1 files changed, 80 insertions, 0 deletions
diff --git a/src/actions/update.rs b/src/actions/update.rs
new file mode 100644
index 0000000..a2bc08d
--- /dev/null
+++ b/src/actions/update.rs
@@ -0,0 +1,80 @@
+use std::io::{self, Read};
+
+use crate::{
+    files::{Locations, RepositoryPaths},
+    history::{FileChange, FileHistory},
+    text_diff::TextChange,
+};
+
+use super::ActionOptions;
+
+pub fn update(command_options: ActionOptions) -> io::Result<()> {
+    let locations = Locations::from(&command_options);
+
+    let entries = locations
+        .get_repository_paths()
+        .expect("Could not traverse files.");
+
+    for element in entries {
+        update_file(element, &locations)?;
+    }
+
+    Ok(())
+}
+
+fn update_file(paths: RepositoryPaths, locations: &Locations) -> io::Result<()> {
+    let new_state = match paths {
+        RepositoryPaths::Deleted(deleted) => {
+            let mut history_file = deleted.load_history_file()?;
+            let file_history = FileHistory::from_file(&mut history_file).unwrap();
+            if !file_history.file_is_deleted() {
+                let mut new_history = file_history;
+                new_history.add_change(FileChange::Deleted);
+                Some((history_file, new_history))
+            } else {
+                None
+            }
+        }
+        RepositoryPaths::Untracked(untracked) => {
+            let mut file = untracked.load_file()?;
+
+            let mut file_content = String::new();
+            file.read_to_string(&mut file_content)?;
+
+            let change = FileChange::Updated(vec![TextChange::Inserted {
+                at: 0,
+                new_content: file_content,
+            }]);
+
+            let mut new_history = FileHistory::default();
+            new_history.add_change(change);
+
+            Some((untracked.create_history_file(locations)?, new_history))
+        }
+        RepositoryPaths::Tracked(tracked) => {
+            let mut history_file = tracked.load_history_file()?;
+            let mut tracked_file = tracked.load_tracked_file()?;
+
+            let file_history = FileHistory::from_file(&mut history_file).unwrap();
+
+            let mut new_content = String::new();
+            tracked_file.read_to_string(&mut new_content)?;
+
+            let old_content = file_history.get_content();
+
+            let changes = TextChange::diff(&old_content, &new_content);
+
+            let mut new_history = file_history;
+            new_history.add_change(FileChange::Updated(changes));
+            new_history.set_cursor(new_history.cursor() + 1);
+
+            Some((history_file, new_history))
+        }
+    };
+
+    if let Some((mut history_file, new_file_history)) = new_state {
+        new_file_history.write_to_file(&mut history_file)?;
+    }
+
+    Ok(())
+}