feat(lsp): registry auto discovery (#10813)

Closes: #10194
Fixes: #10468

8 files changed, 355 insertions, 155 deletions

diff --git a/cli/lsp/README.md b/cli/lsp/README.md
index d480e3133..28ae50c6a 100644
--- a/cli/lsp/README.md
+++ b/cli/lsp/README.md
@@ -5,9 +5,8 @@ The Deno Language Server provides a server implementation of the
 which is specifically tailored to provide a _Deno_ view of code. It is
 integrated into the command line and can be started via the `lsp` sub-command.
 
-> :warning: The Language Server is highly experimental and far from feature
-> complete. This document gives an overview of the structure of the language
-> server.
+> :warning: The Language Server is experimental and not feature complete. This
+> document gives an overview of the structure of the language server.
 
 ## Structure
 
@@ -15,6 +14,60 @@ When the language server is started, a `LanguageServer` instance is created
 which holds all of the state of the language server. It also defines all of the
 methods that the client calls via the Language Server RPC protocol.
 
+## Settings
+
+There are several settings that the language server supports for a workspace:
+
+- `deno.enable`
+- `deno.config`
+- `deno.importMap`
+- `deno.codeLens.implementations`
+- `deno.codeLens.references`
+- `deno.codeLens.referencesAllFunctions`
+- `deno.suggest.completeFunctionCalls`
+- `deno.suggest.names`
+- `deno.suggest.paths`
+- `deno.suggest.autoImports`
+- `deno.suggest.imports.autoDiscover`
+- `deno.suggest.imports.hosts`
+- `deno.lint`
+- `deno.unstable`
+
+There are settings that are support on a per resource basis by the language
+server:
+
+- `deno.enable`
+
+There are several points in the process where Deno analyzes these settings.
+First, when the `initialize` request from the client, the
+`initializationOptions` will be assumed to be an object that represents the
+`deno` namespace of options. For example, the following value:
+
+```json
+{
+  "enable": true,
+  "unstable": true
+}
+```
+
+Would enable Deno with the unstable APIs for this instance of the language
+server.
+
+When the language server receives a `workspace/didChangeConfiguration`
+notification, it will assess if the client has indicated if it has a
+`workspaceConfiguration` capability. If it does, it will send a
+`workspace/configuration` request which will include a request for the workspace
+configuration as well as the configuration of all URIs that the language server
+is currently tracking.
+
+If the client has the `workspaceConfiguration` capability, the language server
+will send a configuration request for the URI when it received the
+`textDocument/didOpen` notification in order to get the resources specific
+settings.
+
+If the client does not have the `workspaceConfiguration` capability, the
+language server will assume the workspace setting applies to all resources.
+
 ## Custom requests
 
 The LSP currently supports the following custom requests. A client should
@@ -62,55 +115,27 @@ with Deno:
   }
   ```
 
-## Settings
-
-There are several settings that the language server supports for a workspace:
-
-- `deno.enable`
-- `deno.config`
-- `deno.import_map`
-- `deno.code_lens.implementations`
-- `deno.code_lens.references`
-- `deno.code_lens.references_all_functions`
-- `deno.suggest.complete_function_calls`
-- `deno.suggest.names`
-- `deno.suggest.paths`
-- `deno.suggest.auto_imports`
-- `deno.imports.hosts`
-- `deno.lint`
-- `deno.unstable`
-
-There are settings that are support on a per resource basis by the language
-server:
-
-- `deno.enable`
+## Custom notifications
 
-There are several points in the process where Deno analyzes these settings.
-First, when the `initialize` request from the client, the
-`initializationOptions` will be assumed to be an object that represents the
-`deno` namespace of options. For example, the following value:
-
-```json
-{
-  "enable": true,
-  "unstable": true
-}
-```
+There is currently one custom notification that is send from the server to the
+client:
 
-Would enable Deno with the unstable APIs for this instance of the language
-server.
+- `deno/registryStatus` - when `deno.suggest.imports.autoDiscover` is `true` and
+  an origin for an import being added to a document is not explicitly set in
+  `deno.suggest.imports.hosts`, the origin will be checked and the notification
+  will be sent to the client of the status.
 
-When the language server receives a `workspace/didChangeConfiguration`
-notification, it will assess if the client has indicated if it has a
-`workspaceConfiguration` capability. If it does, it will send a
-`workspace/configuration` request which will include a request for the workspace
-configuration as well as the configuration of all URIs that the language server
-is currently tracking.
+  When receiving the notification, if the param `suggestion` is `true`, the
+  client should offer the user the choice to enable the origin and add it to the
+  configuration for `deno.suggest.imports.hosts`. If `suggestion` is `false` the
+  client should add it to the configuration of as `false` to stop the language
+  server from attempting to detect if suggestions are supported.
 
-If the client has the `workspaceConfiguration` capability, the language server
-will send a configuration request for the URI when it received the
-`textDocument/didOpen` notification in order to get the resources specific
-settings.
+  The params for the notification are:
 
-If the client does not have the `workspaceConfiguration` capability, the
-language server will assume the workspace setting applies to all resources.
+  ```ts
+  interface RegistryStatusNotificationParams {
+    origin: string;
+    suggestions: boolean;
+  }
+  ```
diff --git a/cli/lsp/completions.rs b/cli/lsp/completions.rs
index 56abeb9d2..95a13d59a 100644
--- a/cli/lsp/completions.rs
+++ b/cli/lsp/completions.rs
@@ -2,6 +2,7 @@
 
 use super::analysis;
 use super::language_server;
+use super::lsp_custom;
 use super::tsc;
 
 use crate::fs_util::is_supported_ext;
@@ -9,6 +10,7 @@ use crate::media_type::MediaType;
 
 use deno_core::normalize_path;
 use deno_core::resolve_path;
+use deno_core::resolve_url;
 use deno_core::serde::Deserialize;
 use deno_core::serde::Serialize;
 use deno_core::url::Position;
@@ -34,6 +36,64 @@ pub struct CompletionItemData {
   pub tsc: Option<tsc::CompletionItemData>,
 }
 
+/// Check if the origin can be auto-configured for completions, and if so, send
+/// a notification to the client.
+async fn check_auto_config_registry(
+  url_str: &str,
+  snapshot: &language_server::StateSnapshot,
+  client: lspower::Client,
+) {
+  // check to see if auto discovery is enabled
+  if snapshot
+    .config
+    .settings
+    .workspace
+    .suggest
+    .imports
+    .auto_discover
+  {
+    if let Ok(specifier) = resolve_url(url_str) {
+      let scheme = specifier.scheme();
+      let path = &specifier[Position::BeforePath..];
+      if scheme.starts_with("http")
+        && !path.is_empty()
+        && url_str.ends_with(path)
+      {
+        // check to see if this origin is already explicitly set
+        let in_config = snapshot
+          .config
+          .settings
+          .workspace
+          .suggest
+          .imports
+          .hosts
+          .iter()
+          .any(|(h, _)| {
+            resolve_url(h).map(|u| u.origin()) == Ok(specifier.origin())
+          });
+        // if it isn't in the configuration, we will check to see if it supports
+        // suggestions and send a notification to the client.
+        if !in_config {
+          let origin = specifier.origin().ascii_serialization();
+          let suggestions = snapshot
+            .module_registries
+            .fetch_config(&origin)
+            .await
+            .is_ok();
+          client
+            .send_custom_notification::<lsp_custom::RegistryStateNotification>(
+              lsp_custom::RegistryStateNotificationParams {
+                origin,
+                suggestions,
+              },
+            )
+            .await;
+        }
+      }
+    }
+  }
+}
+
 /// Given a specifier, a position, and a snapshot, optionally return a
 /// completion response, which will be valid import completions for the specific
 /// context.
@@ -41,6 +101,7 @@ pub async fn get_import_completions(
   specifier: &ModuleSpecifier,
   position: &lsp::Position,
   state_snapshot: &language_server::StateSnapshot,
+  client: lspower::Client,
 ) -> Option<lsp::CompletionResponse> {
   if let Ok(Some(source)) = state_snapshot.documents.content(specifier) {
     let media_type = MediaType::from(specifier);
@@ -58,6 +119,8 @@ pub async fn get_import_completions(
       }
       // completion of modules from a module registry or cache
       if !current_specifier.is_empty() {
+        check_auto_config_registry(&current_specifier, state_snapshot, client)
+          .await;
         let offset = if position.character > range.start.character {
           (position.character - range.start.character) as usize
         } else {
@@ -808,11 +871,17 @@ mod tests {
   }
 
   #[tokio::test]
-  async fn test_get_import_completions() {
+  async fn test_get_workspace_completions() {
     let specifier = resolve_url("file:///a/b/c.ts").unwrap();
-    let position = lsp::Position {
-      line: 0,
-      character: 21,
+    let range = lsp::Range {
+      start: lsp::Position {
+        line: 0,
+        character: 20,
+      },
+      end: lsp::Position {
+        line: 0,
+        character: 21,
+      },
     };
     let state_snapshot = setup(
       &[
@@ -822,32 +891,29 @@ mod tests {
       &[("https://deno.land/x/a/b/c.ts", "console.log(1);\n")],
     );
     let actual =
-      get_import_completions(&specifier, &position, &state_snapshot).await;
+      get_workspace_completions(&specifier, "h", &range, &state_snapshot);
     assert_eq!(
       actual,
-      Some(lsp::CompletionResponse::List(lsp::CompletionList {
-        is_incomplete: false,
-        items: vec![lsp::CompletionItem {
-          label: "https://deno.land/x/a/b/c.ts".to_string(),
-          kind: Some(lsp::CompletionItemKind::File),
-          detail: Some("(remote)".to_string()),
-          sort_text: Some("1".to_string()),
-          text_edit: Some(lsp::CompletionTextEdit::Edit(lsp::TextEdit {
-            range: lsp::Range {
-              start: lsp::Position {
-                line: 0,
-                character: 20
-              },
-              end: lsp::Position {
-                line: 0,
-                character: 21,
-              }
+      vec![lsp::CompletionItem {
+        label: "https://deno.land/x/a/b/c.ts".to_string(),
+        kind: Some(lsp::CompletionItemKind::File),
+        detail: Some("(remote)".to_string()),
+        sort_text: Some("1".to_string()),
+        text_edit: Some(lsp::CompletionTextEdit::Edit(lsp::TextEdit {
+          range: lsp::Range {
+            start: lsp::Position {
+              line: 0,
+              character: 20
             },
-            new_text: "https://deno.land/x/a/b/c.ts".to_string(),
-          })),
-          ..Default::default()
-        }]
-      }))
+            end: lsp::Position {
+              line: 0,
+              character: 21,
+            }
+          },
+          new_text: "https://deno.land/x/a/b/c.ts".to_string(),
+        })),
+        ..Default::default()
+      }]
     );
   }
 }
diff --git a/cli/lsp/config.rs b/cli/lsp/config.rs
index 33f9122da..e46e8dd52 100644
--- a/cli/lsp/config.rs
+++ b/cli/lsp/config.rs
@@ -28,7 +28,7 @@ pub struct ClientCapabilities {
   pub line_folding_only: bool,
 }
 
-#[derive(Debug, Clone, Deserialize)]
+#[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
 #[serde(rename_all = "camelCase")]
 pub struct CodeLensSettings {
   /// Flag for providing implementation code lenses.
@@ -53,16 +53,20 @@ impl Default for CodeLensSettings {
   }
 }
 
-#[derive(Debug, Clone, Deserialize)]
+fn is_true() -> bool {
+  true
+}
+
+#[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
 #[serde(rename_all = "camelCase")]
 pub struct CompletionSettings {
   #[serde(default)]
   pub complete_function_calls: bool,
-  #[serde(default)]
+  #[serde(default = "is_true")]
   pub names: bool,
-  #[serde(default)]
+  #[serde(default = "is_true")]
   pub paths: bool,
-  #[serde(default)]
+  #[serde(default = "is_true")]
   pub auto_imports: bool,
   #[serde(default)]
   pub imports: ImportCompletionSettings,
@@ -80,9 +84,15 @@ impl Default for CompletionSettings {
   }
 }
 
-#[derive(Debug, Clone, Deserialize)]
+#[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
 #[serde(rename_all = "camelCase")]
 pub struct ImportCompletionSettings {
+  /// A flag that indicates if non-explicitly set origins should be checked for
+  /// supporting import suggestions.
+  #[serde(default = "is_true")]
+  pub auto_discover: bool,
+  /// A map of origins which have had explicitly set if import suggestions are
+  /// enabled.
   #[serde(default)]
   pub hosts: HashMap<String, bool>,
 }
@@ -90,6 +100,7 @@ pub struct ImportCompletionSettings {
 impl Default for ImportCompletionSettings {
   fn default() -> Self {
     Self {
+      auto_discover: true,
       hosts: HashMap::default(),
     }
   }
@@ -104,10 +115,11 @@ pub struct SpecifierSettings {
 }
 
 /// Deno language server specific settings that are applied to a workspace.
-#[derive(Debug, Default, Clone, Deserialize)]
+#[derive(Debug, Default, Clone, Deserialize, PartialEq, Eq)]
 #[serde(rename_all = "camelCase")]
 pub struct WorkspaceSettings {
   /// A flag that indicates if Deno is enabled for the workspace.
+  #[serde(default)]
   pub enable: bool,
 
   /// An option that points to a path string of the config file to apply to
@@ -420,4 +432,38 @@ mod tests {
       .expect("could not update");
     assert!(config.specifier_enabled(&specifier));
   }
+
+  #[test]
+  fn test_set_workspace_settings_defaults() {
+    let config = setup();
+    config
+      .set_workspace_settings(json!({}))
+      .expect("could not update");
+    assert_eq!(
+      config.get_workspace_settings(),
+      WorkspaceSettings {
+        enable: false,
+        config: None,
+        import_map: None,
+        code_lens: CodeLensSettings {
+          implementations: false,
+          references: false,
+          references_all_functions: false,
+        },
+        internal_debug: false,
+        lint: false,
+        suggest: CompletionSettings {
+          complete_function_calls: false,
+          names: true,
+          paths: true,
+          auto_imports: true,
+          imports: ImportCompletionSettings {
+            auto_discover: true,
+            hosts: HashMap::new(),
+          }
+        },
+        unstable: false,
+      }
+    );
+  }
 }
diff --git a/cli/lsp/language_server.rs b/cli/lsp/language_server.rs
index c8b959596..3a751e319 100644
--- a/cli/lsp/language_server.rs
+++ b/cli/lsp/language_server.rs
@@ -3,8 +3,6 @@
 use deno_core::error::anyhow;
 use deno_core::error::AnyError;
 use deno_core::resolve_url;
-use deno_core::serde::Deserialize;
-use deno_core::serde::Serialize;
 use deno_core::serde_json;
 use deno_core::serde_json::json;
 use deno_core::serde_json::Value;
@@ -44,6 +42,7 @@ use super::config::SETTINGS_SECTION;
 use super::diagnostics;
 use super::diagnostics::DiagnosticSource;
 use super::documents::DocumentCache;
+use super::lsp_custom;
 use super::performance::Performance;
 use super::registries;
 use super::sources;
@@ -385,10 +384,9 @@ impl Inner {
       .iter()
     {
       if *enabled {
-        info!("Enabling auto complete registry for: {}", registry);
+        info!("Enabling import suggestions for: {}", registry);
         self.module_registries.enable(registry).await?;
       } else {
-        info!("Disabling auto complete registry for: {}", registry);
         self.module_registries.disable(registry).await?;
       }
     }
@@ -552,17 +550,11 @@ impl Inner {
   async fn initialized(&mut self, _: InitializedParams) {
     // Check to see if we need to setup the import map
     if let Err(err) = self.update_import_map().await {
-      self
-        .client
-        .show_message(MessageType::Warning, err.to_string())
-        .await;
+      self.client.show_message(MessageType::Warning, err).await;
     }
     // Check to see if we need to setup any module registries
     if let Err(err) = self.update_registries().await {
-      self
-        .client
-        .show_message(MessageType::Warning, err.to_string())
-        .await;
+      self.client.show_message(MessageType::Warning, err).await;
     }
 
     if self
@@ -713,22 +705,13 @@ impl Inner {
 
     self.update_debug_flag();
     if let Err(err) = self.update_import_map().await {
-      self
-        .client
-        .show_message(MessageType::Warning, err.to_string())
-        .await;
+      self.client.show_message(MessageType::Warning, err).await;
     }
     if let Err(err) = self.update_registries().await {
-      self
-        .client
-        .show_message(MessageType::Warning, err.to_string())
-        .await;
+      self.client.show_message(MessageType::Warning, err).await;
     }
     if let Err(err) = self.update_tsconfig().await {
-      self
-        .client
-        .show_message(MessageType::Warning, err.to_string())
-        .await;
+      self.client.show_message(MessageType::Warning, err).await;
     }
     if let Err(err) = self.diagnostics_server.update() {
       error!("{}", err);
@@ -748,10 +731,7 @@ impl Inner {
     if let Some(import_map_uri) = &self.maybe_import_map_uri {
       if params.changes.iter().any(|fe| *import_map_uri == fe.uri) {
         if let Err(err) = self.update_import_map().await {
-          self
-            .client
-            .show_message(MessageType::Warning, err.to_string())
-            .await;
+          self.client.show_message(MessageType::Warning, err).await;
         }
       }
     }
@@ -759,10 +739,7 @@ impl Inner {
     if let Some(config_uri) = &self.maybe_config_uri {
       if params.changes.iter().any(|fe| *config_uri == fe.uri) {
         if let Err(err) = self.update_tsconfig().await {
-          self
-            .client
-            .show_message(MessageType::Warning, err.to_string())
-            .await;
+          self.client.show_message(MessageType::Warning, err).await;
         }
       }
     }
@@ -1549,6 +1526,7 @@ impl Inner {
       &specifier,
       &params.text_document_position.position,
       &self.snapshot()?,
+      self.client.clone(),
     )
     .await
     {
@@ -2004,27 +1982,31 @@ impl Inner {
     params: Option<Value>,
   ) -> LspResult<Option<Value>> {
     match method {
-      "deno/cache" => match params.map(serde_json::from_value) {
+      lsp_custom::CACHE_REQUEST => match params.map(serde_json::from_value) {
         Some(Ok(params)) => self.cache(params).await,
         Some(Err(err)) => Err(LspError::invalid_params(err.to_string())),
         None => Err(LspError::invalid_params("Missing parameters")),
       },
-      "deno/performance" => Ok(Some(self.get_performance())),
-      "deno/reloadImportRegistries" => self.reload_import_registries().await,
-      "deno/virtualTextDocument" => match params.map(serde_json::from_value) {
-        Some(Ok(params)) => Ok(Some(
-          serde_json::to_value(self.virtual_text_document(params).await?)
-            .map_err(|err| {
-              error!(
-                "Failed to serialize virtual_text_document response: {}",
-                err
-              );
-              LspError::internal_error()
-            })?,
-        )),
-        Some(Err(err)) => Err(LspError::invalid_params(err.to_string())),
-        None => Err(LspError::invalid_params("Missing parameters")),
-      },
+      lsp_custom::PERFORMANCE_REQUEST => Ok(Some(self.get_performance())),
+      lsp_custom::RELOAD_IMPORT_REGISTRIES_REQUEST => {
+        self.reload_import_registries().await
+      }
+      lsp_custom::VIRTUAL_TEXT_DOCUMENT => {
+        match params.map(serde_json::from_value) {
+          Some(Ok(params)) => Ok(Some(
+            serde_json::to_value(self.virtual_text_document(params).await?)
+              .map_err(|err| {
+                error!(
+                  "Failed to serialize virtual_text_document response: {}",
+                  err
+                );
+                LspError::internal_error()
+              })?,
+          )),
+          Some(Err(err)) => Err(LspError::invalid_params(err.to_string())),
+          None => Err(LspError::invalid_params("Missing parameters")),
+        }
+      }
       _ => {
         error!("Got a {} request, but no handler is defined", method);
         Err(LspError::method_not_found())
@@ -2437,28 +2419,14 @@ impl lspower::LanguageServer for LanguageServer {
   }
 }
 
-#[derive(Debug, Deserialize, Serialize)]
-#[serde(rename_all = "camelCase")]
-struct CacheParams {
-  /// The document currently open in the editor.  If there are no `uris`
-  /// supplied, the referrer will be cached.
-  referrer: TextDocumentIdentifier,
-  /// Any documents that have been specifically asked to be cached via the
-  /// command.
-  uris: Vec<TextDocumentIdentifier>,
-}
-
-#[derive(Debug, Deserialize, Serialize)]
-#[serde(rename_all = "camelCase")]
-struct VirtualTextDocumentParams {
-  text_document: TextDocumentIdentifier,
-}
-
 // These are implementations of custom commands supported by the LSP
 impl Inner {
   /// Similar to `deno cache` on the command line, where modules will be cached
   /// in the Deno cache, including any of their dependencies.
-  async fn cache(&mut self, params: CacheParams) -> LspResult<Option<Value>> {
+  async fn cache(
+    &mut self,
+    params: lsp_custom::CacheParams,
+  ) -> LspResult<Option<Value>> {
     let mark = self.performance.mark("cache", Some(&params));
     let referrer = self.url_map.normalize_url(&params.referrer.uri);
     if !params.uris.is_empty() {
@@ -2519,7 +2487,7 @@ impl Inner {
 
   async fn virtual_text_document(
     &mut self,
-    params: VirtualTextDocumentParams,
+    params: lsp_custom::VirtualTextDocumentParams,
   ) -> LspResult<Option<String>> {
     let mark = self
       .performance
diff --git a/cli/lsp/lsp_custom.rs b/cli/lsp/lsp_custom.rs
new file mode 100644
index 000000000..c543a6c1b
--- /dev/null
+++ b/cli/lsp/lsp_custom.rs
@@ -0,0 +1,42 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+use deno_core::serde::Deserialize;
+use deno_core::serde::Serialize;
+use lspower::lsp;
+
+pub const CACHE_REQUEST: &str = "deno/cache";
+pub const PERFORMANCE_REQUEST: &str = "deno/performance";
+pub const RELOAD_IMPORT_REGISTRIES_REQUEST: &str =
+  "deno/reloadImportRegistries";
+pub const VIRTUAL_TEXT_DOCUMENT: &str = "deno/virtualTextDocument";
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct CacheParams {
+  /// The document currently open in the editor.  If there are no `uris`
+  /// supplied, the referrer will be cached.
+  pub referrer: lsp::TextDocumentIdentifier,
+  /// Any documents that have been specifically asked to be cached via the
+  /// command.
+  pub uris: Vec<lsp::TextDocumentIdentifier>,
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+pub struct RegistryStateNotificationParams {
+  pub origin: String,
+  pub suggestions: bool,
+}
+
+pub enum RegistryStateNotification {}
+
+impl lsp::notification::Notification for RegistryStateNotification {
+  type Params = RegistryStateNotificationParams;
+
+  const METHOD: &'static str = "deno/registryState";
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct VirtualTextDocumentParams {
+  pub text_document: lsp::TextDocumentIdentifier,
+}
diff --git a/cli/lsp/mod.rs b/cli/lsp/mod.rs
index 9d9c1ff86..488507a5b 100644
--- a/cli/lsp/mod.rs
+++ b/cli/lsp/mod.rs
@@ -11,6 +11,7 @@ mod config;
 mod diagnostics;
 mod documents;
 pub(crate) mod language_server;
+mod lsp_custom;
 mod path_to_regex;
 mod performance;
 mod registries;
diff --git a/cli/lsp/registries.rs b/cli/lsp/registries.rs
index 877f03be3..29ec3258b 100644
--- a/cli/lsp/registries.rs
+++ b/cli/lsp/registries.rs
@@ -219,7 +219,7 @@ fn validate_config(config: &RegistryConfigurationJson) -> Result<(), AnyError> {
 }
 
 #[derive(Debug, Clone, Deserialize)]
-struct RegistryConfigurationVariable {
+pub(crate) struct RegistryConfigurationVariable {
   /// The name of the variable.
   key: String,
   /// The URL with variable substitutions of the endpoint that will provide
@@ -228,7 +228,7 @@ struct RegistryConfigurationVariable {
 }
 
 #[derive(Debug, Clone, Deserialize)]
-struct RegistryConfiguration {
+pub(crate) struct RegistryConfiguration {
   /// A Express-like path which describes how URLs are composed for a registry.
   schema: String,
   /// The variables denoted in the `schema` should have a variable entry.
@@ -339,7 +339,7 @@ impl ModuleRegistry {
   }
 
   /// Attempt to fetch the configuration for a specific origin.
-  async fn fetch_config(
+  pub(crate) async fn fetch_config(
     &self,
     origin: &str,
   ) -> Result<Vec<RegistryConfiguration>, AnyError> {
@@ -443,6 +443,11 @@ impl ModuleRegistry {
                         .await
                       {
                         let end = if p.is_some() { i + 1 } else { i };
+                        let end = if end > tokens.len() {
+                          tokens.len()
+                        } else {
+                          end
+                        };
                         let compiler = Compiler::new(&tokens[..end], None);
                         for (idx, item) in items.into_iter().enumerate() {
                           let label = if let Some(p) = &p {
diff --git a/cli/tests/integration_tests_lsp.rs b/cli/tests/integration_tests_lsp.rs
index 999d2de71..e4b963f2b 100644
--- a/cli/tests/integration_tests_lsp.rs
+++ b/cli/tests/integration_tests_lsp.rs
@@ -1840,6 +1840,53 @@ fn lsp_completions_registry_empty() {
 }
 
 #[test]
+fn lsp_auto_discover_registry() {
+  let _g = http_server();
+  let mut client = init("initialize_params.json");
+  did_open(
+    &mut client,
+    json!({
+      "textDocument": {
+        "uri": "file:///a/file.ts",
+        "languageId": "typescript",
+        "version": 1,
+        "text": "import * as a from \"http://localhost:4545/x/a@\""
+      }
+    }),
+  );
+  let (maybe_res, maybe_err) = client
+    .write_request::<_, _, Value>(
+      "textDocument/completion",
+      json!({
+        "textDocument": {
+          "uri": "file:///a/file.ts"
+        },
+        "position": {
+          "line": 0,
+          "character": 46
+        },
+        "context": {
+          "triggerKind": 2,
+          "triggerCharacter": "@"
+        }
+      }),
+    )
+    .unwrap();
+  assert!(maybe_err.is_none());
+  assert!(maybe_res.is_some());
+  let (method, maybe_res) = client.read_notification().unwrap();
+  assert_eq!(method, "deno/registryState");
+  assert_eq!(
+    maybe_res,
+    Some(json!({
+      "origin": "http://localhost:4545",
+      "suggestions": true,
+    }))
+  );
+  shutdown(&mut client);
+}
+
+#[test]
 fn lsp_diagnostics_warn() {
   let _g = http_server();
   let mut client = init("initialize_params.json");