#include <ntlite/atomic.h>
#include <ntlite/syscall.h>
#include <kernel/ke_power.h>
#include <kernel/ke_process.h>
#include <kernel/ke_event.h>
#include <kernel/ke_spinlock.h>
#include <kernel/ke_irq.h>
#include <kernel/ke_dpc.h>
#include <kernel/ke_settings.h>
#include <kernel/ke_debug.h>
#include <kernel/hal/hal_api.h>
#include <string.h>

static SPINLOCK gPowerLock = SPINLOCK_INIT;
static EVENT* gPowerRequest;
static EVENT* gPowerComplete;
static PROCESS* gInit;
static uint32_t gAction;
static bool gCommitted;
static const HAL_API* gButtonHal;
static uint32_t gButtonAction;
static KDPC gPowerButtonDpc;

KSTATUS KePowerInitialize(void) {
    if (gPowerRequest) return NTLSTATUS_ALREADY_EXISTS;
    KSTATUS st = KeEventCreate(EventManualReset, false, &gPowerRequest);
    if (!KSUCCESS(st)) return st;
    st = KeEventCreate(EventManualReset, false, &gPowerComplete);
    return st;
}

// Delivers the physical action after interrupt-exit processing.
static void KiPowerButtonDpc(KDPC* dpc, void* context, void* arg1, void* arg2) {
    (void)dpc;
    (void)context;
    (void)arg1;
    (void)arg2;
    (void)KePowerRequestHardware(gButtonAction);
}

// The ACPI SCI handler only acknowledges the fixed event and queues normal work.
static void KiPowerButtonIsr(void) {
    if (!gButtonHal || !gButtonHal->Power.ConsumeFixedButton ||
        !gButtonHal->Power.ConsumeFixedButton()) return;
    (void)KeInsertQueueDpc(&gPowerButtonDpc, NULL, NULL);
}

// Reads immutable boot-time button policy and attaches it to the fixed ACPI SCI.
void KePowerInitializeButton(const HAL_API* hal) {
    char mode[24];
    KSTATUS status = KeGetSettingString("power", "button", mode, sizeof(mode));
    if (!KSUCCESS(status))
        KePanic(KE_PANIC_CODE_INIT, "power: missing [power] button, status=0x%x\n", status);
    if (strcmp(mode, "ignore") == 0) {
        DbgPrint("power: ACPI power button ignored by policy\n");
        return;
    }
    if (strcmp(mode, "shutdown") == 0) gButtonAction = SYS_POWER_ACTION_SHUTDOWN;
    else if (strcmp(mode, "restart") == 0) gButtonAction = SYS_POWER_ACTION_RESTART;
    else KePanic(KE_PANIC_CODE_INIT, "power: invalid [power] button=%s\n", mode);

    if (!hal || !hal->Power.QueryFixedButtonIrq || !hal->Power.ArmFixedButton ||
        !hal->Power.ConsumeFixedButton) {
        DbgPrint("power: no ACPI fixed power button HAL support\n");
        return;
    }
    uint8_t irq = 0;
    status = hal->Power.QueryFixedButtonIrq(&irq);
    if (!KSUCCESS(status)) {
        DbgPrint("power: ACPI fixed button unavailable (0x%x); AML button not yet supported\n", status);
        return;
    }
    // The IOAPIC is still masked for this IRQ. Arm the firmware source first,
    // then install the kernel handler and finally unmask via KeIrqRegister.
    status = hal->Power.ArmFixedButton();
    if (!KSUCCESS(status)) {
        DbgPrint("power: cannot arm fixed button IRQ %u, status=0x%x\n", irq, status);
        return;
    }
    KeInitializeDpc(&gPowerButtonDpc, KiPowerButtonDpc, NULL);
    gButtonHal = hal;
    KeIrqRegister(irq, KiPowerButtonIsr);
    DbgPrint("power: ACPI fixed button armed on IRQ %u, action=%s\n", irq, mode);
}

void KePowerSetInitProcess(PROCESS* init) {
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    gInit = init;
    KeReleaseSpinlock(&gPowerLock, flags);
}

// Records one power transition under the coordinator lock. The hardware event
// may arrive before init exists; syscall-originated requests require init.
static KSTATUS KiPowerQueueRequest(uint32_t action, bool requireInit) {
    if (action != SYS_POWER_ACTION_SHUTDOWN && action != SYS_POWER_ACTION_RESTART)
        return NTLSTATUS_INVALID_PARAMETER;
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    KSTATUS status = NTLSTATUS_SUCCESS;
    if (!gPowerRequest || (requireInit && !gInit)) status = NTLSTATUS_NOT_SUPPORTED;
    else if (gAction) status = NTLSTATUS_ALREADY_EXISTS;
    else gAction = action;
    KeReleaseSpinlock(&gPowerLock, flags);
    if (KSUCCESS(status)) KeSignalEvent(gPowerRequest);
    return status;
}

// Accepts a privileged explicit power request only after init exists.
KSTATUS KePowerRequest(uint32_t action) { return KiPowerQueueRequest(action, true); }

// Latches a physical power-button request even during init startup.
KSTATUS KePowerRequestHardware(uint32_t action) { return KiPowerQueueRequest(action, false); }

EVENT* KePowerRequestEvent(PROCESS* caller) {
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    EVENT* event = caller && caller == gInit ? gPowerRequest : (EVENT*)0;
    KeReleaseSpinlock(&gPowerLock, flags);
    return event;
}

KSTATUS KePowerGetRequest(PROCESS* caller, uint32_t* actionOut) {
    if (!actionOut) return NTLSTATUS_INVALID_PARAMETER;
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    KSTATUS st = caller && caller == gInit ? NTLSTATUS_SUCCESS : NTLSTATUS_ACCESS_DENIED;
    if (KSUCCESS(st)) *actionOut = gAction;
    KeReleaseSpinlock(&gPowerLock, flags);
    return st;
}

KSTATUS KePowerComplete(PROCESS* caller, uint32_t action) {
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    KSTATUS st = caller && caller == gInit ? NTLSTATUS_SUCCESS : NTLSTATUS_ACCESS_DENIED;
    if (KSUCCESS(st) && (!gAction || action != gAction || gCommitted))
        st = NTLSTATUS_INVALID_PARAMETER;
    if (KSUCCESS(st)) gCommitted = true;
    KeReleaseSpinlock(&gPowerLock, flags);
    if (KSUCCESS(st)) KeSignalEvent(gPowerComplete);
    return st;
}

EVENT* KePowerCompletionEvent(void) { return gPowerComplete; }

uint32_t KePowerCommittedAction(void) {
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    uint32_t result = gCommitted ? gAction : 0;
    KeReleaseSpinlock(&gPowerLock, flags);
    return result;
}