ui: wip: Markdown doc renderer.

6 files changed, 144 insertions, 4 deletions

diff --git a/helix-term/Cargo.toml b/helix-term/Cargo.toml
index 34b37636..eaf8ebd7 100644
--- a/helix-term/Cargo.toml
+++ b/helix-term/Cargo.toml
@@ -39,3 +39,5 @@ fuzzy-matcher = "0.3"
 ignore = "0.4"
 # shellexpand = "2.1"
 dirs-next = "2.0"
+# markdown doc rendering
+pulldown-cmark = { version = "0.8", default-features = false }
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index d45e7168..e6b7cebd 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -1179,7 +1179,7 @@ pub fn hover(cx: &mut Context) {
 
         // skip if contents empty
 
-        let contents = ui::Text::new(contents);
+        let contents = ui::Markdown::new(contents);
         let mut popup = Popup::new(Box::new(contents));
         cx.push_layer(Box::new(popup));
     }
diff --git a/helix-term/src/ui/markdown.rs b/helix-term/src/ui/markdown.rs
new file mode 100644
index 00000000..8456ef74
--- /dev/null
+++ b/helix-term/src/ui/markdown.rs
@@ -0,0 +1,137 @@
+use crate::compositor::{Component, Compositor, Context, EventResult};
+use crossterm::event::{Event, KeyCode, KeyEvent, KeyModifiers};
+use tui::buffer::Buffer as Surface;
+use tui::{
+    layout::Rect,
+    style::{Color, Style},
+    text::Text,
+};
+
+use std::borrow::Cow;
+
+use helix_core::Position;
+use helix_view::Editor;
+
+pub struct Markdown {
+    contents: String,
+}
+
+impl Markdown {
+    pub fn new(contents: String) -> Self {
+        Self { contents }
+    }
+}
+impl Component for Markdown {
+    fn render(&self, area: Rect, surface: &mut Surface, cx: &mut Context) {
+        use tui::widgets::{Paragraph, Widget, Wrap};
+
+        use pulldown_cmark::{CodeBlockKind, CowStr, Event, Options, Parser, Tag};
+        use tui::text::{Span, Spans, Text};
+
+        // also 2021-03-04T16:33:58.553 helix_lsp::transport [INFO] <- {"contents":{"kind":"markdown","value":"\n```rust\ncore::num\n```\n\n```rust\npub const fn saturating_sub(self, rhs:Self) ->Self\n```\n\n---\n\n```rust\n```"},"range":{"end":{"character":61,"line":101},"start":{"character":47,"line":101}}}
+        let text = "\n```rust\ncore::iter::traits::iterator::Iterator\n```\n\n```rust\nfn collect<B: FromIterator<Self::Item>>(self) -> B\nwhere\n        Self: Sized,\n```\n\n---\n\nTransforms an iterator into a collection.\n\n`collect()` can take anything iterable, and turn it into a relevant\ncollection. This is one of the more powerful methods in the standard\nlibrary, used in a variety of contexts.\n\nThe most basic pattern in which `collect()` is used is to turn one\ncollection into another. You take a collection, call [`iter`](https://doc.rust-lang.org/nightly/core/iter/traits/iterator/trait.Iterator.html) on it,\ndo a bunch of transformations, and then `collect()` at the end.\n\n`collect()` can also create instances of types that are not typical\ncollections. For example, a [`String`](https://doc.rust-lang.org/nightly/core/iter/std/string/struct.String.html) can be built from [`char`](type@char)s,\nand an iterator of [`Result<T, E>`](https://doc.rust-lang.org/nightly/core/result/enum.Result.html) items can be collected\ninto `Result<Collection<T>, E>`. See the examples below for more.\n\nBecause `collect()` is so general, it can cause problems with type\ninference. As such, `collect()` is one of the few times you'll see\nthe syntax affectionately known as the 'turbofish': `::<>`. This\nhelps the inference algorithm understand specifically which collection\nyou're trying to collect into.\n\n# Examples\n\nBasic usage:\n\n```rust\nlet a = [1, 2, 3];\n\nlet doubled: Vec<i32> = a.iter()\n                         .map(|&x| x * 2)\n                         .collect();\n\nassert_eq!(vec![2, 4, 6], doubled);\n```\n\nNote that we needed the `: Vec<i32>` on the left-hand side. This is because\nwe could collect into, for example, a [`VecDeque<T>`](https://doc.rust-lang.org/nightly/core/iter/std/collections/struct.VecDeque.html) instead:\n\n```rust\nuse std::collections::VecDeque;\n\nlet a = [1, 2, 3];\n\nlet doubled: VecDeque<i32> = a.iter().map(|&x| x * 2).collect();\n\nassert_eq!(2, doubled[0]);\nassert_eq!(4, doubled[1]);\nassert_eq!(6, doubled[2]);\n```\n\nUsing the 'turbofish' instead of annotating `doubled`:\n\n```rust\nlet a = [1, 2, 3];\n\nlet doubled = a.iter().map(|x| x * 2).collect::<Vec<i32>>();\n\nassert_eq!(vec![2, 4, 6], doubled);\n```\n\nBecause `collect()` only cares about what you're collecting into, you can\nstill use a partial type hint, `_`, with the turbofish:\n\n```rust\nlet a = [1, 2, 3];\n\nlet doubled = a.iter().map(|x| x * 2).collect::<Vec<_>>();\n\nassert_eq!(vec![2, 4, 6], doubled);\n```\n\nUsing `collect()` to make a [`String`](https://doc.rust-lang.org/nightly/core/iter/std/string/struct.String.html):\n\n```rust\nlet chars = ['g', 'd', 'k', 'k', 'n'];\n\nlet hello: String = chars.iter()\n    .map(|&x| x as u8)\n    .map(|x| (x + 1) as char)\n    .collect();\n\nassert_eq!(\"hello\", hello);\n```\n\nIf you have a list of [`Result<T, E>`](https://doc.rust-lang.org/nightly/core/result/enum.Result.html)s, you can use `collect()` to\nsee if any of them failed:\n\n```rust\nlet results = [Ok(1), Err(\"nope\"), Ok(3), Err(\"bad\")];\n\nlet result: Result<Vec<_>, &str> = results.iter().cloned().collect();\n\n// gives us the first error\nassert_eq!(Err(\"nope\"), result);\n\nlet results = [Ok(1), Ok(3)];\n\nlet result: Result<Vec<_>, &str> = results.iter().cloned().collect();\n\n// gives us the list of answers\nassert_eq!(Ok(vec![1, 3]), result);\n```";
+
+        let mut options = Options::empty();
+        options.insert(Options::ENABLE_STRIKETHROUGH);
+        let parser = Parser::new_ext(&self.contents, options);
+
+        // TODO: if possible, render links as terminal hyperlinks: https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
+        let mut tags = Vec::new();
+        let mut spans = Vec::new();
+        let mut lines = Vec::new();
+
+        fn to_span(text: pulldown_cmark::CowStr) -> Span {
+            use std::ops::Deref;
+            Span::raw::<std::borrow::Cow<_>>(match text {
+                CowStr::Borrowed(s) => s.into(),
+                CowStr::Boxed(s) => s.to_string().into(),
+                CowStr::Inlined(s) => s.deref().to_owned().into(),
+            })
+        }
+
+        let text_style = Style::default().fg(Color::Rgb(164, 160, 232)); // lavender
+        let code_style = Style::default().fg(Color::Rgb(255, 255, 255)); // white
+        let heading_style = Style::default().fg(Color::Rgb(219, 191, 239)); // lilac
+
+        for event in parser {
+            match event {
+                Event::Start(tag) => tags.push(tag),
+                Event::End(tag) => {
+                    tags.pop();
+                    match tag {
+                        Tag::Heading(_) | Tag::Paragraph => {
+                            // whenever paragraph closes, new line
+                            let spans = std::mem::replace(&mut spans, Vec::new());
+                            lines.push(Spans::from(spans));
+                            lines.push(Spans::default());
+                        }
+                        Tag::CodeBlock(CodeBlockKind::Fenced(_)) => {
+                            let spans = std::mem::replace(&mut spans, Vec::new());
+                            lines.push(Spans::from(spans));
+                        }
+                        _ => (),
+                    }
+                }
+                Event::Text(text) => {
+                    if let Some(Tag::CodeBlock(CodeBlockKind::Fenced(_))) = tags.last() {
+                        for line in text.lines() {
+                            let mut span = Span::styled(line.to_string(), code_style);
+                            lines.push(Spans::from(span));
+                        }
+                    } else if let Some(Tag::Heading(_)) = tags.last() {
+                        let mut span = to_span(text);
+                        span.style = heading_style;
+                        spans.push(span);
+                    } else {
+                        let mut span = to_span(text);
+                        span.style = text_style;
+                        spans.push(span);
+                    }
+                }
+                Event::Code(text) | Event::Html(text) => {
+                    let mut span = to_span(text);
+                    span.style = code_style;
+                    spans.push(span);
+                }
+                Event::SoftBreak | Event::HardBreak => {
+                    // let spans = std::mem::replace(&mut spans, Vec::new());
+                    // lines.push(Spans::from(spans));
+                    spans.push(Span::raw(" "));
+                }
+                Event::Rule => {
+                    lines.push(Spans::from("---"));
+                    lines.push(Spans::default());
+                }
+                // TaskListMarker(bool) true if checked
+                _ => (),
+            }
+            // build up a vec of Paragraph tui widgets
+        }
+
+        if !spans.is_empty() {
+            lines.push(Spans::from(spans));
+        }
+
+        let contents = Text::from(lines);
+
+        let par = Paragraph::new(contents).wrap(Wrap { trim: false });
+        // .scroll(x, y) offsets
+
+        // padding on all sides
+        let area = Rect::new(area.x + 1, area.y + 1, area.width - 2, area.height - 2);
+        par.render(area, surface);
+    }
+
+    fn size_hint(&self, area: Rect) -> Option<(usize, usize)> {
+        let contents = tui::text::Text::from(self.contents.clone());
+        Some((contents.width(), contents.height()))
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn it_works() {}
+}
diff --git a/helix-term/src/ui/mod.rs b/helix-term/src/ui/mod.rs
index 593da3ae..b175c646 100644
--- a/helix-term/src/ui/mod.rs
+++ b/helix-term/src/ui/mod.rs
@@ -1,4 +1,5 @@
 mod editor;
+mod markdown;
 mod menu;
 mod picker;
 mod popup;
@@ -6,6 +7,7 @@ mod prompt;
 mod text;
 
 pub use editor::EditorView;
+pub use markdown::Markdown;
 pub use menu::Menu;
 pub use picker::Picker;
 pub use popup::Popup;
diff --git a/helix-term/src/ui/popup.rs b/helix-term/src/ui/popup.rs
index 7260a997..625ee2b3 100644
--- a/helix-term/src/ui/popup.rs
+++ b/helix-term/src/ui/popup.rs
@@ -82,8 +82,8 @@ impl Component for Popup {
             .size_hint(viewport)
             .expect("Component needs size_hint implemented in order to be embedded in a popup");
 
-        let width = width.min(150) as u16;
-        let height = height.min(13) as u16;
+        let width = width.min(120) as u16;
+        let height = height.min(26) as u16;
 
         // -- make sure frame doesn't stick out of bounds
         let mut rel_x = position.col as u16;
diff --git a/helix-term/src/ui/text.rs b/helix-term/src/ui/text.rs
index bacb68b8..133cdd25 100644
--- a/helix-term/src/ui/text.rs
+++ b/helix-term/src/ui/text.rs
@@ -4,7 +4,6 @@ use tui::buffer::Buffer as Surface;
 use tui::{
     layout::Rect,
     style::{Color, Style},
-    widgets::{Block, Borders},
 };
 
 use std::borrow::Cow;