prepare for page

3 files changed, 104 insertions, 37 deletions

diff --git a/include/line/cursor.h b/include/line/cursor.h
index cdea934..7cae165 100644
--- a/include/line/cursor.h
+++ b/include/line/cursor.h
@@ -13,6 +13,12 @@ struct T_position
     int col;
 };
 
+enum class T_cursor_movement_direction
+{
+    LEFT,
+    RIGHT,
+};
+
 // 1-based
 inline int cursor_row;
 inline int cursor_col;
@@ -23,17 +29,23 @@ inline int window_size_row;
 inline int window_size_col;
 
 // 0-based index
-inline int line_buffer_index;
+inline int line_buffer_index_cursor;
+// index [begin, end] is displayed
+// NB: CLOSE interval
+inline int line_buffer_index_begin;
+inline int line_buffer_index_end;
 
 inline int buffer_len;
 
+inline std::string line_buffer;
+
 T_position get_cursor_position();
 
 void print_override(const std::string &s);
 
 void move_cursor(char c);
 
-void cursor_input(char c, std::string &buffer);
+void cursor_input_char(char c);
 
 int get_cursor_real_pos();
 
@@ -41,5 +53,7 @@ void update_window_size();
 
 void update_line_end_pos();
 
+void move_cursor(T_cursor_movement_direction d);
+
 }
 
diff --git a/src/line/cursor.cc b/src/line/cursor.cc
index 64c3da8..1489d61 100644
--- a/src/line/cursor.cc
+++ b/src/line/cursor.cc
@@ -48,20 +48,21 @@ T_position get_cursor_position()
 
 void print_override(const std::string &s)
 {
-
+    // save current cursor position
     print("\x1b[s"); fflush(stdout);
-    print("\r"); fflush(stdout);
 
     // move to the "start" of the zone
     // should skip prompt zone
+    print("\r"); fflush(stdout);
     print("\x1b[{}C", line_begin_pos-1); fflush(stdout);
 
-    // erase rest of it
+    // erase rest of the line
     print("\x1b[K"); fflush(stdout);
     
-    print("{}", s);
-    fflush(stdout);
+    print("{}", s.substr(line_buffer_index_begin, line_buffer_index_end-line_buffer_index_begin+1)); fflush(stdout);
     //line_end_pos = s.size()+1;
+
+    // restore cursor position
     print("\x1b[u"); fflush(stdout);
 }
 
@@ -80,50 +81,62 @@ void move_cursor(char c)
         //     cursor_row++;
         //     break;
         case 'C':
-            if (get_cursor_real_pos() < line_end_pos)
-            {
-                print("\x1b[C");
-                fflush(stdout);
-                line_buffer_index++;
-            }
+            // if (get_cursor_real_pos() < line_end_pos)
+            // {
+            //     // print("\x1b[C");
+            //     // fflush(stdout);
+            //     // line_buffer_index_cursor++;
+            //     move_cursor(T_cursor_movement_direction::RIGHT);
+            // }
+            move_cursor(T_cursor_movement_direction::RIGHT);
             break;
         case 'D':
-            if (get_cursor_real_pos() > line_begin_pos)
-            {
-                print("\x1b[D");
-                fflush(stdout);
-                line_buffer_index--;
-            }
+            // if (get_cursor_real_pos() > line_begin_pos)
+            // {
+            //     // print("\x1b[D");
+            //     // fflush(stdout);
+            //     // line_buffer_index_cursor--;
+            //     move_cursor(T_cursor_movement_direction::LEFT);
+            // }
+            move_cursor(T_cursor_movement_direction::LEFT);
             break;
         default:
             return;
     }
 }
 
-void cursor_input(char c, std::string &buffer)
+void cursor_input_char(char c)
 {
     // normal input
     if (c != '\b')
     {
-        buffer.insert(line_buffer_index, 1, c);
-        print("\x1b[C"); fflush(stdout);
-        line_buffer_index++;
-        buffer_len = buffer.size();
+        line_buffer.insert(line_buffer_index_cursor, 1, c);
+        // print("\x1b[C"); fflush(stdout); // move cursor to the right
+        // line_buffer_index_cursor++;
         update_line_end_pos();
+        int end_possible_buffer_index = window_size_col-line_begin_pos-1;
+        line_buffer_index_end = 
+            (end_possible_buffer_index > (line_buffer_index_end)+1) 
+            ? (line_buffer_index_end)+1
+            : end_possible_buffer_index;
+        move_cursor(T_cursor_movement_direction::RIGHT);
+        
         return;
     }
 
     // BACKSPACE
-    buffer.erase(line_buffer_index, 1);
-    print("\x1b[D"); fflush(stdout);
-    line_buffer_index--;
-    buffer_len = buffer.size();
+    line_buffer.erase(line_buffer_index_cursor, 1);
+    // print("\x1b[D"); fflush(stdout); // move cursor to the left
+    // line_buffer_index_cursor--;
     update_line_end_pos();
+    // TODO: backspace page
+    move_cursor(T_cursor_movement_direction::LEFT);
+    
 }
 
 int get_cursor_real_pos()
 {
-    return line_begin_pos + line_buffer_index;
+    return line_begin_pos + line_buffer_index_cursor;
 }
 
 void update_window_size() 
@@ -138,8 +151,49 @@ void update_window_size()
 
 void update_line_end_pos()
 {
-    line_end_pos = line_begin_pos + buffer_len;
+    line_end_pos = line_begin_pos + line_buffer.size();
     line_end_pos = (line_end_pos > window_size_col) ? window_size_col : line_end_pos;
 }
 
+void move_cursor(T_cursor_movement_direction d)
+{
+    switch (d)
+    {
+        case T_cursor_movement_direction::LEFT:
+            // if cursor is not at left margin
+            if (line_begin_pos < (line_buffer_index_cursor+1))
+            {
+                line_buffer_index_cursor--;
+                print("\x1b[D"); fflush(stdout); // move cursor to the left
+            }
+            // margin
+            else
+            {
+                line_buffer_index_cursor--;
+                line_buffer_index_begin--;
+                line_buffer_index_end--;
+            }
+            break;
+
+        case T_cursor_movement_direction::RIGHT:
+            // if cursor is not at right margin
+            if (line_end_pos > (line_buffer_index_cursor+1))
+            {
+                line_buffer_index_cursor++;
+                print("\x1b[C"); fflush(stdout); // move cursor to the right
+            }
+            // margin
+            else
+            {
+                line_buffer_index_cursor++;
+                line_buffer_index_begin++;
+                line_buffer_index_end++;
+            }
+            break;
+
+        default:
+            exit(-1); // TODO: fix
+    }
+}
+
 }
diff --git a/src/line/mode.cc b/src/line/mode.cc
index 80e8531..7a91528 100644
--- a/src/line/mode.cc
+++ b/src/line/mode.cc
@@ -20,7 +20,7 @@ void disable_raw()
 
 void enable_raw()
 {
-    if (raw_enabled == false) return;
+    if (raw_enabled) return;
      
     raw_enabled = true;
     termios attr_raw;
@@ -72,7 +72,6 @@ string readline()
 
     T_position pos = get_cursor_position();
     line_begin_pos = pos.col;
-    string buffer;
     char c;
     while (read(STDIN_FILENO, &c, 1) == 1)
     {
@@ -91,8 +90,8 @@ string readline()
             //fflush(stdout);
             if (c == 13) // \n
             {
-                //print("line: {}\r\n", buffer);
-                return buffer;
+                //print("line: {}\r\n", line_buffer);
+                return line_buffer;
             }
 
             // ESC sequence
@@ -113,11 +112,11 @@ string readline()
         // normal char
         else
         {
-            cursor_input(c, buffer);
-            print_override(buffer);
+            cursor_input_char(c);
+            print_override(line_buffer);
         }
     }
-    return buffer;
+    return line_buffer;
 }