import platform.pch.pic as pic
import platform.pch.pit as pit
import sched.sched as sched
import drivers.core.cpu.apic as apic
import asm


define TIMER_FREQUENCY       = 1000
define TICKS_PER_SECOND      = TIMER_FREQUENCY
define MILLISECONDS_PER_TICK = (1000 / TIMER_FREQUENCY)

static ticks:         volatile uint64 = 0
static seconds:       volatile uint32 = 0
static milliseconds:  volatile uint32 = 0
static timer_running: volatile bool   = False

def timer_init():
    global ticks, seconds, milliseconds, timer_running
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    ticks = 0
    seconds = 0
    milliseconds = 0
    timer_running = True
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    pit.pit_init(TIMER_FREQUENCY)

def timer_handler():
    global ticks, seconds, milliseconds, timer_running
    if not timer_running:
        pic.eoi(0)
        apic.eoi()
        return
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    ticks = ticks + 1
    milliseconds = milliseconds + MILLISECONDS_PER_TICK
    if milliseconds >= 1000:
        seconds = seconds + 1
        milliseconds = milliseconds - 1000
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    sched.Scheduler.sched_tick()
    pic.eoi(0)
    # LAPIC EOI：APIC 启用后中断经 LINT0(EXTINT) 送达会置 LAPIC ISR，
    # 只发 PIC EOI 不清 LAPIC ISR → 首个定时中断后后续中断被屏蔽 →
    # ticks 不推进 → msleep 永久挂起（QEMU/OVMF 下 APIC 必启用）。
    apic.eoi()

def timer_start():
    global timer_running
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    timer_running = True
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])

def timer_stop():
    global timer_running
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    timer_running = False
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])

def timer_reset():
    global ticks, seconds, milliseconds
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    ticks = 0
    seconds = 0
    milliseconds = 0
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])

def timer_get_ticks() -> uint64:
    current_ticks: uint64
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    current_ticks = ticks
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    return current_ticks

def timer_get_seconds() -> uint32:
    current_seconds: uint32
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    current_seconds = seconds
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    return current_seconds

def timer_get_milliseconds() -> uint32:
    current_milliseconds: uint32
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    current_milliseconds = milliseconds
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    return current_milliseconds

def timer_get_time(out_seconds: uint32*, out_milliseconds: uint32*):
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
    if out_seconds:
        *out_seconds = seconds
    if out_milliseconds:
        *out_milliseconds = milliseconds
    __asm__("mfence", op=[ASM_DESCR.CLOBBER_MEMORY])

def timer_msleep(ms: uint32):
    target: uint64 = ticks + (ms + MILLISECONDS_PER_TICK - 1) / MILLISECONDS_PER_TICK
    while ticks < target:
        asm.sti()
        asm.hlt()
        sched.Scheduler._yield()

def timer_sleep(sec: uint32):
    target: uint64 = ticks + sec * TICKS_PER_SECOND
    while ticks < target:
        asm.sti()
        asm.hlt()
        sched.Scheduler._yield()