5 files changed, 106 insertions, 4 deletions

diff --git a/apps/servers/octopus/supergit/src/bin/test.rs b/apps/servers/octopus/supergit/src/bin/test.rs
index 830c8b62f136..b7dba0379df3 100644
--- a/apps/servers/octopus/supergit/src/bin/test.rs
+++ b/apps/servers/octopus/supergit/src/bin/test.rs
@@ -23,5 +23,11 @@ fn main() {
     let head = main.get_head();
     let tree = head.get_tree();
 
-    println!("{:?}", tree.load(""));
+    println!(
+        "{:?}",
+        tree.history(main.get_all(), "Cargo.toml")
+            .into_iter()
+            .map(|c| c.summary())
+            .collect::<Vec<_>>()
+    );
 }
diff --git a/apps/servers/octopus/supergit/src/branch.rs b/apps/servers/octopus/supergit/src/branch.rs
index 432227900247..3261d23b9177 100644
--- a/apps/servers/octopus/supergit/src/branch.rs
+++ b/apps/servers/octopus/supergit/src/branch.rs
@@ -248,4 +248,14 @@ impl BranchCommit {
         }
         .clone()
     }
+
+    /// Get the underlying commit, regardless of type
+    pub fn commit(&self) -> &Commit {
+        use BranchCommit::*;
+        match self {
+            Commit(ref c) => c,
+            Merge(ref c, _) => c,
+            Octopus(ref c, _) => c,
+        }
+    }
 }
diff --git a/apps/servers/octopus/supergit/src/commit.rs b/apps/servers/octopus/supergit/src/commit.rs
index bc7383d1ed6d..99c4dbba6fce 100644
--- a/apps/servers/octopus/supergit/src/commit.rs
+++ b/apps/servers/octopus/supergit/src/commit.rs
@@ -1,4 +1,4 @@
-use crate::{FileTree, HashId};
+use crate::{Diff, FileTree, HashId};
 use git2::Repository;
 use std::sync::Arc;
 
@@ -71,6 +71,44 @@ impl Commit {
         FileTree::new(&self.repo, self.id.clone())
     }
 
+    /// Get the list of paths in the repository touched by this commit
+    ///
+    /// Using this function directly is often not what you want.
+    /// Instead, use the `get_history(...)` function on `FileTree`,
+    /// which uses this function.
+    pub fn get_paths(&self) -> Vec<String> {
+        self.get_diff()
+            .map(|d| Diff::from(d))
+            .map_or(vec![], |d| d.get_paths())
+    }
+
+    /// Utility function to get a merged diff from all parents
+    fn get_diff(&self) -> Option<git2::Diff> {
+        // Get all diffs with parents
+        let stree = self.find().tree().unwrap();
+        let mut vec = self
+            .parents()
+            .into_iter()
+            .filter_map(|p| {
+                self.repo
+                    .diff_tree_to_tree(Some(&stree), Some(p.find().tree().as_ref().unwrap()), None)
+                    .ok()
+            })
+            .collect::<Vec<_>>();
+
+        // If there are no parents
+        if vec.len() == 0 {
+            vec = vec![self.repo.diff_tree_to_tree(Some(&stree), None, None).ok()?];
+        }
+
+        // Take the first and merge onto
+        let first = vec.remove(0);
+        Some(vec.iter().fold(first, |mut acc, diff| {
+            acc.merge(diff).unwrap();
+            acc
+        }))
+    }
+
     fn find(&self) -> git2::Commit {
         self.repo.find_commit(self.id.to_oid()).unwrap()
     }
diff --git a/apps/servers/octopus/supergit/src/diff.rs b/apps/servers/octopus/supergit/src/diff.rs
index e92a4cd1804c..e83903cf6ebc 100644
--- a/apps/servers/octopus/supergit/src/diff.rs
+++ b/apps/servers/octopus/supergit/src/diff.rs
@@ -1,5 +1,32 @@
-
 /// A diff between two commits
+///
+/// At the moment this type doesn't properly express a Diff, and is
+/// only used to compute the change set between commits to generate a
+/// file history.
 pub struct Diff {
+    paths: Vec<String>,
+}
+
+impl Diff {
+    /// Generate a new Diff from a git2::Diff
+    pub(crate) fn from(d: git2::Diff) -> Self {
+        Self {
+            paths: d.deltas().fold(vec![], |mut vec, delta| {
+                append(&mut vec, delta.old_file());
+                append(&mut vec, delta.new_file());
+                vec
+            }),
+        }
+    }
+
+    /// Get all paths touched by a diff
+    pub fn get_paths(&self) -> Vec<String> {
+        self.paths.clone()
+    }
+}
 
+fn append(vec: &mut Vec<String>, f: git2::DiffFile) {
+    if let Some(path) = f.path().map(|p| p.to_str().unwrap().into()) {
+        vec.push(path);
+    }
 }
diff --git a/apps/servers/octopus/supergit/src/files.rs b/apps/servers/octopus/supergit/src/files.rs
index fa68fbc2f3dc..c593a4923921 100644
--- a/apps/servers/octopus/supergit/src/files.rs
+++ b/apps/servers/octopus/supergit/src/files.rs
@@ -1,7 +1,7 @@
 use crate::{Branch, BranchIter, Commit, HashId};
 use atomptr::AtomPtr;
 use git2::{ObjectType, TreeWalkMode, TreeWalkResult};
-use std::collections::BTreeMap;
+use std::collections::{BTreeMap, BTreeSet};
 use std::{path::PathBuf, sync::Arc};
 
 /// A tree of files
@@ -76,6 +76,27 @@ impl FileTree {
     pub fn load(&self, path: &str) -> Option<Yield> {
         self.get_entry(path).and_then(|e| e.load(&self.repo))
     }
+
+    /// Get the history of a path with a branch iterator
+    ///
+    /// This function is very computationally intensive, because it
+    /// will step through the entire iterator to pull commits from,
+    /// and see if they touch the respective path.
+    pub fn history(&self, iter: BranchIter, path: &str) -> Vec<Commit> {
+        iter.filter_map(|c| {
+            if c.commit()
+                .get_paths()
+                .into_iter()
+                .collect::<BTreeSet<_>>()
+                .contains(path)
+            {
+                Some(c.commit().clone())
+            } else {
+                None
+            }
+        })
+        .collect()
+    }
 }
 
 /// Data yielded from loading a part of the file tree