/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University.
 *                         All rights reserved.
 * Copyright (c) 2004-2005 The Trustees of the University of Tennessee.
 *                         All rights reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart, 
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * $COPYRIGHT$
 * 
 * Additional copyrights may follow
 * 
 * $HEADER$
 */

#include "ompi_config.h"
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "opal/util/path.h"
#include "opal/util/argv.h"

/*
 * PATH environment variable separator
 */
#ifdef WIN32
#define PATHENVSEP  ';'
#else
#define PATHENVSEP  ':'
#endif

static void path_env_load(char *path, int *pargc, char ***pargv);
static char *path_access(char *fname, char *path, int mode);
static char *list_env_get(char *var, char **list);


/**
 *  Locates a file with certain permissions
 */
char *opal_path_find(char *fname, char **pathv, int mode, char **envv)
{
    char *fullpath;  
    char *delimit;  
    char *env;     
    char *pfix;   
    int i;

    /* If absolute path is given, return it without searching. */

    if ('/' == *fname) {
        return path_access(fname, "", mode);
    }

    /* Initialize. */

    fullpath = NULL;
    i = 0;

    /* Consider each directory until the file is found.  Thus, the
       order of directories is important. */

    while (pathv[i] && NULL == fullpath) {

        /* Replace environment variable at the head of the string. */

        if ('$' == *pathv[i]) {
            delimit = strchr(pathv[i], '/');
            if (delimit) {
                *delimit = '\0';
            }
            env = list_env_get(pathv[i]+1, envv);
            if (delimit) {
                *delimit = '/';
            }
            if (NULL != env) {
                if (!delimit) {
                    fullpath = path_access(fname, env, mode);
                } else {
                    pfix = (char*) malloc(strlen(env) + strlen(delimit) + 1);
                    if (NULL == pfix) {
                        return NULL;
                    }
                    strcpy(pfix, env);
                    strcat(pfix, delimit);
                    fullpath = path_access(fname, pfix, mode);
                    free(pfix);
                }
            }
        }
        else {
            fullpath = path_access(fname, pathv[i], mode);
        }
        i++;
    }
    return fullpath;
}

/*
 * Locates a file with certain permissions from a list of search paths
 */
char *opal_path_findv(char *fname, int mode, char **envv, char *wrkdir)
{
    char **dirv;     
    char *fullpath; 
    char *path;    
    int dirc;    
    int i;
    bool found_dot = false;

    /* Set the local search paths. */

    dirc = 0;
    dirv = NULL;

    if (NULL != (path = list_env_get("PATH", envv))) {
        path_env_load(path, &dirc, &dirv);
    }

    /* Replace the "." path by the working directory. */

    if (NULL != wrkdir) { 
        for (i = 0; i < dirc; ++i) {
            if (0 == strcmp(dirv[i], ".")) {
                found_dot = true;
                free(dirv[i]);
                dirv[i] = strdup(wrkdir);
                if (NULL == dirv[i]){
                    return NULL;
                }
            }
        }
    }

    /* If we didn't find "." in the path and we have a wrkdir, append
       the wrkdir to the end of the path */

    if (!found_dot && NULL != wrkdir) {
        opal_argv_append(&dirc, &dirv, wrkdir);
    }

    if(NULL == dirv)
        return NULL;
    fullpath = opal_path_find(fname, dirv, mode, envv);
    opal_argv_free(dirv);
    return fullpath;
}


/**
 *  Forms a complete pathname and checks it for existance and
 *  permissions
 *            
 *  Accepts:
 *      -fname File name
 *      -path  Path prefix 
 *      -mode  Target permissions which must be satisfied
 *
 *  Returns:
 *      -Full pathname of located file Success
 *      -NULL Failure
 */
static char *path_access(char *fname, char *path, int mode)
{
    char *fullpath;

    /* Allocate space for the full pathname. */

    fullpath = (char*) malloc(strlen(path) + strlen(fname) + 2);
    if (NULL == fullpath) {
        return NULL;
    }

    if (strlen(path) > 0) {
        strcpy(fullpath, path);
        strcat(fullpath, "/");
        strcat(fullpath, fname);
    } else {
        strcpy(fullpath, fname);
    }

    /* Get status on the full path name to check for existance.  Then
       check the permissions. */

    if (access(fullpath, mode)) {
        free(fullpath);
        fullpath = NULL;
    }

    return fullpath;
}


/**
 *
 *  Loads argument array with $PATH env var.
 *
 *  Accepts
 *      -path String contiaing the $PATH
 *      -argc Pointer to argc
 *      -argv Pointer to list of argv
 */
static void path_env_load(char *path, int *pargc, char ***pargv)
{
    char *p;
    char saved;

    if (NULL == path) {
        *pargc = 0;
        return;
    }

    /* Loop through the paths (delimited by PATHENVSEP), adding each
       one to argv. */

    while ('\0' != *path) {

       /* Locate the delimiter. */

        for (p = path; *p && (*p != PATHENVSEP); ++p) {
            continue;
        }

        /* Add the path. */

        if (p != path) {
            saved = *p;
            *p = '\0';
            opal_argv_append(pargc, pargv, path);
            *p = saved;
            path = p;
        }

        /* Skip past the delimiter, if present. */

        if (*path) {
            ++path;
        }
    }
}


/**
 *  Gets value of variable in list or environment. Looks in the list first
 *
 *  Accepts:
 *      -var  String variable
 *      -list Pointer to environment list
 *
 *  Returns:
 *      -List Pointer to environment list Success
 *      -NULL Failure
 */
static char *list_env_get(char *var, char **list)
{
    int n;

    if (NULL != list) {
        n = strlen(var);

        while (NULL != *list) {
            if ((0 == strncmp(var, *list, n)) && ('=' == (*list)[n])) {
                return (*list + n + 1);
            }
            ++list;
        }
    }
    return getenv(var);
}