use super::{run, run_output, Image, LoopDevice, Mount};
use crate::IMAGE_SIZE_GB;
use anyhow::{anyhow, Context as _};
use std::{
	fs::{self, File},
	path::PathBuf
};

pub fn prepare_img() -> anyhow::Result<Image> {
	eprintln!("Preparing empty image ...");

	// let's create a file with the correct size
	let path = PathBuf::from("alpi.img");
	let file = File::create(&path).context("Failed to create alpi.img")?;
	file.set_len(IMAGE_SIZE_GB * 1024 * 1024 * 1024)?;
	drop(file);

	// lets get the thing partitioned
	let size = format!("{IMAGE_SIZE_GB}G");
	run_parted!(path, "mktable", "msdos")?;
	run_parted!(path, "mkpart", "primary", "fat32", "0G", "128M")?;
	run_parted!(path, "mkpart", "primary", "ext4", "128M", &size)?;

	// create a loopback device
	let output = run_output(&["losetup", "-f", "--show", path.to_str().unwrap()])?;
	print!("{output}");
	let idx = output.find("/dev/loop").ok_or_else(|| anyhow!("Unable to identify loop device"))?;
	let mut end = idx + "/dev/loop".len();
	while (output.as_bytes()[end] as char).is_ascii_digit() {
		end += 1;
	}
	let device = LoopDevice(output[idx .. end].to_owned());

	// TODO: Somehow create the file systems without root
	run(&["mkfs.fat", "-n", "ALPI-BOOT", "-F", "32", &device.part(1)])?;
	run(&["mkfs.ext4", "-q", "-F", "-L", "ALPI", "-O", "^has_journal", &device.part(2)])?;
	run_parted!(path, "p")?;

	// mount everything
	let root = Mount::create(&device.part(2))?;
	let boot = root.0.join("boot");
	fs::create_dir_all(&boot)?;
	run(&["mount", &device.part(1), boot.to_str().unwrap()])?;
	let boot = Mount(boot);
	let dev = root.0.join("dev");
	fs::create_dir_all(&dev)?;
	run(&["mount", "udev", dev.to_str().unwrap(), "-t", "devtmpfs", "-o", "mode=0755,nosuid"])?;
	let dev = Mount(dev);

	Ok(Image {
		path,
		device,
		boot,
		dev,
		root
	})
}