/*
  Copyright (c) 2008-2009 Z RESEARCH, Inc. <http://www.zresearch.com>
  This file is part of GlusterFS.

  GlusterFS 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 3 of the License,
  or (at your option) any later version.

  GlusterFS 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, see
  <http://www.gnu.org/licenses/>.
*/

#ifndef CORE_PRIVATE
#define CORE_PRIVATE
#endif

#include <httpd.h>
#include <http_config.h>
#include <http_core.h>
#include <http_request.h>
#include <http_protocol.h>
#include <http_log.h>
#include <http_main.h>
#include <util_script.h>
#include <libglusterfsclient.h>
#include <sys/uio.h>
#include <pthread.h>

#define GLUSTERFS_INVALID_LOGLEVEL "mod_glusterfs: Unrecognized log-level "\
                                   "\"%s\", possible values are \"DEBUG|"\
                                   "WARNING|ERROR|CRITICAL|NONE\"\n"

#define GLUSTERFS_HANDLER "glusterfs-handler"
#define GLUSTERFS_CHUNK_SIZE 131072 

module MODULE_VAR_EXPORT glusterfs_module;

/*TODO: verify error returns to server core */

typedef struct glusterfs_dir_config {
        char *logfile;
        char *loglevel;
        char *specfile;
        char *mount_dir;
        char *buf;
        size_t xattr_file_size;
        uint32_t cache_timeout;
} glusterfs_dir_config_t;

typedef struct glusterfs_async_local {
        int op_ret;
        int op_errno;
        char async_read_complete;
        off_t length;
        off_t read_bytes;
        glusterfs_iobuf_t *buf;
        request_rec *request;
        pthread_mutex_t lock;
        pthread_cond_t cond;
}glusterfs_async_local_t;

#define GLUSTERFS_CMD_PERMS ACCESS_CONF

static glusterfs_dir_config_t *
mod_glusterfs_dconfig(request_rec *r)
{
        glusterfs_dir_config_t *dir_config = NULL;
        if (r->per_dir_config != NULL) {
                dir_config = ap_get_module_config (r->per_dir_config,
                                                   &glusterfs_module);
        }

        return dir_config;
}

static 
const char *add_xattr_file_size(cmd_parms *cmd, void *dummy, char *arg)
{
        glusterfs_dir_config_t *dir_config = dummy;
        dir_config->xattr_file_size = atoi (arg);
        return NULL;
}

static
const char *set_cache_timeout(cmd_parms *cmd, void *dummy, char *arg)
{
        glusterfs_dir_config_t *dir_config = dummy;
        dir_config->cache_timeout = atoi (arg);
        return NULL;
}

static
const char *set_loglevel(cmd_parms *cmd, void *dummy, char *arg)
{
        glusterfs_dir_config_t *dir_config = dummy;
        char *error = NULL;
        if (strncasecmp (arg, "DEBUG", strlen ("DEBUG")) 
            && strncasecmp (arg, "WARNING", strlen ("WARNING")) 
            && strncasecmp (arg, "CRITICAL", strlen ("CRITICAL")) 
            && strncasecmp (arg, "NONE", strlen ("NONE")) 
            && strncasecmp (arg, "ERROR", strlen ("ERROR")))
                error = GLUSTERFS_INVALID_LOGLEVEL;
        else
                dir_config->loglevel = arg;

        return error;
}

static 
const char *add_logfile(cmd_parms *cmd, void *dummy, char *arg)
{
        glusterfs_dir_config_t *dir_config = dummy;
        dir_config->logfile = arg;

        return NULL;
}

static 
const char *add_specfile(cmd_parms *cmd, void *dummy, char *arg)
{
        glusterfs_dir_config_t *dir_config = dummy;

        dir_config->specfile = arg;

        return NULL;
}

static void *
mod_glusterfs_create_dir_config(pool *p, char *dirspec)
{
        glusterfs_dir_config_t *dir_config = NULL;

        dir_config = (glusterfs_dir_config_t *) ap_pcalloc(p,
                                                           sizeof(*dir_config));

        dir_config->mount_dir = dirspec;
        dir_config->logfile = dir_config->specfile = (char *)0;
        dir_config->loglevel = "warning";
        dir_config->cache_timeout = 0;
        dir_config->buf = NULL;

        return (void *) dir_config;
}

static void 
mod_glusterfs_child_init(server_rec *s, pool *p)
{
        void **urls = NULL;
        int n, i;
        core_server_config *mod_core_config = ap_get_module_config (s->module_config,
                                                                    &core_module);
        glusterfs_dir_config_t *dir_config = NULL;
        glusterfs_init_params_t params = {0, };
  
        n = mod_core_config->sec_url->nelts;
        urls = (void **)mod_core_config->sec_url->elts;
        for (i = 0; i < n; i++) {
                dir_config = ap_get_module_config (urls[i], &glusterfs_module);

                if (dir_config) {
                        memset (&params, 0, sizeof (params));

                        params.logfile = dir_config->logfile;
                        params.loglevel = dir_config->loglevel;
                        params.lookup_timeout = dir_config->cache_timeout;
                        params.stat_timeout = dir_config->cache_timeout;
                        params.specfile = dir_config->specfile;

                        glusterfs_mount (dir_config->mount_dir, &params);
                }
                dir_config = NULL;
        }
}

static void 
mod_glusterfs_child_exit(server_rec *s, pool *p)
{
        void **urls = NULL;
        int n, i;
        core_server_config *mod_core_config = NULL;
        glusterfs_dir_config_t *dir_config = NULL;
  
        mod_core_config = ap_get_module_config (s->module_config, &core_module);
        n = mod_core_config->sec_url->nelts;
        urls = (void **)mod_core_config->sec_url->elts;
        for (i = 0; i < n; i++) {
                dir_config = ap_get_module_config (urls[i], &glusterfs_module);
                if (dir_config) {
                        glusterfs_umount (dir_config->mount_dir);
                }
        }
}

static int mod_glusterfs_fixup(request_rec *r)
{
        glusterfs_dir_config_t *dir_config = NULL;
        int access_status;
        int ret;
        char *path = NULL;

        dir_config = mod_glusterfs_dconfig(r);

        if (dir_config && dir_config->mount_dir
            && !(strncmp (ap_pstrcat (r->pool, dir_config->mount_dir, "/",
                                      NULL),
                          r->uri, strlen (dir_config->mount_dir) + 1)
                 && !r->handler)) 
                r->handler = ap_pstrdup (r->pool, GLUSTERFS_HANDLER);

        if (!r->handler || (r->handler && strcmp (r->handler,
                                                  GLUSTERFS_HANDLER)))
                return DECLINED;

        path = r->uri;

        memset (&r->finfo, 0, sizeof (r->finfo));

        dir_config->buf = calloc (1, dir_config->xattr_file_size);
        if (!dir_config->buf) {
                return HTTP_INTERNAL_SERVER_ERROR;
        }

        ret = glusterfs_get (path, dir_config->buf, 
                             dir_config->xattr_file_size, &r->finfo);

        if (ret == -1 || r->finfo.st_size > dir_config->xattr_file_size
            || S_ISDIR (r->finfo.st_mode)) {
                free (dir_config->buf);
                dir_config->buf = NULL;

                if (ret == -1) {
                        int error = HTTP_NOT_FOUND;
                        char *emsg = NULL;
                        if (r->path_info == NULL) {
                                emsg = ap_pstrcat(r->pool, strerror (errno),
                                                  r->filename, NULL);
                        }
                        else {
                                emsg = ap_pstrcat(r->pool, strerror (errno),
                                                  r->filename, r->path_info,
                                                  NULL);
                        }
                        ap_log_rerror(APLOG_MARK, APLOG_ERR|APLOG_NOERRNO, r,
                                      "%s", emsg);
                        if (errno != ENOENT) {
                                error = HTTP_INTERNAL_SERVER_ERROR;
                        }
                        return error;
                }
        }
    
        if (r->uri && strlen (r->uri) && r->uri[strlen(r->uri) - 1] == '/') 
                r->handler = NULL;

        r->filename = ap_pstrcat (r->pool, r->filename, r->path_info, NULL);

        if ((access_status = ap_find_types(r)) != 0) {
                return DECLINED;
        }

        return OK;
}


int 
mod_glusterfs_readv_async_cbk (int32_t op_ret, int32_t op_errno,
                               glusterfs_iobuf_t *buf, void *cbk_data)
{
        glusterfs_async_local_t *local = cbk_data;

        pthread_mutex_lock (&local->lock);
        {
                local->async_read_complete = 1;
                local->buf = buf;
                local->op_ret = op_ret;
                local->op_errno = op_errno;
                pthread_cond_signal (&local->cond);
        }
        pthread_mutex_unlock (&local->lock);

        return 0;
}

/* use read_async just to avoid memcpy of read buffer in libglusterfsclient */
static int
mod_glusterfs_read_async (request_rec *r, glusterfs_file_t fd, off_t offset,
                          off_t length)
{
        glusterfs_async_local_t local;
        off_t end;
        int nbytes;
        int complete;
        pthread_cond_init (&local.cond, NULL);
        pthread_mutex_init (&local.lock, NULL);
  
        memset (&local, 0, sizeof (local));
        local.request = r;

        if (length > 0)
                end = offset + length;

        do {
                glusterfs_iobuf_t *buf;
                int i;
                if (length > 0) {
                        nbytes = end - offset;
                        if (nbytes > GLUSTERFS_CHUNK_SIZE)
                                nbytes = GLUSTERFS_CHUNK_SIZE;
                } else
                        nbytes = GLUSTERFS_CHUNK_SIZE;

                glusterfs_read_async(fd, 
                                     nbytes,
                                     offset,
                                     mod_glusterfs_readv_async_cbk,
                                     (void *)&local);

                pthread_mutex_lock (&local.lock);
                {
                        while (!local.async_read_complete) {
                                pthread_cond_wait (&local.cond, &local.lock);
                        }

                        local.async_read_complete = 0;
                        buf = local.buf;

                        if (length < 0)
                                complete = (local.op_ret <= 0);
                        else {
                                local.read_bytes += local.op_ret;
                                complete = ((local.read_bytes == length) 
                                            || (local.op_ret < 0));
                        }
                }
                pthread_mutex_unlock (&local.lock);

                for (i = 0; i < buf->count; i++) {
                        if (ap_rwrite (buf->vector[i].iov_base,
                                       buf->vector[i].iov_len, r) < 0) {
                                local.op_ret = -1;
                                complete = 1;
                                break;
                        }
                }      

                glusterfs_free (buf);

                offset += nbytes;
        } while (!complete);

        return (local.op_ret < 0 ? SERVER_ERROR : OK);
}

static int 
mod_glusterfs_handler(request_rec *r)
{
        glusterfs_dir_config_t *dir_config;
        char *path = NULL;
        int error = OK;
        int rangestatus = 0;
        int errstatus = OK;
        glusterfs_file_t fd;
  
        if (!r->handler || (r->handler && strcmp (r->handler,
                                                  GLUSTERFS_HANDLER)))
                return DECLINED;

        if (r->uri[0] == '\0' || r->uri[strlen(r->uri) - 1] == '/') {
                return DECLINED;
        }
  
        dir_config = mod_glusterfs_dconfig (r);
  
        if (r->method_number != M_GET) {
                return METHOD_NOT_ALLOWED;
        }

        ap_update_mtime(r, r->finfo.st_mtime);
        ap_set_last_modified(r);
        ap_set_etag(r);
        ap_table_setn(r->headers_out, "Accept-Ranges", "bytes");
        if (((errstatus = ap_meets_conditions(r)) != OK)
            || (errstatus = ap_set_content_length(r, r->finfo.st_size))) {
                return errstatus;
        }
        rangestatus =  ap_set_byterange(r);
        ap_send_http_header(r);

        if (r->finfo.st_size <= dir_config->xattr_file_size && dir_config->buf) {
                if (!r->header_only) {
                        error = OK;
                        ap_log_rerror (APLOG_MARK, APLOG_NOTICE, r, 
                                       "fetching data from glusterfs through "
                                       "xattr interface\n");
      
                        if (!rangestatus) {
                                if (ap_rwrite (dir_config->buf,
                                               r->finfo.st_size, r) < 0) {
                                        error = HTTP_INTERNAL_SERVER_ERROR;
                                }
                        } else {
                                long offset, length;
                                while (ap_each_byterange (r, &offset, &length)) {
                                        if (ap_rwrite (dir_config->buf + offset,
                                                       length, r) < 0) {
                                                error = HTTP_INTERNAL_SERVER_ERROR;
                                                break;
                                        }
                                }
                        }
                }

                free (dir_config->buf);
                dir_config->buf = NULL;

                return error;
        }

        path = r->uri;
        fd = glusterfs_open (path , O_RDONLY, 0);
  
        if (fd == 0) {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, r,
                              "file permissions deny server access: %s",
                              r->filename);
                return FORBIDDEN;
        }
  
        if (!r->header_only) {
                if (!rangestatus) {
                        mod_glusterfs_read_async (r, fd, 0, -1);
                } else {
                        long offset, length;
                        while (ap_each_byterange(r, &offset, &length)) {
                                mod_glusterfs_read_async (r, fd, offset, length);
                        }
                }
        }
  
        glusterfs_close (fd);
        return error;
}

static const command_rec mod_glusterfs_cmds[] =
{
        {"GlusterfsLogfile", add_logfile, NULL,
         GLUSTERFS_CMD_PERMS, TAKE1,
         "Glusterfs Logfile"},
        {"GlusterfsLoglevel", set_loglevel, NULL,
         GLUSTERFS_CMD_PERMS, TAKE1,
         "Glusterfs Loglevel:anyone of none, critical, error, warning, debug"},
        {"GlusterfsCacheTimeout", set_cache_timeout, NULL,
         GLUSTERFS_CMD_PERMS, TAKE1,
         "Timeout value in seconds for caching lookups and stats"},
        {"GlusterfsVolumeSpecfile", add_specfile, NULL,
         GLUSTERFS_CMD_PERMS, TAKE1,
         "Glusterfs Specfile required to access contents of this directory"},
        {"GlusterfsXattrFileSize", add_xattr_file_size, NULL, 
         GLUSTERFS_CMD_PERMS, TAKE1,
         "Maximum size of the file to be fetched using xattr interface of "
         "glusterfs"},
        {NULL}
};

static const handler_rec mod_glusterfs_handlers[] =
{
        {GLUSTERFS_HANDLER, mod_glusterfs_handler},
        {NULL}
};

module glusterfs_module =
{
        STANDARD_MODULE_STUFF,
        NULL, 
        mod_glusterfs_create_dir_config,  /* per-directory config creator */
        NULL,
        NULL,       /* server config creator */
        NULL,        /* server config merger */
        mod_glusterfs_cmds,               /* command table */
        mod_glusterfs_handlers,           /* [7] list of handlers */
        NULL,  /* [2] filename-to-URI translation */
        NULL,      /* [5] check/validate user_id */
        NULL,       /* [6] check user_id is valid *here* */
        NULL,     /* [4] check access by host address */
        NULL,       /* [7] MIME type checker/setter */
        mod_glusterfs_fixup,        /* [8] fixups */
        NULL,             /* [10] logger */
#if MODULE_MAGIC_NUMBER >= 19970103
        NULL,      /* [3] header parser */
#endif
#if MODULE_MAGIC_NUMBER >= 19970719
        mod_glusterfs_child_init,         /* process initializer */
#endif
#if MODULE_MAGIC_NUMBER >= 19970728
        mod_glusterfs_child_exit,         /* process exit/cleanup */
#endif
#if MODULE_MAGIC_NUMBER >= 19970902
        NULL   /* [1] post read_request handling */
#endif
};