From 94a9e28e35aaf35a1539ae25a5ec1a4d29b79632 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Mon, 20 Mar 2023 13:22:14 +0100
Subject: [PATCH] Start on `SuggestionMap`

---
 crates/editor/src/display_map.rs              |  1 +
 .../editor/src/display_map/suggestion_map.rs  | 71 +++++++++++++++++++
 2 files changed, 72 insertions(+)
 create mode 100644 crates/editor/src/display_map/suggestion_map.rs

diff --git a/crates/editor/src/display_map.rs b/crates/editor/src/display_map.rs
index f8154e6642..777fa2e9f5 100644
--- a/crates/editor/src/display_map.rs
+++ b/crates/editor/src/display_map.rs
@@ -1,5 +1,6 @@
 mod block_map;
 mod fold_map;
+mod suggestion_map;
 mod tab_map;
 mod wrap_map;
 
diff --git a/crates/editor/src/display_map/suggestion_map.rs b/crates/editor/src/display_map/suggestion_map.rs
new file mode 100644
index 0000000000..b02a5e8866
--- /dev/null
+++ b/crates/editor/src/display_map/suggestion_map.rs
@@ -0,0 +1,71 @@
+use super::fold_map::{FoldEdit, FoldOffset, FoldSnapshot};
+use gpui::fonts::HighlightStyle;
+use language::{Edit, Rope};
+use parking_lot::Mutex;
+
+pub type SuggestionEdit = Edit<SuggestionOffset>;
+
+#[derive(Copy, Clone, Debug, Default, Eq, Ord, PartialOrd, PartialEq)]
+pub struct SuggestionOffset(pub usize);
+
+#[derive(Clone)]
+pub struct Suggestion {
+    position: FoldOffset,
+    text: Rope,
+    highlight_style: HighlightStyle,
+}
+
+pub struct SuggestionMap(Mutex<SuggestionSnapshot>);
+
+impl SuggestionMap {
+    pub fn sync(
+        &self,
+        fold_snapshot: FoldSnapshot,
+        fold_edits: Vec<FoldEdit>,
+    ) -> (SuggestionSnapshot, Vec<SuggestionEdit>) {
+        let mut snapshot = self.0.lock();
+        let mut suggestion_edits = Vec::new();
+
+        let mut suggestion_old_len = 0;
+        let mut suggestion_new_len = 0;
+        for fold_edit in fold_edits {
+            let start = fold_edit.new.start;
+            let end = FoldOffset(start.0 + fold_edit.old_len().0);
+            if let Some(suggestion) = snapshot.suggestion.as_mut() {
+                if end < suggestion.position {
+                    suggestion.position.0 += fold_edit.new_len().0;
+                    suggestion.position.0 -= fold_edit.old_len().0;
+                } else if start > suggestion.position {
+                    suggestion_old_len = suggestion.text.len();
+                    suggestion_new_len = suggestion_old_len;
+                } else {
+                    suggestion_old_len = suggestion.text.len();
+                    snapshot.suggestion.take();
+                    suggestion_edits.push(SuggestionEdit {
+                        old: SuggestionOffset(fold_edit.old.start.0)
+                            ..SuggestionOffset(fold_edit.old.end.0 + suggestion_old_len),
+                        new: SuggestionOffset(fold_edit.new.start.0)
+                            ..SuggestionOffset(fold_edit.new.end.0),
+                    });
+                    continue;
+                }
+            }
+
+            suggestion_edits.push(SuggestionEdit {
+                old: SuggestionOffset(fold_edit.old.start.0 + suggestion_old_len)
+                    ..SuggestionOffset(fold_edit.old.end.0 + suggestion_old_len),
+                new: SuggestionOffset(fold_edit.new.start.0 + suggestion_new_len)
+                    ..SuggestionOffset(fold_edit.new.end.0 + suggestion_new_len),
+            });
+        }
+        snapshot.folds_snapshot = fold_snapshot;
+
+        (snapshot.clone(), suggestion_edits)
+    }
+}
+
+#[derive(Clone)]
+pub struct SuggestionSnapshot {
+    folds_snapshot: FoldSnapshot,
+    suggestion: Option<Suggestion>,
+}