//! VFS + ramfs, used directly from the kernel (no user mode involved).
#![no_std]
#![no_main]
#![feature(custom_test_frameworks)]
#![test_runner(rust_kernel::test_runner)]
#![reexport_test_harness_main = "test_main"]

extern crate alloc;

use alloc::{string::String, vec};
use bootloader::{BootInfo, entry_point};
use core::panic::PanicInfo;
use rust_kernel::errno::Errno;
use rust_kernel::fs::file::{File, InodeFile};
use rust_kernel::fs::{self, InodeKind, ramfs::RamFs};
use rust_kernel::memory::{self, BootInfoFrameAllocator};
use rust_kernel::allocator;
use x86_64::VirtAddr;

entry_point!(main);

fn main(boot_info: &'static BootInfo) -> ! {
    rust_kernel::init();
    let phys_mem_offset = VirtAddr::new(boot_info.physical_memory_offset);
    let mut mapper = unsafe { memory::init(phys_mem_offset) };
    let mut frame_allocator = unsafe { BootInfoFrameAllocator::init(&boot_info.memory_map) };
    allocator::init_heap(&mut mapper, &mut frame_allocator).expect("heap initialization failed");
    fs::init();

    test_main();
    rust_kernel::hlt_loop();
}

#[test_case]
fn read_boot_files() {
    let file = InodeFile::open(fs::lookup("/hello.txt").unwrap()).unwrap();
    let mut buf = [0u8; 64];
    let n = file.read(&mut buf).unwrap();
    assert!(buf[..n].starts_with(b"Hello from the ramfs!"));
    assert_eq!(file.read(&mut buf), Ok(0)); // EOF
    assert_eq!(fs::lookup("/etc/motd").unwrap().kind(), InodeKind::File);
    assert_eq!(fs::lookup("/etc").unwrap().kind(), InodeKind::Directory);
    assert_eq!(fs::lookup("//etc/./motd").unwrap().kind(), InodeKind::File);
}

#[test_case]
fn lookup_errors() {
    assert_eq!(fs::lookup("/nope").err(), Some(Errno::ENOENT));
    assert_eq!(fs::lookup("/hello.txt/x").err(), Some(Errno::ENOTDIR));
    assert_eq!(fs::lookup("relative").err(), Some(Errno::EINVAL));
    assert_eq!(InodeFile::open(fs::lookup("/etc").unwrap()).err(), Some(Errno::EISDIR));
}

#[test_case]
fn mounts_are_separate_file_systems() {
    // /tmp is its own ramfs: files created there don't show up in "/"'s tmp dir.
    fs::create("/tmp/a.txt", InodeKind::File).unwrap();
    assert!(fs::lookup("/tmp/a.txt").is_ok());
    let root_tmp_dir = fs::lookup("/").unwrap().lookup("tmp").unwrap();
    assert_eq!(root_tmp_dir.list().unwrap().len(), 0);
    assert_eq!(fs::create("/tmp/a.txt", InodeKind::File).err(), Some(Errno::EEXIST));

    // Mount a third one; the longest matching mount point wins.
    fs::create("/tmp/deeper", InodeKind::Directory).unwrap();
    fs::mount("/tmp/deeper", RamFs::new()).unwrap();
    assert_eq!(fs::lookup("/tmp/deeper").unwrap().list().unwrap().len(), 0);
    assert_eq!(fs::mount("/tmp/deeper", RamFs::new()).err(), Some(Errno::EEXIST));
    assert_eq!(fs::mounts().len(), 3);
}

#[test_case]
fn write_grow_and_list() {
    let inode = fs::create("/tmp/grow.bin", InodeKind::File).unwrap();
    inode.write_at(4, b"abc").unwrap(); // gap is filled with zeros
    let mut buf = vec![0xffu8; 10];
    assert_eq!(inode.read_at(0, &mut buf), Ok(7));
    assert_eq!(&buf[..7], b"\0\0\0\0abc");
    let names = fs::lookup("/").unwrap().list().unwrap();
    assert_eq!(names, vec![String::from("etc"), String::from("hello.txt"), String::from("tmp")]);
}

#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
    rust_kernel::test_panic_handler(info)
}