/******************************************************************************
                __               ____                __
               / /   ___  ____ _/ __/_____________ _/ /__
              / /   / _ \/ __ `/ /_/ ___/ ___/ __ `/ / _ \
             / /___/  __/ /_/ / __(__  ) /__/ /_/ / /  __/
            /_____/\___/\__,_/_/ /____/\___/\__,_/_/\___/

    (C)opyright 2025-2026, Leafscale, LLC -  https://www.leafscale.com

    Project: zyginit
   Filename: shutdown.reef
    Authors: Chris Tusa <chris.tusa@leafscale.com>
    License: <see LICENSE file included with this source code>
Description: PID-1 shutdown primitives — uadmin(2) FFI and shutdown-type
             constants.

******************************************************************************/

module shutdown

export
    // Shutdown function codes (sys/uadmin.h A_SHUTDOWN fcn values)
    fn AD_HALT(): int
    fn AD_BOOT(): int
    fn AD_POWEROFF(): int

    // Symbolic shutdown-type codes used internally by zyginit.
    // These are NOT the uadmin AD_* codes — they're zyginit's own
    // enum for distinguishing what a shutdown was triggered as,
    // before it's mapped to AD_* at the actual uadmin call site.
    fn SHUT_NONE(): int
    fn SHUT_HALT(): int
    fn SHUT_REBOOT(): int
    fn SHUT_POWEROFF(): int

    // Map our internal type to the uadmin fcn code.
    fn to_ad_code(shut_type: int): int

    // Call uadmin(A_SHUTDOWN, fcn, 0). Returns 0 on success, -1 on error.
    // Only succeeds when running as PID 1.
    fn do_shutdown(fcn: int): int

    // Flush dirty page-cache buffers to disk (POSIX sync(2)).
    proc do_sync()
end export

extern "C" fn zyginit_shutdown(fcn: int): int
extern "C" proc zyginit_sync()

fn AD_HALT(): int     return 0 end AD_HALT
fn AD_BOOT(): int     return 1 end AD_BOOT
fn AD_POWEROFF(): int return 6 end AD_POWEROFF

fn SHUT_NONE(): int     return 0 end SHUT_NONE
fn SHUT_HALT(): int     return 1 end SHUT_HALT
fn SHUT_REBOOT(): int   return 2 end SHUT_REBOOT
fn SHUT_POWEROFF(): int return 3 end SHUT_POWEROFF

fn to_ad_code(shut_type: int): int
    if shut_type == SHUT_HALT()
        return AD_HALT()
    elif shut_type == SHUT_REBOOT()
        return AD_BOOT()
    elif shut_type == SHUT_POWEROFF()
        return AD_POWEROFF()
    end if
    // Default to halt for unknown / NONE
    return AD_HALT()
end to_ad_code

fn do_shutdown(fcn: int): int
    return zyginit_shutdown(fcn)
end do_shutdown

proc do_sync()
    zyginit_sync()
end do_sync

end module