diff --git a/editor.cpp b/editor.cpp
index 1ca01d7..76983ba 100644
--- a/editor.cpp
+++ b/editor.cpp
@@ -185,6 +185,7 @@ bool Editor::take_action() {
 					break;
 				case 'i':
 					mode = INSERT;
+					current_insert = file.get_line(file_offset + cur.r, 0);
 					break;
 				case 'v':
 					mode = SELECT;
@@ -223,40 +224,36 @@ bool Editor::take_action() {
 			}
 			break;
 		case INSERT:
-			// TODO remake insert mode for better undo
 			switch(ch) {
 				case ESC:
 					mode = NORMAL;
-					// Change current row into current_insert TODO
-					print_current_line();
+					file.set_line(cur.r, current_insert);
+					print_text(cur.r, Treap::substitute_tabs(current_insert));
+					current_insert = "";
 					break;
 				case BS:
-					// Modify current_insert TODO
 					if(cur.c > 0) {
 						cur.c -= 1;
-						file.remove(cur + file_offset);
+						current_insert.erase(cur.c - Treap::get_tab_offset(cur.c, current_insert), 1);
 					}
-					print_current_line();
+					print_text(cur.r, Treap::substitute_tabs(current_insert));
 					break;
 				case ENTER:
-					// Modify current_insert and update TODO
+					file.set_line(cur.r, current_insert);
 					file.split_line(cur + file_offset);
+					cur.r++; cur.c = 0; move(cur);
+					current_insert = file.get_line(cur.r);
 					print_file(file_offset);
-					cur.r++;
-					cur.c = 0;
-					move(cur);
 					break;
 				case '\t':
-					// Modify current_insert TODO
-					file.insert(cur + file_offset, "\t");
+					current_insert.insert(cur.c - Treap::get_tab_offset(cur.c, current_insert), "\t");
 					cur.c += TAB_SIZE - (cur.c % TAB_SIZE);
-					print_current_line();
+					print_text(cur.r, Treap::substitute_tabs(current_insert));
 					break;
 				default:
-					// Modify current_insert TODO
-					file.insert(cur + file_offset, string(1, ch));
+					current_insert.insert(cur.c - Treap::get_tab_offset(cur.c, current_insert), string(1, ch));
 					cur.c += 1;
-					print_current_line();
+					print_text(cur.r, Treap::substitute_tabs(current_insert));
 					break;
 			}
 			break;
diff --git a/everything.hpp b/everything.hpp
index 4dab148..125ecd2 100644
--- a/everything.hpp
+++ b/everything.hpp
@@ -40,8 +40,11 @@ class Treap {
 	line* find(count_type k);
 	count_type bulk_find(vector<string> *vec, line *l, count_type k, count_type count);
 
-	string substitute_tabs(string s);
 public:
+	static string substitute_tabs(string s);
+	static count_type get_tab_offset(count_type c, string text);
+	count_type get_tab_offset(position p) { return get_tab_offset(p.c, get_line(p.r, 0)); }
+
 	// General operations
 	Treap() { srand(120); root = nullptr; }
 	count_type size() { return get_size(root); }
@@ -50,11 +53,11 @@ public:
 	// Line operations
 	string get_line(count_type r, bool substitute_tab = 1);
 	vector<string> bulk_get_line(count_type r, count_type count);
-	count_type get_tab_offset(position p);
-	void split_line(position p);
 
+	void split_line(position p);
 	void insert(count_type k, string s);
 	void remove(count_type k);
+	void set_line(count_type k, string s) { find(k)->text = s; }
 
 	// Substring operations
 	void insert(position p, string t);
diff --git a/treap.cpp b/treap.cpp
index 4d0bc90..d14e82e 100644
--- a/treap.cpp
+++ b/treap.cpp
@@ -19,6 +19,17 @@ string Treap::substitute_tabs(string s) {
 	}
 	return ret;
 }
+// Get how much tabs changed position on a row
+count_type Treap::get_tab_offset(count_type c, string text) {
+	count_type tab_offset = 0;
+	for(count_type i = 0; i + tab_offset < c; ++i) {
+		if(text[i] == '\t')
+			tab_offset += TAB_SIZE - (i+tab_offset) % TAB_SIZE - 1;
+		if(i + tab_offset > c)
+			tab_offset -= i + tab_offset - c;
+	}
+	return tab_offset;
+}
 
 // Split treap by k-th element
 two_lines Treap::split(line *l, count_type k) {
@@ -147,18 +158,6 @@ vector<string> Treap::bulk_get_line(count_type r, count_type count) {
 	return ret;
 }
 
-// Get how much tabs changed position on a row
-count_type Treap::get_tab_offset(position p) {
-	count_type tab_offset = 0;
-	string line = get_line(p.r, false);
-	for(count_type i = 0; i + tab_offset < p.c; ++i) {
-		if(line[i] == '\t')
-			tab_offset += TAB_SIZE - (i+tab_offset) % TAB_SIZE - 1;
-		if(i + tab_offset > p.c)
-			tab_offset -= i + tab_offset - p.c;
-	}
-	return tab_offset;
-}
 void Treap::insert(position p, string t) {
 	find(p.r)->text.insert(p.c-get_tab_offset(p), t);
 }