use ratatui::{
layout::Rect,
style::{Color, Style},
text::{Line, Span},
widgets::{
Block, Borders, Padding, Paragraph, Scrollbar, ScrollbarOrientation, ScrollbarState,
},
Frame,
};
use crate::{markdown::MarkdownRenderer, theme::RichTextTheme};
pub struct MarkdownViewer {
content: String,
lines: Vec<Line<'static>>,
scroll: u16,
doc_h: u16,
content_h: u16,
cached_width: usize,
title: String,
key_hints: String,
max_width: usize,
}
impl Default for MarkdownViewer {
fn default() -> Self {
Self::new()
}
}
impl MarkdownViewer {
pub fn new() -> Self {
Self {
content: String::new(),
lines: Vec::new(),
scroll: 0,
doc_h: 0,
content_h: 0,
cached_width: 0,
title: String::new(),
key_hints: String::new(),
max_width: 0,
}
}
pub fn with_title(mut self, title: impl Into<String>) -> Self {
self.title = title.into();
self
}
pub fn with_key_hints(mut self, hints: impl Into<String>) -> Self {
self.key_hints = hints.into();
self
}
pub fn with_max_width(mut self, width: usize) -> Self {
self.max_width = width;
self
}
pub fn set_content(&mut self, content: &str, theme: &impl RichTextTheme) {
if self.content != content {
self.content = content.to_string();
self.lines.clear();
self.cached_width = 0;
}
self.ensure_rendered(theme);
}
pub fn scroll_up(&mut self, n: u16) {
self.scroll = self.scroll.saturating_sub(n);
}
pub fn scroll_down(&mut self, n: u16) {
self.scroll = self.scroll.saturating_add(n);
self.clamp_scroll();
}
pub fn page_up(&mut self) {
let step = self.content_h.max(1);
self.scroll = self.scroll.saturating_sub(step);
}
pub fn page_down(&mut self) {
let step = self.content_h.max(1);
self.scroll = self.scroll.saturating_add(step);
self.clamp_scroll();
}
pub fn scroll_to_top(&mut self) {
self.scroll = 0;
}
pub fn scroll_to_bottom(&mut self) {
self.scroll = self.doc_h.saturating_sub(self.content_h);
}
pub fn render(&mut self, f: &mut Frame, area: Rect, theme: &impl RichTextTheme) {
self.ensure_rendered(theme);
let block_area = Rect::new(
area.x,
area.y,
area.width,
area.height
.saturating_sub(if self.key_hints.is_empty() { 0 } else { 1 }),
);
let mut block = Block::default()
.borders(Borders::ALL)
.padding(Padding::new(1, 1, 0, 0));
if !self.title.is_empty() {
block = block.title(format!(" {} ", self.title));
}
let inner = block.inner(block_area);
self.content_h = inner.height;
let inner_w = inner.width as usize;
self.clamp_scroll();
let scroll = self.scroll as usize;
let visible = self.content_h as usize;
let blank = Line::from(Span::raw(" ".repeat(inner_w)));
let mut padded: Vec<Line<'static>> = Vec::with_capacity(visible);
for i in scroll..scroll.saturating_add(visible).min(self.lines.len()) {
let spans = self.lines[i].spans.clone();
let used: usize = spans.iter().map(|s| s.width()).sum();
if used < inner_w {
let mut s = spans;
s.push(Span::raw(" ".repeat(inner_w - used)));
padded.push(Line::from(s));
} else if used > inner_w {
let mut taken = 0usize;
let mut short: Vec<Span<'static>> = Vec::new();
for sp in spans {
let sp_w = sp.width();
if taken + sp_w > inner_w {
let keep = inner_w - taken;
let chop: String = sp.content.chars().take(keep).collect();
short.push(Span::styled(chop, sp.style));
break;
}
taken += sp_w;
short.push(sp);
}
while taken < inner_w {
short.push(Span::raw(" "));
taken += 1;
}
padded.push(Line::from(short));
} else {
padded.push(Line::from(spans));
}
}
while padded.len() < visible {
padded.push(blank.clone());
}
f.render_widget(block, block_area);
f.render_widget(Paragraph::new(padded), inner);
if self.doc_h > self.content_h && self.content_h > 0 {
let sb_col = block_area.x + block_area.width.saturating_sub(1);
let sb_area = Rect::new(sb_col, inner.y, 1, self.content_h);
let content_len = self.doc_h.saturating_sub(self.content_h).saturating_add(1);
let sb = Scrollbar::default()
.orientation(ScrollbarOrientation::VerticalRight)
.thumb_symbol("\u{2588}")
.track_symbol(Some("\u{2502}"))
.style(Style::default().fg(Color::DarkGray))
.thumb_style(Style::default().fg(Color::Cyan));
let mut sb_state = ScrollbarState::default()
.content_length(content_len as usize)
.viewport_content_length(self.content_h as usize)
.position(self.scroll as usize);
f.render_stateful_widget(sb, sb_area, &mut sb_state);
}
if !self.key_hints.is_empty() {
let info_area = Rect::new(area.x, area.height.saturating_sub(1), area.width, 1);
f.render_widget(
Paragraph::new(vec![Line::from(Span::styled(
format!(" {}", self.key_hints),
Style::default().fg(Color::DarkGray),
))]),
info_area,
);
}
}
fn ensure_rendered(&mut self, theme: &impl RichTextTheme) {
if self.lines.is_empty() && !self.content.is_empty() {
let w = if self.max_width > 0 {
self.max_width
} else {
76
};
let renderer = MarkdownRenderer::new(w);
let blocks = renderer.parse(&self.content);
self.lines = renderer.render(&blocks, theme);
self.doc_h = self.lines.len() as u16;
self.clamp_scroll();
}
}
fn clamp_scroll(&mut self) {
let max = self.doc_h.saturating_sub(self.content_h);
if self.scroll > max {
self.scroll = max;
}
}
}