use std::{
    fs::{self, File},
    io::{self, Write},
};

use convert_case::{Case, Casing};

use crate::data::Data;

use super::{get_project_root, CHAPTER};


pub fn generate_new_chapter(name: String) -> io::Result<()> {
    let project_root = get_project_root().unwrap();

    let raw_data_file = fs::read_to_string(project_root.join("lpm.toml")).unwrap();
    let mut data_file: Data = toml::from_str(&raw_data_file).unwrap();
    let mut main_file = fs::read_to_string(project_root.join("main.tex")).unwrap();

    fs::create_dir(project_root.join(format!("content/{}", name.to_case(Case::Snake),))).unwrap();
    let mut new_chapter = File::create(project_root.join(format!(
        "content/{}/chapter_{:02}.tex",
        name.to_case(Case::Snake),
        data_file.last_chapter.number + 1
    ))).unwrap();
    new_chapter.write_all(CHAPTER.replace("REPLACEMENT_CHAPTER", &name).as_bytes()).unwrap();

    fs::create_dir(project_root.join(format!("content/{}/sections", name.to_case(Case::Snake),))).unwrap();

    main_file = main_file.replace(
        &format!(
            "\\includeonly{{content/{}/{}}}",
            &data_file.last_chapter.user_name,
            &format!("chapter_{:02}", data_file.last_chapter.number)
        ),
        &format!(
            "\\includeonly{{content/{}/{}}}",
            name.to_case(Case::Snake),
            &format!("chapter_{:02}", data_file.last_chapter.number + 1)
        ),
    );
    let find_index = main_file.find("% NEXT_CHAPTER").unwrap();
    main_file.insert_str(
        find_index,
        &format!(
            "\\include{{content/{}/{}}}\n    ",
            name.to_case(Case::Snake),
            &format!("chapter_{:02}", data_file.last_chapter.number + 1)
        ),
    );

    data_file.last_chapter.user_name = name.to_case(Case::Snake);
    data_file.last_chapter.number += 1;

    fs::write(
        project_root.join("lpm.toml"),
        toml::to_string(&data_file).expect("We changed it ourselfes, the conversion should work"),
    ).unwrap();

    fs::write(project_root.join("main.tex"), main_file).unwrap();

    Ok(())
}