//! Real fixture bytes retained by in-memory reader guards after unlink.
use super::*;
use os_turkfs_reader::{BlockReader, Extent, File as DiskFile};
use os_turkfs_open_unlink::{Error, File};

const EXPECTED: &[u8; 64] = b"5ab4d3c0b1612817d6c4335036f9445aead46ff52ff5ae3a00d4245b98582854";
struct Transport<'a>(&'a mut virtio_ro_turkfs::RoDisk);
impl BlockReader for Transport<'_> {
    fn read_block(&mut self, lba: u64, output: &mut [u8; 512]) -> Result<(), ()> {
        self.0.read(lba, output).map_err(|_| ())
    }
}
fn hash_ok(bytes: &[u8]) -> bool {
    &turkos_kernel::program_hash::hex_lower(&turkos_kernel::turkfs::file_sha256(bytes)) == EXPECTED
}

pub fn run(boot: &BootData, allocator: &mut memory::FrameAllocator) -> Result<(), &'static str> {
    let frames_before = allocator.remaining_pages();
    let disk_file = DiskFile::validate([
        Extent {first_block: 100, block_count: 1},
        Extent {first_block: 104, block_count: 1},
        Extent {first_block: 108, block_count: 1}], 1300, 2048)
        .map_err(|_| "k1655-extents")?;
    let mut disk = virtio_ro_turkfs::RoDisk::open(boot, allocator, "TURKOS/OS/K1655-GET")?;
    let mut bytes = [0u8; 1300];
    let read = disk_file.read_all(&mut Transport(&mut disk), &mut bytes);
    disk.close(allocator)?;
    if read != Ok(1300) || !hash_ok(&bytes) { return Err("k1655-disk-read"); }
    let file = File::new(b"file", [10, 20, 30], bytes).map_err(|_| "k1655-file")?;
    let first = file.open(b"file").map_err(|_| "k1655-first")?;
    let second = file.open(b"file").map_err(|_| "k1655-second")?;
    let bits = file.ownership().blocks;
    let mut output = [0xa5; 1301];
    if first.read_all(&mut output) != Ok(1300) || output[1300] != 0xa5
        || !hash_ok(&output[..1300]) { return Err("k1655-before-hash"); }
    write_line("TURKOS/OS/K1655-UNLINK: BEFORE-SHA256=5ab4d3c0b1612817d6c4335036f9445aead46ff52ff5ae3a00d4245b98582854");
    file.unlink(b"file").map_err(|_| "k1655-unlink")?;
    if file.lookup(b"file") || !matches!(file.open(b"file"), Err(Error::NotFound))
        || file.ownership().readers != 2 || file.ownership().blocks != bits
        || bits.count_ones() != 3 { return Err("k1655-live-backing"); }
    write_line("TURKOS/OS/K1655-UNLINK: NAME=ABSENT READERS=2 BLOCKS=3");
    if first.read_all(&mut output) != Ok(1300) || !hash_ok(&output[..1300]) {
        return Err("k1655-after-first");
    }
    drop(first);
    if file.ownership().readers != 1 || file.ownership().blocks != bits
        || second.read_all(&mut output) != Ok(1300) || output[1300] != 0xa5
        || !hash_ok(&output[..1300]) { return Err("k1655-after-second"); }
    write_line("TURKOS/OS/K1655-UNLINK: AFTER-SHA256=5ab4d3c0b1612817d6c4335036f9445aead46ff52ff5ae3a00d4245b98582854");
    drop(second);
    if file.ownership().readers != 0 || file.ownership().blocks != 0
        || allocator.remaining_pages() != frames_before { return Err("k1655-retire"); }
    write_line("TURKOS/OS/K1655-UNLINK: LAST-CLOSE=RETIRED FRAMES=UNCHANGED");
    Ok(())
}