#![no_std]
#![no_main]

use lancer_user::fs::{self, MOUNT_INFO_ENTRY_SIZE, MountInfoEntry};
use lancer_user::net;
use lancer_user::println;
use lancer_user::syscall;

fn fs_type_name(t: u8) -> &'static str {
    match t {
        0 => "lancerfs",
        1 => "ramfs",
        2 => "generic",
        _ => "unknown",
    }
}

fn fmt_u64(val: u64, buf: &mut [u8; 20]) -> &str {
    match val {
        0 => "0",
        _ => {
            let mut tmp = [0u8; 20];
            fn fill(v: u64, tmp: &mut [u8; 20], pos: usize) -> usize {
                match v {
                    0 => pos,
                    _ => {
                        tmp[pos] = b'0' + (v % 10) as u8;
                        fill(v / 10, tmp, pos + 1)
                    }
                }
            }
            let digits = fill(val, &mut tmp, 0);
            (0..digits).for_each(|j| {
                buf[j] = tmp[digits - 1 - j];
            });
            match core::str::from_utf8(&buf[..digits]) {
                Ok(s) => s,
                Err(_) => "?",
            }
        }
    }
}

#[unsafe(no_mangle)]
pub extern "C" fn lancer_main() -> ! {
    let _ = net::init();

    let mut client = unsafe { fs::init() };

    println!("Mount      Type      Total    Used     Free     Use%");

    let mut buf = [0u8; MOUNT_INFO_ENTRY_SIZE * 16];
    let count = match client.mount_info(&mut buf) {
        Ok(c) => c,
        Err(e) => {
            println!("df: {}", e.name());
            syscall::exit();
        }
    };

    (0..count).for_each(|i| {
        let off = i * MOUNT_INFO_ENTRY_SIZE;
        if let Some(entry) = MountInfoEntry::from_bytes(&buf[off..]) {
            let prefix = entry.prefix_slice();
            let mount_str = match prefix.is_empty() {
                true => "/",
                false => core::str::from_utf8(prefix).unwrap_or("?"),
            };
            let needs_slash = !prefix.is_empty() && prefix[0] != b'/';

            let total = entry.total_blocks;
            let free = entry.free_blocks;
            let used = total.saturating_sub(free);
            let pct = match total {
                0 => 0u64,
                t => (used * 100) / t,
            };

            let mut tb = [0u8; 20];
            let mut ub = [0u8; 20];
            let mut fb = [0u8; 20];
            let mut pb = [0u8; 20];

            let ts = fmt_u64(total, &mut tb);
            let us = fmt_u64(used, &mut ub);
            let fs = fmt_u64(free, &mut fb);
            let ps = fmt_u64(pct, &mut pb);

            let ft = fs_type_name(entry.fs_type);

            match needs_slash {
                true => println!(
                    "/{:<9} {:<9} {:<8} {:<8} {:<8} {}%",
                    mount_str, ft, ts, us, fs, ps
                ),
                false => println!(
                    "{:<10} {:<9} {:<8} {:<8} {:<8} {}%",
                    mount_str, ft, ts, us, fs, ps
                ),
            };
        }
    });

    syscall::exit()
}