wip: Move to new rendering structure.

6 files changed, 655 insertions, 432 deletions

diff --git a/helix-term/src/application.rs b/helix-term/src/application.rs
index 589aaf6e..7a74f8ba 100644
--- a/helix-term/src/application.rs
+++ b/helix-term/src/application.rs
@@ -1,13 +1,9 @@
-use crate::{
-    commands,
-    keymap::{self, Keymaps},
-};
 use clap::ArgMatches as Args;
-use helix_core::{indent::TAB_WIDTH, syntax::HighlightEvent, Position, Range, State};
 
 use helix_view::{document::Mode, Document, Editor, Theme, View};
 
 use crate::compositor::{Component, Compositor, EventResult};
+use crate::editor_view::EditorView;
 use crate::prompt::Prompt;
 
 use log::{debug, info};
@@ -37,426 +33,54 @@ use tui::{
     style::{Color, Modifier, Style},
 };
 
-type Terminal = tui::Terminal<CrosstermBackend<std::io::Stdout>>;
-
-const BASE_WIDTH: u16 = 30;
+type Terminal = crate::terminal::Terminal<CrosstermBackend<std::io::Stdout>>;
 
-pub struct Application<'a> {
+pub struct Application {
     compositor: Compositor,
     editor: Editor,
-    renderer: Renderer,
+    terminal: Terminal,
 
-    executor: &'a smol::Executor<'a>,
+    executor: &'static smol::Executor<'static>,
     language_server: helix_lsp::Client,
 }
 
-pub struct Renderer {
-    size: (u16, u16),
-    terminal: Terminal,
-    surface: Surface,
-    cache: Surface,
-    text_color: Style,
+// TODO: temp
+#[inline(always)]
+pub fn text_color() -> Style {
+    return Style::default().fg(Color::Rgb(219, 191, 239)); // lilac
 }
 
-impl Renderer {
-    pub fn new() -> Result<Self, Error> {
+// pub fn render_cursor(&mut self, view: &View, prompt: Option<&Prompt>, viewport: Rect) {
+//     let mut stdout = stdout();
+//     match view.doc.mode() {
+//         Mode::Insert => write!(stdout, "\x1B[6 q"),
+//         mode => write!(stdout, "\x1B[2 q"),
+//     };
+//     let pos = if let Some(prompt) = prompt {
+//         Position::new(self.size.0 as usize, 2 + prompt.cursor)
+//     } else {
+//         let cursor = view.doc.state.selection().cursor();
+
+//         let mut pos = view
+//             .screen_coords_at_pos(&view.doc.text().slice(..), cursor)
+//             .expect("Cursor is out of bounds.");
+//         pos.col += viewport.x as usize;
+//         pos.row += viewport.y as usize;
+//         pos
+//     };
+
+//     execute!(stdout, cursor::MoveTo(pos.col as u16, pos.row as u16));
+// }
+
+impl Application {
+    pub fn new(mut args: Args, executor: &'static smol::Executor<'static>) -> Result<Self, Error> {
         let backend = CrosstermBackend::new(stdout());
         let mut terminal = Terminal::new(backend)?;
-        let size = terminal::size().unwrap();
-        let text_color: Style = Style::default().fg(Color::Rgb(219, 191, 239)); // lilac
-
-        let area = Rect::new(0, 0, size.0, size.1);
-
-        Ok(Self {
-            size,
-            terminal,
-            surface: Surface::empty(area),
-            cache: Surface::empty(area),
-            text_color,
-        })
-    }
-
-    pub fn resize(&mut self, width: u16, height: u16) {
-        self.size = (width, height);
-        let area = Rect::new(0, 0, width, height);
-        self.surface = Surface::empty(area);
-        self.cache = Surface::empty(area);
-    }
-
-    pub fn render_view(&mut self, view: &mut View, viewport: Rect, theme: &Theme) {
-        self.render_buffer(view, viewport, theme);
-        self.render_statusline(view, theme);
-    }
-
-    // TODO: ideally not &mut View but highlights require it because of cursor cache
-    pub fn render_buffer(&mut self, view: &mut View, viewport: Rect, theme: &Theme) {
-        let area = Rect::new(0, 0, self.size.0, self.size.1);
-
-        //  clear with background color
-        self.surface.set_style(area, theme.get("ui.background"));
-
-        // TODO: inefficient, should feed chunks.iter() to tree_sitter.parse_with(|offset, pos|)
-        let source_code = view.doc.text().to_string();
-
-        let last_line = view.last_line();
-
-        let range = {
-            // calculate viewport byte ranges
-            let start = view.doc.text().line_to_byte(view.first_line);
-            let end = view.doc.text().line_to_byte(last_line)
-                + view.doc.text().line(last_line).len_bytes();
-
-            start..end
-        };
-
-        // TODO: range doesn't actually restrict source, just highlight range
-        // TODO: cache highlight results
-        // TODO: only recalculate when state.doc is actually modified
-        let highlights: Vec<_> = match view.doc.syntax.as_mut() {
-            Some(syntax) => {
-                syntax
-                    .highlight_iter(source_code.as_bytes(), Some(range), None, |_| None)
-                    .unwrap()
-                    .collect() // TODO: we collect here to avoid double borrow, fix later
-            }
-            None => vec![Ok(HighlightEvent::Source {
-                start: range.start,
-                end: range.end,
-            })],
-        };
-        let mut spans = Vec::new();
-        let mut visual_x = 0;
-        let mut line = 0u16;
-        let visible_selections: Vec<Range> = view
-            .doc
-            .state
-            .selection()
-            .ranges()
-            .iter()
-            // TODO: limit selection to one in viewport
-            // .filter(|range| !range.is_empty()) // && range.overlaps(&Range::new(start, end + 1))
-            .copied()
-            .collect();
-
-        'outer: for event in highlights {
-            match event.unwrap() {
-                HighlightEvent::HighlightStart(span) => {
-                    spans.push(span);
-                }
-                HighlightEvent::HighlightEnd => {
-                    spans.pop();
-                }
-                HighlightEvent::Source { start, end } => {
-                    // TODO: filter out spans out of viewport for now..
-
-                    let start = view.doc.text().byte_to_char(start);
-                    let end = view.doc.text().byte_to_char(end); // <-- index 744, len 743
-
-                    let text = view.doc.text().slice(start..end);
-
-                    use helix_core::graphemes::{grapheme_width, RopeGraphemes};
-
-                    let style = match spans.first() {
-                        Some(span) => theme.get(theme.scopes()[span.0].as_str()),
-                        None => Style::default().fg(Color::Rgb(164, 160, 232)), // lavender
-                    };
-
-                    // TODO: we could render the text to a surface, then cache that, that
-                    // way if only the selection/cursor changes we can copy from cache
-                    // and paint the new cursor.
-
-                    let mut char_index = start;
-
-                    // iterate over range char by char
-                    for grapheme in RopeGraphemes::new(&text) {
-                        // TODO: track current char_index
-
-                        if grapheme == "\n" {
-                            visual_x = 0;
-                            line += 1;
-
-                            // TODO: with proper iter this shouldn't be necessary
-                            if line >= viewport.height {
-                                break 'outer;
-                            }
-                        } else if grapheme == "\t" {
-                            visual_x += (TAB_WIDTH as u16);
-                        } else {
-                            // Cow will prevent allocations if span contained in a single slice
-                            // which should really be the majority case
-                            let grapheme = Cow::from(grapheme);
-                            let width = grapheme_width(&grapheme) as u16;
-
-                            // TODO: this should really happen as an after pass
-                            let style = if visible_selections
-                                .iter()
-                                .any(|range| range.contains(char_index))
-                            {
-                                // cedar
-                                style.clone().bg(Color::Rgb(128, 47, 0))
-                            } else {
-                                style
-                            };
-
-                            let style = if visible_selections
-                                .iter()
-                                .any(|range| range.head == char_index)
-                            {
-                                style.clone().bg(Color::Rgb(255, 255, 255))
-                            } else {
-                                style
-                            };
-
-                            // ugh, improve with a traverse method
-                            // or interleave highlight spans with selection and diagnostic spans
-                            let style = if view.doc.diagnostics.iter().any(|diagnostic| {
-                                diagnostic.range.0 <= char_index && diagnostic.range.1 > char_index
-                            }) {
-                                style.clone().add_modifier(Modifier::UNDERLINED)
-                            } else {
-                                style
-                            };
-
-                            // TODO: paint cursor heads except primary
-
-                            self.surface.set_string(
-                                viewport.x + visual_x,
-                                viewport.y + line,
-                                grapheme,
-                                style,
-                            );
-
-                            visual_x += width;
-                        }
-
-                        char_index += 1;
-                    }
-                }
-            }
-        }
-
-        let style: Style = theme.get("ui.linenr");
-        let warning: Style = theme.get("warning");
-        let last_line = view.last_line();
-        for (i, line) in (view.first_line..last_line).enumerate() {
-            if view.doc.diagnostics.iter().any(|d| d.line == line) {
-                self.surface.set_stringn(0, i as u16, "●", 1, warning);
-            }
-
-            self.surface
-                .set_stringn(1, i as u16, format!("{:>5}", line + 1), 5, style);
-        }
-    }
-
-    pub fn render_statusline(&mut self, view: &View, theme: &Theme) {
-        let mode = match view.doc.mode() {
-            Mode::Insert => "INS",
-            Mode::Normal => "NOR",
-            Mode::Goto => "GOTO",
-        };
-        // statusline
-        self.surface.set_style(
-            Rect::new(0, self.size.1 - 2, self.size.0, 1),
-            theme.get("ui.statusline"),
-        );
-        self.surface
-            .set_string(1, self.size.1 - 2, mode, self.text_color);
-
-        if let Some(path) = view.doc.path() {
-            self.surface
-                .set_string(6, self.size.1 - 2, path.to_string_lossy(), self.text_color);
-        }
-
-        self.surface.set_string(
-            self.size.0 - 10,
-            self.size.1 - 2,
-            format!("{}", view.doc.diagnostics.len()),
-            self.text_color,
-        );
-    }
-
-    pub fn render_prompt(&mut self, prompt: &Prompt, theme: &Theme) {
-        // completion
-        if !prompt.completion.is_empty() {
-            // TODO: find out better way of clearing individual lines of the screen
-            let mut row = 0;
-            let mut col = 0;
-            let max_col = self.size.0 / BASE_WIDTH;
-            let col_height = ((prompt.completion.len() as u16 + max_col - 1) / max_col);
-
-            for i in (3..col_height + 3) {
-                self.surface.set_string(
-                    0,
-                    self.size.1 - i as u16,
-                    " ".repeat(self.size.0 as usize),
-                    self.text_color,
-                );
-            }
-            self.surface.set_style(
-                Rect::new(0, self.size.1 - col_height - 2, self.size.0, col_height),
-                theme.get("ui.statusline"),
-            );
-            for (i, command) in prompt.completion.iter().enumerate() {
-                let color = if prompt.completion_selection_index.is_some()
-                    && i == prompt.completion_selection_index.unwrap()
-                {
-                    Style::default().bg(Color::Rgb(104, 060, 232))
-                } else {
-                    self.text_color
-                };
-                self.surface.set_stringn(
-                    1 + col * BASE_WIDTH,
-                    self.size.1 - col_height - 2 + row,
-                    &command,
-                    BASE_WIDTH as usize - 1,
-                    color,
-                );
-                row += 1;
-                if row > col_height - 1 {
-                    row = 0;
-                    col += 1;
-                }
-                if col > max_col {
-                    break;
-                }
-            }
-        }
-        // render buffer text
-        self.surface
-            .set_string(1, self.size.1 - 1, &prompt.prompt, self.text_color);
-        self.surface
-            .set_string(2, self.size.1 - 1, &prompt.line, self.text_color);
-    }
-
-    pub fn draw_and_swap(&mut self) {
-        use tui::backend::Backend;
-        // TODO: theres probably a better place for this
-        self.terminal
-            .backend_mut()
-            .draw(self.cache.diff(&self.surface).into_iter());
-        // swap the buffer
-        std::mem::swap(&mut self.surface, &mut self.cache);
-        self.surface.reset(); // reset is faster than allocating new empty surface
-    }
-
-    pub fn render_cursor(&mut self, view: &View, prompt: Option<&Prompt>, viewport: Rect) {
-        let mut stdout = stdout();
-        match view.doc.mode() {
-            Mode::Insert => write!(stdout, "\x1B[6 q"),
-            mode => write!(stdout, "\x1B[2 q"),
-        };
-        let pos = if let Some(prompt) = prompt {
-            Position::new(self.size.0 as usize, 2 + prompt.cursor)
-        } else {
-            let cursor = view.doc.state.selection().cursor();
-
-            let mut pos = view
-                .screen_coords_at_pos(&view.doc.text().slice(..), cursor)
-                .expect("Cursor is out of bounds.");
-            pos.col += viewport.x as usize;
-            pos.row += viewport.y as usize;
-            pos
-        };
-
-        execute!(stdout, cursor::MoveTo(pos.col as u16, pos.row as u16));
-    }
-}
-
-struct EditorView {
-    keymap: Keymaps,
-}
-
-impl EditorView {
-    fn new() -> Self {
-        Self {
-            keymap: keymap::default(),
-        }
-    }
-}
-
-use crate::compositor::Context;
-
-impl Component for EditorView {
-    fn handle_event(&mut self, event: Event, cx: &mut Context) -> EventResult {
-        match event {
-            Event::Resize(width, height) => {
-                // TODO: simplistic ensure cursor in view for now
-                // TODO: loop over views
-                if let Some(view) = cx.editor.view_mut() {
-                    view.size = (width, height);
-                    view.ensure_cursor_in_view()
-                };
-                EventResult::Consumed(None)
-            }
-            Event::Key(event) => {
-                if let Some(view) = cx.editor.view_mut() {
-                    let keys = vec![event];
-                    // TODO: sequences (`gg`)
-                    let mode = view.doc.mode();
-                    // TODO: handle count other than 1
-                    let mut cx = commands::Context {
-                        view,
-                        executor: cx.executor,
-                        count: 1,
-                        callback: None,
-                    };
-
-                    match mode {
-                        Mode::Insert => {
-                            if let Some(command) = self.keymap[&Mode::Insert].get(&keys) {
-                                command(&mut cx);
-                            } else if let KeyEvent {
-                                code: KeyCode::Char(c),
-                                ..
-                            } = event
-                            {
-                                commands::insert::insert_char(&mut cx, c);
-                            }
-                        }
-                        mode => {
-                            if let Some(command) = self.keymap[&mode].get(&keys) {
-                                command(&mut cx);
-
-                                // TODO: simplistic ensure cursor in view for now
-                            }
-                        }
-                    }
-                    // appease borrowck
-                    let callback = cx.callback.take();
-
-                    view.ensure_cursor_in_view();
-
-                    EventResult::Consumed(callback)
-                } else {
-                    EventResult::Ignored
-                }
-            }
-            Event::Mouse(_) => EventResult::Ignored,
-        }
-    }
-    fn render(&mut self, renderer: &mut Renderer, cx: &mut Context) {
-        const OFFSET: u16 = 7; // 1 diagnostic + 5 linenr + 1 gutter
-        let viewport = Rect::new(OFFSET, 0, renderer.size.0, renderer.size.1 - 2); // - 2 for statusline and prompt
-
-        // SAFETY: we cheat around the view_mut() borrow because it doesn't allow us to also borrow
-        // theme. Theme is immutable mutating view won't disrupt theme_ref.
-        let theme_ref = unsafe { &*(&cx.editor.theme as *const Theme) };
-        if let Some(view) = cx.editor.view_mut() {
-            renderer.render_view(view, viewport, theme_ref);
-        }
-
-        // TODO: drop unwrap
-        renderer.render_cursor(cx.editor.view().unwrap(), None, viewport);
-    }
-}
-
-impl<'a> Application<'a> {
-    pub fn new(mut args: Args, executor: &'a smol::Executor<'a>) -> Result<Self, Error> {
-        let renderer = Renderer::new()?;
         let mut editor = Editor::new();
+        let size = terminal.size()?;
 
         if let Some(file) = args.values_of_t::<PathBuf>("files").unwrap().pop() {
-            editor.open(file, renderer.size)?;
+            editor.open(file, (size.width, size.height))?;
         }
 
         let mut compositor = Compositor::new();
@@ -466,7 +90,7 @@ impl<'a> Application<'a> {
 
         let mut app = Self {
             editor,
-            renderer,
+            terminal,
             // TODO; move to state
             compositor,
 
@@ -478,12 +102,17 @@ impl<'a> Application<'a> {
     }
 
     fn render(&mut self) {
-        let mut cx = crate::compositor::Context {
-            editor: &mut self.editor,
-            executor: &self.executor,
-        };
-        self.compositor.render(&mut self.renderer, &mut cx); // viewport,
-        self.renderer.draw_and_swap();
+        let executor = &self.executor;
+        let editor = &mut self.editor;
+        let compositor = &self.compositor;
+
+        // TODO: should be unnecessary
+        // self.terminal.autoresize();
+        let mut cx = crate::compositor::Context { editor, executor };
+        let area = self.terminal.size().unwrap();
+        compositor.render(area, self.terminal.current_buffer_mut(), &mut cx);
+
+        self.terminal.draw();
     }
 
     pub async fn event_loop(&mut self) {
@@ -524,7 +153,7 @@ impl<'a> Application<'a> {
         // Handle key events
         let should_redraw = match event {
             Some(Ok(Event::Resize(width, height))) => {
-                self.renderer.resize(width, height);
+                self.terminal.resize(Rect::new(0, 0, width, height));
 
                 self.compositor
                     .handle_event(Event::Resize(width, height), &mut cx)
diff --git a/helix-term/src/compositor.rs b/helix-term/src/compositor.rs
index 3cf6bf03..1d94ee63 100644
--- a/helix-term/src/compositor.rs
+++ b/helix-term/src/compositor.rs
@@ -13,10 +13,10 @@
 // Q: how does this work with popups?
 // cursive does compositor.screen_mut().add_layer_at(pos::absolute(x, y), <component>)
 
-use crate::application::Renderer;
 use crossterm::event::Event;
 use smol::Executor;
 use tui::buffer::Buffer as Surface;
+use tui::layout::Rect;
 
 pub type Callback = Box<dyn Fn(&mut Compositor)>;
 
@@ -36,9 +36,9 @@ pub enum EventResult {
 
 use helix_view::{Editor, View};
 // shared with commands.rs
-pub struct Context<'a, 'b> {
+pub struct Context<'a> {
     pub editor: &'a mut Editor,
-    pub executor: &'a smol::Executor<'b>,
+    pub executor: &'static smol::Executor<'static>,
 }
 
 pub trait Component {
@@ -51,7 +51,7 @@ pub trait Component {
         true
     }
 
-    fn render(&mut self, renderer: &mut Renderer, ctx: &mut Context);
+    fn render(&self, area: Rect, frame: &mut Surface, ctx: &mut Context);
 }
 
 // struct Editor { };
@@ -133,9 +133,9 @@ impl Compositor {
         false
     }
 
-    pub fn render(&mut self, renderer: &mut Renderer, cx: &mut Context) {
-        for layer in &mut self.layers {
-            layer.render(renderer, cx)
+    pub fn render(&self, area: Rect, surface: &mut Surface, cx: &mut Context) {
+        for layer in &self.layers {
+            layer.render(area, surface, cx)
         }
     }
 }
diff --git a/helix-term/src/editor_view.rs b/helix-term/src/editor_view.rs
new file mode 100644
index 00000000..0181623a
--- /dev/null
+++ b/helix-term/src/editor_view.rs
@@ -0,0 +1,311 @@
+use crate::application::text_color;
+use crate::commands;
+use crate::compositor::{Component, Compositor, EventResult};
+use crate::keymap::{self, Keymaps};
+use crossterm::{
+    cursor,
+    event::{read, Event, EventStream, KeyCode, KeyEvent},
+};
+use helix_view::{document::Mode, Document, Editor, Theme, View};
+use std::borrow::Cow;
+use tui::{
+    backend::CrosstermBackend,
+    buffer::Buffer as Surface,
+    layout::Rect,
+    style::{Color, Modifier, Style},
+};
+
+use helix_core::{indent::TAB_WIDTH, syntax::HighlightEvent, Position, Range, State};
+
+pub struct EditorView {
+    keymap: Keymaps,
+}
+
+impl EditorView {
+    pub fn new() -> Self {
+        Self {
+            keymap: keymap::default(),
+        }
+    }
+    pub fn render_view(
+        &self,
+        view: &mut View,
+        viewport: Rect,
+        surface: &mut Surface,
+        theme: &Theme,
+    ) {
+        const OFFSET: u16 = 7; // 1 diagnostic + 5 linenr + 1 gutter
+        let area = Rect::new(OFFSET, 0, viewport.width - OFFSET, viewport.height - 2); // - 2 for statusline and prompt
+        self.render_buffer(view, area, surface, theme);
+        let area = Rect::new(0, viewport.height - 2, viewport.width, 1);
+        self.render_statusline(view, viewport, surface, theme);
+    }
+
+    // TODO: ideally not &mut View but highlights require it because of cursor cache
+    pub fn render_buffer(
+        &self,
+        view: &mut View,
+        viewport: Rect,
+        surface: &mut Surface,
+        theme: &Theme,
+    ) {
+        //  clear with background color
+        surface.set_style(viewport, theme.get("ui.background"));
+
+        // TODO: inefficient, should feed chunks.iter() to tree_sitter.parse_with(|offset, pos|)
+        let source_code = view.doc.text().to_string();
+
+        let last_line = view.last_line();
+
+        let range = {
+            // calculate viewport byte ranges
+            let start = view.doc.text().line_to_byte(view.first_line);
+            let end = view.doc.text().line_to_byte(last_line)
+                + view.doc.text().line(last_line).len_bytes();
+
+            start..end
+        };
+
+        // TODO: range doesn't actually restrict source, just highlight range
+        // TODO: cache highlight results
+        // TODO: only recalculate when state.doc is actually modified
+        let highlights: Vec<_> = match view.doc.syntax.as_mut() {
+            Some(syntax) => {
+                syntax
+                    .highlight_iter(source_code.as_bytes(), Some(range), None, |_| None)
+                    .unwrap()
+                    .collect() // TODO: we collect here to avoid double borrow, fix later
+            }
+            None => vec![Ok(HighlightEvent::Source {
+                start: range.start,
+                end: range.end,
+            })],
+        };
+        let mut spans = Vec::new();
+        let mut visual_x = 0;
+        let mut line = 0u16;
+        let visible_selections: Vec<Range> = view
+            .doc
+            .state
+            .selection()
+            .ranges()
+            .iter()
+            // TODO: limit selection to one in viewport
+            // .filter(|range| !range.is_empty()) // && range.overlaps(&Range::new(start, end + 1))
+            .copied()
+            .collect();
+
+        'outer: for event in highlights {
+            match event.unwrap() {
+                HighlightEvent::HighlightStart(span) => {
+                    spans.push(span);
+                }
+                HighlightEvent::HighlightEnd => {
+                    spans.pop();
+                }
+                HighlightEvent::Source { start, end } => {
+                    // TODO: filter out spans out of viewport for now..
+
+                    let start = view.doc.text().byte_to_char(start);
+                    let end = view.doc.text().byte_to_char(end); // <-- index 744, len 743
+
+                    let text = view.doc.text().slice(start..end);
+
+                    use helix_core::graphemes::{grapheme_width, RopeGraphemes};
+
+                    let style = match spans.first() {
+                        Some(span) => theme.get(theme.scopes()[span.0].as_str()),
+                        None => Style::default().fg(Color::Rgb(164, 160, 232)), // lavender
+                    };
+
+                    // TODO: we could render the text to a surface, then cache that, that
+                    // way if only the selection/cursor changes we can copy from cache
+                    // and paint the new cursor.
+
+                    let mut char_index = start;
+
+                    // iterate over range char by char
+                    for grapheme in RopeGraphemes::new(&text) {
+                        // TODO: track current char_index
+
+                        if grapheme == "\n" {
+                            visual_x = 0;
+                            line += 1;
+
+                            // TODO: with proper iter this shouldn't be necessary
+                            if line >= viewport.height {
+                                break 'outer;
+                            }
+                        } else if grapheme == "\t" {
+                            visual_x += (TAB_WIDTH as u16);
+                        } else {
+                            // Cow will prevent allocations if span contained in a single slice
+                            // which should really be the majority case
+                            let grapheme = Cow::from(grapheme);
+                            let width = grapheme_width(&grapheme) as u16;
+
+                            // TODO: this should really happen as an after pass
+                            let style = if visible_selections
+                                .iter()
+                                .any(|range| range.contains(char_index))
+                            {
+                                // cedar
+                                style.clone().bg(Color::Rgb(128, 47, 0))
+                            } else {
+                                style
+                            };
+
+                            let style = if visible_selections
+                                .iter()
+                                .any(|range| range.head == char_index)
+                            {
+                                style.clone().bg(Color::Rgb(255, 255, 255))
+                            } else {
+                                style
+                            };
+
+                            // ugh, improve with a traverse method
+                            // or interleave highlight spans with selection and diagnostic spans
+                            let style = if view.doc.diagnostics.iter().any(|diagnostic| {
+                                diagnostic.range.0 <= char_index && diagnostic.range.1 > char_index
+                            }) {
+                                style.clone().add_modifier(Modifier::UNDERLINED)
+                            } else {
+                                style
+                            };
+
+                            // TODO: paint cursor heads except primary
+
+                            surface.set_string(
+                                viewport.x + visual_x,
+                                viewport.y + line,
+                                grapheme,
+                                style,
+                            );
+
+                            visual_x += width;
+                        }
+
+                        char_index += 1;
+                    }
+                }
+            }
+        }
+
+        let style: Style = theme.get("ui.linenr");
+        let warning: Style = theme.get("warning");
+        let last_line = view.last_line();
+        for (i, line) in (view.first_line..last_line).enumerate() {
+            if view.doc.diagnostics.iter().any(|d| d.line == line) {
+                surface.set_stringn(0, i as u16, "●", 1, warning);
+            }
+
+            surface.set_stringn(1, i as u16, format!("{:>5}", line + 1), 5, style);
+        }
+    }
+
+    pub fn render_statusline(
+        &self,
+        view: &View,
+        viewport: Rect,
+        surface: &mut Surface,
+        theme: &Theme,
+    ) {
+        let mode = match view.doc.mode() {
+            Mode::Insert => "INS",
+            Mode::Normal => "NOR",
+            Mode::Goto => "GOTO",
+        };
+        // statusline
+        surface.set_style(
+            Rect::new(0, viewport.y, viewport.height, 1),
+            theme.get("ui.statusline"),
+        );
+        surface.set_string(1, viewport.y, mode, text_color());
+
+        if let Some(path) = view.doc.path() {
+            surface.set_string(6, viewport.y, path.to_string_lossy(), text_color());
+        }
+
+        surface.set_string(
+            viewport.width - 10,
+            viewport.y,
+            format!("{}", view.doc.diagnostics.len()),
+            text_color(),
+        );
+    }
+}
+
+use crate::compositor::Context;
+
+impl Component for EditorView {
+    fn handle_event(&mut self, event: Event, cx: &mut Context) -> EventResult {
+        match event {
+            Event::Resize(width, height) => {
+                // TODO: simplistic ensure cursor in view for now
+                // TODO: loop over views
+                if let Some(view) = cx.editor.view_mut() {
+                    view.size = (width, height);
+                    view.ensure_cursor_in_view()
+                };
+                EventResult::Consumed(None)
+            }
+            Event::Key(event) => {
+                if let Some(view) = cx.editor.view_mut() {
+                    let keys = vec![event];
+                    // TODO: sequences (`gg`)
+                    let mode = view.doc.mode();
+                    // TODO: handle count other than 1
+                    let mut cx = commands::Context {
+                        view,
+                        executor: cx.executor,
+                        count: 1,
+                        callback: None,
+                    };
+
+                    match mode {
+                        Mode::Insert => {
+                            if let Some(command) = self.keymap[&Mode::Insert].get(&keys) {
+                                command(&mut cx);
+                            } else if let KeyEvent {
+                                code: KeyCode::Char(c),
+                                ..
+                            } = event
+                            {
+                                commands::insert::insert_char(&mut cx, c);
+                            }
+                        }
+                        mode => {
+                            if let Some(command) = self.keymap[&mode].get(&keys) {
+                                command(&mut cx);
+
+                                // TODO: simplistic ensure cursor in view for now
+                            }
+                        }
+                    }
+                    // appease borrowck
+                    let callback = cx.callback.take();
+
+                    view.ensure_cursor_in_view();
+
+                    EventResult::Consumed(callback)
+                } else {
+                    EventResult::Ignored
+                }
+            }
+            Event::Mouse(_) => EventResult::Ignored,
+        }
+    }
+
+    fn render(&self, area: Rect, surface: &mut Surface, cx: &mut Context) {
+        // SAFETY: we cheat around the view_mut() borrow because it doesn't allow us to also borrow
+        // theme. Theme is immutable mutating view won't disrupt theme_ref.
+        let theme_ref = unsafe { &*(&cx.editor.theme as *const Theme) };
+        if let Some(view) = cx.editor.view_mut() {
+            self.render_view(view, area, surface, theme_ref);
+        }
+
+        // TODO: drop unwrap
+        // TODO: !!! self.render_cursor(cx.editor.view().unwrap(), None, viewport);
+    }
+}
diff --git a/helix-term/src/main.rs b/helix-term/src/main.rs
index 92ab10c2..63fbe52d 100644
--- a/helix-term/src/main.rs
+++ b/helix-term/src/main.rs
@@ -3,8 +3,10 @@
 mod application;
 mod commands;
 mod compositor;
+mod editor_view;
 mod keymap;
 mod prompt;
+mod terminal;
 
 use application::Application;
 
diff --git a/helix-term/src/prompt.rs b/helix-term/src/prompt.rs
index 689eac66..4747c9f5 100644
--- a/helix-term/src/prompt.rs
+++ b/helix-term/src/prompt.rs
@@ -1,9 +1,7 @@
-use crate::{
-    application::Renderer,
-    compositor::{Component, Context, EventResult},
-};
+use crate::compositor::{Component, Context, EventResult};
 use crossterm::event::{Event, KeyCode, KeyEvent, KeyModifiers};
 use helix_view::Editor;
+use helix_view::Theme;
 use std::string::String;
 
 pub struct Prompt {
@@ -85,6 +83,68 @@ impl Prompt {
     }
 }
 
+use tui::{
+    buffer::Buffer as Surface,
+    layout::Rect,
+    style::{Color, Modifier, Style},
+};
+
+const BASE_WIDTH: u16 = 30;
+use crate::application::text_color;
+
+impl Prompt {
+    pub fn render_prompt(&self, area: Rect, surface: &mut Surface, theme: &Theme) {
+        // completion
+        if !self.completion.is_empty() {
+            // TODO: find out better way of clearing individual lines of the screen
+            let mut row = 0;
+            let mut col = 0;
+            let max_col = area.width / BASE_WIDTH;
+            let col_height = ((self.completion.len() as u16 + max_col - 1) / max_col);
+
+            for i in (3..col_height + 3) {
+                surface.set_string(
+                    0,
+                    area.height - i as u16,
+                    " ".repeat(area.width as usize),
+                    text_color(),
+                );
+            }
+            surface.set_style(
+                Rect::new(0, area.height - col_height - 2, area.width, col_height),
+                theme.get("ui.statusline"),
+            );
+            for (i, command) in self.completion.iter().enumerate() {
+                let color = if self.completion_selection_index.is_some()
+                    && i == self.completion_selection_index.unwrap()
+                {
+                    Style::default().bg(Color::Rgb(104, 060, 232))
+                } else {
+                    text_color()
+                };
+                surface.set_stringn(
+                    1 + col * BASE_WIDTH,
+                    area.height - col_height - 2 + row,
+                    &command,
+                    BASE_WIDTH as usize - 1,
+                    color,
+                );
+                row += 1;
+                if row > col_height - 1 {
+                    row = 0;
+                    col += 1;
+                }
+                if col > max_col {
+                    break;
+                }
+            }
+        }
+        // render buffer text
+        surface.set_string(1, area.height - 1, &self.prompt, text_color());
+        surface.set_string(2, area.height - 1, &self.line, text_color());
+    }
+}
+
 impl Component for Prompt {
     fn handle_event(&mut self, event: Event, cx: &mut Context) -> EventResult {
         let event = match event {
@@ -137,7 +197,7 @@ impl Component for Prompt {
         EventResult::Consumed(None)
     }
 
-    fn render(&mut self, renderer: &mut Renderer, cx: &mut Context) {
-        renderer.render_prompt(self, &cx.editor.theme)
+    fn render(&self, area: Rect, surface: &mut Surface, cx: &mut Context) {
+        self.render_prompt(area, surface, &cx.editor.theme)
     }
 }
diff --git a/helix-term/src/terminal.rs b/helix-term/src/terminal.rs
new file mode 100644
index 00000000..e40343bd
--- /dev/null
+++ b/helix-term/src/terminal.rs
@@ -0,0 +1,221 @@
+use std::io;
+use tui::{
+    backend::Backend,
+    buffer::Buffer,
+    layout::Rect,
+    widgets::{StatefulWidget, Widget},
+};
+
+#[derive(Debug, Clone, PartialEq)]
+/// UNSTABLE
+enum ResizeBehavior {
+    Fixed,
+    Auto,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+/// UNSTABLE
+pub struct Viewport {
+    area: Rect,
+    resize_behavior: ResizeBehavior,
+}
+
+impl Viewport {
+    /// UNSTABLE
+    pub fn fixed(area: Rect) -> Viewport {
+        Viewport {
+            area,
+            resize_behavior: ResizeBehavior::Fixed,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+/// Options to pass to [`Terminal::with_options`]
+pub struct TerminalOptions {
+    /// Viewport used to draw to the terminal
+    pub viewport: Viewport,
+}
+
+/// Interface to the terminal backed by Termion
+#[derive(Debug)]
+pub struct Terminal<B>
+where
+    B: Backend,
+{
+    backend: B,
+    /// Holds the results of the current and previous draw calls. The two are compared at the end
+    /// of each draw pass to output the necessary updates to the terminal
+    buffers: [Buffer; 2],
+    /// Index of the current buffer in the previous array
+    current: usize,
+    /// Whether the cursor is currently hidden
+    hidden_cursor: bool,
+    /// Viewport
+    viewport: Viewport,
+}
+
+impl<B> Drop for Terminal<B>
+where
+    B: Backend,
+{
+    fn drop(&mut self) {
+        // Attempt to restore the cursor state
+        if self.hidden_cursor {
+            if let Err(err) = self.show_cursor() {
+                eprintln!("Failed to show the cursor: {}", err);
+            }
+        }
+    }
+}
+
+impl<B> Terminal<B>
+where
+    B: Backend,
+{
+    /// Wrapper around Terminal initialization. Each buffer is initialized with a blank string and
+    /// default colors for the foreground and the background
+    pub fn new(backend: B) -> io::Result<Terminal<B>> {
+        let size = backend.size()?;
+        Terminal::with_options(
+            backend,
+            TerminalOptions {
+                viewport: Viewport {
+                    area: size,
+                    resize_behavior: ResizeBehavior::Auto,
+                },
+            },
+        )
+    }
+
+    /// UNSTABLE
+    pub fn with_options(backend: B, options: TerminalOptions) -> io::Result<Terminal<B>> {
+        Ok(Terminal {
+            backend,
+            buffers: [
+                Buffer::empty(options.viewport.area),
+                Buffer::empty(options.viewport.area),
+            ],
+            current: 0,
+            hidden_cursor: false,
+            viewport: options.viewport,
+        })
+    }
+
+    // /// Get a Frame object which provides a consistent view into the terminal state for rendering.
+    // pub fn get_frame(&mut self) -> Frame<B> {
+    //     Frame {
+    //         terminal: self,
+    //         cursor_position: None,
+    //     }
+    // }
+
+    pub fn current_buffer_mut(&mut self) -> &mut Buffer {
+        &mut self.buffers[self.current]
+    }
+
+    pub fn backend(&self) -> &B {
+        &self.backend
+    }
+
+    pub fn backend_mut(&mut self) -> &mut B {
+        &mut self.backend
+    }
+
+    /// Obtains a difference between the previous and the current buffer and passes it to the
+    /// current backend for drawing.
+    pub fn flush(&mut self) -> io::Result<()> {
+        let previous_buffer = &self.buffers[1 - self.current];
+        let current_buffer = &self.buffers[self.current];
+        let updates = previous_buffer.diff(current_buffer);
+        self.backend.draw(updates.into_iter())
+    }
+
+    /// Updates the Terminal so that internal buffers match the requested size. Requested size will
+    /// be saved so the size can remain consistent when rendering.
+    /// This leads to a full clear of the screen.
+    pub fn resize(&mut self, area: Rect) -> io::Result<()> {
+        self.buffers[self.current].resize(area);
+        self.buffers[1 - self.current].resize(area);
+        self.viewport.area = area;
+        self.clear()
+    }
+
+    /// Queries the backend for size and resizes if it doesn't match the previous size.
+    pub fn autoresize(&mut self) -> io::Result<()> {
+        if self.viewport.resize_behavior == ResizeBehavior::Auto {
+            let size = self.size()?;
+            if size != self.viewport.area {
+                self.resize(size)?;
+            }
+        };
+        Ok(())
+    }
+
+    /// Synchronizes terminal size, calls the rendering closure, flushes the current internal state
+    /// and prepares for the next draw call.
+    pub fn draw(&mut self) -> io::Result<()> {
+        // // Autoresize - otherwise we get glitches if shrinking or potential desync between widgets
+        // // and the terminal (if growing), which may OOB.
+        // self.autoresize()?;
+
+        // let mut frame = self.get_frame();
+        // f(&mut frame);
+        // // We can't change the cursor position right away because we have to flush the frame to
+        // // stdout first. But we also can't keep the frame around, since it holds a &mut to
+        // // Terminal. Thus, we're taking the important data out of the Frame and dropping it.
+        // let cursor_position = frame.cursor_position;
+
+        // Draw to stdout
+        self.flush()?;
+
+        // match cursor_position {
+        //     None => self.hide_cursor()?,
+        //     Some((x, y)) => {
+        //         self.show_cursor()?;
+        //         self.set_cursor(x, y)?;
+        //     }
+        // }
+
+        // Swap buffers
+        self.buffers[1 - self.current].reset();
+        self.current = 1 - self.current;
+
+        // Flush
+        self.backend.flush()?;
+        Ok(())
+    }
+
+    pub fn hide_cursor(&mut self) -> io::Result<()> {
+        self.backend.hide_cursor()?;
+        self.hidden_cursor = true;
+        Ok(())
+    }
+
+    pub fn show_cursor(&mut self) -> io::Result<()> {
+        self.backend.show_cursor()?;
+        self.hidden_cursor = false;
+        Ok(())
+    }
+
+    pub fn get_cursor(&mut self) -> io::Result<(u16, u16)> {
+        self.backend.get_cursor()
+    }
+
+    pub fn set_cursor(&mut self, x: u16, y: u16) -> io::Result<()> {
+        self.backend.set_cursor(x, y)
+    }
+
+    /// Clear the terminal and force a full redraw on the next draw call.
+    pub fn clear(&mut self) -> io::Result<()> {
+        self.backend.clear()?;
+        // Reset the back buffer to make sure the next update will redraw everything.
+        self.buffers[1 - self.current].reset();
+        Ok(())
+    }
+
+    /// Queries the real size of the backend.
+    pub fn size(&self) -> io::Result<Rect> {
+        self.backend.size()
+    }
+}