/*
* Based on xorg-xset
* https://github.com/freedesktop/xorg-xset/blob/master/xset.c
*/

#include "dpms.h"

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <stdbool.h>
#include <string.h>

#include <X11/Xlib.h>
#include <X11/extensions/dpms.h>


int check_dpms_extension(Display* disp)
{
    int err = 0;
    int dummy;

    if (DPMSQueryExtension(disp, &dummy, &dummy))
    {
        if (!DPMSCapable(disp))
            err = NOTDPMSCAPABLE;
    }
    else
        err = NODPMSEXTENSION;

    return err;
}

/*
* status->state can result in:
*  - DPMSModeOn
*  - DPMSModeStandby
*  - DPMSModeSuspend
*  - DPMSModeOff
*
* anything else means unknown state
*/
int check_dpms_status(Display* disp, CARD16* state)
{
    BOOL dpmsEnabled;

    int error = check_dpms_extension(disp);
    if (!error)
    {
        DPMSInfo(disp, state, &dpmsEnabled);
        if (!dpmsEnabled)
            return DPMSDISABLED;
    }
    else
        return error;

    return 0;
}

int is_display_on(const char* xDisplayName, bool* isOn)
{
    Display* disp = XOpenDisplay(xDisplayName);
    if (disp == NULL)
        return BADDISPLAY;

    CARD16 state;
    int returnError = 0;
    int error = check_dpms_status(disp, &state);

    if (!error)
    {
        switch (state)
        {
        case DPMSModeOn:
            *isOn = true;
            break;
        case DPMSModeStandby: case DPMSModeSuspend: case DPMSModeOff:
            *isOn = false;
            break;
        default:
            returnError = UNKNOWNDPMSMODE;
            break;
        }
    }
    else if (error == DPMSDISABLED)
        *isOn = true;
    else if (error)
        returnError = error;

    XCloseDisplay(disp);
    return returnError;
}

/*
* Citing the original xorg-xset:
*
* The calls to usleep below are necessary to
* delay the actual DPMS mode setting briefly.
* Without them, it's likely that the mode will be
* set between the Down and Up key transitions, in
* which case the Up transition may immediately
* turn the display back on.
*/
int dpms_force_off(Display* disp)
{
    int error = check_dpms_extension(disp);
    if (!error)
    {
        DPMSEnable(disp);
        usleep(100000);
        DPMSForceLevel(disp, DPMSModeOff);
    }
    return error;
}


int turn_display_off(const char* xDisplayName)
{
    Display* disp = XOpenDisplay(xDisplayName);
    if (disp == NULL)
        return BADDISPLAY;

    int returnError = 0;
    int error = dpms_force_off(disp);
    if (error)
        returnError = error;

    XCloseDisplay(disp);
    return returnError;
}