/*
 * Copyright (c) 2014, Red Hat
 * All rights reserved.

 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.  Redistributions in binary
 * form must reproduce the above copyright notice, this list of conditions and
 * the following disclaimer in the documentation and/or other materials
 * provided with the distribution.

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/file.h>

#include "mem-pool.h"

/*
 * Mock implementation of etcd
 * The etcd file is simulated in /tmp/<server-names>
 * Writes from Multiple writers are protected using file lock.
*/

#include "etcd-api.h"
#define MAX_KEY_LEN 64
#define MAX_VALUE_LEN 64
#define MAX_EXPIRE_LEN 16

etcd_session
etcd_open (etcd_server *server_list)
{
        return NULL;
}

typedef struct _etcd_sim_s {
        char *path;
} etcd_sim_t;

void
etcd_close (etcd_session this)
{
        etcd_sim_t *sim = (etcd_sim_t *)this;
        free(sim->path);
        free(this);
}


char *
etcd_get_1 (FILE *stream, char *key)
{
        char *str = NULL;
        size_t len;
        unsigned long expires;
	char *ret;

        // Read the file
        while(1) {
                if(str) {
                        free(str);
                        str = NULL;
                }
                if (getline((char **)&str, &len,stream) == -1) {
                        break;
                }
                if (!strncmp(str, key, strlen(key))) {
			char k[256], s[256];
			sscanf(str,"%s %s %lu",k, s, &expires);
			// check if key is expired.
			if (time(NULL) > expires) {
				/* Keep looking for an unexpired entry. */
				continue;
			}
		        ret = calloc(1, strlen(s) + 1);
		        strcpy(ret,s);
		        free(str);
		        return(ret);
                }
        }
        return NULL;
}


char *
etcd_get (etcd_session this, char *key)
{
        etcd_sim_t      *sim            = (etcd_sim_t *)this;
        int             fd;
        FILE            *stream;
        char            *retval;

        fd = open(sim->path,O_RDONLY);
        if (!fd) {
                return NULL;
        }

        stream = fdopen(fd,"r");
        (void)flock(fd,LOCK_SH);
        retval = etcd_get_1(stream,key);
        (void)flock(fd,LOCK_UN);
        fclose(stream); /* closes fd as well */

        return retval;
}


etcd_result
etcd_set_1 (FILE *stream, char *key, char *value,
            char *precond, unsigned int ttl)
{
        char *str = NULL;
        char tp[255];
        size_t len;
        unsigned long expires;

        while(1) {
                if(str) {
                        free(str);
                        str = NULL;
                }
                if (getline((char **)&str, &len,stream) == -1) {
                        break;
                }
                if (!strncmp(str, key, strlen(key))) {
                        char k[256], s[256];
                        sscanf(str,"%s %s %lu",k, s, &expires);
                        // check if the present key is expired
                        if (time(NULL) > expires) {
				/* Keep looking for an unexpired entry. */
				continue;
			}
			/*
			 * The only case in which we should fail here is if a
			 * precondition was specified and does not match the
                         * current (non-expired) value.
			 */
			if (precond && strcmp(precond, s)) {
				free(str);
				return ETCD_WTF;
			}
                        fseek(stream, -strlen(str), SEEK_CUR);               
                        free(str);
                        goto here;
                }
        }
here:
        memset(tp, 0, 255);
        sprintf(tp,"%*s %*s %*lu\n",
                -MAX_KEY_LEN, key, -MAX_VALUE_LEN, value,
                -MAX_EXPIRE_LEN, ttl ? time(NULL) + ttl : ~0);
        if (fwrite(tp, 1,strlen(tp), stream) != strlen(tp)) {
                return ETCD_WTF;
        }
        fflush(stream);
        fsync(fileno(stream));
        return ETCD_OK;
}


etcd_result
etcd_set (etcd_session this, char *key, char *value,
          char *precond, unsigned int ttl)
{
        etcd_sim_t      *sim = (etcd_sim_t *)this;
        int             fd;
        FILE            *stream;
        etcd_result     retval;

        fd = open(sim->path,O_RDWR);
        if (fd < 0) {
                return ETCD_WTF;
        }

        stream = fdopen(fd,"r+");
        (void)flock(fd,LOCK_EX);
        retval = etcd_set_1(stream,key,value,precond,ttl);
        (void)flock(fd,LOCK_UN);
        fclose(stream); /* closes fd as well */

        return retval;
}


etcd_session
etcd_open_str (char *server_names)
{
        etcd_sim_t      *sim;
        int             fd;

        sim = calloc(1, sizeof(etcd_sim_t));
        (void)asprintf(&sim->path,"/tmp/%s",server_names);

        fd = open(sim->path, O_RDWR | O_CREAT, 0777);
        if (fd == -1) {
                free(sim->path);
                free(sim);
                return NULL;
        }

        close(fd);
        return ((void *)sim);
}


void
etcd_close_str (etcd_session this)
{
        etcd_close(this);
}

etcd_result
etcd_delete (etcd_session this, char *key)
{
	return ETCD_WTF;
}

char *
etcd_leader (etcd_session this_as_void)
{
	return NULL;
}

etcd_result
etcd_watch (etcd_session this, char *pfx, char **keyp, char **valuep,
	    int *index_in, int *index_out)
{
	return ETCD_WTF;
}

etcd_result
etcd_lock (etcd_session session_as_void, char *key, unsigned int ttl,
           char *index_in, char **index_out)
{
        char    *path;
        int     fd;

        if (!index_in) {
                if (gf_asprintf(&path,"/var/tmp/%s",key) < 0) {
                        return ETCD_WTF;
                }
                fd = open(path,O_RDWR|O_CREAT,0666);
                GF_FREE(path);
                if (fd < 0) {
                        return ETCD_WTF;
                }
                if (flock(fd,LOCK_EX) < 0) {
                        close(fd);
                        return ETCD_WTF;
                }
                *index_out = strdup("42");
        }

        /*
         * Yes, we leak an fd by not closing it here (and nobody else even
         * knows about it).  That would be awful in any other context, but
         * for test scripts it won't matter.
         */
        return ETCD_OK;
}