_name, most_recent_proposal_patch_chain)
+            .context("cannot apply patch chain")?;
         println!("applied {} new commits", applied.len(),);
     }
+    // if parent commit doesnt exist
+    else if !git_repo.does_commit_exist(&proposal_base_commit.to_string())? {
+        println!(
+            "a new version of the proposal has a prant commit that doesnt exist in your local repository."
+        );
+        println!("your '{main_branch_name}' branch may not be up-to-date.");
+        println!("manually run `git pull` on '{main_branch_name}' and try again");
+    }
+    // if tip of local in proposal history (new, ammended or rebased version but no
+    // local changes)
+    else if commit_events.iter().any(|patch| {
+        get_commit_id_from_patch(patch)
+            .unwrap_or_default()
+            .eq(&local_branch_tip.to_string())
+    }) {
+        check_clean(&git_repo)?;
+
+        git_repo.create_branch_at_commit(&branch_name, &proposal_base_commit.to_string())?;
+        let applied = git_repo
+            .apply_patch_chain(&branch_name, most_recent_proposal_patch_chain)
+            .context("cannot apply patch chain")?;
+
+        println!(
+            "pulled new version of proposal ({} ahead {} behind '{main_branch_name}'), replacing old version ({} ahead {} behind '{main_branch_name}')",
+            applied.len(),
+            proposal_behind_main.len(),
+            local_ahead_of_main.len(),
+            local_beind_main.len(),
+        );
+    }
+    // if tip of proposal in branch in history (local appendments made to up-to-date
+    // proposal)
+    else if let Ok((local_ahead_of_proposal, _)) =
+        git_repo.get_commits_ahead_behind(&proposal_tip, &local_branch_tip)
+    {
+        println!(
+            "local proposal branch exists with {} unpublished commits on top of the most up-to-date version of the proposal",
+            local_ahead_of_proposal.len()
+        );
+    }
+    // user has probably has an unpublished rebase of the latest proposal version
+    // if tip of proposal commits exist (were once part of branch but have been
+    // ammended and git clean up job hasn't removed them)
+    else if git_repo.does_commit_exist(&proposal_tip.to_string())? {
+        println!(
+            "you have previously applied the latest version of the proposal ({} ahead {} behind '{main_branch_name}') but your local proposal branch has other unpublished changes ({} ahead {} behind '{main_branch_name}')",
+            most_recent_proposal_patch_chain.len(),
+            proposal_behind_main.len(),
+            local_ahead_of_main.len(),
+            local_beind_main.len(),
+        );
+        println!(
+            "if this sounds right then consider publishing your rebase `ngit push --force` or discarding your local branch"
+        );
+    }
+    // user has probaly has an unpublished rebase of an older version of the
+    // proposal
+    else {
+        println!(
+            "your local proposal branch ({} ahead {} behind '{main_branch_name}') has conflicting changes with the latest published proposal ({} ahead {} behind '{main_branch_name}')",
+            local_ahead_of_main.len(),
+            local_beind_main.len(),
+            most_recent_proposal_patch_chain.len(),
+            proposal_behind_main.len(),
+        );
+        println!(
+            "its likely that you are working off an old proposal version because git has no record of the latest proposal commit."
+        );
+        println!(
+            "it is possible that you have ammended the latest version and git has delete this commit as part of a clean up"
+        );
+
+        println!("to view the latest proposal but retain your changes:");
+        println!("  1) create a new branch off the tip commit of this one to store your changes");
+        println!("  2) run `ngit list` and checkout the latest published version of this proposal");
+
+        println!("if you are confident in your changes consider running `ngit push --force`");
+    }
+    Ok(())
+}
 
+fn check_clean(git_repo: &Repo) -> Result<()> {
+    if git_repo.has_outstanding_changes()? {
+        bail!(
+            "cannot pull proposal branch when repository is not clean. discard or stash (un)staged changes and try again."
+        );
+    }
     Ok(())
 }