Support sending and displaying formatted messages (#10)

src/message/printer.rs

@@ -0,0 +1,157 @@
+use std::borrow::Cow;
+
+use modalkit::tui::layout::Alignment;
+use modalkit::tui::style::Style;
+use modalkit::tui::text::{Span, Spans, Text};
+use unicode_width::UnicodeWidthStr;
+
+use crate::util::{space_span, take_width};
+
+pub struct TextPrinter<'a> {
+    text: Text<'a>,
+    width: usize,
+    base_style: Style,
+    hide_reply: bool,
+
+    alignment: Alignment,
+    curr_spans: Vec<Span<'a>>,
+    curr_width: usize,
+}
+
+impl<'a> TextPrinter<'a> {
+    pub fn new(width: usize, base_style: Style, hide_reply: bool) -> Self {
+        TextPrinter {
+            text: Text::default(),
+            width,
+            base_style,
+            hide_reply,
+
+            alignment: Alignment::Left,
+            curr_spans: vec![],
+            curr_width: 0,
+        }
+    }
+
+    pub fn align(mut self, alignment: Alignment) -> Self {
+        self.alignment = alignment;
+        self
+    }
+
+    pub fn hide_reply(&self) -> bool {
+        self.hide_reply
+    }
+
+    pub fn width(&self) -> usize {
+        self.width
+    }
+
+    pub fn sub(&self, indent: usize) -> Self {
+        TextPrinter {
+            text: Text::default(),
+            width: self.width.saturating_sub(indent),
+            base_style: self.base_style,
+            hide_reply: self.hide_reply,
+
+            alignment: self.alignment,
+            curr_spans: vec![],
+            curr_width: 0,
+        }
+    }
+
+    fn remaining(&self) -> usize {
+        self.width - self.curr_width
+    }
+
+    pub fn commit(&mut self) {
+        if self.curr_width > 0 {
+            self.push_break();
+        }
+    }
+
+    fn push(&mut self) {
+        self.curr_width = 0;
+        self.text.lines.push(Spans(std::mem::take(&mut self.curr_spans)));
+    }
+
+    pub fn push_break(&mut self) {
+        if self.curr_width == 0 && self.text.lines.is_empty() {
+            // Disallow leading breaks.
+            return;
+        }
+
+        let remaining = self.remaining();
+
+        if remaining > 0 {
+            match self.alignment {
+                Alignment::Left => {
+                    let tspan = space_span(remaining, self.base_style);
+                    self.curr_spans.push(tspan);
+                },
+                Alignment::Center => {
+                    let trailing = remaining / 2;
+                    let leading = remaining - trailing;
+
+                    let tspan = space_span(trailing, self.base_style);
+                    let lspan = space_span(leading, self.base_style);
+
+                    self.curr_spans.push(tspan);
+                    self.curr_spans.insert(0, lspan);
+                },
+                Alignment::Right => {
+                    let lspan = space_span(remaining, self.base_style);
+                    self.curr_spans.insert(0, lspan);
+                },
+            }
+        }
+
+        self.push();
+    }
+
+    pub fn push_str<T>(&mut self, s: T, style: Style)
+    where
+        T: Into<Cow<'a, str>>,
+    {
+        let style = self.base_style.patch(style);
+        let mut cow = s.into();
+
+        loop {
+            let sw = UnicodeWidthStr::width(cow.as_ref());
+
+            if self.curr_width + sw <= self.width {
+                // The text fits within the current line.
+                self.curr_spans.push(Span::styled(cow, style));
+                self.curr_width += sw;
+                break;
+            }
+
+            // Take a leading portion of the text that fits in the line.
+            let ((s0, w), s1) = take_width(cow, self.remaining());
+            cow = s1;
+
+            self.curr_spans.push(Span::styled(s0, style));
+            self.curr_width += w;
+
+            self.commit();
+        }
+
+        if self.curr_width == self.width {
+            // If the last bit fills the full line, start a new one.
+            self.push();
+        }
+    }
+
+    pub fn push_line(&mut self, spans: Spans<'a>) {
+        self.commit();
+        self.text.lines.push(spans);
+    }
+
+    pub fn push_text(&mut self, text: Text<'a>) {
+        self.commit();
+        self.text.lines.extend(text.lines);
+    }
+
+    pub fn finish(mut self) -> Text<'a> {
+        self.commit();
+        self.text
+    }
+}