Show changes relative to VCS in diagnostics

Cargo.toml

@@ -6,6 +6,7 @@ members = [
   "helix-tui",
   "helix-syntax",
   "helix-lsp",
+  "helix-vcs",
 ]
 
 # Build helix-syntax in release mode to make the code path faster in development.

helix-term/Cargo.toml

@@ -25,6 +25,7 @@ path = "src/main.rs"
 helix-core = { version = "0.3", path = "../helix-core" }
 helix-view = { version = "0.3", path = "../helix-view" }
 helix-lsp = { version = "0.3", path = "../helix-lsp" }
+helix-vcs = { version = "0.3", path = "../helix-vcs"}
 
 anyhow = "1"
 once_cell = "1.8"

helix-term/src/ui/editor.rs

@@ -12,6 +12,7 @@ use helix_core::{
     syntax::{self, HighlightEvent},
     LineEnding, Position, Range,
 };
+use helix_vcs::LineChange;
 use helix_view::{
     document::Mode,
     graphics::{CursorKind, Modifier, Rect, Style},
@@ -327,8 +328,30 @@ impl EditorView {
         let info: Style = theme.get("info");
         let hint: Style = theme.get("hint");
 
+        let line_added: Style = theme.get("diff.added");
+        let line_removed_above: Style = theme.get("diff.removed.above");
+        let line_removed_below: Style = theme.get("diff.removed.below");
+        let line_modified: Style = theme.get("diff.modified");
+
         for (i, line) in (view.first_line..last_line).enumerate() {
             use helix_core::diagnostic::Severity;
+            if let Some(line_changes) = doc.vcs_line_changes() {
+                if let Some(line_change) = line_changes.get(&(line + 1)) {
+                    surface.set_stringn(
+                        viewport.x - OFFSET,
+                        viewport.y + i as u16,
+                        // TODO: set this in a theme
+                        line_change.as_str(),
+                        1,
+                        match line_change {
+                            LineChange::Added => line_added,
+                            LineChange::RemovedAbove => line_removed_above,
+                            LineChange::RemovedBelow => line_removed_below,
+                            LineChange::Modified => line_modified,
+                        },
+                    );
+                }
+            }
             if let Some(diagnostic) = doc.diagnostics().iter().find(|d| d.line == line) {
                 surface.set_stringn(
                     viewport.x - OFFSET,

helix-vcs/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "helix-vcs"
+version = "0.3.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+git2 = { version = "0.13", default-features = false }
+helix-core = { version = "0.3", path = "../helix-core" } 

helix-vcs/src/git.rs

@@ -0,0 +1,102 @@
+use std::collections::HashMap;
+use std::fs;
+use std::path::{Path, PathBuf};
+
+use git2::{DiffOptions, IntoCString, Repository};
+
+use crate::{LineChange, LineChanges};
+
+pub struct Git {
+    relative_path: PathBuf,
+    repo: Repository,
+    pub line_changes: Option<LineChanges>,
+}
+impl Git {
+    pub fn from_path(filename: &Path) -> Option<Self> {
+        if let Ok(repo) = Repository::discover(&filename) {
+            let repo_path_absolute = fs::canonicalize(repo.workdir()?).ok()?;
+
+            let relative_path = fs::canonicalize(&filename)
+                .ok()?
+                .strip_prefix(&repo_path_absolute)
+                .ok()?
+                .to_path_buf();
+            Some(Git {
+                repo,
+                relative_path,
+                line_changes: None,
+            })
+        } else {
+            None
+        }
+    }
+
+    /// Taken from https://github.com/sharkdp/bat/blob/master/src/diff.rs
+    pub fn diff(&mut self) {
+        let mut diff_options = DiffOptions::new();
+        let pathspec = if let Ok(p) = self.relative_path.clone().into_c_string() {
+            p
+        } else {
+            return;
+        };
+        diff_options.pathspec(pathspec);
+        diff_options.context_lines(0);
+
+        let diff = if let Ok(d) = self
+            .repo
+            .diff_index_to_workdir(None, Some(&mut diff_options))
+        {
+            d
+        } else {
+            return;
+        };
+
+        let mut line_changes: LineChanges = HashMap::new();
+
+        let mark_section =
+            |line_changes: &mut LineChanges, start: u32, end: i32, change: LineChange| {
+                for line in start..=end as u32 {
+                    line_changes.insert(line as usize, change);
+                }
+            };
+
+        let _ = diff.foreach(
+            &mut |_, _| true,
+            None,
+            Some(&mut |delta, hunk| {
+                let path = delta.new_file().path().unwrap_or_else(|| Path::new(""));
+
+                if self.relative_path != path {
+                    return false;
+                }
+
+                let old_lines = hunk.old_lines();
+                let new_start = hunk.new_start();
+                let new_lines = hunk.new_lines();
+                let new_end = (new_start + new_lines) as i32 - 1;
+
+                if old_lines == 0 && new_lines > 0 {
+                    mark_section(&mut line_changes, new_start, new_end, LineChange::Added);
+                } else if new_lines == 0 && old_lines > 0 {
+                    if new_start == 0 {
+                        mark_section(&mut line_changes, 1, 1, LineChange::RemovedAbove);
+                    } else {
+                        mark_section(
+                            &mut line_changes,
+                            new_start,
+                            new_start as i32,
+                            LineChange::RemovedBelow,
+                        );
+                    }
+                } else {
+                    mark_section(&mut line_changes, new_start, new_end, LineChange::Modified);
+                }
+
+                true
+            }),
+            None,
+        );
+
+        self.line_changes = Some(line_changes);
+    }
+}

helix-vcs/src/lib.rs

@@ -0,0 +1,45 @@
+use std::collections::HashMap;
+use std::path::Path;
+
+mod git;
+use git::Git;
+
+#[derive(Copy, Clone, Debug)]
+pub enum LineChange {
+    Added,
+    RemovedAbove,
+    RemovedBelow,
+    Modified,
+}
+impl LineChange {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            LineChange::Added => &"▌",
+            LineChange::RemovedAbove => &"▘",
+            LineChange::RemovedBelow => &"▖",
+            LineChange::Modified => &"▐",
+        }
+    }
+}
+
+pub type LineChanges = HashMap<usize, LineChange>;
+
+//#[derive(Clone)]
+pub enum VCS {
+    Git(Git),
+}
+impl VCS {
+    pub fn from_path(filename: &Path) -> Option<Self> {
+        Some(VCS::Git(Git::from_path(filename)?))
+    }
+    pub fn get_line_changes(&self) -> Option<&LineChanges> {
+        match self {
+            VCS::Git(git) => git.line_changes.as_ref(),
+        }
+    }
+    pub fn diff(&mut self) {
+        match self {
+            VCS::Git(git) => git.diff(),
+        }
+    }
+}

helix-view/Cargo.toml

@@ -18,6 +18,7 @@ bitflags = "1.0"
 anyhow = "1"
 helix-core = { version = "0.3", path = "../helix-core" }
 helix-lsp = { version = "0.3", path = "../helix-lsp"}
+helix-vcs = { version = "0.3", path = "../helix-vcs"}
 crossterm = { version = "0.20", optional = true }
 
 # Conversion traits