// Kernel power coordinator and optional firmware-provider binding.

#include <ntlite/syscall.h>
#include <ntlite/ddk/power.h>
#include <kernel/ke_power.h>
#include <kernel/ke_process.h>
#include <kernel/ke_event.h>
#include <kernel/ke_spinlock.h>
#include <kernel/ke_settings.h>
#include <kernel/ke_debug.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 bool gPolicyReady;
static bool gEarlyButtonPressed;
static uint32_t gButtonAction;
static NTL_FIRMWARE_POWER_PROVIDER gFirmwareProvider;
static bool gFirmwarePrepared;
static uint32_t gPreparedAction;

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;
}

// The resident firmware owner may be ACPICA or another platform implementation.
__declspec(dllexport) KSTATUS KeRegisterFirmwarePowerProvider(
    const NTL_FIRMWARE_POWER_PROVIDER* provider) {
    if (!provider || provider->Size != sizeof(*provider) ||
        !provider->Prepare || !provider->Enter)
        return NTLSTATUS_INVALID_PARAMETER;
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    KSTATUS status = gFirmwareProvider.Size ? NTLSTATUS_ALREADY_EXISTS : NTLSTATUS_SUCCESS;
    if (KSUCCESS(status)) gFirmwareProvider = *provider;
    KeReleaseSpinlock(&gPowerLock, flags);
    if (KSUCCESS(status)) DbgPrint("power: firmware provider registered\n");
    return status;
}

// Events before system-root policy becomes available are retained once.
__declspec(dllexport) KSTATUS KeNotifyPowerButton(void) {
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    if (!gPowerRequest) {
        KeReleaseSpinlock(&gPowerLock, flags);
        return NTLSTATUS_NOT_SUPPORTED;
    }
    if (!gPolicyReady) {
        gEarlyButtonPressed = true;
        KeReleaseSpinlock(&gPowerLock, flags);
        return NTLSTATUS_SUCCESS;
    }
    uint32_t action = gButtonAction;
    KeReleaseSpinlock(&gPowerLock, flags);
    return action ? KePowerRequestHardware(action) : NTLSTATUS_SUCCESS;
}

// System-root policy is loaded independently of the presence of a firmware driver.
void KePowerInitializePolicy(void) {
    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);
    uint32_t action = 0;
    if (strcmp(mode, "shutdown") == 0) action = SYS_POWER_ACTION_SHUTDOWN;
    else if (strcmp(mode, "restart") == 0) action = SYS_POWER_ACTION_RESTART;
    else if (strcmp(mode, "ignore") != 0)
        KePanic(KE_PANIC_CODE_INIT, "power: invalid [power] button=%s\n", mode);

    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    gButtonAction = action;
    gPolicyReady = true;
    bool pending = gEarlyButtonPressed;
    bool providerPresent = gFirmwareProvider.Size != 0;
    gEarlyButtonPressed = false;
    KeReleaseSpinlock(&gPowerLock, flags);
    DbgPrint("power: button policy=%s firmware provider=%s\n",
             mode, providerPresent ? "present" : "absent");
    if (pending && action) (void)KePowerRequestHardware(action);
}

// A provider prepares firmware while threads, device resources and AML can run.
KSTATUS KePowerPrepareFirmware(uint32_t action) {
    if (action != SYS_POWER_ACTION_SHUTDOWN && action != SYS_POWER_ACTION_RESTART)
        return NTLSTATUS_INVALID_PARAMETER;
    NTL_FIRMWARE_POWER_PROVIDER provider;
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    provider = gFirmwareProvider;
    KeReleaseSpinlock(&gPowerLock, flags);
    if (!provider.Size) return NTLSTATUS_NOT_SUPPORTED;
    flags = KeAcquireSpinlock(&gPowerLock);
    gFirmwarePrepared = false;
    gPreparedAction = 0;
    KeReleaseSpinlock(&gPowerLock, flags);
    KSTATUS status = provider.Prepare(provider.Context, action);
    if (KSUCCESS(status)) {
        flags = KeAcquireSpinlock(&gPowerLock);
        gFirmwarePrepared = true;
        gPreparedAction = action;
        KeReleaseSpinlock(&gPowerLock, flags);
    }
    return status;
}

// Any returned transition leaves the HAL as the supported final fallback.
KSTATUS KePowerEnterFirmware(uint32_t action) {
    NTL_FIRMWARE_POWER_PROVIDER provider;
    uintptr_t flags = KeAcquireSpinlock(&gPowerLock);
    bool prepared = gFirmwarePrepared && gPreparedAction == action;
    provider = gFirmwareProvider;
    KeReleaseSpinlock(&gPowerLock, flags);
    if (!prepared || !provider.Size) return NTLSTATUS_NOT_SUPPORTED;
    return provider.Enter(provider.Context, action);
}

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;
}