use mdbook_tagger::Tagger;
use clap::{Arg, ArgMatches, Command};
use mdbook::errors::Error;
use mdbook::preprocess::{CmdPreprocessor, Preprocessor};
use semver::{Version, VersionReq};
use std::io;
use std::process;


pub fn make_app() -> Command {
  Command::new("mdbook-tagger")
    .about("A mdbook preprocessor to collect and build tag data in Json format")
    .subcommand(
      Command::new("supports")
        .arg(Arg::new("renderer").required(true))
        .about("Check whether a renderer is supported by this preprocessor"),
    )
}

fn main() {
  let matches = make_app().get_matches();

  // Users will want to construct their own preprocessor here
  let preprocessor = Tagger::new();

  if let Some(sub_args) = matches.subcommand_matches("supports") {
    handle_supports(&preprocessor, sub_args);
  } else if let Err(e) = handle_preprocessing(&preprocessor) {
    eprintln!("{}", e);
    process::exit(1);
  }
}

fn handle_preprocessing(pre: &dyn Preprocessor) -> Result<(), Error> {
  let (ctx, book) = CmdPreprocessor::parse_input(io::stdin())?;

  let book_version = Version::parse(&ctx.mdbook_version)?;
  let version_req = VersionReq::parse(mdbook::MDBOOK_VERSION)?;

  if !version_req.matches(&book_version) {
    eprintln!(
      "Warning: The {} plugin was built against version {} of mdbook, \
       but we're being called from version {}",
      pre.name(),
      mdbook::MDBOOK_VERSION,
      ctx.mdbook_version
    );
  }

  let processed_book = pre.run(&ctx, book)?;
  serde_json::to_writer(io::stdout(), &processed_book)?;

  Ok(())
}

fn handle_supports(pre: &dyn Preprocessor, sub_args: &ArgMatches) -> ! {
  let renderer = sub_args
    .get_one::<String>("renderer")
    .expect("Required argument");
  let supported = pre.supports_renderer(renderer);

  // Signal whether the renderer is supported by exiting with 1 or 0.
  if supported {
    process::exit(0);
  } else {
    process::exit(1);
  }
}