/*
   Copyright (c) 2008-2009 Gluster, Inc. <http://www.gluster.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 _CONFIG_H
#define _CONFIG_H
#include "config.h"
#endif


#include "glusterfs.h"
#include "xlator.h"
#include "dht-common.h"


int
dht_selfheal_dir_finish (call_frame_t *frame, xlator_t *this, int ret)
{
	dht_local_t  *local = NULL;


	local = frame->local;
	local->selfheal.dir_cbk (frame, NULL, frame->this, ret,
				 local->op_errno);

	return 0;
}


int
dht_selfheal_dir_xattr_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
			    int op_ret, int op_errno)
{
	dht_local_t  *local = NULL;
	call_frame_t *prev = NULL;
	xlator_t     *subvol = NULL;
	int           i = 0;
	dht_layout_t *layout = NULL;
	int           err = 0;
	int           this_call_cnt = 0;

	local = frame->local;
	layout = local->selfheal.layout;
	prev = cookie;
	subvol = prev->this;

	if (op_ret == 0)
		err = 0;
	else
		err = op_errno;

	for (i = 0; i < layout->cnt; i++) {
		if (layout->list[i].xlator == subvol) {
			layout->list[i].err = err;
			break;
		}
	}

	this_call_cnt = dht_frame_return (frame);

	if (is_last_call (this_call_cnt)) {
		dht_selfheal_dir_finish (frame, this, 0);
	}

	return 0;
}


int
dht_selfheal_dir_xattr_persubvol (call_frame_t *frame, loc_t *loc,
				  dht_layout_t *layout, int i)
{
	xlator_t          *subvol = NULL;
	dict_t            *xattr = NULL;
	int                ret = 0;
	xlator_t          *this = NULL;
	int32_t           *disk_layout = NULL;


	subvol = layout->list[i].xlator;
	this = frame->this;

	xattr = get_new_dict ();
	if (!xattr) {
		gf_log (this->name, GF_LOG_ERROR,
			"Out of memory");
		goto err;
	}

	ret = dht_disk_layout_extract (this, layout, i, &disk_layout);
	if (ret == -1) {
		gf_log (this->name, GF_LOG_DEBUG,
			"failed to extract disk layout");
		goto err;
	}

	ret = dict_set_bin (xattr, "trusted.glusterfs.dht",
			    disk_layout, 4 * 4);
	if (ret == -1) {
		gf_log (this->name, GF_LOG_DEBUG,
			"failed to set xattr dictionary");
		goto err;
	}
	disk_layout = NULL;

	gf_log (this->name, GF_LOG_TRACE,
		"setting hash range %u - %u (type %d) on subvolume %s for %s",
		layout->list[i].start, layout->list[i].stop,
		layout->type, subvol->name, loc->path);

	dict_ref (xattr);

	STACK_WIND (frame, dht_selfheal_dir_xattr_cbk,
		    subvol, subvol->fops->setxattr,
		    loc, xattr, 0);

	dict_unref (xattr);

	return 0;

err:
	if (xattr)
		dict_destroy (xattr);

	if (disk_layout)
		FREE (disk_layout);

	dht_selfheal_dir_xattr_cbk (frame, subvol, frame->this,
				    -1, ENOMEM);
	return 0;
}


int
dht_selfheal_dir_xattr (call_frame_t *frame, loc_t *loc, dht_layout_t *layout)
{
	dht_local_t *local = NULL;
	int          missing_xattr = 0;
	int          i = 0;
	int          ret = 0;
	xlator_t    *this = NULL;

	local = frame->local;
	this = frame->this;

	for (i = 0; i < layout->cnt; i++) {
		if (layout->list[i].err != -1 || !layout->list[i].stop) {
			/* err != -1 would mean xattr present on the directory
			 * or the directory is itself non existant.
			 * !layout->list[i].stop would mean layout absent
			 */
			continue;
		}
		missing_xattr++;
	}

	gf_log (this->name, GF_LOG_TRACE,
		"%d subvolumes missing xattr for %s",
		missing_xattr, loc->path);

	if (missing_xattr == 0) {
		dht_selfheal_dir_finish (frame, this, 0);
		return 0;
	}

	local->call_cnt = missing_xattr;

	for (i = 0; i < layout->cnt; i++) {
		if (layout->list[i].err != -1 || !layout->list[i].stop)
			continue;

		ret = dht_selfheal_dir_xattr_persubvol (frame, loc, layout, i);

		if (--missing_xattr == 0)
			break;
	}
	return 0;
}


int
dht_selfheal_dir_mkdir_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
			    int op_ret, int op_errno,
			    inode_t *inode, struct stat *stbuf)
{
	dht_local_t   *local = NULL;
	dht_layout_t  *layout = NULL;
	call_frame_t  *prev = NULL;
	xlator_t      *subvol = NULL;
	int            i = 0;
	int            this_call_cnt = 0;


	local  = frame->local;
	layout = local->selfheal.layout;
	prev   = cookie;
	subvol = prev->this;

	if ((op_ret == 0) || (op_errno == EEXIST)) {
		for (i = 0; i < layout->cnt; i++) {
			if (layout->list[i].xlator == subvol) {
				layout->list[i].err = -1;
				break;
			}
		}
	}

	this_call_cnt = dht_frame_return (frame);

	if (is_last_call (this_call_cnt)) {
		dht_selfheal_dir_xattr (frame, &local->loc, layout);
	}

	return 0;
}


int
dht_selfheal_dir_mkdir (call_frame_t *frame, loc_t *loc,
			dht_layout_t *layout, int force)
{
	int           missing_dirs = 0;
	int           i = 0;
	dht_local_t  *local = NULL;
	xlator_t     *this = NULL;


	local = frame->local;
	this = frame->this;

	for (i = 0; i < layout->cnt; i++) {
		if (layout->list[i].err == ENOENT || force)
			missing_dirs++;
	}

	if (missing_dirs == 0) {
		dht_selfheal_dir_xattr (frame, loc, layout);
		return 0;
	}

	local->call_cnt = missing_dirs;
	for (i = 0; i < layout->cnt; i++) {
		if (layout->list[i].err == ENOENT || force) {
			gf_log (this->name, GF_LOG_TRACE,
				"creating directory %s on subvol %s",
				loc->path, layout->list[i].xlator->name);

			STACK_WIND (frame, dht_selfheal_dir_mkdir_cbk,
				    layout->list[i].xlator,
				    layout->list[i].xlator->fops->mkdir,
				    loc, local->stbuf.st_mode);
		}
	}

	return 0;
}


int
dht_selfheal_layout_alloc_start (xlator_t *this, loc_t *loc,
                                 dht_layout_t *layout)
{
        int           start = 0;
        dht_conf_t   *conf = NULL;
        uint32_t      hashval = 0;
        int           ret = 0;

        conf = this->private;

        ret = dht_hash_compute (layout->type, loc->path, &hashval);
        if (ret == 0) {
                start = (hashval % layout->cnt);
        }

        return start;
}


void
dht_selfheal_layout_new_directory (call_frame_t *frame, loc_t *loc,
				   dht_layout_t *layout)
{
	dht_conf_t  *conf = NULL;
	xlator_t    *this = NULL;
	uint32_t     chunk = 0;
	int          i = 0;
	uint32_t     start = 0;
	int          cnt = 0;
	int          err = 0;
        int          start_subvol = 0;

	this = frame->this;
	conf = this->private;

	for (i = 0; i < layout->cnt; i++) {
		err = layout->list[i].err;
		if (err == -1 || err == 0) {
			layout->list[i].err = -1;
			cnt++;
		}
	}

        /* no subvolume has enough space, but can't stop directory creation */
        if (!cnt) {
                for (i = 0; i < layout->cnt; i++) {
                        err = layout->list[i].err;
                        if (err == ENOSPC) {
                                layout->list[i].err = -1;
                                cnt++;
                        }
                }
        }

	chunk = ((unsigned long) 0xffffffff) / cnt;

	start_subvol = dht_selfheal_layout_alloc_start (this, loc, layout);

	for (i = start_subvol; i < layout->cnt; i++) {
		err = layout->list[i].err;
		if (err == -1) {
			layout->list[i].start = start;
			layout->list[i].stop  = start + chunk - 1;
			
			start = start + chunk;

			gf_log (this->name, GF_LOG_TRACE,
				"gave fix: %u - %u on %s for %s",
				layout->list[i].start, layout->list[i].stop,
				layout->list[i].xlator->name, loc->path);
			if (--cnt == 0) {
				layout->list[i].stop = 0xffffffff;
				break;
			}
		}
	}

	for (i = 0; i < start_subvol; i++) {
		err = layout->list[i].err;
		if (err == -1) {
			layout->list[i].start = start;
			layout->list[i].stop  = start + chunk - 1;
			
			start = start + chunk;

			gf_log (this->name, GF_LOG_TRACE,
				"gave fix: %u - %u on %s for %s",
				layout->list[i].start, layout->list[i].stop,
				layout->list[i].xlator->name, loc->path);
			if (--cnt == 0) {
				layout->list[i].stop = 0xffffffff;
				break;
			}
		}
	}
}


int
dht_selfheal_dir_getafix (call_frame_t *frame, loc_t *loc,
			  dht_layout_t *layout)
{
	dht_conf_t  *conf = NULL;
	xlator_t    *this = NULL;
	dht_local_t *local = NULL;
	int          missing = -1;
	int          down = -1;
	int          holes = -1;
	int          ret = -1;
	int          i = -1;
	int          overlaps = -1;

	this = frame->this;
	conf = this->private;
	local = frame->local;

	missing = local->selfheal.missing;
	down = local->selfheal.down;
	holes = local->selfheal.hole_cnt;
	overlaps = local->selfheal.overlaps_cnt;

	if ((missing + down) == conf->subvolume_cnt) {
		dht_selfheal_layout_new_directory (frame, loc, layout);
		ret = 0;
	}

	if (holes <= down) {
		/* the down subvol might fill up the holes */
		ret = 0;
	}

	if (holes || missing || overlaps) {
		dht_selfheal_layout_new_directory (frame, loc, layout);
		ret = 0;
	}

	for (i = 0; i < layout->cnt; i++) {
		/* directory not present */
		if (layout->list[i].err == ENOENT) {
			ret = 0;
			break;
		}
	}

	/* TODO: give a fix to these non-virgins */

	return ret;
}

int
dht_selfheal_new_directory (call_frame_t *frame, 
			    dht_selfheal_dir_cbk_t dir_cbk,
			    dht_layout_t *layout)
{
	dht_local_t *local = NULL;

	local = frame->local;

	local->selfheal.dir_cbk = dir_cbk;
	local->selfheal.layout = layout;

	dht_layout_sort_volname (layout);
	dht_selfheal_layout_new_directory (frame, &local->loc, layout);	
	dht_selfheal_dir_xattr (frame, &local->loc, layout);
	return 0;
}


int
dht_selfheal_directory (call_frame_t *frame, dht_selfheal_dir_cbk_t dir_cbk,
			loc_t *loc, dht_layout_t *layout)
{
	dht_local_t *local    = NULL;
	uint32_t     holes    = 0;
	uint32_t     overlaps = 0;
	uint32_t     missing  = 0;
	uint32_t     down     = 0;
	uint32_t     misc     = 0;
	int          ret      = 0;
	xlator_t    *this     = NULL;

	local = frame->local;
	this = frame->this;

	ret = dht_layout_anomalies (this, loc, layout,
				    &local->selfheal.hole_cnt,
				    &local->selfheal.overlaps_cnt,
				    &local->selfheal.missing,
				    &local->selfheal.down,
				    &local->selfheal.misc);

	holes    = local->selfheal.hole_cnt;
	overlaps = local->selfheal.overlaps_cnt;
	missing  = local->selfheal.missing;
	down     = local->selfheal.down;
	misc     = local->selfheal.misc;

	local->selfheal.dir_cbk = dir_cbk;
	local->selfheal.layout = layout;

	if (down) {
		gf_log (this->name, GF_LOG_DEBUG,
			"%d subvolumes down -- not fixing", down);
		ret = 0;
		goto sorry_no_fix;
	}

	if (misc) {
		gf_log (this->name, GF_LOG_DEBUG,
			"%d subvolumes have unrecoverable errors", misc);
		ret = 0;
		goto sorry_no_fix;
	}

	dht_layout_sort_volname (layout);
	ret = dht_selfheal_dir_getafix (frame, loc, layout);

	if (ret == -1) {
		gf_log (this->name, GF_LOG_DEBUG,
			"not able to form layout for the directory");
		goto sorry_no_fix;
	}

	dht_selfheal_dir_mkdir (frame, loc, layout, 0);

	return 0;

sorry_no_fix:
	/* TODO: need to put appropriate local->op_errno */
	dht_selfheal_dir_finish (frame, this, ret);

	return 0;
}


int
dht_selfheal_restore (call_frame_t *frame, dht_selfheal_dir_cbk_t dir_cbk,
		      loc_t *loc, dht_layout_t *layout)
{
	int          ret = 0;
	dht_local_t *local    = NULL;


	local = frame->local;

	local->selfheal.dir_cbk = dir_cbk;
	local->selfheal.layout = layout;

	ret = dht_selfheal_dir_mkdir (frame, loc, layout, 1);

	return 0;
}