Cargo.toml

[package]
name = "cbztoepub"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
argh = "0.1.12"
color-eyre = "0.6.2"
pandoc = "0.8.10"
tempfile = "3.8.1"
zip = "0.6.6"

main.rs

use std::{
    fs::{create_dir_all, remove_dir_all, File},
    io::Write,
    path::PathBuf,
};

use argh::FromArgs;
use color_eyre::eyre::ContextCompat;
use tempfile::tempdir;

#[derive(FromArgs)]
/// Easy conversion from cbz to epub.
struct Arguments {
    /// input file.
    #[argh(option, short = 'i')]
    input: PathBuf,
    /// an optional nickname for the pilot
    #[argh(option, short = 'o')]
    output: PathBuf,
}

fn main() -> color_eyre::Result<()> {
    color_eyre::install()?;
    let args: Arguments = argh::from_env();
    let file = File::open(args.input)?;

    let mut archive = zip::ZipArchive::new(file)?;
    let temp_dir = tempdir()?.into_path();
    archive.extract(&temp_dir)?;

    let html_path = temp_dir.join("html_pages");
    let mut pandoc = pandoc::new();
    create_dir_all(&html_path)?;
    let mut sorted_filenames = archive.file_names().collect::<Vec<_>>();
    sorted_filenames.sort_unstable();
    for (str, path) in sorted_filenames.iter().map(|x| {
        (
            format!(
                "<img src='{}/{x}' style='height: 100%; width: auto'>",
                temp_dir.display()
            ),
            html_path.join(x),
        )
    }) {
        let with_html_extension = path.with_extension("html");
        let mut file = File::create(&with_html_extension)?;
        pandoc.add_input(&with_html_extension);
        write!(&mut file, "{str}")?;
    }
    let first_picture = temp_dir.join(sorted_filenames.first().context("archive is empty.")?);

    pandoc.add_option(pandoc::PandocOption::EpubCoverImage(first_picture));

    pandoc.set_output(pandoc::OutputKind::File(args.output.with_extension("epub")));

    pandoc.execute()?;

    remove_dir_all(temp_dir)?;
    Ok(())
}