use crate::nop_lib::NopPost;
use clap::{Arg, ArgMatches, Command};
use mdxbook::errors::Error;
use mdxbook::postprocess::{CmdPostprocessor, Postprocessor, Rendered};
use semver::{Version, VersionReq};
use std::io;
use std::process;

pub fn make_app() -> Command {
    Command::new("nop-postprocessor")
        .about("A mdxbook postprocessor which does precisely nothing")
        .subcommand(
            Command::new("supports")
                .arg(Arg::new("renderer").required(true))
                .about("Check whether a renderer is supported by this postprocessor"),
        )
}

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

    // Users will want to construct their own preprocessor here
    let preprocessor = NopPost::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 Postprocessor) -> Result<(), Error> {
    let (ctx, book) = CmdPostprocessor::parse_input(io::stdin())?;

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

    let processed_book = match book {
        Rendered::Book(b) => serde_json::to_writer(io::stdout(), &pre.postprocess_book(&ctx, b)?)?,
        Rendered::Document(d) => {
            serde_json::to_writer(io::stdout(), &pre.postprocess_document(&ctx, d)?)?
        }
    };

    Ok(processed_book)
}

fn handle_supports(pre: &dyn Postprocessor, 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);
    }
}

/// The actual implementation of the `NopPost` preprocessor. This would usually go
/// in your main `lib.rs` file.
mod nop_lib {
    use super::*;
    use mdxbook::postprocess::{
        CmdPostprocessor, Postprocessor, PostprocessorContext, RenderedBook, RenderedDocumentOfBook,
    };

    /// A no-op preprocessor.
    #[derive(Clone)]
    pub struct NopPost;

    impl NopPost {
        pub fn new() -> NopPost {
            NopPost
        }
    }

    impl Postprocessor for NopPost {
        fn name(&self) -> &str {
            "nop-postprocessor"
        }

        fn supports_renderer(&self, renderer: &str) -> bool {
            renderer != "not-supported"
        }

        fn postprocess_document(
            &self,
            context: &PostprocessorContext,
            rendered_document: RenderedDocumentOfBook,
        ) -> Result<RenderedDocumentOfBook, Error> {
            // In testing we want to tell the postprocessor to blow up by setting a
            // particular config value
            if let Some(nop_cfg) = context.config.get_postprocessor(self.name()) {
                if nop_cfg.contains_key("blow-up") {
                    anyhow::bail!("Boom!!1!");
                }
            }

            // we *are* a no-op preprocessor after all
            Ok(rendered_document)
        }

        fn postprocess_book(
            &self,
            context: &PostprocessorContext,
            rendered_book: RenderedBook,
        ) -> Result<RenderedBook, Error> {
            // In testing we want to tell the preprocessor to blow up by setting a
            // particular config value
            if let Some(nop_cfg) = context.config.get_postprocessor(self.name()) {
                if nop_cfg.contains_key("blow-up") {
                    anyhow::bail!("Boom!!1!");
                }
            }

            // we *are* a no-op preprocessor after all
            Ok(rendered_book)
        }

        fn clone_dyn(&self) -> Box<dyn Postprocessor> {
            Box::new(self.clone())
        }

        fn to_cmd_postprocessor(&self) -> Option<CmdPostprocessor> {
            Some(CmdPostprocessor::new(
                self.name().to_string(),
                "cargo run --example nop-postprocessor --".to_string(),
            ))
        }
    }
}