/*
 * Copyright 2001 by Marco d'Itri <md@linux.it>
 *
 * Original version by Mike Baker, then maintained by pcg@goof.com.
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */
#include "config.h"
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <time.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/types.h>
#if HAS_REGEX
#include <regex.h>
#endif
#include <X11/Xlib.h>
#include <X11/Xutil.h>
/* data structures */
struct logfile_entry {
    char *fname;                /* name of file                         */
    char *desc;                        /* alternative description              */
    FILE *fp;                        /* FILE struct associated with file     */
    ino_t inode;                /* inode of the file opened                */
    off_t last_size;                /* file size at the last check                */
    unsigned long color;        /* color to be used for printing        */
    struct logfile_entry *next;
};
struct linematrix {
    char *line;
    unsigned long color;
};
/* global variables */
unsigned int width = STD_WIDTH, listlen = STD_HEIGHT;
int win_x = LOC_X, win_y = LOC_Y;
int w = -1, h = -1, font_width, font_height, font_descent;
int do_reopen;
struct timeval interval = { 2, 400000 };        /* see Knuth */
/* command line options */
int opt_noinitial, opt_shade, opt_frame, opt_reverse, opt_nofilename,
    geom_mask, reload = 3600;
const char *command = NULL,
    *fontname = USE_FONT, *dispname = NULL, *def_color = DEF_COLOR;
struct logfile_entry *loglist = NULL, *loglist_tail = NULL;
Display *disp;
Window new_root, real_root;
GC WinGC;
#if HAS_REGEX
struct re_list {
    regex_t from;
    const char *to;
    struct re_list *next;
};
struct re_list *re_head, *re_tail;
#endif
/* prototypes */
void list_files(int);
void force_reopen(int);
void force_refresh(int);
void blank_window(int);
Window ToonGetRootWindow(Display *, int, Window *);
void InitWindow(void);
unsigned long GetColor(const char *);
void redraw(void);
void refresh(struct linematrix *, int, int);
void transform_line(char *s);
int lineinput(char *, int, FILE *);
void reopen(void);
void check_open_files(void);
FILE *openlog(struct logfile_entry *);
void main_loop(void);
void display_version(void);
void display_help(char *);
void install_signal(int, void (*)(int));
void *xstrdup(const char *);
void *xmalloc(size_t);
int daemonize(void);
/* signal handlers */
void list_files(int dummy)
{
    struct logfile_entry *e;
    fprintf(stderr, "Files opened:\n");
    for (e = loglist; e; e = e->next)
        fprintf(stderr, "\t%s (%s)\n", e->fname, e->desc);
}
void force_reopen(int dummy)
{
    do_reopen = 1;
}
void force_refresh(int dummy)
{
    XClearWindow(disp, new_root);
    redraw();
}
void blank_window(int dummy)
{
    XClearWindow(disp, new_root);
    XFlush(disp);
    exit(0);
}
/* X related functions */
unsigned long GetColor(const char *ColorName)
{
    XColor Color;
    XWindowAttributes Attributes;
    XGetWindowAttributes(disp, real_root, &Attributes);
    Color.pixel = 0;
    if (!XParseColor(disp, Attributes.colormap, ColorName, &Color))
        fprintf(stderr, "can't parse %s\n", ColorName);
    else if (!XAllocColor(disp, Attributes.colormap, &Color))
        fprintf(stderr, "can't allocate %s\n", ColorName);
    return Color.pixel;
}
void InitWindow(void)
{
    XGCValues gcv;
    Font font;
    unsigned long gcm;
    XFontStruct *info;
    int screen, ScreenWidth, ScreenHeight;
    if (!(disp = XOpenDisplay(dispname))) {
        fprintf(stderr, "Can't open display %s.\n", dispname);
        exit(1);
    }
    screen = DefaultScreen(disp);
    ScreenHeight = DisplayHeight(disp, screen);
    ScreenWidth = DisplayWidth(disp, screen);
    real_root = RootWindow(disp, screen);
    new_root = ToonGetRootWindow( disp, screen, &real_root );
    gcm = GCBackground;
    gcv.graphics_exposures = True;
    WinGC = XCreateGC(disp, new_root, gcm, &gcv);
    XMapWindow(disp, new_root);
    XSetForeground(disp, WinGC, GetColor(DEF_COLOR));
    font = XLoadFont(disp, fontname);
    XSetFont(disp, WinGC, font);
    info = XQueryFont(disp, font);
    font_width = info->max_bounds.width;
    font_descent = info->max_bounds.descent;
    font_height = info->max_bounds.ascent + font_descent;
    w = width * font_width;
    h = listlen * font_height;
    if (geom_mask & XNegative)
        win_x = win_x + ScreenWidth - w;
    if (geom_mask & YNegative)
        win_y = win_y + ScreenHeight - h;
    XSelectInput(disp, new_root, ExposureMask|FocusChangeMask);
}
char * 
detabificate (char *s)
{
  char * out;
  int i, j;
  out = malloc (8 * strlen (s) + 1);
  for(i = 0, j = 0; s[i]; i++) 
    {
      if (s[i] == '\t') 
        do 
          out[j++] = ' ';
        while (j % 8);      
      else
        out[j++] = s[i];
    }
  out[j] = '\0';
  return out;
}
/*
 * redraw does a complete redraw, rather than an update (i.e. the area
 * gets cleared first)
 * the rest is handled by regular refresh()'es
 */
void redraw(void)
{
    XClearArea(disp, new_root, win_x, win_y, w, h + font_descent + 2, True);
}
/* Just redraw everything without clearing (i.e. after an EXPOSE event) */
void refresh(struct linematrix *lines, int miny, int maxy)
{
    int lin;
    int offset = (listlen + 1) * font_height;
    unsigned long black_color = GetColor("black");
    miny -= win_y + font_height;
    maxy -= win_y - font_height;
    for (lin = listlen; lin--;)
      {
        char *temp;
        offset -= font_height;
        if (offset < miny || offset > maxy)
          continue;
#define LIN ((opt_reverse)?(listlen-lin-1):(lin))
        temp = detabificate (lines[LIN].line);
        if (opt_shade)
          {
            XSetForeground (disp, WinGC, black_color);
            XDrawString (disp, new_root, WinGC, win_x + 2, win_y + offset + 2,
                         temp, strlen (temp));
          }
        XSetForeground (disp, WinGC, lines[LIN].color);
        XDrawString (disp, new_root, WinGC, win_x, win_y + offset,
                     temp, strlen (temp));
        free (temp);
    }
    if (opt_frame) {
        int bot_y = win_y + h + font_descent + 2;
        XDrawLine(disp, new_root, WinGC, win_x, win_y, win_x + w, win_y);
        XDrawLine(disp, new_root, WinGC, win_x + w, win_y, win_x + w, bot_y);
        XDrawLine(disp, new_root, WinGC, win_x + w, bot_y, win_x, bot_y);
        XDrawLine(disp, new_root, WinGC, win_x, bot_y, win_x, win_y);
    }
}
#if HAS_REGEX
void transform_line(char *s)
{
#ifdef I_AM_Md
    int i;
    if (1) {
        for (i = 16; s[i]; i++)
            s[i] = s[i + 11];
    }
    s[i + 1] = '\0';
#endif
    if (transformre) {
        int i;
        regmatch_t matched[16];
        i = regexec(&transformre, string, 16, matched, 0);
        if (i == 0) {                        /* matched */
        }
    }
}
#endif
/*
 * This routine should read 'width' characters and not more. However,
 * we really want to read width + 1 charachters if the last char is a '\n',
 * which we should remove afterwards. So, read width+1 chars and ungetc
 * the last character if it's not a newline. This means 'string' must be
 * width + 2 wide!
 */
int lineinput(char *string, int slen, FILE *f)
{
    int len;
    do {
        if (fgets(string, slen, f) == NULL)        /* EOF or Error */
            return 0;
        len = strlen(string);
    } while (len == 0);
    if (string[len - 1] == '\n')
        string[len - 1] = '\0';                        /* erase newline */
    else if (len >= slen - 1) {
        ungetc(string[len - 1], f);
        string[len - 1] = '\0';
    }
#if HAS_REGEX
    transform_line(string);
#endif
    return len;
}
/* input: reads file->fname
 * output: fills file->fp, file->inode
 * returns file->fp
 * in case of error, file->fp is NULL
 */
FILE *openlog(struct logfile_entry *file)
{
    struct stat stats;
    if ((file->fp = fopen(file->fname, "r")) == NULL) {
        file->fp = NULL;
        return NULL;
    }
    fstat(fileno(file->fp), &stats);
    if (S_ISFIFO(stats.st_mode)) {
        if (fcntl(fileno(file->fp), F_SETFL, O_NONBLOCK) < 0)
            perror("fcntl"), exit(1);
        file->inode = 0;
    } else
        file->inode = stats.st_ino;
    if (opt_noinitial)
      fseek (file->fp, 0, SEEK_END);
    else if (stats.st_size > (listlen + 1) * width)
      {
        char dummy[255];
        fseek(file->fp, -((listlen + 2) * width), SEEK_END);
        /* the pointer might point halfway some line. Let's
           be nice and skip this damaged line */
        lineinput(dummy, sizeof(dummy), file->fp);
      }
    file->last_size = stats.st_size;
    return file->fp;
}
void reopen(void)
{
    struct logfile_entry *e;
    for (e = loglist; e; e = e->next) {
        if (!e->inode)
            continue;                        /* skip stdin */
        if (e->fp)
            fclose(e->fp);
        /* if fp is NULL we will try again later */
        openlog(e);
    }
    do_reopen = 0;
}
void check_open_files(void)
{
    struct logfile_entry *e;
    struct stat stats;
    for (e = loglist; e; e = e->next) {
        if (!e->inode)
            continue;                                /* skip stdin */
        if (stat(e->fname, &stats) < 0) {        /* file missing? */
            sleep(1);
            if (e->fp)
                fclose(e->fp);
            if (openlog(e) == NULL)
                break;
        }
        if (stats.st_ino != e->inode)        {        /* file renamed? */
            if (e->fp)
                fclose(e->fp);
            if (openlog(e) == NULL)
                break;
        }
        if (stats.st_size < e->last_size) {        /* file truncated? */
            fseek(e->fp, 0, SEEK_SET);
            e->last_size = stats.st_size;
        }
    }
}
#define SCROLL_UP(lines, listlen)                                \
{                                                                \
    int cur_line;                                                \
    for (cur_line = 0; cur_line < (listlen - 1); cur_line++) {        \
        strcpy(lines[cur_line].line, lines[cur_line + 1].line);        \
        lines[cur_line].color = lines[cur_line + 1].color;        \
    }                                                                \
}
void main_loop(void)
{
    struct linematrix *lines = xmalloc(sizeof(struct linematrix) * listlen);
    int lin, miny, maxy, buflen;
    char *buf;
    time_t lastreload;
    Region region = XCreateRegion();
    XEvent xev;
    maxy = 0;
    miny = win_y + h;
    buflen = width + 2;
    buf = xmalloc(buflen);
    lastreload = time(NULL);
    /* Initialize linematrix */
    for (lin = 0; lin < listlen; lin++) {
        lines[lin].line = xmalloc(buflen);
        strcpy(lines[lin].line, "~");
        lines[lin].color = GetColor(def_color);
    }
    if (!opt_noinitial)
        while (lineinput(buf, buflen, loglist->fp) != 0) {
            SCROLL_UP(lines, listlen);
            /* print the next line */
            strcpy(lines[listlen - 1].line, buf);
        }
    for (;;) {
        int need_update = 0;
        struct logfile_entry *current;
        static struct logfile_entry *lastprinted = NULL;
        /* read logs */
        for (current = loglist; current; current = current->next) {
            if (!current->fp)
                continue;                /* skip missing files */
            clearerr(current->fp);
            while (lineinput(buf, buflen, current->fp) != 0) {
                /* print filename if any, and if last line was from
                   different file */
                if (!opt_nofilename &&
                        !(lastprinted && lastprinted == current) &&
                        current->desc[0]) {
                    SCROLL_UP(lines, listlen);
                    sprintf(lines[listlen - 1].line, "[%s]", current->desc);
                    lines[listlen - 1].color = current->color;
                }
                SCROLL_UP(lines, listlen);
                strcpy(lines[listlen - 1].line, buf);
                lines[listlen - 1].color = current->color;
                lastprinted = current;
                need_update = 1;
            }
        }
        if (need_update)
            redraw();
        else {
            XFlush(disp);
            if (!XPending(disp)) {
                fd_set fdr;
                struct timeval to = interval;
                FD_ZERO(&fdr);
                FD_SET(ConnectionNumber(disp), &fdr);
                select(ConnectionNumber(disp) + 1, &fdr, 0, 0, &to);
            }
        }
        check_open_files();
        if (do_reopen)
            reopen();
        /* we ignore possible errors due to window resizing &c */
        while (XPending(disp)) {
            XNextEvent(disp, &xev);
            switch (xev.type) {
            case Expose:
                {
                    XRectangle r;
                    r.x = xev.xexpose.x;
                    r.y = xev.xexpose.y;
                    r.width = xev.xexpose.width;
                    r.height = xev.xexpose.height;
                    XUnionRectWithRegion(&r, region, region);
                    if (miny > r.y)
                        miny = r.y;
                    if (maxy < r.y + r.height)
                        maxy = r.y + r.height;
                }
                break;
            default:
#ifdef DEBUGMODE
                fprintf(stderr, "PANIC! Unknown event %d\n", xev.type);
#endif
                break;
            }
        }
        /* reload if requested */
        if (reload && lastreload + reload < time(NULL)) {
            if (command)
                system(command);
            reopen();
            lastreload = time(NULL);
        }
        if (!XEmptyRegion(region)) {
            XSetRegion(disp, WinGC, region);
            refresh(lines, miny, maxy);
            XDestroyRegion(region);
            region = XCreateRegion();
            maxy = 0;
            miny = win_y + h;
        }
    }
}
int main(int argc, char *argv[])
{
    int i;
    int opt_daemonize = 0;
#if HAS_REGEX
    char *transform = NULL;
#endif
    /* window needs to be initialized before colorlookups can be done */
    /* just a dummy to get the color lookups right */
    geom_mask = NoValue;
    InitWindow();
    for (i = 1; i < argc; i++) {
        if (argv[i][0] == '-' && argv[i][1] != '\0' && argv[i][1] != ',') {
            if (!strcmp(argv[i], "--?") ||
                !strcmp(argv[i], "--help") || !strcmp(argv[i], "-h"))
                display_help(argv[0]);
            else if (!strcmp(argv[i], "-V"))
                display_version();
            else if (!strcmp(argv[i], "-g") || !strcmp(argv[i], "-geometry"))
                geom_mask = XParseGeometry(argv[++i],
                        &win_x, &win_y, &width, &listlen);
            else if (!strcmp(argv[i], "-display"))
                dispname = argv[++i];
            else if (!strcmp(argv[i], "-font") || !strcmp(argv[i], "-fn"))
                fontname = argv[++i];
#if HAS_REGEX
            else if (!strcmp(argv[i], "-t"))
                transform = argv[++i];
#endif
            else if (!strcmp(argv[i], "-fork") || !strcmp(argv[i], "-f"))
                opt_daemonize = 1;
            else if (!strcmp(argv[i], "-reload")) {
                reload = atoi(argv[++i]);
                command = argv[++i];
            }
            else if (!strcmp(argv[i], "-shade"))
                opt_shade = 1;
            else if (!strcmp(argv[i], "-frame"))
                opt_frame = 1;
            else if (!strcmp(argv[i], "-no-filename"))
                opt_nofilename = 1;
            else if (!strcmp(argv[i], "-reverse"))
                opt_reverse = 1;
            else if (!strcmp(argv[i], "-color"))
                def_color = argv[++i];
            else if (!strcmp(argv[i], "-noinitial"))
                opt_noinitial = 1;
            else if (!strcmp(argv[i], "-interval") || !strcmp(argv[i], "-i")) {
                double iv = atof(argv[++i]);
                interval.tv_sec = (int) iv;
                interval.tv_usec = (iv - interval.tv_sec) * 1e6;
            } else {
                fprintf(stderr, "Unknown option '%s'.\n"
                        "Try --help for more information.\n", argv[i]);
                exit(1);
            }
        } else {                /* it must be a filename */
            struct logfile_entry *e;
            const char *fname, *desc, *fcolor = def_color;
            char *p;
            /* this is not foolproof yet (',' in filenames are not allowed) */
            fname = desc = argv[i];
            if ((p = strchr(argv[i], ','))) {
                *p = '\0';
                fcolor = p + 1;
                if ((p = strchr(fcolor, ','))) {
                    *p = '\0';
                    desc = p + 1;
                }
            }
            e = xmalloc(sizeof(struct logfile_entry));
            if (argv[i][0] == '-' && argv[i][1] == '\0') {
                if ((e->fp = fdopen(0, "r")) == NULL)
                    perror("fdopen"), exit(1);
                if (fcntl(0, F_SETFL, O_NONBLOCK) < 0)
                    perror("fcntl"), exit(1);
                e->fname = NULL;
                e->inode = 0;
                e->desc = xstrdup("stdin");
            } else {
                int l;
                e->fname = xstrdup(fname);
                if (openlog(e) == NULL)
                    perror(fname), exit(1);
                l = strlen(desc);
                if (l > width - 2)                /* must account for [ ] */
                    l = width - 2;
                e->desc = xmalloc(l + 1);
                memcpy(e->desc, desc, l);
                *(e->desc + l) = '\0';
            }
            e->color = GetColor(fcolor);
            e->next = NULL;
            if (!loglist)
                loglist = e;
            if (loglist_tail)
                loglist_tail->next = e;
            loglist_tail = e;
        }
    }
    if (!loglist) {
        fprintf(stderr, "You did not specify any files to tail\n"
                "use %s --help for help\n", argv[0]);
        exit(1);
    }
#if HAS_REGEX
    if (transform) {
        int i;
        transformre = xmalloc(sizeof(transformre));
        i = regcomp(&transformre, transform, REG_EXTENDED);
        if (i != 0) {
            char buf[512];
            regerror(i, &transformre, buf, sizeof(buf));
            fprintf(stderr, "Cannot compile regular expression: %s\n", buf);
        }
    }
#endif
    InitWindow();
    install_signal(SIGINT, blank_window);
    install_signal(SIGQUIT, blank_window);
    install_signal(SIGTERM, blank_window);
    install_signal(SIGHUP, force_reopen);
    install_signal(SIGUSR1, list_files);
    install_signal(SIGUSR2, force_refresh);
    if (opt_daemonize)
        daemonize();
    main_loop();
    exit(1);                        /* to make gcc -Wall stop complaining */
}
void install_signal(int sig, void (*handler)(int))
{
    struct sigaction action;
    action.sa_handler = handler;
    sigemptyset(&action.sa_mask);
    action.sa_flags = SA_RESTART;
    if (sigaction(sig, &action, NULL) < 0)
        fprintf(stderr, "sigaction(%d): %s\n", sig, strerror(errno)), exit(1);
}
void *xstrdup(const char *string)
{
    void *p;
    while ((p = strdup(string)) == NULL) {
        fprintf(stderr, "Memory exausted.");
        sleep(10);
    }
    return p;
}
void *xmalloc(size_t size)
{
    void *p;
    while ((p = malloc(size)) == NULL) {
        fprintf(stderr, "Memory exausted.");
        sleep(10);
    }
    return p;
}
void display_help(char *myname)
{
    printf("Usage: %s [options] file1[,color[,desc]] "
           "[file2[,color[,desc]] ...]\n", myname);
    printf(" -g | -geometry geometry   -g WIDTHxHEIGHT+X+Y\n"
            " -color    color           use color $color as default\n"
            " -reload sec command       reload after $sec and run command\n"
            "                           by default -- 3 mins\n"
            " -font FONTSPEC            (-fn) font to use\n"
            " -f | -fork                fork into background\n"
            " -reverse                  print new lines at the top\n"
            " -shade                    add shading to font\n"
            " -noinitial                don't display the last file lines on\n"
            "                           startup\n"
            " -i | -interval seconds    interval between checks (fractional\n"
            "                           values o.k.). Default 3\n"
            " -V                        display version information and exit\n"
            "\n");
    printf("Example:\n%s -g 80x25+100+50 -font fixed /var/log/messages,green "
         "/var/log/secure,red,'ALERT'\n", myname);
    exit(0);
}
void display_version(void) {
    printf("root-tail version " VERSION "\n");
    exit(0);
}
int daemonize(void) {
    switch (fork()) {
    case -1:
        return -1;
    case 0:
        break;
    default:
        _exit(0);
    }
    if (setsid() == -1)
        return -1;
    return 0;
}
/* toon_root.c - finding the correct background window / virtual root
 * Copyright (C) 1999-2001  Robin Hogan
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/* Since xpenguins version 2.1, the ToonGetRootWindow() function
 * attempts to find the window IDs of
 *
 * 1) The background window that is behind the toplevel client
 *    windows; this is the window that we draw the toons on.
 *
 * 2) The parent window of the toplevel client windows; this is used
 *    by ToonLocateWindows() to build up a map of the space that the
 *    toons can occupy.
 * 
 * In simple (sensible?) window managers (e.g. blackbox, sawfish, fvwm
 * and countless others), both of these are the root window. The other
 * more complex scenarios that ToonGetRootWindow() attempts to cope
 * with are:
 *
 * Some `virtual' window managers (e.g. amiwm, swm and tvtwm) that
 * reparent all client windows to a desktop window that sits on top of
 * the root window. This desktop window is easy to find - we just look
 * for a property __SWM_VROOT in the immediate children of the root
 * window that contains the window ID of this desktop window. The
 * desktop plays both roles (1 and 2 above). This functionality was
 * detected in xpenguins 1.x with the vroot.h header file.
 *
 * Enlightenment (0.16) can have a number of desktops with different
 * backgrounds; client windows on these are reparented, except for
 * Desktop 0 which is the root window. Therefore versions less than
 * 2.1 of xpenguins worked on Desktop 0 but not on any others. To fix
 * this we look for a root-window property _WIN_WORKSPACE which
 * contains the numerical index of the currently active desktop. The
 * active desktop is then simply the immediate child of the root
 * window that has a property ENLIGHTENMENT_DESKTOP set to this value.
 *
 * KDE 2.0: Oh dear. The kdesktop is a program separate from the
 * window manager that launches a window which sits behind all the
 * other client windows and has all the icons on it. Thus the other
 * client windows are still children of the root window, but we want
 * to draw to the uppermost window of the kdesktop. This is difficult
 * to find - it is the great-great-grandchild of the root window and
 * in KDE 2.0 has nothing to identify it from its siblings other than
 * its size. KDE 2.1+ usefully implements the __SWM_VROOT property in
 * a child of the root window, but the client windows are still
 * children of the root window. A problem is that the penguins erase
 * the desktop icons when they walk which is a bit messy. The icons
 * are not lost - they reappear when the desktop window gets an expose
 * event (i.e. move some windows over where they were and back again).
 *
 * Nautilus (GNOME 1.4+): Creates a background window to draw icons
 * on, but does not reparent the client windows. The toplevel window
 * of the desktop is indicated by the root window property
 * NAUTILUS_DESKTOP_WINDOW_ID, but then we must descend down the tree
 * from this toplevel window looking for subwindows that are the same
 * size as the screen. The bottom one is the one to draw to. Hopefully
 * one day Nautilus will implement __SWM_VROOT in exactly the same way
 * as KDE 2.1+.
 *
 * Other cases: CDE, the common desktop environment. This is a
 * commercial product that has been packaged with Sun (and other)
 * workstations. It typically implements four virtual desktops but
 * provides NO properties at all for apps such as xpenguins to use to
 * work out where to draw to. Seeing as Sun are moving over to GNOME,
 * CDE use is on the decline so I don't have any current plans to try
 * and get xpenguins to work with it.
 *
 * As a note to developers of window managers and big screen hoggers
 * like kdesktop, please visit www.freedesktop.org and implement their
 * Extended Window Manager Hints spec that help pagers and apps like
 * xpenguins and xearth to find their way around. In particular,
 * please use the _NET_CURRENT_DESKTOP and _NET_VIRTUAL_ROOTS
 * properties if you reparent any windows (e.g. Enlightenment). Since
 * no window managers that I know yet use these particular hints, I
 * haven't yet added any code to parse them.  */
// #include "toon.h"
#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <X11/Xproto.h>
#include <stdio.h>
#include <string.h>
/* Time to throw up. Here is a kludgey function that recursively calls
 * itself (up to a limit) to find the window ID of the KDE desktop to
 * draw on. It works with KDE 2.0, but since KDE 2.0 is less stable
 * than Windows 95, I don't expect many people to remain using it now
 * that 2.1 is available, which implements __SWM_VROOT and makes this
 * function redundant. This is the hierarchy we're trying to traverse:
 *
 * -> The root window
 * 0 -> window with name="KDE Desktop"
 * 1   -> window with no name
 * 2     -> window with name="KDE Desktop" & _NET_WM_WINDOW_TYPE_DESKTOP
 * 3       -> window with no name and width >= width of screen
 * 
 * The last window in the hierarchy is the one to draw to.  The
 * numbers show the value of the `depth' argument.  */
static
Window
__ToonGetKDEDesktop(Display *display, int screen, Window window,
                    Atom atom, char *atomname, int depth)
{
  char *name = NULL;
  Atom *wintype = NULL;
  Window winreturn = 0;
  unsigned long nitems, bytesafter;
  Atom actual_type;
  int actual_format;
  Window rootReturn, parentReturn, *children;
  unsigned int nChildren;
  char go_deeper = 0;
  if (XFetchName(display, window, &name)) {
    if (strcasecmp(name, "KDE Desktop") == 0) {
      /* Presumably either at depth 0 or 2 */
      if (XGetWindowProperty(display, window, atom, 0, 1,
                             False, XA_ATOM,
                             &actual_type, &actual_format,
                             &nitems, &bytesafter,
                             (unsigned char **) &wintype) == Success
          && wintype) {
        char *tmpatomname = XGetAtomName(display, *wintype);
        if (tmpatomname) {
          if (strcmp(atomname, tmpatomname) == 0 && depth == 2) {
            /* OK, at depth 2 */
            go_deeper = 1;
          }
          XFree((char *) tmpatomname);
        }
      }
      else if (depth < 2) {
        go_deeper = 1;
      }
    }
    else if (depth == 1) {
      go_deeper = 1;
    }
    XFree((char *) name);
  }
  else if (depth == 1) {
    go_deeper = 1;
  }
  /* If go_deeper is 1 then there is a possibility that the background
   * window is a descendant of the current window; otherwise we're
   * barking up the wrong tree. */
  if (go_deeper && XQueryTree(display, window, &rootReturn,
                              &parentReturn, &children,
                              &nChildren)) {
    int i;
    for (i = 0; i < nChildren; ++i) {
      /* children[i] is now at depth 3 */
      if (depth == 2) {
        XWindowAttributes attributes;
        if (XGetWindowAttributes(display, children[i], &attributes)) {
          if (attributes.width >= DisplayWidth(display, screen)/2
              && attributes.height > 0) {
            /* Found it! */
            winreturn = children[i];
            break;
          }
        }
      }
      else if ((winreturn = __ToonGetKDEDesktop(display, screen,
                                                children[i],
                                                atom, atomname,
                                                depth+1))) {
        break;
      }
    }
    XFree((char *) children);
  }
  return winreturn;
}
/* Look for the Nautilus desktop window to draw to, given the toplevel
 * window of the Nautilus desktop. Basically recursively calls itself
 * looking for subwindows the same size as the root window. */
static
Window
__ToonGetNautilusDesktop(Display *display, int screen, Window window,
                         int depth)
{
  Window rootReturn, parentReturn, *children;
  Window winreturn = window;
  unsigned int nChildren;
  if (depth > 5) {
    return ((Window) 0);
  }
  else if (XQueryTree(display, window, &rootReturn, &parentReturn,
                 &children, &nChildren)) {
    int i;
    for (i = 0; i < nChildren; ++i) {
      XWindowAttributes attributes;
      if (XGetWindowAttributes(display, children[i], &attributes)) {
        if (attributes.width == DisplayWidth(display, screen)
            && attributes.height == DisplayHeight(display, screen)) {
          /* Found a possible desktop window */
          winreturn = __ToonGetNautilusDesktop(display, screen,
                                               children[i], depth+1);
        }
      }  
    }
    XFree((char *) children);
  }
  return winreturn;
}
/* 
 * Returns the window ID of the `background' window on to which the
 * toons should be drawn. Also returned (in clientparent) is the ID of
 * the parent of all the client windows, since this may not be the
 * same as the background window. If no recognised virtual window
 * manager or desktop environment is found then the root window is
 * returned in both cases. The string toon_message contains
 * information about the window manager that was found.
 */
Window
ToonGetRootWindow(Display *display, int screen, Window *clientparent)
{
  Window background = 0; /* The return value */
  Window root = RootWindow(display, screen);
  Window rootReturn, parentReturn, *children;
  Window *toplevel = (Window *) 0;
  unsigned int nChildren;
  unsigned long nitems, bytesafter;
  Atom actual_type;
  int actual_format;
  unsigned long *workspace = NULL;
  unsigned long *desktop = NULL;
  Atom NAUTILUS_DESKTOP_WINDOW_ID = XInternAtom(display,
                           "NAUTILUS_DESKTOP_WINDOW_ID",
                                                False);
  *clientparent = root;
  if (XGetWindowProperty(display, root,
                         NAUTILUS_DESKTOP_WINDOW_ID,
                         0, 1, False, XA_WINDOW,
                         &actual_type, &actual_format,
                         &nitems, &bytesafter,
                         (unsigned char **) &toplevel) == Success
      && toplevel) {
    /* Nautilus is running */
    background = __ToonGetNautilusDesktop(display, screen,
                                          *toplevel, 0);
    XFree((char *) toplevel);
    if (background) {
      printf("Drawing to Nautilus Desktop");
    }
  }
  /* Next look for a virtual root or a KDE Desktop */
  if (!background
      && XQueryTree(display, root, &rootReturn, &parentReturn,
                    &children, &nChildren)) {
    int i;
    Atom _NET_WM_WINDOW_TYPE = XInternAtom(display, 
                             "_NET_WM_WINDOW_TYPE",
                                           False);
    Atom __SWM_VROOT = XInternAtom(display, "__SWM_VROOT", False);
    for (i = 0; i < nChildren && !background; ++i) {
      Window *newroot = (Window *) 0;
      if (XGetWindowProperty(display, children[i],
                             __SWM_VROOT, 0, 1, False, XA_WINDOW,
                             &actual_type, &actual_format,
                             &nitems, &bytesafter,
                             (unsigned char **) &newroot) == Success
          && newroot) {
        /* Found a window with a __SWM_VROOT property that contains
         * the window ID of the virtual root. Now we must check
         * whether it is KDE (2.1+) or not. If it is KDE then it does
         * not reparent the clients. If the root window has the
         * _NET_SUPPORTED property but not the _NET_VIRTUAL_ROOTS
         * property then we assume it is KDE. */
        Atom _NET_SUPPORTED = XInternAtom(display,
                                          "_NET_SUPPORTED",
                                          False);
        Atom *tmpatom;
        if (XGetWindowProperty(display, root,
                               _NET_SUPPORTED, 0, 1, False,
                               XA_ATOM, &actual_type, &actual_format,
                               &nitems, &bytesafter,
                               (unsigned char **) &tmpatom) == Success
            && tmpatom) {
          Window *tmpwindow = (Window *) 0;
          Atom _NET_VIRTUAL_ROOTS = XInternAtom(display,
                                                "_NET_VIRTUAL_ROOTS",
                                                False);
          XFree((char *) tmpatom);
          if (XGetWindowProperty(display, root,
                                 _NET_VIRTUAL_ROOTS, 0, 1, False,
                                 XA_WINDOW, &actual_type, &actual_format,
                                 &nitems, &bytesafter,
                                 (unsigned char **) &tmpwindow) != Success
              || !tmpwindow) {
            /* Must be KDE 2.1+ */
            printf("Drawing to KDE Desktop");
            background = *newroot;
          }
          else if (tmpwindow) {
            XFree((char *) tmpwindow);
          }
        }
        if (!background) {  
          /* Not KDE: assume windows are reparented */
          printf("Drawing to virtual root window");
          background = *clientparent = *newroot;
        }
        XFree((char *) newroot);
      }
      else if ((background = __ToonGetKDEDesktop(display, screen, children[i],
                                                 _NET_WM_WINDOW_TYPE,
                                                 "_NET_WM_WINDOW_TYPE_DESKTOP",
                                                 0))) {
        /* Found a KDE 2.0 desktop and located the background window */
        /* Note that the clientparent is still the root window */
        printf( "Drawing to KDE desktop");
      }
    }
    XFree((char *) children);
  }
  if (!background) {
    /* Look for a _WIN_WORKSPACE property, used by Enlightenment */
    Atom _WIN_WORKSPACE = XInternAtom(display, "_WIN_WORKSPACE", False);
    if (XGetWindowProperty(display, root, _WIN_WORKSPACE,
                           0, 1, False, XA_CARDINAL,
                           &actual_type, &actual_format,
                           &nitems, &bytesafter,
                           (unsigned char **) &workspace) == Success
        && workspace) {
      /* Found a _WIN_WORKSPACE property - this is the desktop to look for.
       * For now assume that this is Enlightenment.
       * We're looking for a child of the root window that has an
       * ENLIGHTENMENT_DESKTOP atom with a value equal to the root window's
       * _WIN_WORKSPACE atom. */
      Atom ENLIGHTENMENT_DESKTOP = XInternAtom(display, 
                                               "ENLIGHTENMENT_DESKTOP",
                                               False);
      /* First check to see if the root window is the current desktop... */
      if (XGetWindowProperty(display, root,
                             ENLIGHTENMENT_DESKTOP, 0, 1,
                             False, XA_CARDINAL,
                             &actual_type, &actual_format,
                             &nitems, &bytesafter,
                             (unsigned char **) &desktop) == Success
          && desktop && *desktop == *workspace) {
        /* The root window is the current Enlightenment desktop */
        printf( "Drawing to Enlightenment Desktop %lu (the root window)");
        background = root;
        XFree((char *) desktop);
      }
      /* Now look at each immediate child window of root to see if it is
       * the current desktop */
      else if (XQueryTree(display, root, &rootReturn, &parentReturn,
                          &children, &nChildren)) {
        int i;
        for (i = 0; i < nChildren; ++i) {
          if (XGetWindowProperty(display, children[i],
                                 ENLIGHTENMENT_DESKTOP, 0, 1,
                                 False, XA_CARDINAL,
                                 &actual_type, &actual_format,
                                 &nitems, &bytesafter,
                                 (unsigned char **) &desktop) == Success
              && desktop && *desktop == *workspace) {
            /* Found current Enlightenment desktop */
            printf("Drawing to Enlightenment Desktop %lu");
            background = *clientparent = children[i];
            XFree((char *) desktop);
          }
        }
        XFree((char *) children);
      }
      XFree((char *) workspace);
    }
  }
  if (background) {
    return background;
  }
  else {
    return root;
  }
}