ruff: Refactor language server loading (#15852)

This PR refactors the language server loading in the Ruff extension to
mirror our other extensions.

Also fixed an issue where the cached binary path was not being
respected.

Release Notes:

- N/A

extensions/ruff/src/ruff.rs

@@ -2,18 +2,49 @@ use std::fs;
 use zed::LanguageServerId;
 use zed_extension_api::{self as zed, settings::LspSettings, Result};
 
+struct RuffBinary {
+    path: String,
+    args: Option<Vec<String>>,
+}
+
 struct RuffExtension {
     cached_binary_path: Option<String>,
 }
 
 impl RuffExtension {
-    fn language_server_binary_path(
+    fn language_server_binary(
         &mut self,
         language_server_id: &LanguageServerId,
         worktree: &zed::Worktree,
-    ) -> Result<String> {
+    ) -> Result<RuffBinary> {
+        let binary_settings = LspSettings::for_worktree("ruff", worktree)
+            .ok()
+            .and_then(|lsp_settings| lsp_settings.binary);
+        let binary_args = binary_settings
+            .as_ref()
+            .and_then(|binary_settings| binary_settings.arguments.clone());
+
+        if let Some(path) = binary_settings.and_then(|binary_settings| binary_settings.path) {
+            return Ok(RuffBinary {
+                path,
+                args: binary_args,
+            });
+        }
+
         if let Some(path) = worktree.which("ruff") {
-            return Ok(path);
+            return Ok(RuffBinary {
+                path,
+                args: binary_args,
+            });
+        }
+
+        if let Some(path) = &self.cached_binary_path {
+            if fs::metadata(&path).map_or(false, |stat| stat.is_file()) {
+                return Ok(RuffBinary {
+                    path: path.clone(),
+                    args: binary_args,
+                });
+            }
         }
 
         zed::set_language_server_installation_status(
@@ -83,7 +114,10 @@ impl RuffExtension {
         }
 
         self.cached_binary_path = Some(binary_path.clone());
-        Ok(binary_path)
+        Ok(RuffBinary {
+            path: binary_path,
+            args: binary_args,
+        })
     }
 }
 
@@ -96,31 +130,13 @@ impl zed::Extension for RuffExtension {
 
     fn language_server_command(
         &mut self,
-        server_id: &LanguageServerId,
+        language_server_id: &LanguageServerId,
         worktree: &zed::Worktree,
     ) -> Result<zed::Command> {
-        let mut binary = None;
-        let mut args = None;
-        if let Some(binary_settings) = LspSettings::for_worktree(server_id.as_ref(), worktree)
-            .ok()
-            .and_then(|lsp_settings| lsp_settings.binary)
-        {
-            if let Some(bin_path) = binary_settings.path {
-                binary = Some(bin_path);
-            }
-            if let Some(bin_args) = binary_settings.arguments {
-                args = Some(bin_args);
-            }
-        }
-        let command = if let Some(binary) = binary {
-            binary
-        } else {
-            self.language_server_binary_path(server_id, worktree)?
-        };
-        let args = args.unwrap_or_else(|| vec!["server".into()]);
+        let ruff_binary = self.language_server_binary(language_server_id, worktree)?;
         Ok(zed::Command {
-            command,
-            args,
+            command: ruff_binary.path,
+            args: ruff_binary.args.unwrap_or_else(|| vec!["server".into()]),
             env: vec![],
         })
     }