//! Commit-gated replay observed on an isolated block device.
use super::*;
use os_turkfs_recovery_replay::{Block, Outcome, Recovery, HOMES};

fn print_hash(label: &str, homes: &[Block;3]) {
    let mut bytes = [0;1536];
    for (i, block) in homes.iter().enumerate() { bytes[i*512..(i+1)*512].copy_from_slice(block); }
    let digest = turkos_kernel::program_hash::hex_lower(&turkos_kernel::turkfs::file_sha256(&bytes));
    write_str(label); write_line(core::str::from_utf8(&digest).unwrap());
}

pub fn run(boot: &BootData, allocator: &mut memory::FrameAllocator) -> Result<(), &'static str> {
    let before = allocator.remaining_pages();
    let mut disk = k1685_virtio_replay::Disk::open(boot, allocator).map_err(|_| "k1685-open")?;
    let result = (|| {
        let mut blocks: [Block;6] = [[0;512];6];
        for (i,lba) in [111,112,113,HOMES[0],HOMES[1],HOMES[2]].iter().enumerate() {
            disk.read(*lba,&mut blocks[i]).map_err(|_| "k1685-read")?;
        }
        if &blocks[0][..16] != b"K1685DISPOSABLE!" { return Err("k1685-control"); }
        let mut recovery = Recovery::new(&blocks[1],&blocks[2]).map_err(|_| "k1685-format")?;
        let old = [blocks[3],blocks[4],blocks[5]];
        print_hash("TURKOS/OS/K1685-REPLAY: BEFORE-SHA256=",&old);
        let outcome = recovery.replay(&mut disk,&old).map_err(|_| "k1685-replay")?;
        match outcome {
            Outcome::NoCommit => write_line("TURKOS/OS/K1685-REPLAY: MISSING-COMMIT=UNCHANGED NO-WRITES"),
            Outcome::AlreadyApplied => write_line("TURKOS/OS/K1685-REPLAY: SECOND=UNCHANGED NO-WRITES"),
            Outcome::Replayed {writes:3} => write_line("TURKOS/OS/K1685-REPLAY: RECORDS=3 FLUSHED"),
            _ => return Err("k1685-unexpected-fixture"),
        }
        let mut after = [[0;512];3];
        for (i,lba) in HOMES.iter().enumerate() {
            disk.read(*lba,&mut after[i]).map_err(|_| "k1685-readback")?;
        }
        let expected = if outcome==Outcome::NoCommit {&old} else {recovery.expected()};
        if &after != expected { return Err("k1685-readback-bytes"); }
        print_hash("TURKOS/OS/K1685-REPLAY: AFTER-SHA256=",&after);
        Ok(())
    })();
    let closed = disk.close(allocator).map_err(|_| "k1685-reset");
    result?; closed?;
    if allocator.remaining_pages() != before { return Err("k1685-frames"); }
    write_line("TURKOS/OS/K1685-REPLAY: FRAMES=UNCHANGED");
    Ok(())
}