diff --git a/crates/els/code_action.rs b/crates/els/code_action.rs
index eb5e991c..15ef747d 100644
--- a/crates/els/code_action.rs
+++ b/crates/els/code_action.rs
@@ -1,5 +1,7 @@
 use std::collections::HashMap;
 
+use erg_common::consts::ERG_MODE;
+use erg_common::deepen_indent;
 use erg_common::traits::Locational;
 use erg_compiler::artifact::BuildRunnable;
 use erg_compiler::erg_parser::token::{Token, TokenKind};
@@ -7,7 +9,7 @@ use erg_compiler::hir::Expr;
 
 use lsp_types::{
     CodeAction, CodeActionKind, CodeActionOrCommand, CodeActionParams, CodeActionResponse,
-    TextEdit, Url, WorkspaceEdit,
+    Position, Range, TextEdit, Url, WorkspaceEdit,
 };
 
 use crate::server::{send_log, ELSResult, Server};
@@ -16,10 +18,10 @@ use crate::util::{self, NormalizedUrl};
 impl<Checker: BuildRunnable> Server<Checker> {
     fn gen_eliminate_unused_vars_action(
         &self,
-        params: CodeActionParams,
+        params: &CodeActionParams,
     ) -> ELSResult<Option<CodeAction>> {
-        let uri = NormalizedUrl::new(params.text_document.uri);
-        let diags = params.context.diagnostics;
+        let uri = NormalizedUrl::new(params.text_document.uri.clone());
+        let diags = &params.context.diagnostics;
         let Some(diag) = diags.get(0).cloned() else {
             return Ok(None);
         };
@@ -134,7 +136,17 @@ impl<Checker: BuildRunnable> Server<Checker> {
         Some(action)
     }
 
-    fn send_normal_action(&self, params: CodeActionParams) -> ELSResult<Vec<CodeAction>> {
+    fn gen_extract_function_action(&self, params: &CodeActionParams) -> Option<CodeAction> {
+        let action = CodeAction {
+            title: "Extract into function".to_string(),
+            kind: Some(CodeActionKind::REFACTOR_EXTRACT),
+            data: Some(serde_json::to_value(params.clone()).unwrap()),
+            ..Default::default()
+        };
+        Some(action)
+    }
+
+    fn send_normal_action(&self, params: &CodeActionParams) -> ELSResult<Vec<CodeAction>> {
         let mut actions = vec![];
         let uri = NormalizedUrl::new(params.text_document.uri.clone());
         if let Some(token) = self.file_cache.get_token(&uri, params.range.start) {
@@ -144,10 +156,11 @@ impl<Checker: BuildRunnable> Server<Checker> {
             }
         }
         actions.extend(self.send_quick_fix(params)?);
+        actions.extend(self.gen_extract_function_action(params));
         Ok(actions)
     }
 
-    fn send_quick_fix(&self, params: CodeActionParams) -> ELSResult<Vec<CodeAction>> {
+    fn send_quick_fix(&self, params: &CodeActionParams) -> ELSResult<Vec<CodeAction>> {
         let mut result: Vec<CodeAction> = vec![];
         let diags = &params.context.diagnostics;
         if diags.is_empty() {
@@ -174,8 +187,8 @@ impl<Checker: BuildRunnable> Server<Checker> {
             .as_ref()
             .and_then(|kinds| kinds.first().map(|s| s.as_str()))
         {
-            Some("quickfix") => self.send_quick_fix(params)?,
-            None => self.send_normal_action(params)?,
+            Some("quickfix") => self.send_quick_fix(&params)?,
+            None => self.send_normal_action(&params)?,
             Some(other) => {
                 send_log(&format!("Unknown code action requested: {other}"))?;
                 vec![]
@@ -188,4 +201,42 @@ impl<Checker: BuildRunnable> Server<Checker> {
                 .collect(),
         ))
     }
+
+    pub(crate) fn handle_code_action_resolve(
+        &mut self,
+        action: CodeAction,
+    ) -> ELSResult<CodeAction> {
+        send_log(format!("code action resolve requested: {action:?}"))?;
+        match &action.title[..] {
+            "Extract into function" => self.resolve_extract_function_action(action),
+            _ => Ok(action),
+        }
+    }
+
+    fn resolve_extract_function_action(&self, mut action: CodeAction) -> ELSResult<CodeAction> {
+        let params = action
+            .data
+            .take()
+            .and_then(|v| serde_json::from_value::<CodeActionParams>(v).ok())
+            .ok_or("invalid params")?;
+        let uri = NormalizedUrl::new(params.text_document.uri);
+        let range = Range::new(Position::new(params.range.start.line, 0), params.range.end);
+        let code = self.file_cache.get_ranged(&uri, range)?.unwrap_or_default();
+        let indent_len = code.chars().take_while(|c| *c == ' ').count();
+        let code = deepen_indent(code);
+        let new_func = if ERG_MODE {
+            format!("{}new_func() =\n{code}\n\n", " ".repeat(indent_len))
+        } else {
+            format!("{}def new_func():\n{code}\n\n", " ".repeat(indent_len))
+        };
+        let edit1 = TextEdit::new(range, new_func);
+        let edit2 = TextEdit::new(
+            Range::new(range.end, range.end),
+            format!("{}new_func()", " ".repeat(indent_len)),
+        );
+        let mut changes = HashMap::new();
+        changes.insert(uri.raw(), vec![edit1, edit2]);
+        action.edit = Some(WorkspaceEdit::new(changes));
+        Ok(action)
+    }
 }
diff --git a/crates/els/command.rs b/crates/els/command.rs
index 2bc860ca..f0f90bb5 100644
--- a/crates/els/command.rs
+++ b/crates/els/command.rs
@@ -6,7 +6,8 @@ use erg_compiler::hir::Expr;
 
 use lsp_types::{Command, ExecuteCommandParams, Location, Url};
 
-use crate::server::{send_log, ELSResult, Server};
+use crate::_log;
+use crate::server::{ELSResult, Server};
 use crate::util::{self, NormalizedUrl};
 
 impl<Checker: BuildRunnable> Server<Checker> {
@@ -14,11 +15,11 @@ impl<Checker: BuildRunnable> Server<Checker> {
         &mut self,
         params: ExecuteCommandParams,
     ) -> ELSResult<Option<Value>> {
-        send_log(format!("command requested: {}", params.command))?;
+        _log!("command requested: {}", params.command);
         #[allow(clippy::match_single_binding)]
         match &params.command[..] {
             other => {
-                send_log(format!("unknown command: {other}"))?;
+                _log!("unknown command {other}: {params:?}");
                 Ok(None)
             }
         }
diff --git a/crates/els/server.rs b/crates/els/server.rs
index df6db2fd..108a7ff0 100644
--- a/crates/els/server.rs
+++ b/crates/els/server.rs
@@ -25,9 +25,9 @@ use erg_compiler::module::{SharedCompilerResource, SharedModuleIndex};
 use erg_compiler::ty::HasType;
 
 use lsp_types::request::{
-    CodeActionRequest, CodeLensRequest, Completion, ExecuteCommand, GotoDefinition, HoverRequest,
-    InlayHintRequest, References, Rename, Request, ResolveCompletionItem,
-    SemanticTokensFullRequest, SignatureHelpRequest, WillRenameFiles,
+    CodeActionRequest, CodeActionResolveRequest, CodeLensRequest, Completion, ExecuteCommand,
+    GotoDefinition, HoverRequest, InlayHintRequest, References, Rename, Request,
+    ResolveCompletionItem, SemanticTokensFullRequest, SignatureHelpRequest, WillRenameFiles,
 };
 use lsp_types::{
     ClientCapabilities, CodeActionKind, CodeActionOptions, CodeActionProviderCapability,
@@ -328,7 +328,7 @@ impl<Checker: BuildRunnable> Server<Checker> {
         } else {
             let options = CodeActionProviderCapability::Options(CodeActionOptions {
                 code_action_kinds: Some(vec![CodeActionKind::QUICKFIX, CodeActionKind::REFACTOR]),
-                resolve_provider: Some(false),
+                resolve_provider: Some(true),
                 work_done_progress_options: WorkDoneProgressOptions::default(),
             });
             Some(options)
@@ -491,6 +491,9 @@ impl<Checker: BuildRunnable> Server<Checker> {
             CodeActionRequest::METHOD => {
                 self.wrap::<CodeActionRequest>(id, msg, Self::handle_code_action)
             }
+            CodeActionResolveRequest::METHOD => {
+                self.wrap::<CodeActionResolveRequest>(id, msg, Self::handle_code_action_resolve)
+            }
             SignatureHelpRequest::METHOD => {
                 self.wrap::<SignatureHelpRequest>(id, msg, Self::handle_signature_help)
             }
diff --git a/crates/erg_common/lib.rs b/crates/erg_common/lib.rs
index 46560785..34bbd65d 100644
--- a/crates/erg_common/lib.rs
+++ b/crates/erg_common/lib.rs
@@ -189,3 +189,16 @@ pub fn trim_eliminate_top_indent(code: String) -> String {
     }
     result
 }
+
+pub fn deepen_indent(code: String) -> String {
+    let mut result = String::new();
+    for line in code.lines() {
+        result.push_str("    ");
+        result.push_str(line);
+        result.push('\n');
+    }
+    if !result.is_empty() {
+        result.pop();
+    }
+    result
+}