really jank file preview in grep panel

src/core/core.odin

@@ -102,10 +102,12 @@ FileBufferPanel :: struct {
 
 GrepPanel :: struct {
     query_arena: mem.Arena,
+    query_region: mem.Arena_Temp_Memory,
     buffer: int,
     selected_result: int,
     search_query: string,
     query_results: []GrepQueryResult,
+    glyphs: GlyphBuffer,
 }
 
 GrepQueryResult :: struct {

src/core/file_buffer.odin

@@ -43,11 +43,6 @@ Selection :: struct {
     end: Cursor,
 }
 
-Glyph :: struct {
-    codepoint: u8,
-    color: theme.PaletteColor,
-}
-
 FileBuffer :: struct {
     allocator: mem.Allocator,
 
@@ -63,9 +58,7 @@ FileBuffer :: struct {
     added_content: [dynamic]u8,
     content_slices: [dynamic][]u8,
 
-    glyph_buffer_width: int,
-    glyph_buffer_height: int,
-    glyph_buffer: [dynamic]Glyph,
+    glyphs: GlyphBuffer,
 
     input_buffer: [dynamic]u8,
 }
@@ -527,9 +520,12 @@ move_cursor_down :: proc(buffer: ^FileBuffer, amount: int = 1, cursor: Maybe(^Cu
             break;
         }
     }
+    if it.hit_end {
+        return
+    }
 
     line_length := file_buffer_line_length(buffer, it.cursor.index);
-    if it.cursor.col < line_length && it.cursor.col < current_col {
+    if it.cursor.col < line_length-1 && it.cursor.col < current_col {
         for _ in iterate_file_buffer(&it) {
             if it.cursor.col >= line_length-1 || it.cursor.col >= current_col {
                 break;
@@ -705,10 +701,7 @@ new_virtual_file_buffer :: proc(allocator: mem.Allocator) -> FileBuffer {
         added_content = make([dynamic]u8, 0, 1024*1024),
         content_slices = make([dynamic][]u8, 0, 1024*1024),
 
-        glyph_buffer_width = width,
-        glyph_buffer_height = height,
-        glyph_buffer = make([dynamic]Glyph, width*height, width*height),
-
+        glyphs = make_glyph_buffer(width, height),
         input_buffer = make([dynamic]u8, 0, 1024),
     };
 
@@ -760,10 +753,7 @@ new_file_buffer :: proc(allocator: mem.Allocator, file_path: string, base_dir: s
             added_content = make([dynamic]u8, 0, 1024*1024),
             content_slices = make([dynamic][]u8, 0, 1024*1024),
 
-            glyph_buffer_width = width,
-            glyph_buffer_height = height,
-            glyph_buffer = make([dynamic]Glyph, width*height, width*height),
-
+            glyphs = make_glyph_buffer(width, height),
             input_buffer = make([dynamic]u8, 0, 1024),
         };
 
@@ -809,11 +799,12 @@ next_buffer :: proc(state: ^State, prev_buffer: ^int) -> int {
     return index;
 }
 
+// TODO: replace this with arena for the file buffer
 free_file_buffer :: proc(buffer: ^FileBuffer) {
     delete(buffer.original_content);
     delete(buffer.added_content);
     delete(buffer.content_slices);
-    delete(buffer.glyph_buffer);
+    delete(buffer.glyphs.buffer);
     delete(buffer.input_buffer);
 }
 
@@ -827,9 +818,9 @@ color_character :: proc(buffer: ^FileBuffer, start: Cursor, end: Cursor, palette
         start.line -= buffer.top_line;
     }
 
-    if end.line >= buffer.top_line + buffer.glyph_buffer_height {
-        end.line = buffer.glyph_buffer_height - 1;
-        end.col = buffer.glyph_buffer_width - 1;
+    if end.line >= buffer.top_line + buffer.glyphs.height {
+        end.line = buffer.glyphs.height - 1;
+        end.col = buffer.glyphs.width - 1;
     } else {
         end.line -= buffer.top_line;
     }
@@ -839,72 +830,19 @@ color_character :: proc(buffer: ^FileBuffer, start: Cursor, end: Cursor, palette
         end_col := end.col;
         if j > start.line && j < end.line {
             start_col = 0;
-            end_col = buffer.glyph_buffer_width;
+            end_col = buffer.glyphs.width;
         } else if j < end.line {
-            end_col = buffer.glyph_buffer_width;
+            end_col = buffer.glyphs.width;
         } else if j > start.line && j == end.line {
             start_col = 0;
         }
 
-        for i in start_col..<math.min(end_col+1, buffer.glyph_buffer_width) {
-            buffer.glyph_buffer[i + j * buffer.glyph_buffer_width].color = palette_index;
+        for i in start_col..<math.min(end_col+1, buffer.glyphs.width) {
+            buffer.glyphs.buffer[i + j * buffer.glyphs.width].color = palette_index;
         }
     }
 }
 
-update_glyph_buffer :: proc(buffer: ^FileBuffer) {
-    for &glyph in buffer.glyph_buffer {
-        glyph = Glyph{};
-    }
-
-    begin := buffer.top_line;
-    rendered_col: int;
-    rendered_line: int;
-
-    it := new_file_buffer_iter(buffer);
-    for character in iterate_file_buffer(&it) {
-        if character == '\r' { continue; }
-
-        screen_line := rendered_line - begin;
-        // don't render past the screen
-        if rendered_line >= begin && screen_line >= buffer.glyph_buffer_height { break; }
-
-        // render INSERT mode text into glyph buffer
-        if len(buffer.input_buffer) > 0 && rendered_line == buffer.cursor.line && rendered_col >= buffer.cursor.col && rendered_col < buffer.cursor.col + len(buffer.input_buffer) {
-            for k in 0..<len(buffer.input_buffer) {
-                screen_line = rendered_line - begin;
-
-                if buffer.input_buffer[k] == '\n' {
-                    rendered_col = 0;
-                    rendered_line += 1;
-                    continue;
-                }
-
-                if rendered_line >= begin && rendered_col < buffer.glyph_buffer_width {
-                    buffer.glyph_buffer[rendered_col + screen_line * buffer.glyph_buffer_width].color = .Foreground;
-                    buffer.glyph_buffer[rendered_col + screen_line * buffer.glyph_buffer_width].codepoint = buffer.input_buffer[k];
-
-                    rendered_col += 1;
-                }
-            }
-        }
-
-        screen_line = rendered_line - begin;
-
-        if character == '\n' {
-            rendered_col = 0;
-            rendered_line += 1;
-            continue;
-        }
-
-        if rendered_line >= begin && rendered_col < buffer.glyph_buffer_width {
-            buffer.glyph_buffer[rendered_col + screen_line * buffer.glyph_buffer_width] = Glyph { codepoint = character, color = .Foreground };
-        }
-
-        rendered_col += 1;
-    }
-}
-
 draw_file_buffer :: proc(state: ^State, buffer: ^FileBuffer, x: int, y: int, show_line_numbers: bool = true) {
     update_glyph_buffer(buffer);
 
@@ -961,7 +899,8 @@ draw_file_buffer :: proc(state: ^State, buffer: ^FileBuffer, x: int, y: int, sho
         draw_rect(state, cursor_x, cursor_y, state.source_font_width, state.source_font_height, .Blue);
     }
 
-    for j in 0..<buffer.glyph_buffer_height {
+    // TODO: replace with glyph_buffer.draw_glyph_buffer
+    for j in 0..<buffer.glyphs.height {
         text_y := y + state.source_font_height * j;
 
         if show_line_numbers {
@@ -969,9 +908,9 @@ draw_file_buffer :: proc(state: ^State, buffer: ^FileBuffer, x: int, y: int, sho
         }
 
         line_length := 0;
-        for i in 0..<buffer.glyph_buffer_width {
+        for i in 0..<buffer.glyphs.width {
             text_x := x + padding + i * state.source_font_width;
-            glyph := buffer.glyph_buffer[i + j * buffer.glyph_buffer_width];
+            glyph := buffer.glyphs.buffer[i + j * buffer.glyphs.width];
 
             if glyph.codepoint == 0 { break; }
             line_length += 1;
@@ -1015,14 +954,14 @@ update_file_buffer_scroll :: proc(buffer: ^FileBuffer, cursor: Maybe(^Cursor) =
         cursor = &buffer.cursor;
     }
 
-    if cursor.?.line > (buffer.top_line + buffer.glyph_buffer_height - 5) {
-        buffer.top_line = math.max(cursor.?.line - buffer.glyph_buffer_height + 5, 0);
+    if cursor.?.line > (buffer.top_line + buffer.glyphs.height - 5) {
+        buffer.top_line = math.max(cursor.?.line - buffer.glyphs.height + 5, 0);
     } else if cursor.?.line < (buffer.top_line + 5) {
         buffer.top_line = math.max(cursor.?.line - 5, 0);
     }
 
-    // if buffer.cursor.line > (buffer.top_line + buffer.glyph_buffer_height - 5) {
-    //     buffer.top_line = math.max(buffer.cursor.line - buffer.glyph_buffer_height + 5, 0);
+    // if buffer.cursor.line > (buffer.top_line + buffer.glyphs.height - 5) {
+    //     buffer.top_line = math.max(buffer.cursor.line - buffer.glyphs.height + 5, 0);
     // } else if buffer.cursor.line < (buffer.top_line + 5) {
     //     buffer.top_line = math.max(buffer.cursor.line - 5, 0);
     // }

src/core/glyph_buffer.odin

@@ -0,0 +1,139 @@
+package core
+
+import "core:fmt"
+
+import "../theme"
+
+GlyphBuffer :: struct {
+    buffer: []Glyph,
+    width: int,
+    height: int,
+}
+
+Glyph :: struct {
+    codepoint: u8,
+    color: theme.PaletteColor,
+}
+
+make_glyph_buffer :: proc(width, height: int, allocator := context.allocator) -> GlyphBuffer {
+    context.allocator = allocator
+
+    return GlyphBuffer {
+        width = width,
+        height = height,
+        buffer = make([]Glyph, width*height)
+    }
+}
+
+update_glyph_buffer_from_file_buffer :: proc(buffer: ^FileBuffer) {
+    for &glyph in buffer.glyphs.buffer {
+        glyph = Glyph{};
+    }
+
+    begin := buffer.top_line;
+    rendered_col: int;
+    rendered_line: int;
+
+    it := new_file_buffer_iter(buffer);
+    for character in iterate_file_buffer(&it) {
+        if character == '\r' { continue; }
+
+        screen_line := rendered_line - begin;
+        // don't render past the screen
+        if rendered_line >= begin && screen_line >= buffer.glyphs.height { break; }
+
+        // render INSERT mode text into glyph buffer
+        if len(buffer.input_buffer) > 0 && rendered_line == buffer.cursor.line && rendered_col >= buffer.cursor.col && rendered_col < buffer.cursor.col + len(buffer.input_buffer) {
+            for k in 0..<len(buffer.input_buffer) {
+                screen_line = rendered_line - begin;
+
+                if buffer.input_buffer[k] == '\n' {
+                    rendered_col = 0;
+                    rendered_line += 1;
+                    continue;
+                }
+
+                if rendered_line >= begin && rendered_col < buffer.glyphs.width {
+                    buffer.glyphs.buffer[rendered_col + screen_line * buffer.glyphs.width].color = .Foreground;
+                    buffer.glyphs.buffer[rendered_col + screen_line * buffer.glyphs.width].codepoint = buffer.input_buffer[k];
+
+                    rendered_col += 1;
+                }
+            }
+        }
+
+        screen_line = rendered_line - begin;
+
+        if character == '\n' {
+            rendered_col = 0;
+            rendered_line += 1;
+            continue;
+        }
+
+        if rendered_line >= begin && rendered_col < buffer.glyphs.width {
+            buffer.glyphs.buffer[rendered_col + screen_line * buffer.glyphs.width] = Glyph { codepoint = character, color = .Foreground };
+        }
+
+        rendered_col += 1;
+    }
+}
+
+update_glyph_buffer_from_bytes :: proc(glyphs: ^GlyphBuffer, data: []u8, top_line: int) {
+    for &glyph in glyphs.buffer {
+        glyph = Glyph{};
+    }
+
+    begin := top_line;
+    rendered_col: int;
+    rendered_line: int;
+
+    for character in data {
+        if character == '\r' { continue; }
+
+        screen_line := rendered_line - begin;
+        // don't render past the screen
+        if rendered_line >= begin && screen_line >= glyphs.height { break; }
+
+        screen_line = rendered_line - begin;
+
+        if character == '\n' {
+            rendered_col = 0;
+            rendered_line += 1;
+            continue;
+        }
+
+        if rendered_line >= begin && rendered_col < glyphs.width {
+            glyphs.buffer[rendered_col + screen_line * glyphs.width] = Glyph { codepoint = character, color = .Foreground };
+        }
+
+        rendered_col += 1;
+    }
+}
+
+update_glyph_buffer :: proc{update_glyph_buffer_from_file_buffer, update_glyph_buffer_from_bytes}
+
+draw_glyph_buffer :: proc(state: ^State, glyphs: ^GlyphBuffer, x: int, y: int, top_line: int, show_line_numbers: bool = true) {
+    padding := 0;
+    if show_line_numbers {
+        padding = state.source_font_width * 5;
+    }
+
+    for j in 0..<glyphs.height {
+        text_y := y + state.source_font_height * j;
+
+        if show_line_numbers {
+            draw_text(state, fmt.tprintf("%d", top_line + j + 1), x, text_y);
+        }
+
+        line_length := 0;
+        for i in 0..<glyphs.width {
+            text_x := x + padding + i * state.source_font_width;
+            glyph := glyphs.buffer[i + j * glyphs.width];
+
+            if glyph.codepoint == 0 { break; }
+            line_length += 1;
+
+            draw_codepoint(state, rune(glyph.codepoint), text_x, text_y, glyph.color);
+        }
+    }
+}

src/input/input.odin

@@ -1,5 +1,6 @@
 package input
 
+import "base:runtime"
 import "core:log"
 
 import "vendor:sdl2"
@@ -220,11 +221,16 @@ register_default_text_input_actions :: proc(input_map: ^core.InputActions) {
     // TODO: add shift+o to insert newline above current one
 
     core.register_key_action(input_map, .O, proc(state: ^State) {
-        core.move_cursor_end_of_line(core.current_buffer(state), false);
-        core.insert_content(core.current_buffer(state), []u8{'\n'});
+        if buffer := core.current_buffer(state); buffer != nil {
+            core.move_cursor_end_of_line(buffer, false);
+            runtime.clear(&buffer.input_buffer)
+
+            append(&buffer.input_buffer, '\n')
+
             state.mode = .Insert;
 
             sdl2.StartTextInput();
+        }
     }, "insert mode on newline");
 
     // Copy-Paste

src/main.odin

@@ -54,8 +54,8 @@ ui_font_height :: proc() -> i32 {
 
 draw :: proc(state: ^State) {
     if buffer := core.current_buffer(state); buffer != nil {
-        buffer.glyph_buffer_height = math.min(256, int((state.screen_height - state.source_font_height*2) / state.source_font_height)) + 1;
-        buffer.glyph_buffer_width = math.min(256, int((state.screen_width - state.source_font_width) / state.source_font_width));
+        buffer.glyphs.height = math.min(256, int((state.screen_height - state.source_font_height*2) / state.source_font_height)) + 1;
+        buffer.glyphs.width = math.min(256, int((state.screen_width - state.source_font_width) / state.source_font_width));
     }
 
     render_color := theme.get_palette_color(.Background);
@@ -168,8 +168,8 @@ ui_file_buffer :: proc(s: ^ui.State, buffer: ^FileBuffer) {
     draw_func := proc(state: ^State, e: ui.UI_Element, user_data: rawptr) {
         buffer := transmute(^FileBuffer)user_data;
         if buffer != nil {
-            buffer.glyph_buffer_width = e.layout.size.x / state.source_font_width;
-            buffer.glyph_buffer_height = e.layout.size.y / state.source_font_height + 1;
+            buffer.glyphs.width = e.layout.size.x / state.source_font_width;
+            buffer.glyphs.height = e.layout.size.y / state.source_font_height + 1;
 
             core.draw_file_buffer(state, buffer, e.layout.pos.x, e.layout.pos.y);
         }

src/panels/panels.odin

@@ -120,7 +120,9 @@ close :: proc(state: ^core.State, panel_id: int) {
         util.delete(&state.panels, panel_id)
 
         // TODO: keep track of the last active panel instead of focusing back to the first one
-        state.current_panel = util.get_first_active_index(&state.panels).?
+        if first_active, ok := util.get_first_active_index(&state.panels).?; ok {
+            state.current_panel = first_active
+        }
 
         core.reset_input_map(state)
     }
@@ -152,8 +154,8 @@ render_file_buffer :: proc(state: ^core.State, s: ^ui.State, buffer: ^core.FileB
     draw_func := proc(state: ^core.State, e: ui.UI_Element, user_data: rawptr) {
         buffer := transmute(^core.FileBuffer)user_data;
         if buffer != nil {
-            buffer.glyph_buffer_width = e.layout.size.x / state.source_font_width;
-            buffer.glyph_buffer_height = e.layout.size.y / state.source_font_height + 1;
+            buffer.glyphs.width = e.layout.size.x / state.source_font_width;
+            buffer.glyphs.height = e.layout.size.y / state.source_font_height + 1;
 
             core.draw_file_buffer(state, buffer, e.layout.pos.x, e.layout.pos.y);
         }
@@ -205,8 +207,8 @@ render_raw_buffer :: proc(state: ^core.State, s: ^ui.State, buffer: ^core.FileBu
     draw_func := proc(state: ^core.State, e: ui.UI_Element, user_data: rawptr) {
         buffer := transmute(^core.FileBuffer)user_data;
         if buffer != nil {
-            buffer.glyph_buffer_width = e.layout.size.x / state.source_font_width;
-            buffer.glyph_buffer_height = e.layout.size.y / state.source_font_height + 1;
+            buffer.glyphs.width = e.layout.size.x / state.source_font_width;
+            buffer.glyphs.height = e.layout.size.y / state.source_font_height + 1;
 
             core.draw_file_buffer(state, buffer, e.layout.pos.x, e.layout.pos.y, false);
         }
@@ -219,6 +221,24 @@ render_raw_buffer :: proc(state: ^core.State, s: ^ui.State, buffer: ^core.FileBu
     
 }
 
+render_glyph_buffer :: proc(state: ^core.State, s: ^ui.State, glyphs: ^core.GlyphBuffer) {
+    draw_func := proc(state: ^core.State, e: ui.UI_Element, user_data: rawptr) {
+        glyphs := transmute(^core.GlyphBuffer)user_data;
+        if glyphs != nil {
+            glyphs.width = e.layout.size.x / state.source_font_width;
+            glyphs.height = e.layout.size.y / state.source_font_height + 1;
+
+            core.draw_glyph_buffer(state, glyphs, e.layout.pos.x, e.layout.pos.y, 0, true);
+        }
+    };
+
+    ui.open_element(s, ui.UI_Element_Kind_Custom{fn = draw_func, user_data = transmute(rawptr)glyphs}, {
+        kind = {ui.Grow{}, ui.Grow{}}
+    })
+    ui.close_element(s)
+    
+}
+
 make_file_buffer_panel :: proc(buffer_index: int) -> core.Panel {
     input_map := core.new_input_map()
 
@@ -256,15 +276,19 @@ make_file_buffer_panel :: proc(buffer_index: int) -> core.Panel {
 
 make_grep_panel :: proc(state: ^core.State) -> core.Panel {
     query_arena: mem.Arena
-    mem.arena_init(&query_arena, make([]u8, 1024*1024, state.ctx.allocator))
+    mem.arena_init(&query_arena, make([]u8, 1024*1024*2, state.ctx.allocator))
+
+    glyphs := core.make_glyph_buffer(256,256, allocator = mem.arena_allocator(&query_arena))
 
     input_map := core.new_input_map()
     grep_input_buffer := core.new_virtual_file_buffer(context.allocator)
     runtime.append(&state.buffers, grep_input_buffer)
 
     run_query :: proc(panel_state: ^core.GrepPanel, query: string, directory: string) {
-        mem.arena_free_all(&panel_state.query_arena)
-        panel_state.query_results = nil
+        if panel_state.query_region.arena != nil {
+            mem.end_arena_temp_memory(panel_state.query_region)
+        }
+        panel_state.query_region = mem.begin_arena_temp_memory(&panel_state.query_arena)
 
         context.allocator = mem.arena_allocator(&panel_state.query_arena)
 
@@ -275,6 +299,13 @@ make_grep_panel :: proc(state: ^core.State) -> core.Panel {
 
         panel_state.query_results = rs_grep_as_results(&rs_results)
         free_grep_results(rs_results)
+
+        panel_state.selected_result = 0
+        core.update_glyph_buffer_from_bytes(
+            &panel_state.glyphs,
+            transmute([]u8)panel_state.query_results[panel_state.selected_result].file_context,
+            panel_state.query_results[panel_state.selected_result].line,
+        )
     }
 
     core.register_key_action(&input_map.mode[.Normal], .ENTER, proc(state: ^core.State) {
@@ -308,6 +339,12 @@ make_grep_panel :: proc(state: ^core.State) -> core.Panel {
             if panel_state, ok := &current_panel.panel_state.(core.GrepPanel); ok {
                 // TODO: bounds checking
                 panel_state.selected_result -= 1
+
+                core.update_glyph_buffer_from_bytes(
+                    &panel_state.glyphs,
+                    transmute([]u8)panel_state.query_results[panel_state.selected_result].file_context,
+                    panel_state.query_results[panel_state.selected_result].line,
+                )
             }
         }
     }, "move selection up");
@@ -318,6 +355,12 @@ make_grep_panel :: proc(state: ^core.State) -> core.Panel {
             if panel_state, ok := &current_panel.panel_state.(core.GrepPanel); ok {
                 // TODO: bounds checking
                 panel_state.selected_result += 1
+
+                core.update_glyph_buffer_from_bytes(
+                    &panel_state.glyphs,
+                    transmute([]u8)panel_state.query_results[panel_state.selected_result].file_context,
+                    panel_state.query_results[panel_state.selected_result].line,
+                )
             }
         }
     }, "move selection down");
@@ -338,6 +381,7 @@ make_grep_panel :: proc(state: ^core.State) -> core.Panel {
             query_arena = query_arena,
             buffer = len(state.buffers)-1,
             query_results = nil,
+            glyphs = glyphs,
         },
         input_map = input_map,
         buffer_proc = proc(state: ^core.State, panel_state: ^core.PanelState) -> (buffer: ^core.FileBuffer, ok: bool) {
@@ -357,8 +401,7 @@ make_grep_panel :: proc(state: ^core.State) -> core.Panel {
             }
         },
         render_proc = proc(state: ^core.State, panel_state: ^core.PanelState) -> (ok: bool) {
-            panel_state := panel_state.(core.GrepPanel) or_return;
-
+            if panel_state, ok := &panel_state.(core.GrepPanel); ok {
                 s := transmute(^ui.State)state.ui
 
                 ui.open_element(s, nil, {
@@ -405,10 +448,7 @@ make_grep_panel :: proc(state: ^core.State) -> core.Panel {
 
                             // file contents
                             selected_result := &panel_state.query_results[panel_state.selected_result]
-                        ui.open_element(s, selected_result.file_context, {
-                            kind = {ui.Grow{}, ui.Grow{}}
-                        })
-                        ui.close_element(s)
+                            render_glyph_buffer(state, s, &panel_state.glyphs)
                         }
                     }
                     ui.close_element(s)
@@ -427,5 +467,8 @@ make_grep_panel :: proc(state: ^core.State) -> core.Panel {
 
                 return true
             }
+
+            return false
+        }
     }
 }

src/pkg/grep_lib/src/lib.rs

@@ -49,7 +49,8 @@ impl Match {
         let column = value.bytes_range_in_buffer().len() as u64;
 
         Ok(Self {
-            text: line,
+            // TODO: only return N-lines of context instead of the entire freakin' buffer
+            text: value.buffer().to_vec(),
             path: path.unwrap_or_default(),
             line_number: value.line_number(),
             column,

src/tests/tests.odin

@@ -322,23 +322,48 @@ delete_across_slices :: proc(t: ^testing.T) {
     testing.expectf(t, contents == expected_text, "got '%v', expected '%v'", contents, expected_text)
 }
 
-// @(test)
-// insert_line_under_current :: proc(t: ^testing.T) {
-//     e := new_test_editor()
-//     setup_empty_buffer(&e)
+@(test)
+move_down_next_line_has_shorter_length :: proc(t: ^testing.T) {
+    e := new_test_editor()
+    setup_empty_buffer(&e)
 
-//     buffer := &e.buffers[0]
+    is_ctrl_pressed := false
 
-//     inputted_text := "Hello, world!\nThis is a new line"
-//     expected_text := fmt.aprintf("%v\n", inputted_text)
-//     run_text_insertion(&e, inputted_text)
+    buffer := &e.buffers[0]
 
-//     expect_line_col(t, buffer.cursor, 1, 17)
-//     expect_cursor_index(t, buffer.cursor, 0, 31)
+    run_text_insertion(&e, "012345678\n0")
 
-//     contents := buffer_to_string(core.current_buffer(&e))
-//     testing.expectf(t, contents == expected_text, "got '%v', expected '%v'", contents, expected_text)
-// }
+    // Move up to the first line
+    run_input_multiple(&e, press_key(.K), 1)
+
+    // Move to the end of the line
+    run_inputs(&e, []ArtificialInput{ press_key(.G), press_key(.L)})
+
+    // Move down to the second line
+    run_input_multiple(&e, press_key(.J), 1)
+
+    expect_line_col(t, buffer.cursor, 1, 0)
+    expect_cursor_index(t, buffer.cursor, 0, 10)
+}
+
+@(test)
+move_down_on_last_line :: proc(t: ^testing.T) {
+    e := new_test_editor()
+    setup_empty_buffer(&e)
+
+    is_ctrl_pressed := false
+
+    buffer := &e.buffers[0]
+
+    run_text_insertion(&e, "012345678")
+
+    // Try to move down
+    run_input_multiple(&e, press_key(.J), 1)
+
+    // Cursor should stay where it is
+    expect_line_col(t, buffer.cursor, 0, 8)
+    expect_cursor_index(t, buffer.cursor, 0, 8)
+}
 
 @(test)
 move_left_at_beginning_of_file :: proc(t: ^testing.T) {
@@ -478,6 +503,42 @@ move_to_beginning_of_line_from_start :: proc(t: ^testing.T) {
     expect_cursor_index(t, buffer.cursor, 0, 0)
 }
 
+@(test)
+insert_line_under_current :: proc(t: ^testing.T) {
+    e := new_test_editor()
+    setup_empty_buffer(&e)
+
+    buffer := &e.buffers[0]
+
+    initial_text := "Hello, world!\nThis is a new line"
+    run_text_insertion(&e, initial_text)
+
+    expected_text := "Hello, world!\nThis is the second line\nThis is a new line\n"
+    //                -------------                         ---------------------- 
+    //                             -------------------------                      
+    //                0            1                        3                     
+
+    // Move cursor up onto the end of "Hello, world!"
+    run_input_multiple(&e, press_key(.K), 1)
+
+    // Insert line below and enter insert mode
+    run_input_multiple(&e, press_key(.O), 1)
+
+    // Technically the cursor is still on the first line, because the `input_buffer`
+    // has been modified but not the actual contents of the filebuffer
+    expect_line_col(t, buffer.cursor, 0, 13)
+    expect_cursor_index(t, buffer.cursor, 0, 13)
+
+    run_text_insertion(&e, "This is the second line")
+
+    expect_line_col(t, buffer.cursor, 1, 22)
+    expect_cursor_index(t, buffer.cursor, 1, 23)
+
+    contents := buffer_to_string(core.current_buffer(&e))
+    testing.expectf(t, contents == expected_text, "got '%v', expected '%v'", contents, expected_text)
+}
+
+
 run_editor_frame :: proc(state: ^core.State, input: ArtificialInput, is_ctrl_pressed: ^bool) {
     log.infof("running input: %v", input)