use crate::utils::decode_bin;
use ansi_colours::AsRGB;
use anyhow::{anyhow, Context, Result};
use crossterm::style::{Color, Stylize};
use crossterm::terminal;
use std::collections::HashMap;
use std::sync::LazyLock;
use syntect::highlighting::{Color as SyntectColor, FontStyle, Style, Theme};
use syntect::parsing::SyntaxSet;
use syntect::{easy::HighlightLines, parsing::SyntaxReference};
const SYNTAXES: &[u8] = include_bytes!("../../assets/syntaxes.bin");
static LANG_MAPS: LazyLock<HashMap<String, String>> = LazyLock::new(|| {
let mut m = HashMap::new();
m.insert("csharp".into(), "C#".into());
m.insert("php".into(), "PHP Source".into());
m
});
pub struct MarkdownRender {
options: RenderOptions,
syntax_set: SyntaxSet,
code_color: Option<Color>,
md_syntax: SyntaxReference,
code_syntax: Option<SyntaxReference>,
prev_line_type: LineType,
wrap_width: Option<u16>,
}
impl MarkdownRender {
pub fn init(options: RenderOptions) -> Result<Self> {
let syntax_set: SyntaxSet =
decode_bin(SYNTAXES).with_context(|| "MarkdownRender: invalid syntaxes binary")?;
let code_color = options
.theme
.as_ref()
.map(|theme| get_code_color(theme, options.truecolor));
let md_syntax = syntax_set.find_syntax_by_extension("md").unwrap().clone();
let line_type = LineType::Normal;
let wrap_width = match options.wrap.as_deref() {
None => None,
Some(value) => match terminal::size() {
Ok((columns, _)) => {
if value == "auto" {
Some(columns)
} else {
let value = value
.parse::<u16>()
.map_err(|_| anyhow!("Invalid wrap value"))?;
Some(columns.min(value))
}
}
Err(_) => None,
},
};
Ok(Self {
syntax_set,
code_color,
md_syntax,
code_syntax: None,
prev_line_type: line_type,
wrap_width,
options,
})
}
pub fn render(&mut self, text: &str) -> String {
text.split('\n')
.map(|line| self.render_line_mut(line))
.collect::<Vec<String>>()
.join("\n")
}
pub fn render_line(&self, line: &str) -> String {
let (_, code_syntax, is_code) = self.check_line(line);
if is_code {
self.highlight_code_line(line, &code_syntax)
} else {
self.highlight_line(line, &self.md_syntax, false)
}
}
fn render_line_mut(&mut self, line: &str) -> String {
let (line_type, code_syntax, is_code) = self.check_line(line);
let output = if is_code {
self.highlight_code_line(line, &code_syntax)
} else {
self.highlight_line(line, &self.md_syntax, false)
};
self.prev_line_type = line_type;
self.code_syntax = code_syntax;
output
}
fn check_line(&self, line: &str) -> (LineType, Option<SyntaxReference>, bool) {
let mut line_type = self.prev_line_type;
let mut code_syntax = self.code_syntax.clone();
let mut is_code = false;
if let Some(lang) = detect_code_block(line) {
match line_type {
LineType::Normal | LineType::CodeEnd => {
line_type = LineType::CodeBegin;
code_syntax = if lang.is_empty() {
None
} else {
self.find_syntax(&lang).cloned()
};
}
LineType::CodeBegin | LineType::CodeInner => {
line_type = LineType::CodeEnd;
code_syntax = None;
}
}
} else {
match line_type {
LineType::Normal => {}
LineType::CodeEnd => {
line_type = LineType::Normal;
}
LineType::CodeBegin => {
if code_syntax.is_none() {
if let Some(syntax) = self.syntax_set.find_syntax_by_first_line(line) {
code_syntax = Some(syntax.clone());
}
}
line_type = LineType::CodeInner;
is_code = true;
}
LineType::CodeInner => {
is_code = true;
}
}
}
(line_type, code_syntax, is_code)
}
fn highlight_line(&self, line: &str, syntax: &SyntaxReference, is_code: bool) -> String {
let ws: String = line.chars().take_while(|c| c.is_whitespace()).collect();
let trimmed_line: &str = &line[ws.len()..];
let mut line_highlighted = None;
if let Some(theme) = &self.options.theme {
let mut highlighter = HighlightLines::new(syntax, theme);
if let Ok(ranges) = highlighter.highlight_line(trimmed_line, &self.syntax_set) {
line_highlighted = Some(format!(
"{ws}{}",
as_terminal_escaped(&ranges, self.options.truecolor)
))
}
}
let line = line_highlighted.unwrap_or_else(|| line.into());
self.wrap_line(line, is_code)
}
fn highlight_code_line(&self, line: &str, code_syntax: &Option<SyntaxReference>) -> String {
if let Some(syntax) = code_syntax {
self.highlight_line(line, syntax, true)
} else {
let line = match self.code_color {
Some(color) => line.with(color).to_string(),
None => line.to_string(),
};
self.wrap_line(line, true)
}
}
fn wrap_line(&self, line: String, is_code: bool) -> String {
if let Some(width) = self.wrap_width {
if is_code && !self.options.wrap_code {
return line;
}
wrap(&line, width as usize)
} else {
line
}
}
fn find_syntax(&self, lang: &str) -> Option<&SyntaxReference> {
if let Some(new_lang) = LANG_MAPS.get(&lang.to_ascii_lowercase()) {
self.syntax_set.find_syntax_by_name(new_lang)
} else {
self.syntax_set
.find_syntax_by_token(lang)
.or_else(|| self.syntax_set.find_syntax_by_extension(lang))
}
}
}
fn wrap(text: &str, width: usize) -> String {
let indent: usize = text.chars().take_while(|c| *c == ' ').count();
let wrap_options = textwrap::Options::new(width)
.wrap_algorithm(textwrap::WrapAlgorithm::FirstFit)
.initial_indent(&text[0..indent]);
textwrap::wrap(&text[indent..], wrap_options).join("\n")
}
#[derive(Debug, Clone, Default)]
pub struct RenderOptions {
pub theme: Option<Theme>,
pub wrap: Option<String>,
pub wrap_code: bool,
pub truecolor: bool,
}
impl RenderOptions {
pub(crate) fn new(
theme: Option<Theme>,
wrap: Option<String>,
wrap_code: bool,
truecolor: bool,
) -> Self {
Self {
theme,
wrap,
wrap_code,
truecolor,
}
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum LineType {
Normal,
CodeBegin,
CodeInner,
CodeEnd,
}
fn as_terminal_escaped(ranges: &[(Style, &str)], truecolor: bool) -> String {
let mut output = String::new();
for (style, text) in ranges {
let fg = blend_fg_color(style.foreground, style.background);
let mut text = text.with(convert_color(fg, truecolor));
if style.font_style.contains(FontStyle::BOLD) {
text = text.bold();
}
if style.font_style.contains(FontStyle::UNDERLINE) {
text = text.underlined();
}
output.push_str(&text.to_string());
}
output
}
fn convert_color(c: SyntectColor, truecolor: bool) -> Color {
if truecolor {
Color::Rgb {
r: c.r,
g: c.g,
b: c.b,
}
} else {
let value = (c.r, c.g, c.b).to_ansi256();
let value = match value {
7 | 15 | 231 | 252..=255 => 252,
_ => value,
};
Color::AnsiValue(value)
}
}
fn blend_fg_color(fg: SyntectColor, bg: SyntectColor) -> SyntectColor {
if fg.a == 0xff {
return fg;
}
let ratio = u32::from(fg.a);
let r = (u32::from(fg.r) * ratio + u32::from(bg.r) * (255 - ratio)) / 255;
let g = (u32::from(fg.g) * ratio + u32::from(bg.g) * (255 - ratio)) / 255;
let b = (u32::from(fg.b) * ratio + u32::from(bg.b) * (255 - ratio)) / 255;
SyntectColor {
r: u8::try_from(r).unwrap_or(u8::MAX),
g: u8::try_from(g).unwrap_or(u8::MAX),
b: u8::try_from(b).unwrap_or(u8::MAX),
a: 255,
}
}
fn detect_code_block(line: &str) -> Option<String> {
let line = line.trim_start();
if !line.starts_with("```") {
return None;
}
let lang = line
.chars()
.skip(3)
.take_while(|v| !v.is_whitespace())
.collect();
Some(lang)
}
fn get_code_color(theme: &Theme, truecolor: bool) -> Color {
let scope = theme.scopes.iter().find(|v| {
v.scope
.selectors
.iter()
.any(|v| v.path.scopes.iter().any(|v| v.to_string() == "string"))
});
scope
.and_then(|v| v.style.foreground)
.map_or_else(|| Color::Yellow, |c| convert_color(c, truecolor))
}
#[cfg(test)]
mod tests {
use super::*;
const TEXT: &str = r#"
To unzip a file in Rust, you can use the `zip` crate. Here's an example code that shows how to unzip a file:
```rust
use std::fs::File;
fn unzip_file(path: &str, output_dir: &str) -> Result<(), Box<dyn std::error::Error>> {
todo!()
}
```
"#;
const TEXT_NO_WRAP_CODE: &str = r#"
To unzip a file in Rust, you can use the `zip` crate. Here's an example code
that shows how to unzip a file:
```rust
use std::fs::File;
fn unzip_file(path: &str, output_dir: &str) -> Result<(), Box<dyn std::error::Error>> {
todo!()
}
```
"#;
const TEXT_WRAP_ALL: &str = r#"
To unzip a file in Rust, you can use the `zip` crate. Here's an example code
that shows how to unzip a file:
```rust
use std::fs::File;
fn unzip_file(path: &str, output_dir: &str) -> Result<(), Box<dyn
std::error::Error>> {
todo!()
}
```
"#;
#[test]
fn test_render() {
let options = RenderOptions::default();
let render = MarkdownRender::init(options).unwrap();
assert!(render.find_syntax("csharp").is_some());
}
#[test]
fn no_theme() {
let options = RenderOptions::default();
let mut render = MarkdownRender::init(options).unwrap();
let output = render.render(TEXT);
assert_eq!(TEXT, output);
}
#[test]
fn no_wrap_code() {
let options = RenderOptions::default();
let mut render = MarkdownRender::init(options).unwrap();
render.wrap_width = Some(80);
let output = render.render(TEXT);
assert_eq!(TEXT_NO_WRAP_CODE, output);
}
#[test]
fn wrap_all() {
let options = RenderOptions {
wrap_code: true,
..Default::default()
};
let mut render = MarkdownRender::init(options).unwrap();
render.wrap_width = Some(80);
let output = render.render(TEXT);
assert_eq!(TEXT_WRAP_ALL, output);
}
#[test]
fn test_detect_code_block() {
assert_eq!(detect_code_block("```rust"), Some("rust".into()));
assert_eq!(detect_code_block("```c++"), Some("c++".into()));
assert_eq!(detect_code_block(" ```rust"), Some("rust".into()));
assert_eq!(detect_code_block("```"), Some("".into()));
assert_eq!(detect_code_block("``rust"), None);
}
}