/*
 *  This is a simple X11 program that displays the battery percentage
 *  on NetBSD.
 *
 *  If you are curious about how it works, you can download the commented
 *  version of the source code at the following address:
 *
 *     http://img.ankarstrom.se/xbattext.pdf
 *
 *  xbattext should be compiled with the following flags:
 *
 *     CFLAGS = -I/usr/X11R7/include -I/usr/pkg/include
 *     LDFLAGS = -lXm -L/usr/X11R7/lib -L/usr/pkg/lib
 *     LDFLAGS += -Wl,-R/usr/X11R7/lib -Wl,-R/usr/pkg/lib
 *
 *  It requires x11/motif to be installed.
 *
 *  The follow resources are used:
 *
 *      xbattext*fontList		= normal font
 *      xbattext*foreground		= normal text color
 *      xbattext*alertFontList		= font when battery is low
 *      xbattext*alertForeground	= text color when battery is low
 *      xbattext*chargeFontList		= font when charging
 *      xbattext*chargeForeground	= text color when charging
 *
 *  Set their values in ~/.Xdefaults to customize the battery display.
 *
 *  xbattext is written by John Ankarstr\xf6m <john@ankarstrom.se> and
 *  is released into the public domain; do whatever you want with it.
 */

#include <err.h>
#include <fcntl.h>
#include <machine/apmvar.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <Xm/Label.h>

/* interval in seconds */
#define INTERVAL 5

/* low battery level */
#define ALERT 25

/* resources */
struct res {
	XmFontList font_list;
	XmFontList alert_font_list;
	XmFontList charge_font_list;
	Pixel foreground;
	Pixel alert_foreground;
	Pixel charge_foreground;
} res;
static XtResource res_opts[] = {
	{"fontList", "FontList", XmRFontList, sizeof(XmFontList),
	XtOffset(struct res*, font_list), XtRImmediate, (caddr_t)NULL},
	{"alertFontList", "AlertFontList", XmRFontList, sizeof(XmFontList),
	XtOffset(struct res*, alert_font_list), XtRImmediate, (caddr_t)NULL},
	{"chargeFontList", "ChargeFontList", XmRFontList, sizeof(XmFontList),
	XtOffset(struct res*, charge_font_list), XtRImmediate, (caddr_t)NULL},
	{"foreground", "foreground", XmRPixel, sizeof(Pixel),
	XtOffset(struct res*, foreground), XtRImmediate, (caddr_t)NULL},
	{"alertForeground", "AlertForeground", XmRPixel, sizeof(Pixel),
	XtOffset(struct res*, alert_foreground), XtRImmediate, (caddr_t)NULL},
	{"chargeForeground", "ChargeForeground", XmRPixel, sizeof(Pixel),
	XtOffset(struct res*, charge_foreground), XtRImmediate, (caddr_t)NULL},
};

/* state changes */
enum {
	SET_NONE = 0,
	SET_NOALERT = 1 << 0,
	SET_NOCHARGE = 1 << 1,
	SET_ALERT = 1 << 2,
	SET_CHARGE = 1 << 3
} change;

/* application state */
Arg wargs[10];
char *s;
int alerting, apmfd, charging, i;
struct apm_power_info info;
Widget toplevel, label;
XmString xms;
XtAppContext app_context;

void update(XtPointer, XtIntervalId *);

/* program start */
int
main(int argc, char* argv[])
{
	toplevel = XtVaAppInitialize(
		&app_context,
		"xbattext",
		NULL, 0,
		&argc, argv,
		NULL,
		NULL);

	if ((apmfd = open("/dev/apm", O_RDONLY)) == -1)
		err(1, "open");

	if ((s = malloc(5*sizeof(char))) == NULL)
		err(1, "malloc");

	/* load application resources */
	XtGetApplicationResources(toplevel,
		&res, res_opts, XtNumber(res_opts), NULL, 0);

	/* create motif label */
	label = XtVaCreateManagedWidget("label",
		xmLabelWidgetClass, toplevel,
		XmNlabel, "",
		NULL);
	alerting = 0;
	charging = 0;

	update(NULL, NULL);
	XtRealizeWidget(toplevel);
	XtAppMainLoop(app_context);
}

/* update battery status and (re-)add timer */
void
update(XtPointer client_data, XtIntervalId *t)
{
	/* reset temporary variables */
	i = 0;
	change = SET_NONE;

	/* get battery info */
	memset(&info, 0, sizeof(info));
	if (ioctl(apmfd, APM_IOC_GETPOWER, &info) == -1)
		err(1, "ioctl");

	/* put battery status into label */
	sprintf(s, "%d%%", info.battery_life);
	xms = XmStringCreate(s, XmFONTLIST_DEFAULT_TAG);
	XtSetArg(wargs[i], XmNlabelString, xms); i++;

	/* check charging status */
	if (!charging && info.ac_state == APM_AC_ON)
		change |= SET_CHARGE;
	else if (charging && info.ac_state != APM_AC_ON)
		change |= SET_NOCHARGE;
	charging = info.ac_state == APM_AC_ON;

	/* check low battery */
	if (!alerting && info.battery_life < ALERT)
		change |= SET_ALERT;
	else if (alerting && info.battery_life >= ALERT)
		change |= SET_NOALERT;
	alerting = info.battery_life < ALERT;

	/* prioritize charging and low battery indications */
	if (change & SET_CHARGE) change = SET_CHARGE;
	if (change & SET_NOCHARGE && alerting) change = SET_ALERT;
	if (change & SET_NOALERT && charging) change = SET_CHARGE;

	/* act on state changes */
	switch(change & 0xf) {
	case SET_NOCHARGE:
	case SET_NOALERT:
		XtSetArg(wargs[i], XtNforeground, res.foreground);
		i++;
		if (res.font_list != NULL) {
			XtSetArg(wargs[i], XmNfontList, res.font_list);
			i++;
		}
		break;
	case SET_ALERT:
		XtSetArg(wargs[i], XtNforeground, res.alert_foreground);
		i++;
		if (res.alert_font_list != NULL) {
			XtSetArg(wargs[i], XmNfontList, res.alert_font_list);
			i++;
		}
		break;
	case SET_CHARGE:
		XtSetArg(wargs[i], XtNforeground, res.charge_foreground);
		i++;
		if (res.charge_font_list != NULL) {
			XtSetArg(wargs[i], XmNfontList, res.charge_font_list);
			i++;
		} else if (res.font_list != NULL) {
			XtSetArg(wargs[i], XmNfontList, res.font_list);
			i++;
		}
		break;
	}

set:	XtSetValues(label, wargs, i);
	XmStringFree(xms);

	/* add new timer */
end:	XtAppAddTimeOut(app_context, INTERVAL * 1000, update, NULL);
}