#include <stdio.h>
#include <stdlib.h>

extern const char *__progname;

#include <X11/X.h>
#include <X11/Xlib.h>

static const char *dispstr = 0;
#define OM_UNSPEC 1
#define OM_SET    2
#define OM_QUERY  3
static int opmode = OM_UNSPEC;
static int args_c;
static char **args_v;
static Display *disp;

static void usage(void)
{
 fprintf(stderr,"Usage: %s [options] [operation] [arguments]\n",__progname);
 fprintf(stderr,"options:\n");
 fprintf(stderr,"    -display DISP       set display to connect to\n");
 fprintf(stderr,"operation and arguments:\n");
 fprintf(stderr,"    -set WINDOWID PROPERTY-NAME TYPE SIZE [DATA...]\n");
 fprintf(stderr,"    -query WINDOWID PROPERTY-NAME [FORMAT...]\n");
 fprintf(stderr,"WINDOWID is a window ID number, or the word `root'\n");
 fprintf(stderr,"PROPERTY-NAME is a string naming the property\n");
 fprintf(stderr,"TYPE is a string naming the property's type\n");
 fprintf(stderr,"SIZE is 8, 16, or 32\n");
 fprintf(stderr,"DATA is zero or more numbers, or if SIZE is `string', a string\n");
 fprintf(stderr,"FORMAT is zero or more format specifiers:\n");
 fprintf(stderr,"    x                   print next element in hex\n");
 exit(1);
}

static void handleargs(int ac, char **av)
{
 int skip;
 int errs;

 skip = 0;
 errs = 0;
 if (0)
  {
needarg:;
    fprintf(stderr,"%s: %s needs a following argument\n",__progname,*av);
    exit(1);
  }
 for (ac--,av++;;ac--,av++)
  { if (ac < 1) usage();
    if (skip > 0)
     { skip --;
       continue;
     }
#define WANTARG() do { if (++skip >= ac) goto needarg; } while (0)
    if (!strcmp(*av,"-display"))
     { WANTARG();
       dispstr = av[skip];
       continue;
     }
    if (!strcmp(*av,"-set"))
     { opmode = OM_SET;
       break;
     }
    if (!strcmp(*av,"-query"))
     { opmode = OM_QUERY;
       break;
     }
    fprintf(stderr,"%s: unrecognized operation `%s'\n",__progname,*av);
    errs ++;
#undef WANTARG
  }
 ac --;
 av ++;
 if (errs)
  { usage();
    exit(1);
  }
 switch (opmode)
  { case OM_UNSPEC:
       usage();
       break;
    case OM_SET:
       if (ac < 4) usage();
       args_c = ac;
       args_v = av;
       break;
    case OM_QUERY:
       if (ac < 2) usage();
       args_c = ac;
       args_v = av;
       break;
    default:
       abort();
       break;
  }
}

static void opendisp(void)
{
 disp = XOpenDisplay(dispstr);
 if (! disp)
  { fprintf(stderr,"%s: can't open display",__progname);
    if (dispstr) fprintf(stderr," `%s'",dispstr);
    fprintf(stderr,"\n");
    exit(1);
  }
}

static Window getwindowid(const char *s)
{
 char *ep;
 unsigned long int v;

 if (!strcmp(s,"root")) return(XRootWindowOfScreen(XDefaultScreenOfDisplay(disp)));
 v = strtoul(s,&ep,0);
 if (*ep || (ep == s))
  { fprintf(stderr,"%s: invalid window ID `%s'\n",__progname,s);
    exit(1);
  }
 return((Window)v);
}

static int get_size(const char *s)
{
 long int v;
 char *ep;

 static void invalid(void) __attribute__((__noreturn__));
 static void invalid(void)
  { fprintf(stderr,"%s: invalid size `%s'\n",__progname,s);
    usage();
    exit(1);
  }

 v = strtol(s,&ep,0);
 if (*ep || (ep == s)) invalid();
 switch (v)
  { case 8:
    case 16:
    case 32:
       return(v);
       break;
  }
 invalid();
}

static void set_value(void *place, const char *valstr, int size)
{
 unsigned long int v;
 char *ep;

 v = strtoul(valstr,&ep,0);
 if (*ep || (ep == valstr))
  { fprintf(stderr,"%s: invalid value `%s'\n",__progname,valstr);
    usage();
  }
 if ((v >> (size*4)) >> (size*4))
  { fprintf(stderr,"%s: value `%s' out of range\n",__progname,valstr);
    usage();
  }
 switch (size)
  { case 1:
       *(unsigned char *)place = v;
       break;
    case 2:
       *(unsigned short int *)place = v;
       break;
    case 4:
       *(unsigned int *)place = v;
       break;
    default:
       abort();
       break;
  }
}

static void do_set(void)
{
 Window win;
 const char *propname;
 const char *typename;
 int size;
 int n;
 int i;
 unsigned char *databuf;
 Atom pn;
 Atom tn;

 if (args_c < 4) abort();
 opendisp();
 win = getwindowid(args_v[0]);
 propname = args_v[1];
 size = get_size(args_v[2]) >> 3;
 typename = args_v[3];
 n = args_c - 4;
 databuf = malloc(n*size);
 for (i=0;i<n;i++) set_value(databuf+(size*i),args_v[4+i],size);
 pn = XInternAtom(disp,propname,False);
 tn = XInternAtom(disp,typename,False);
 XChangeProperty(disp,win,pn,tn,size*8,PropModeReplace,databuf,n);
 XSync(disp,False);
}

static void print_data(const unsigned char *data, int samples, unsigned int (*fetch)(const unsigned char *), int inc, int ac, char **av)
{
 unsigned int v;

 while ((samples > 0) && (ac > 0))
  { v = (*fetch)(data);
    data += inc;
    if (!strcmp(*av,"x"))
     { printf("%#x\n",v);
     }
    else
     { fprintf(stderr,"%s: bad format spec `%s'\n",__progname,*av);
       exit(1);
     }
    samples --;
    ac --;
    av ++;
  }
}

static unsigned int fetch_8(const unsigned char *data)
{
 return(*data);
}

static unsigned int fetch_16(const unsigned char *data)
{
 return(*(const unsigned short int *)data);
}

static unsigned int fetch_32(const unsigned char *data)
{
 return(*(const unsigned int *)data);
}

static void do_query(void)
{
 Window win;
 const char *propname;
 Atom pn;
 Atom type;
 int format;
 unsigned long int returned;
 unsigned long int left;
 unsigned char *value;

 if (args_c < 2) abort();
 opendisp();
 win = getwindowid(args_v[0]);
 propname = args_v[1];
 pn = XInternAtom(disp,propname,True);
 if (pn == None)
  { fprintf(stderr,"%s: no property `%s' found\n",__progname,propname);
    exit(1);
  }
 if (XGetWindowProperty(disp,win,pn,0,0,False,AnyPropertyType,&type,&format,&returned,&left,&value) != Success)
  { fprintf(stderr,"%s: XGetWindowProperty failed\n",__progname);
    exit(1);
  }
 XFree(value);
 if (type == None)
  { fprintf(stderr,"%s: no property `%s' found\n",__progname,propname);
    exit(1);
  }
 if (left > 65536)
  { fprintf(stderr,"%s: property `%s' too long\n",__progname,propname);
    exit(1);
  }
 if (XGetWindowProperty(disp,win,pn,0,(left+3)>>2,False,AnyPropertyType,&type,&format,&returned,&left,&value) != Success)
  { fprintf(stderr,"%s: XGetWindowProperty failed\n",__progname);
    exit(1);
  }
 if (left > 0)
  { fprintf(stderr,"%s: property `%s' grew\n",__progname,propname);
    exit(1);
  }
 switch (format)
  { case 8:
       print_data(value,returned,fetch_8,1,args_c-2,args_v+2);
       break;
    case 16:
       print_data(value,returned,fetch_16,2,args_c-2,args_v+2);
       break;
    case 32:
       print_data(value,returned,fetch_32,4,args_c-2,args_v+2);
       break;
    default:
       fprintf(stderr,"%s: property `%s' has impossible format %d\n",__progname,propname,format);
       break;
  }
}

int main(int, char **);
int main(int ac, char **av)
{
 handleargs(ac,av);
 switch (opmode)
  { case OM_SET:
       do_set();
       break;
    case OM_QUERY:
       do_query();
       break;
    default:
       abort();
       break;
  }
 exit(0);
}