use std::{
    fs::File,
    io::prelude::*,
    path::Path,
};

use crate::GIT_DIR;
use crate::git_fs::read_lines;

#[derive(Debug)]
pub struct Head {
    pub ref_to: String,
}

impl Head {
    pub fn load() -> Result<Self, ()> {
        let path = Path::new(GIT_DIR).join("HEAD");

        let mut lines = match read_lines(path) {
            Err(_) => return Err(()),
            Ok(lines) => lines,
        };

        let content = match lines.next() {
            Some(Ok(line)) => line,
            _ => return Err(()),
        };

        match content.split_once(": ") {
            None => Err(()),
            Some((_, r)) => Ok(Head { ref_to: String::from(r) })
        }
    }

    pub fn save(&self) -> Result<(), ()> {
        let path = Path::new(GIT_DIR).join("HEAD");
        let mut content = String::from("ref: ");
        content.push_str(&self.ref_to);
        content.push_str("\n");

        let mut file = match File::create(&path) {
            Err(_) => return Err(()),
            Ok(file) => file,
        };

        match file.write(content.as_bytes()) {
            Err(_) => Err(()),
            Ok(_) => Ok(()),
        }
    }
}