#!/usr/bin/env rust-script
//! ```cargo
//! [dependencies]
//! anyhow = "1.0.69"
//! dirs = "4.0.0"
//! ```

use anyhow::Context;

use std::{
	fs::{self, File},
	io::{BufRead, BufReader},
};

const ENV: &str = r#". "$HOME/.cargo/env""#;

fn main() -> anyhow::Result<()> {
	let home = dirs::home_dir().context("can't find home directory")?;
	let mut login_path = home.clone();
	login_path.push(".bash_login");
	let login = BufReader::new(File::open(&login_path).context("failed to read ~/.bash_login")?);
	let mut bashrc_path = home.clone();
	bashrc_path.push(".bashrc");
	let bashrc = BufReader::new(File::open(&bashrc_path).context("failed to read ~/.bashrc")?);

	let mut empty = false;
	let mut new_bashrc = String::new();
	for line in bashrc.lines() {
		let line = line.context("failed to read line in ~/.bashrc")?;
		if line.is_empty() && empty {
			continue;
		}
		empty = line.is_empty();
		if line != ENV {
			new_bashrc.push_str(&line);
			new_bashrc.push('\n');
		}
	}

	let mut empty = false;
	let mut new_login = String::new();
	for line in login.lines() {
		let line = line.context("failed to read line in ~/.bash_login")?;
		if line.is_empty() && empty {
			continue;
		}
		empty = line.is_empty();
		if line != ENV {
			new_login.push_str(&line);
			new_login.push('\n');
		}
		if line == "# custom" {
			new_login.push('\n');
			new_login.push_str(ENV);
			new_login.push_str("\n\n");
			empty = true;
		}
	}

	fs::write(bashrc_path, &new_bashrc).context("failed to write new .bashrc")?;
	fs::write(login_path, &new_login).context("failed to write new .bash_login")?;

	Ok(())
}