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

#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>

#include "completion.h"

struct comp_ {
    char   **path_elem;
    char   **exec_elem;
    size_t   nof_path_elem;
    size_t   nof_exec_elem;
    size_t   curr_elem;
    uid_t    uid;
    gid_t    gid;
};

int
comp_init(comp_t *compp)
{
    comp_t  comp;
    char   *path;
    char   *path_elem_start;
    char   *path_elem_end;
    size_t  path_len;
    size_t  i;

    /*
     * initialize structure
     */
    if (!(comp = malloc(sizeof *comp))) {
	return (1);
    }

    /*
     * initialize path elements
     */
    path_elem_start = path = getenv("PATH");
    path_elem_end   = NULL;
    path_len = strlen(path);
    for (i=0; i<path_len; i++) {
	if (path[i] == ':') {
	    comp->nof_path_elem++;
	    path_elem_end = path+i;
	    if (!(comp->path_elem = realloc(comp->path_elem, comp->nof_path_elem * sizeof (char *)))) {
		return (1);
	    }
	    if (!(comp->path_elem[comp->nof_path_elem-1] = malloc((path_elem_end - path_elem_start + 1) * sizeof (char)))) {
		return (1);
	    }
	    memcpy(comp->path_elem[comp->nof_path_elem-1], path_elem_start, path_elem_end - path_elem_start);
	    comp->path_elem[comp->nof_path_elem-1][path_elem_end - path_elem_start] = '\0';
	    path_elem_start = path+i+1;
	}
    }

    /*
     * initialize other members
     */
    comp->exec_elem = NULL;
    comp->nof_exec_elem = comp->curr_elem = 0;
    comp->uid = getuid();
    comp->gid = getgid();

    *compp = comp;
    return (0);
}

int
comp_cleanup(comp_t comp)
{
    size_t i;

    for (i=0; i<comp->nof_path_elem; i++) {
	free(comp->path_elem[i]);
    }
    free(comp->path_elem);

    for (i=0; i<comp->nof_exec_elem; i++) {
	free(comp->exec_elem[i]);
    }
    free(comp->exec_elem);

    free(comp);
    return (0);
}

int
comp_update(comp_t comp, char *hint)
{
    struct dirent *dp;
    struct stat    sb;
    char           buffer[MAX_CMD_LEN+1];
    DIR           *dirp;
    size_t         hint_len;
    size_t         i;

    for (i=0; i<comp->nof_exec_elem; i++) {
	free(comp->exec_elem[i]);
    }
    free(comp->exec_elem);
    comp->exec_elem = NULL;
    comp->nof_exec_elem = comp->curr_elem = 0;

    if ((hint_len = strlen(hint)) == 0) {
	return (EINVAL);
    }

    /*
     * Each path element
     */
    for (i=0; i<comp->nof_path_elem; i++) {
	if (!(dirp = opendir(comp->path_elem[i]))) {
	    continue;
	}
	while ((dp = readdir(dirp))) {
	    if (!strncmp(dp->d_name, hint, hint_len)) {
		snprintf(buffer, MAX_CMD_LEN, "%s/%s", comp->path_elem[i], dp->d_name);
		if (stat(buffer, &sb)) {
		    continue;
		}
		if (sb.st_mode & S_IFREG) {
		    if ((sb.st_uid == comp->uid && sb.st_mode & S_IXUSR) ||
		        (sb.st_gid == comp->gid && sb.st_mode & S_IXGRP) ||
			sb.st_mode & S_IXOTH) {

			comp->nof_exec_elem++;
			if (!(comp->exec_elem = realloc(comp->exec_elem, comp->nof_exec_elem * sizeof (char *)))) {
			    closedir(dirp);
			    return (ENOMEM);
			}
			if (!(comp->exec_elem[comp->nof_exec_elem-1] = strdup(buffer))) {
			    closedir(dirp);
			    return (ENOMEM);
			}
		    }
		}
	    }
	}
    }
    return (0);
}

char *
comp_next(comp_t comp)
{
    if (!comp->exec_elem) {
	return (NULL);
    }

    if (comp->curr_elem == comp->nof_exec_elem) {
	comp->curr_elem = 0;
    }

    return (comp->exec_elem[comp->curr_elem++]);
}