Checkpoint preparing for a more organized approach to incremental diff

crates/language/src/git.rs

@@ -1,10 +1,14 @@
 use std::ops::Range;
 
+use client::proto::create_buffer_for_peer;
 use sum_tree::{Bias, SumTree};
 use text::{Anchor, BufferSnapshot, OffsetRangeExt, Point, Rope, ToPoint};
 
 pub use git2 as libgit;
-use libgit::{DiffOptions as GitOptions, Patch as GitPatch};
+use libgit::{
+    DiffLine as GitDiffLine, DiffLineType as GitDiffLineType, DiffOptions as GitOptions,
+    Patch as GitPatch,
+};
 
 #[derive(Debug, Clone, Copy)]
 pub enum DiffHunkStatus {
@@ -16,12 +20,12 @@ pub enum DiffHunkStatus {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct DiffHunk<T> {
     pub buffer_range: Range<T>,
-    pub head_range: Range<usize>,
+    pub head_byte_range: Range<usize>,
 }
 
 impl DiffHunk<u32> {
     pub fn status(&self) -> DiffHunkStatus {
-        if self.head_range.is_empty() {
+        if self.head_byte_range.is_empty() {
             DiffHunkStatus::Added
         } else if self.buffer_range.is_empty() {
             DiffHunkStatus::Removed
@@ -37,7 +41,7 @@ impl sum_tree::Item for DiffHunk<Anchor> {
     fn summary(&self) -> Self::Summary {
         DiffHunkSummary {
             buffer_range: self.buffer_range.clone(),
-            head_range: self.head_range.clone(),
+            head_range: self.head_byte_range.clone(),
         }
     }
 }
@@ -70,6 +74,19 @@ impl<'a> sum_tree::Dimension<'a, DiffHunkSummary> for HunkHeadEnd {
     }
 }
 
+#[derive(Debug, Default, Clone, PartialEq, Eq, PartialOrd, Ord)]
+struct HunkBufferStart(u32);
+
+impl<'a> sum_tree::Dimension<'a, DiffHunkSummary> for HunkBufferStart {
+    fn add_summary(&mut self, summary: &'a DiffHunkSummary, buffer: &text::BufferSnapshot) {
+        self.0 = summary.buffer_range.start.to_point(buffer).row;
+    }
+
+    fn from_summary(summary: &'a DiffHunkSummary, buffer: &text::BufferSnapshot) -> Self {
+        HunkBufferStart(summary.buffer_range.start.to_point(buffer).row)
+    }
+}
+
 #[derive(Debug, Default, Clone, PartialEq, Eq, PartialOrd, Ord)]
 struct HunkBufferEnd(u32);
 
@@ -83,6 +100,40 @@ impl<'a> sum_tree::Dimension<'a, DiffHunkSummary> for HunkBufferEnd {
     }
 }
 
+struct HunkLineIter<'a, 'b> {
+    patch: &'a GitPatch<'b>,
+    hunk_index: usize,
+    line_index: usize,
+}
+
+impl<'a, 'b> HunkLineIter<'a, 'b> {
+    fn new(patch: &'a GitPatch<'b>, hunk_index: usize) -> Self {
+        HunkLineIter {
+            patch,
+            hunk_index,
+            line_index: 0,
+        }
+    }
+}
+
+impl<'a, 'b> std::iter::Iterator for HunkLineIter<'a, 'b> {
+    type Item = GitDiffLine<'b>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.line_index >= self.patch.num_lines_in_hunk(self.hunk_index).unwrap() {
+            return None;
+        }
+
+        let line_index = self.line_index;
+        self.line_index += 1;
+        Some(
+            self.patch
+                .line_in_hunk(self.hunk_index, line_index)
+                .unwrap(),
+        )
+    }
+}
+
 #[derive(Clone)]
 pub struct BufferDiffSnapshot {
     tree: SumTree<DiffHunk<Anchor>>,
@@ -94,8 +145,6 @@ impl BufferDiffSnapshot {
         query_row_range: Range<u32>,
         buffer: &'a BufferSnapshot,
     ) -> impl 'a + Iterator<Item = DiffHunk<u32>> {
-        // println!("{} hunks overall", self.tree.iter().count());
-
         self.tree.iter().filter_map(move |hunk| {
             let range = hunk.buffer_range.to_point(&buffer);
 
@@ -108,7 +157,7 @@ impl BufferDiffSnapshot {
 
                 Some(DiffHunk {
                     buffer_range: range.start.row..end_row,
-                    head_range: hunk.head_range.clone(),
+                    head_byte_range: hunk.head_byte_range.clone(),
                 })
             } else {
                 None
@@ -129,18 +178,32 @@ pub struct BufferDiff {
 
 impl BufferDiff {
     pub fn new(head_text: &Option<String>, buffer: &text::BufferSnapshot) -> BufferDiff {
-        let mut instance = BufferDiff {
-            last_update_version: buffer.version().clone(),
-            snapshot: BufferDiffSnapshot {
-                tree: SumTree::new(),
-            },
-        };
+        let mut tree = SumTree::new();
 
         if let Some(head_text) = head_text {
-            instance.update(head_text, buffer);
+            let buffer_text = buffer.as_rope().to_string();
+            let patch = Self::diff(&head_text, &buffer_text);
+
+            if let Some(patch) = patch {
+                let mut buffer_divergence = 0;
+
+                for hunk_index in 0..patch.num_hunks() {
+                    let patch = Self::process_patch_hunk(
+                        &mut buffer_divergence,
+                        &patch,
+                        hunk_index,
+                        buffer,
+                    );
+
+                    tree.push(patch, buffer);
+                }
+            }
         }
 
-        instance
+        BufferDiff {
+            last_update_version: buffer.version().clone(),
+            snapshot: BufferDiffSnapshot { tree },
+        }
     }
 
     pub fn snapshot(&self) -> BufferDiffSnapshot {
@@ -148,100 +211,241 @@ impl BufferDiff {
     }
 
     pub fn update(&mut self, head_text: &str, buffer: &text::BufferSnapshot) {
-        let buffer_string = buffer.as_rope().to_string();
-        let buffer_bytes = buffer_string.as_bytes();
+        // let buffer_string = buffer.as_rope().to_string();
+        // let buffer_bytes = buffer_string.as_bytes();
 
+        // let mut options = GitOptions::default();
+        // options.context_lines(0);
+        // let patch = match GitPatch::from_buffers(
+        //     head_text.as_bytes(),
+        //     None,
+        //     buffer_bytes,
+        //     None,
+        //     Some(&mut options),
+        // ) {
+        //     Ok(patch) => patch,
+        //     Err(_) => todo!("This needs to be handled"),
+        // };
+
+        // let mut hunks = SumTree::<DiffHunk<Anchor>>::new();
+        // let mut delta = 0i64;
+        // for hunk_index in 0..patch.num_hunks() {
+        //     for line_index in 0..patch.num_lines_in_hunk(hunk_index).unwrap() {
+        //         let line = patch.line_in_hunk(hunk_index, line_index).unwrap();
+
+        //         let hunk = match line.origin_value() {
+        //             GitDiffLineType::Addition => {
+        //                 let buffer_start = line.content_offset();
+        //                 let buffer_end = buffer_start as usize + line.content().len();
+        //                 let head_offset = (buffer_start - delta) as usize;
+        //                 delta += line.content().len() as i64;
+        //                 DiffHunk {
+        //                     buffer_range: buffer.anchor_before(buffer_start as usize)
+        //                         ..buffer.anchor_after(buffer_end),
+        //                     head_byte_range: head_offset..head_offset,
+        //                 }
+        //             }
+
+        //             GitDiffLineType::Deletion => {
+        //                 let head_start = line.content_offset();
+        //                 let head_end = head_start as usize + line.content().len();
+        //                 let buffer_offset = (head_start + delta) as usize;
+        //                 delta -= line.content().len() as i64;
+        //                 DiffHunk {
+        //                     buffer_range: buffer.anchor_before(buffer_offset)
+        //                         ..buffer.anchor_after(buffer_offset),
+        //                     head_byte_range: (head_start as usize)..head_end,
+        //                 }
+        //             }
+
+        //             _ => continue,
+        //         };
+
+        //         let mut combined = false;
+        //         hunks.update_last(
+        //             |last_hunk| {
+        //                 if last_hunk.head_byte_range.end == hunk.head_byte_range.start {
+        //                     last_hunk.head_byte_range.end = hunk.head_byte_range.end;
+        //                     last_hunk.buffer_range.end = hunk.buffer_range.end;
+        //                     combined = true;
+        //                 }
+        //             },
+        //             buffer,
+        //         );
+        //         if !combined {
+        //             hunks.push(hunk, buffer);
+        //         }
+        //     }
+        // }
+
+        // println!("=====");
+        // for hunk in hunks.iter() {
+        //     let buffer_range = hunk.buffer_range.to_point(&buffer);
+        //     println!(
+        //         "hunk in buffer range {buffer_range:?}, head slice {:?}",
+        //         &head_text[hunk.head_byte_range.clone()]
+        //     );
+        // }
+        // println!("=====");
+
+        // self.snapshot.tree = hunks;
+    }
+
+    pub fn actual_update(
+        &mut self,
+        head_text: &str,
+        buffer: &BufferSnapshot,
+    ) -> Option<DiffHunk<Anchor>> {
+        for edit_range in self.group_edit_ranges(buffer) {
+            // let patch = self.diff(head, current)?;
+        }
+
+        None
+    }
+
+    fn diff<'a>(head: &'a str, current: &'a str) -> Option<GitPatch<'a>> {
         let mut options = GitOptions::default();
         options.context_lines(0);
-        let patch = match GitPatch::from_buffers(
-            head_text.as_bytes(),
+
+        let patch = GitPatch::from_buffers(
+            head.as_bytes(),
             None,
-            buffer_bytes,
+            current.as_bytes(),
             None,
             Some(&mut options),
-        ) {
-            Ok(patch) => patch,
-            Err(_) => todo!("This needs to be handled"),
-        };
+        );
 
-        let mut hunks = SumTree::<DiffHunk<Anchor>>::new();
-        let mut delta = 0i64;
-        for hunk_index in 0..patch.num_hunks() {
-            for line_index in 0..patch.num_lines_in_hunk(hunk_index).unwrap() {
-                let line = patch.line_in_hunk(hunk_index, line_index).unwrap();
+        match patch {
+            Ok(patch) => Some(patch),
 
-                let hunk = match line.origin_value() {
-                    libgit::DiffLineType::Addition => {
-                        let buffer_start = line.content_offset();
-                        let buffer_end = buffer_start as usize + line.content().len();
-                        let head_offset = (buffer_start - delta) as usize;
-                        delta += line.content().len() as i64;
-                        DiffHunk {
-                            buffer_range: buffer.anchor_before(buffer_start as usize)
-                                ..buffer.anchor_after(buffer_end),
-                            head_range: head_offset..head_offset,
-                        }
-                    }
+            Err(err) => {
+                log::error!("`GitPatch::from_buffers` failed: {}", err);
+                None
+            }
+        }
+    }
 
-                    libgit::DiffLineType::Deletion => {
-                        let head_start = line.content_offset();
-                        let head_end = head_start as usize + line.content().len();
-                        let buffer_offset = (head_start + delta) as usize;
-                        delta -= line.content().len() as i64;
-                        DiffHunk {
-                            buffer_range: buffer.anchor_before(buffer_offset)
-                                ..buffer.anchor_after(buffer_offset),
-                            head_range: (head_start as usize)..head_end,
-                        }
-                    }
+    fn group_edit_ranges(&mut self, buffer: &text::BufferSnapshot) -> Vec<Range<u32>> {
+        const EXPAND_BY: u32 = 20;
+        const COMBINE_DISTANCE: u32 = 5;
 
-                    libgit::DiffLineType::AddEOFNL => todo!(),
-                    libgit::DiffLineType::ContextEOFNL => todo!(),
-                    libgit::DiffLineType::DeleteEOFNL => todo!(),
+        // let mut cursor = self.snapshot.tree.cursor::<HunkBufferStart>();
 
-                    libgit::DiffLineType::FileHeader => continue,
-                    libgit::DiffLineType::HunkHeader => continue,
-                    libgit::DiffLineType::Binary => continue,
+        let mut ranges = Vec::<Range<u32>>::new();
 
-                    //We specifically tell git to not give us context lines
-                    libgit::DiffLineType::Context => unreachable!(),
-                };
+        for edit in buffer.edits_since::<Point>(&self.last_update_version) {
+            let buffer_start = edit.new.start.row.saturating_sub(EXPAND_BY);
+            let buffer_end = (edit.new.end.row + EXPAND_BY).min(buffer.row_count());
 
-                let mut combined = false;
-                hunks.update_last(
-                    |last_hunk| {
-                        if last_hunk.head_range.end == hunk.head_range.start {
-                            last_hunk.head_range.end = hunk.head_range.end;
-                            last_hunk.buffer_range.end = hunk.buffer_range.end;
-                            combined = true;
-                        }
-                    },
-                    buffer,
-                );
-                if !combined {
-                    hunks.push(hunk, buffer);
+            match ranges.last_mut() {
+                Some(last_range) if last_range.end.abs_diff(buffer_end) <= COMBINE_DISTANCE => {
+                    last_range.start = last_range.start.min(buffer_start);
+                    last_range.end = last_range.end.max(buffer_end);
                 }
+
+                _ => ranges.push(buffer_start..buffer_end),
             }
         }
 
-        self.snapshot.tree = hunks;
+        self.last_update_version = buffer.version().clone();
+        ranges
     }
-}
 
-#[derive(Debug, Clone, Copy)]
-pub enum GitDiffEdit {
-    Added(u32),
-    Modified(u32),
-    Removed(u32),
-}
+    fn process_patch_hunk<'a>(
+        buffer_divergence: &mut isize,
+        patch: &GitPatch<'a>,
+        hunk_index: usize,
+        buffer: &text::BufferSnapshot,
+    ) -> DiffHunk<Anchor> {
+        let mut buffer_byte_range: Option<Range<usize>> = None;
+        let mut head_byte_range: Option<Range<usize>> = None;
 
-impl GitDiffEdit {
-    pub fn line(self) -> u32 {
-        use GitDiffEdit::*;
+        for line_index in 0..patch.num_lines_in_hunk(hunk_index).unwrap() {
+            let line = patch.line_in_hunk(hunk_index, line_index).unwrap();
+            let kind = line.origin_value();
+            println!("line index: {line_index}, kind: {kind:?}");
+            let content_offset = line.content_offset() as isize;
 
-        match self {
-            Added(line) | Modified(line) | Removed(line) => line,
+            match (kind, &mut buffer_byte_range, &mut head_byte_range) {
+                (GitDiffLineType::Addition, None, _) => {
+                    let start = *buffer_divergence + content_offset;
+                    let end = start + line.content().len() as isize;
+                    buffer_byte_range = Some(start as usize..end as usize);
+                }
+
+                (GitDiffLineType::Addition, Some(buffer_byte_range), _) => {
+                    buffer_byte_range.end = content_offset as usize;
+                }
+
+                (GitDiffLineType::Deletion, _, None) => {
+                    let end = content_offset + line.content().len() as isize;
+                    head_byte_range = Some(content_offset as usize..end as usize);
+                }
+
+                (GitDiffLineType::Deletion, _, Some(head_byte_range)) => {
+                    let end = content_offset + line.content().len() as isize;
+                    head_byte_range.end = end as usize;
+                }
+
+                _ => {}
+            }
         }
+
+        //unwrap_or deletion without addition
+        let buffer_byte_range = buffer_byte_range.unwrap_or(0..0);
+        //unwrap_or addition without deletion
+        let head_byte_range = head_byte_range.unwrap_or(0..0);
+
+        *buffer_divergence += buffer_byte_range.len() as isize - head_byte_range.len() as isize;
+
+        DiffHunk {
+            buffer_range: buffer.anchor_before(buffer_byte_range.start)
+                ..buffer.anchor_before(buffer_byte_range.end),
+            head_byte_range,
+        }
+    }
+
+    fn name() {
+        // if self.hunk_index >= self.patch.num_hunks() {
+        //     return None;
+        // }
+
+        // let mut line_iter = HunkLineIter::new(&self.patch, self.hunk_index);
+        // let line = line_iter.find(|line| {
+        //     matches!(
+        //         line.origin_value(),
+        //         GitDiffLineType::Addition | GitDiffLineType::Deletion
+        //     )
+        // })?;
+
+        // //For the first line of a hunk the content offset is equally valid for an addition or deletion
+        // let content_offset = line.content_offset() as usize;
+
+        // let mut buffer_range = content_offset..content_offset;
+        // let mut head_byte_range = match line.origin_value() {
+        //     GitDiffLineType::Addition => content_offset..content_offset,
+        //     GitDiffLineType::Deletion => content_offset..content_offset + line.content().len(),
+        //     _ => unreachable!(),
+        // };
+
+        // for line in line_iter {
+        //     match line.origin_value() {
+        //         GitDiffLineType::Addition => {
+        //             // buffer_range.end =
+        //         }
+
+        //         GitDiffLineType::Deletion => {}
+
+        //         _ => continue,
+        //     }
+        // }
+
+        // self.hunk_index += 1;
+        // Some(DiffHunk {
+        //     buffer_range: buffer.anchor_before(buffer_range.start)
+        //         ..buffer.anchor_before(buffer_range.end),
+        //     head_byte_range,
+        // })
     }
 }
 
@@ -293,7 +497,7 @@ mod tests {
         for ((index, hunk), (expected_range, expected_str)) in diff_iter.zip(expected_hunks) {
             assert_eq!(&hunk.buffer_range, expected_range, "for hunk {index}");
             assert_eq!(
-                &head_text[hunk.head_range.clone()],
+                &head_text[hunk.head_byte_range.clone()],
                 *expected_str,
                 "for hunk {index}"
             );