/* This file is part of genrc
Copyryght (C) 2018 Sergey Poznyakoff
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
*/
#include "genrc.h"

struct ps_pid_closure {
	struct genrc_pid_closure generic;
	PROCSCANBUF buf;
};

enum {
	UID_COL = 0,
	PID_COL,
	PPID_COL,
	C_COL,
	STIME_COL,
	TTY_COL,
	TIME_COL,
	CMD_COL
};

static int
match_cmdline(struct ps_pid_closure *clos, struct wordsplit const *ws)
{
	grecs_txtacc_t acc;
	size_t i;
	int rc;
	char *cmdline;
	
	acc = grecs_txtacc_create();
	grecs_txtacc_grow_string(acc, ws->ws_wordv[CMD_COL]);
	for (i = CMD_COL + 1; i < ws->ws_wordc; i++) {
		grecs_txtacc_grow_char(acc, ' ');
		grecs_txtacc_grow_string(acc, ws->ws_wordv[i]);
	}
	grecs_txtacc_grow_char(acc, 0);
	cmdline = grecs_txtacc_finish(acc, 0);
	rc = procscan_match(clos->buf, cmdline);
	grecs_txtacc_free(acc);
	return rc;
}

static int
match_argv0(struct ps_pid_closure *clos, struct wordsplit const *ws)
{
	return procscan_match(clos->buf, ws->ws_wordv[CMD_COL]);
}

static int
match(struct ps_pid_closure *clos, struct wordsplit const *ws)
{
	return ((clos->buf->flags & PROCF_CMDLINE)
		? match_cmdline : match_argv0)(clos, ws);
}

static int
pid_ps_get(GENRC_PID_CLOSURE *clos, PIDLIST *plist)
{
	struct ps_pid_closure *ps_clos = (struct ps_pid_closure *)clos;
	FILE *fp;
	struct wordsplit ws;
	int wsflags;
	ssize_t n;
	char *buf = NULL;
	size_t size = 0;
	size_t line = 0;
	PIDLIST pplist;
	
	fp = popen("ps -ef", "r");
	if (!fp) {
		system_error(errno, "failed to run ps");
		return -1;
	}

	ws.ws_delim = " ";
	ws.ws_error = genrc_error;	
	wsflags = WRDSF_NOCMD
		| WRDSF_NOVAR
		| WRDSF_QUOTE
		| WRDSF_DELIM
		| WRDSF_SQUEEZE_DELIMS
		| WRDSF_ENOMEMABRT
		| WRDSF_SHOWERR
		| WRDSF_ERROR;
	pidlist_init(&pplist);
	while ((n = grecs_getline(&buf, &size, fp)) > 0) {
		line++;
		if (line == 1)
			continue;
		buf[n-1] = 0;
		if (wordsplit(buf, &ws, wsflags))
			exit(1);
		wsflags |= WRDSF_REUSE;
		if (match(ps_clos, &ws) == 0) {
			pid_t ppid = strtopid(ws.ws_wordv[PPID_COL]);
			if (!pidlist_member(&pplist, ppid))
				pidlist_add(&pplist, ppid);
			pidlist_add(plist, strtopid(ws.ws_wordv[PID_COL]));
		}
	}
	fclose(fp);
	free(buf);
	if (wsflags & WRDSF_REUSE)
		wordsplit_free(&ws);
	if (plist->pidc > 1 && !(ps_clos->buf->flags & PROCF_ALL)) {
		size_t i;
		
		for (i = 0; i < pplist.pidc; ) {
			if (pidlist_member(plist, pplist.pidv[i]))
				i++;
			else {
				pidlist_remove(&pplist, i);
			}
		}
		pidlist_free(plist);
		*plist = pplist;
	}

	return 0;
}

GENRC_PID_CLOSURE *
genrc_pid_ps_init(int argc, char **argv)
{
	struct ps_pid_closure *clos;

	if (argc > 3)
		usage_error("expected format: PS[:[<EXE>][:<FLAGS>]]");

	clos = xzalloc(sizeof *clos);
	
	clos->buf = procscan_init((argc >= 2 && argv[1][0] != 0)
				    ? argv[1] : genrc_program,
				  argc > 2 ? argv[2] : NULL);
	if (clos->buf->flags & PROCF_EXE)
		usage_error("flag r isn't compatible with PS");
	clos->generic.pid = pid_ps_get;
	
	return (GENRC_PID_CLOSURE *)clos;
}