//! Renders the preview SVG for the README.
 //!
 //! To update the preview, execute the following command from the top level of
 //! the repository:
 //!
 //! ```sh
 //! cargo run --example readme_preview svg > codespan-reporting/assets/readme_preview.svg
 //! ```
 
 use codespan_reporting::diagnostic::{Diagnostic, Label};
 use codespan_reporting::files::SimpleFile;
 use codespan_reporting::term::termcolor::{Color, ColorSpec, StandardStream, WriteColor};
 use codespan_reporting::term::{self, ColorArg};
 use std::io::{self, Write};
 use structopt::StructOpt;
 
 #[derive(Debug, StructOpt)]
 #[structopt(name = "emit")]
 pub enum Opts {
     /// Render SVG output
     Svg,
     /// Render Stderr output
     Stderr {
         /// Configure coloring of output
         #[structopt(
             long = "color",
             parse(try_from_str),
             default_value = "auto",
             possible_values = ColorArg::VARIANTS,
             case_insensitive = true
         )]
         color: ColorArg,
     },
 }
 
main() -> anyhow::Result<()> fn main() -> anyhow::Result<()> {
     let file = SimpleFile::new(
         "FizzBuzz.fun",
         unindent::unindent(
             r#"
                 module FizzBuzz where
 
                 fizz₁ : Nat → String
                 fizz₁ num = case (mod num 5) (mod num 3) of
                     0 0 => "FizzBuzz"
                     0 _ => "Fizz"
                     _ 0 => "Buzz"
                     _ _ => num
 
                 fizz₂ : Nat → String
                 fizz₂ num =
                     case (mod num 5) (mod num 3) of
                         0 0 => "FizzBuzz"
                         0 _ => "Fizz"
                         _ 0 => "Buzz"
                         _ _ => num
             "#,
         ),
     );
 
     let diagnostics = [Diagnostic::error()
         .with_message("`case` clauses have incompatible types")
         .with_code("E0308")
         .with_labels(vec![
             Label::primary((), 328..331).with_message("expected `String`, found `Nat`"),
             Label::secondary((), 211..331).with_message("`case` clauses have incompatible types"),
             Label::secondary((), 258..268).with_message("this is found to be of type `String`"),
             Label::secondary((), 284..290).with_message("this is found to be of type `String`"),
             Label::secondary((), 306..312).with_message("this is found to be of type `String`"),
             Label::secondary((), 186..192).with_message("expected type `String` found here"),
         ])
         .with_notes(vec![unindent::unindent(
             "
                 expected type `String`
                    found type `Nat`
             ",
         )])];
 
     // let mut files = SimpleFiles::new();
     match Opts::from_args() {
         Opts::Svg => {
             let mut buffer = Vec::new();
             let mut writer = HtmlEscapeWriter::new(SvgWriter::new(&mut buffer));
             let config = codespan_reporting::term::Config {
                 styles: codespan_reporting::term::Styles::with_blue(Color::Blue),
                 ..codespan_reporting::term::Config::default()
             };
 
             for diagnostic in &diagnostics {
                 term::emit(&mut writer, &config, &file, &diagnostic)?;
             }
 
             let num_lines = buffer.iter().filter(|byte| **byte == b'\n').count() + 1;
 
             let padding = 10;
             let font_size = 12;
             let line_spacing = 3;
             let width = 882;
             let height = padding + num_lines * (font_size + line_spacing) + padding;
 
             let stdout = std::io::stdout();
             let writer = &mut stdout.lock();
 
             write!(
                 writer,
                 r#"<svg viewBox="0 0 {width} {height}" xmlns="http://www.w3.org/2000/svg">
   <style>
     /* https://github.com/aaron-williamson/base16-alacritty/blob/master/colors/base16-tomorrow-night-256.yml */
     pre {{
       background: #1d1f21;
       margin: 0;
       padding: {padding}px;
       border-radius: 6px;
       color: #ffffff;
       font: {font_size}px SFMono-Regular, Consolas, Liberation Mono, Menlo, monospace;
     }}
 
     pre .bold {{ font-weight: bold; }}
 
     pre .fg.black   {{ color: #1d1f21; }}
     pre .fg.red     {{ color: #cc6666; }}
     pre .fg.green   {{ color: #b5bd68; }}
     pre .fg.yellow  {{ color: #f0c674; }}
     pre .fg.blue    {{ color: #81a2be; }}
     pre .fg.magenta {{ color: #b294bb; }}
     pre .fg.cyan    {{ color: #8abeb7; }}
     pre .fg.white   {{ color: #c5c8c6; }}
 
     pre .fg.black.bright    {{ color: #969896; }}
     pre .fg.red.bright      {{ color: #cc6666; }}
     pre .fg.green.bright    {{ color: #b5bd68; }}
     pre .fg.yellow.bright   {{ color: #f0c674; }}
     pre .fg.blue.bright     {{ color: #81a2be; }}
     pre .fg.magenta.bright  {{ color: #b294bb; }}
     pre .fg.cyan.bright     {{ color: #8abeb7; }}
     pre .fg.white.bright    {{ color: #ffffff; }}
 
     pre .bg.black   {{ background-color: #1d1f21; }}
     pre .bg.red     {{ background-color: #cc6666; }}
     pre .bg.green   {{ background-color: #b5bd68; }}
     pre .bg.yellow  {{ background-color: #f0c674; }}
     pre .bg.blue    {{ background-color: #81a2be; }}
     pre .bg.magenta {{ background-color: #b294bb; }}
     pre .bg.cyan    {{ background-color: #8abeb7; }}
     pre .bg.white   {{ background-color: #c5c8c6; }}
 
     pre .bg.black.bright    {{ background-color: #969896; }}
     pre .bg.red.bright      {{ background-color: #cc6666; }}
     pre .bg.green.bright    {{ background-color: #b5bd68; }}
     pre .bg.yellow.bright   {{ background-color: #f0c674; }}
     pre .bg.blue.bright     {{ background-color: #81a2be; }}
     pre .bg.magenta.bright  {{ background-color: #b294bb; }}
     pre .bg.cyan.bright     {{ background-color: #8abeb7; }}
     pre .bg.white.bright    {{ background-color: #ffffff; }}
   </style>
 
   <foreignObject x="0" y="0" width="{width}" height="{height}">
     <div xmlns="http://www.w3.org/1999/xhtml">
       <pre>"#,
                 padding = padding,
                 font_size = font_size,
                 width = width,
                 height = height,
             )?;
 
             writer.write_all(&buffer)?;
 
             write!(
                 writer,
                 "</pre>
     </div>
   </foreignObject>
 </svg>
 "
             )?;
         }
         Opts::Stderr { color } => {
             let writer = StandardStream::stderr(color.into());
             let config = codespan_reporting::term::Config::default();
             for diagnostic in &diagnostics {
                 term::emit(&mut writer.lock(), &config, &file, &diagnostic)?;
             }
         }
     }
 
     Ok(())
 }
 
 /// Rudimentary HTML escaper which performs the following conversions:
 ///
 /// - `<` ⇒ `&lt;`
 /// - `>` ⇒ `&gt;`
 /// - `&` ⇒ `&amp;`
 pub struct HtmlEscapeWriter<W> {
     upstream: W,
 }
 
 impl<W> HtmlEscapeWriter<W> {
new(upstream: W) -> HtmlEscapeWriter<W>     pub fn new(upstream: W) -> HtmlEscapeWriter<W> {
         HtmlEscapeWriter { upstream }
     }
 }
 
 impl<W: Write> Write for HtmlEscapeWriter<W> {
write(&mut self, buf: &[u8]) -> io::Result<usize>     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         let mut last_term = 0usize;
         for (i, byte) in buf.iter().enumerate() {
             let escape = match byte {
                 b'<' => &b"&lt;"[..],
                 b'>' => &b"&gt;"[..],
                 b'&' => &b"&amp;"[..],
                 _ => continue,
             };
             self.upstream.write_all(&buf[last_term..i])?;
             last_term = i + 1;
             self.upstream.write_all(escape)?;
         }
         self.upstream.write_all(&buf[last_term..])?;
         Ok(buf.len())
     }
 
flush(&mut self) -> io::Result<()>     fn flush(&mut self) -> io::Result<()> {
         self.upstream.flush()
     }
 }
 
 impl<W: WriteColor> WriteColor for HtmlEscapeWriter<W> {
supports_color(&self) -> bool     fn supports_color(&self) -> bool {
         self.upstream.supports_color()
     }
 
set_color(&mut self, spec: &ColorSpec) -> io::Result<()>     fn set_color(&mut self, spec: &ColorSpec) -> io::Result<()> {
         self.upstream.set_color(spec)
     }
 
reset(&mut self) -> io::Result<()>     fn reset(&mut self) -> io::Result<()> {
         self.upstream.reset()
     }
 }
 
 pub struct SvgWriter<W> {
     upstream: W,
     color: ColorSpec,
 }
 
 impl<W> SvgWriter<W> {
new(upstream: W) -> SvgWriter<W>     pub fn new(upstream: W) -> SvgWriter<W> {
         SvgWriter {
             upstream,
             color: ColorSpec::new(),
         }
     }
 }
 
 impl<W: Write> Write for SvgWriter<W> {
write(&mut self, buf: &[u8]) -> io::Result<usize>     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         self.upstream.write(buf)
     }
 
flush(&mut self) -> io::Result<()>     fn flush(&mut self) -> io::Result<()> {
         self.upstream.flush()
     }
 }
 
 impl<W: Write> WriteColor for SvgWriter<W> {
supports_color(&self) -> bool     fn supports_color(&self) -> bool {
         true
     }
 
set_color(&mut self, spec: &ColorSpec) -> io::Result<()>     fn set_color(&mut self, spec: &ColorSpec) -> io::Result<()> {
         #![allow(unused_assignments)]
 
         if self.color == *spec {
             return Ok(());
         } else {
             if !self.color.is_none() {
                 write!(self, "</span>")?;
             }
             self.color = spec.clone();
         }
 
         if spec.is_none() {
             write!(self, "</span>")?;
             return Ok(());
         } else {
             write!(self, "<span class=\"")?;
         }
 
         let mut first = true;
 
         fn write_first<W: Write>(first: bool, writer: &mut SvgWriter<W>) -> io::Result<bool> {
             if !first {
                 write!(writer, " ")?;
             }
 
             Ok(false)
         };
 
         fn write_color<W: Write>(color: &Color, writer: &mut SvgWriter<W>) -> io::Result<()> {
             match color {
                 Color::Black => write!(writer, "black"),
                 Color::Blue => write!(writer, "blue"),
                 Color::Green => write!(writer, "green"),
                 Color::Red => write!(writer, "red"),
                 Color::Cyan => write!(writer, "cyan"),
                 Color::Magenta => write!(writer, "magenta"),
                 Color::Yellow => write!(writer, "yellow"),
                 Color::White => write!(writer, "white"),
                 // TODO: other colors
                 _ => Ok(()),
             }
         };
 
         if let Some(fg) = spec.fg() {
             first = write_first(first, self)?;
             write!(self, "fg ")?;
             write_color(fg, self)?;
         }
 
         if let Some(bg) = spec.bg() {
             first = write_first(first, self)?;
             write!(self, "bg ")?;
             write_color(bg, self)?;
         }
 
         if spec.bold() {
             first = write_first(first, self)?;
             write!(self, "bold")?;
         }
 
         if spec.underline() {
             first = write_first(first, self)?;
             write!(self, "underline")?;
         }
 
         if spec.intense() {
             first = write_first(first, self)?;
             write!(self, "bright")?;
         }
 
         write!(self, "\">")?;
 
         Ok(())
     }
 
reset(&mut self) -> io::Result<()>     fn reset(&mut self) -> io::Result<()> {
         let color = self.color.clone();
 
         if color != ColorSpec::new() {
             write!(self, "</span>")?;
             self.color = ColorSpec::new();
         }
 
         Ok(())
     }
 }