//! Fixed journal checkpoint, resumed from disk in a new QEMU process.
use super::*;
use os_turkfs_journal_checkpoint::{Block, Checkpoint, Error, Mount, HOMES};

pub fn run(boot: &BootData, allocator: &mut memory::FrameAllocator) -> Result<(), &'static str> {
    let before = allocator.remaining_pages();
    let mut expected_log = [0u8; 512];
    expected_log[..128].copy_from_slice(include_bytes!("k1665-journal.bin"));
    let mut expected_commit = [0u8; 512];
    expected_commit[..8].copy_from_slice(b"TKCOMMIT");
    expected_commit[8..16].copy_from_slice(&7u64.to_le_bytes());
    expected_commit[16..20].copy_from_slice(&expected_log[28..32]);
    expected_commit[32..64].copy_from_slice(&turkos_kernel::turkfs::file_sha256(&[0x44; 512]));
    let mut job = Checkpoint::new(&expected_log, &expected_commit).map_err(|_| "k1680-format")?;
    let mut disk = k1680_virtio_checkpoint::Disk::open(boot, allocator).map_err(|_| "k1680-open")?;
    let result = (|| {
        let mut blocks: [Block; 7] = [[0; 512]; 7];
        for (i, lba) in [111, 112, 113, 114, HOMES[0], HOMES[1], HOMES[2]].iter().enumerate() {
            disk.read(*lba, &mut blocks[i]).map_err(|_| "k1680-read")?;
        }
        if &blocks[0][..16] != b"K1680DISPOSABLE!" { return Err("k1680-control"); }
        let homes = [blocks[4], blocks[5], blocks[6]];
        let mounted = job.mount(&blocks[1], &blocks[2], &blocks[3], &homes).map_err(|_| "k1680-mount")?;
        if job.recycle(&mut disk) != Err(Error::Order) { return Err("k1680-early-recycle"); }
        write_line("TURKOS/OS/K1680-CHECKPOINT: EARLY-RECYCLE=REJECTED");
        if mounted == Mount::Clean {
            write_line("TURKOS/OS/K1680-CHECKPOINT: MOUNT=CLEAN NO-WRITES");
            return Ok(());
        }
        let homes_already_applied = &homes == job.homes();
        job.apply(&mut disk).map_err(|_| "k1680-apply")?;
        if job.recycle(&mut disk) != Err(Error::Order) { return Err("k1680-uncheckpointed-recycle"); }
        write_line("TURKOS/OS/K1680-CHECKPOINT: HOMES=3 FLUSHED COMMIT=RETAINED");
        if homes_already_applied {
            job.persist(&mut disk).map_err(|_| "k1680-checkpoint")?;
            write_line("TURKOS/OS/K1680-CHECKPOINT: CHECKPOINT=FLUSHED");
            job.recycle(&mut disk).map_err(|_| "k1680-recycle")?;
            write_line("TURKOS/OS/K1680-CHECKPOINT: JOURNAL=RECYCLED");
        } else {
            write_line("TURKOS/OS/K1680-CHECKPOINT: RESTART-BOUNDARY=BEFORE-CHECKPOINT");
        }
        Ok(())
    })();
    let closed = disk.close(allocator).map_err(|_| "k1680-reset");
    result?; closed?;
    if allocator.remaining_pages() != before { return Err("k1680-frames"); }
    write_line("TURKOS/OS/K1680-CHECKPOINT: FRAMES=UNCHANGED");
    Ok(())
}