feat(lsp): implement show document request

Implement [window.showDocument](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#window_showDocument)
LSP server-sent request.

This PR builds on top of helix-editor#5820,
moves the external-URL opening functionality into shared crate-level
function that returns a callback that is now used by both the
`open_file` command as well as the window.showDocument handler if
the URL is marked as external.

helix-lsp/src/lib.rs

@@ -549,6 +549,7 @@ pub enum MethodCall {
     WorkspaceConfiguration(lsp::ConfigurationParams),
     RegisterCapability(lsp::RegistrationParams),
     UnregisterCapability(lsp::UnregistrationParams),
+    ShowDocument(lsp::ShowDocumentParams),
 }
 
 impl MethodCall {
@@ -576,6 +577,10 @@ impl MethodCall {
                 let params: lsp::UnregistrationParams = params.parse()?;
                 Self::UnregisterCapability(params)
             }
+            lsp::request::ShowDocument::METHOD => {
+                let params: lsp::ShowDocumentParams = params.parse()?;
+                Self::ShowDocument(params)
+            }
             _ => {
                 return Err(Error::Unhandled);
             }

helix-term/src/application.rs

@@ -7,7 +7,7 @@ use helix_core::{
 };
 use helix_lsp::{
     lsp::{self, notification::Notification},
-    util::lsp_pos_to_pos,
+    util::{lsp_pos_to_pos, lsp_range_to_range},
     LspProgressMap,
 };
 use helix_view::{
@@ -1134,6 +1134,63 @@ impl Application {
                         }
                         Ok(serde_json::Value::Null)
                     }
+                    Ok(MethodCall::ShowDocument(params)) => {
+                        let language_server = language_server!();
+                        let offset_encoding = language_server.offset_encoding();
+
+                        if params.external.unwrap_or_default() {
+                            self.jobs
+                                .callback(crate::open_external_url_callback(params.uri));
+                            return;
+                        }
+
+                        let path = match params.uri.to_file_path() {
+                            Ok(path) => path,
+                            Err(_) => {
+                                log::error!("Unsupported file URI: {}", params.uri);
+                                return;
+                            }
+                        };
+
+                        let action = match params.take_focus {
+                            Some(true) => helix_view::editor::Action::Replace,
+                            _ => helix_view::editor::Action::HorizontalSplit,
+                        };
+
+                        let doc = match self.editor.open(&path, action) {
+                            Ok(id) => doc_mut!(self.editor, &id),
+                            Err(err) => {
+                                log::error!("failed to open path: {:?}: {:?}", params.uri, err);
+                                return;
+                            }
+                        };
+
+                        if let Some(range) = params.selection {
+                            // TODO: convert inside server
+                            let new_range = if let Some(new_range) =
+                                lsp_range_to_range(doc.text(), range, offset_encoding)
+                            {
+                                new_range
+                            } else {
+                                log::warn!("lsp position out of bounds - {:?}", range);
+                                return;
+                            };
+
+                            let view = view_mut!(self.editor);
+
+                            // we flip the range so that the cursor sits on the start of the symbol
+                            // (for example start of the function).
+                            doc.set_selection(
+                                view.id,
+                                Selection::single(new_range.head, new_range.anchor),
+                            );
+                            if action.align_view(view, doc.id()) {
+                                align_view(doc, view, Align::Center);
+                            }
+                        }
+
+                        Ok(serde_json::Value::Null)
+                    }
                 };
 
                 tokio::spawn(language_server!().reply(id, reply));

helix-term/src/commands.rs

@@ -1227,7 +1227,7 @@ fn open_url(cx: &mut Context, url: Url, action: Action) {
         .unwrap_or_default();
 
     if url.scheme() != "file" {
-        return open_external_url(cx, url);
+        return cx.jobs.callback(crate::open_external_url_callback(url));
     }
 
     let content_type = std::fs::File::open(url.path()).and_then(|file| {
@@ -1240,7 +1240,9 @@ fn open_url(cx: &mut Context, url: Url, action: Action) {
     // we attempt to open binary files - files that can't be open in helix - using external
     // program as well, e.g. pdf files or images
     match content_type {
-        Ok(content_inspector::ContentType::BINARY) => open_external_url(cx, url),
+        Ok(content_inspector::ContentType::BINARY) => {
+            cx.jobs.callback(crate::open_external_url_callback(url))
+        }
         Ok(_) | Err(_) => {
             let path = &rel_path.join(url.path());
             if path.is_dir() {
@@ -1253,23 +1255,6 @@ fn open_url(cx: &mut Context, url: Url, action: Action) {
     }
 }
 
-/// Opens URL in external program.
-fn open_external_url(cx: &mut Context, url: Url) {
-    let commands = open::commands(url.as_str());
-    cx.jobs.callback(async {
-        for cmd in commands {
-            let mut command = tokio::process::Command::new(cmd.get_program());
-            command.args(cmd.get_args());
-            if command.output().await.is_ok() {
-                return Ok(job::Callback::Editor(Box::new(|_| {})));
-            }
-        }
-        Ok(job::Callback::Editor(Box::new(move |editor| {
-            editor.set_error("Opening URL in external program failed")
-        })))
-    });
-}
-
 fn extend_word_impl<F>(cx: &mut Context, extend_fn: F)
 where
     F: Fn(RopeSlice, Range, usize) -> Range,

helix-term/src/lib.rs

@@ -12,9 +12,13 @@ pub mod keymap;
 pub mod ui;
 use std::path::Path;
 
+use futures_util::Future;
 use ignore::DirEntry;
+
 pub use keymap::macros::*;
 
+use url::Url;
+
 #[cfg(not(windows))]
 fn true_color() -> bool {
     std::env::var("COLORTERM")
@@ -47,3 +51,22 @@ fn filter_picker_entry(entry: &DirEntry, root: &Path, dedup_symlinks: bool) -> b
 
     true
 }
+
+/// Opens URL in external program.
+fn open_external_url_callback(
+    url: Url,
+) -> impl Future<Output = Result<job::Callback, anyhow::Error>> + Send + 'static {
+    let commands = open::commands(url.as_str());
+    async {
+        for cmd in commands {
+            let mut command = tokio::process::Command::new(cmd.get_program());
+            command.args(cmd.get_args());
+            if command.output().await.is_ok() {
+                return Ok(job::Callback::Editor(Box::new(|_| {})));
+            }
+        }
+        Ok(job::Callback::Editor(Box::new(move |editor| {
+            editor.set_error("Opening URL in external program failed")
+        })))
+    }
+}