/*
 * Copyright (c) 2011 Frantisek Princ
 * 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/** @addtogroup libext4
 * @{
 */ 

/**
 * @file	libext4_balloc.c
 * @brief	Block allocator.
 */

#include <errno.h>
#include <sys/types.h>
#include "libext4.h"

static uint32_t ext4_balloc_blockaddr2_index_in_group(ext4_superblock_t *sb,
		uint32_t block_addr)
{
	uint32_t blocks_per_group = ext4_superblock_get_blocks_per_group(sb);
	uint32_t first_block = ext4_superblock_get_first_data_block(sb);

	// First block == 0 or 1
	if (first_block == 0) {
		return block_addr % blocks_per_group;
	} else {
		return (block_addr - 1) % blocks_per_group;
	}
}

static uint32_t ext4_balloc_index_in_group2blockaddr(ext4_superblock_t *sb,
		uint32_t index, uint32_t bgid)
{
	uint32_t blocks_per_group = ext4_superblock_get_blocks_per_group(sb);

	if (ext4_superblock_get_first_data_block(sb) == 0) {
		return bgid * blocks_per_group + index;
	} else {
		return bgid * blocks_per_group + index + 1;
	}

}

static uint32_t ext4_balloc_get_bgid_of_block(ext4_superblock_t *sb,
		uint32_t block_addr)
{
	uint32_t blocks_per_group = ext4_superblock_get_blocks_per_group(sb);
	uint32_t first_block = ext4_superblock_get_first_data_block(sb);

	// First block == 0 or 1
	if (first_block == 0) {
		return block_addr / blocks_per_group;
	} else {
		return (block_addr - 1) / blocks_per_group;
	}
}


int ext4_balloc_free_block(ext4_filesystem_t *fs, ext4_inode_ref_t *inode_ref, uint32_t block_addr)
{
	int rc;

	uint32_t block_group = ext4_balloc_get_bgid_of_block(fs->superblock, block_addr);
	uint32_t index_in_group = ext4_balloc_blockaddr2_index_in_group(fs->superblock, block_addr);

	ext4_block_group_ref_t *bg_ref;
	rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
	if (rc != EOK) {
		EXT4FS_DBG("error in loading bg_ref \%d", rc);
		return rc;
	}

	uint32_t bitmap_block_addr = ext4_block_group_get_block_bitmap(
			bg_ref->block_group, fs->superblock);
	block_t *bitmap_block;
	rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
	if (rc != EOK) {
		EXT4FS_DBG("error in loading bitmap \%d", rc);
		return rc;
	}

	ext4_bitmap_free_bit(bitmap_block->data, index_in_group);
	bitmap_block->dirty = true;

	rc = block_put(bitmap_block);
	if (rc != EOK) {
		// Error in saving bitmap
		ext4_filesystem_put_block_group_ref(bg_ref);
		EXT4FS_DBG("error in saving bitmap \%d", rc);
		return rc;
	}

	uint32_t block_size = ext4_superblock_get_block_size(fs->superblock);

	// Update superblock free blocks count
	uint32_t sb_free_blocks = ext4_superblock_get_free_blocks_count(fs->superblock);
	sb_free_blocks--;
	ext4_superblock_set_free_blocks_count(fs->superblock, sb_free_blocks);

	// Update inode blocks count
	uint64_t ino_blocks = ext4_inode_get_blocks_count(fs->superblock, inode_ref->inode);
	ino_blocks -= block_size / EXT4_INODE_BLOCK_SIZE;
	ext4_inode_set_blocks_count(fs->superblock, inode_ref->inode, ino_blocks);
	inode_ref->dirty = true;

	// Update block group free blocks count
	uint32_t free_blocks = ext4_block_group_get_free_blocks_count(
			bg_ref->block_group, fs->superblock);
	free_blocks++;
	ext4_block_group_set_free_blocks_count(bg_ref->block_group,
			fs->superblock, free_blocks);
	bg_ref->dirty = true;

	rc = ext4_filesystem_put_block_group_ref(bg_ref);
	if (rc != EOK) {
		EXT4FS_DBG("error in saving bg_ref \%d", rc);
		// TODO error
		return rc;
	}

	return EOK;
}

static uint32_t ext4_balloc_get_first_data_block_in_group(
		ext4_superblock_t *sb, ext4_block_group_t *bg, uint32_t bgid)
{
	uint32_t block_group_count = ext4_superblock_get_block_group_count(sb);
	uint32_t inode_table_first_block = ext4_block_group_get_inode_table_first_block(
			bg, sb);
	uint16_t inode_table_item_size = ext4_superblock_get_inode_size(sb);
	uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
	uint32_t block_size = ext4_superblock_get_block_size(sb);
	uint32_t inode_table_bytes;

	if (bgid < block_group_count - 1) {
		inode_table_bytes = inodes_per_group * inode_table_item_size;
	} else {
		// last block group could be smaller
		uint32_t inodes_count_total = ext4_superblock_get_inodes_count(sb);
		inode_table_bytes =
				(inodes_count_total - ((block_group_count - 1) * inodes_per_group))
				* inode_table_item_size;
	}

	uint32_t inode_table_blocks = inode_table_bytes / block_size;

	if (inode_table_bytes % block_size) {
		inode_table_blocks++;
	}

	return inode_table_first_block + inode_table_blocks;
}


static uint32_t ext4_balloc_find_goal(ext4_filesystem_t *fs, ext4_inode_ref_t *inode_ref)
{
	int rc;
	uint32_t goal = 0;

	uint64_t inode_size = ext4_inode_get_size(fs->superblock, inode_ref->inode);
	uint32_t block_size = ext4_superblock_get_block_size(fs->superblock);
	uint32_t inode_block_count = inode_size / block_size;

	if (inode_size % block_size != 0) {
		inode_block_count++;
	}

	if (inode_block_count > 0) {
		// TODO check retval
		ext4_filesystem_get_inode_data_block_index(fs, inode_ref->inode, inode_block_count - 1, &goal);

		// TODO
		// If goal == 0 -> SPARSE file !!!

		goal++;
		return goal;
	}

	// Identify block group of inode
	uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(fs->superblock);
	uint32_t block_group = (inode_ref->index - 1) / inodes_per_group;
	block_size = ext4_superblock_get_block_size(fs->superblock);

	ext4_block_group_ref_t *bg_ref;
	rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
	if (rc != EOK) {
		return 0;
	}

	uint32_t block_group_count = ext4_superblock_get_block_group_count(fs->superblock);
	uint32_t inode_table_first_block = ext4_block_group_get_inode_table_first_block(
			bg_ref->block_group, fs->superblock);
	uint16_t inode_table_item_size = ext4_superblock_get_inode_size(fs->superblock);
	uint32_t inode_table_bytes;

	if (block_group < block_group_count - 1) {
		inode_table_bytes = inodes_per_group * inode_table_item_size;
	} else {
		// last block group could be smaller
		uint32_t inodes_count_total = ext4_superblock_get_inodes_count(fs->superblock);
		inode_table_bytes =
				(inodes_count_total - ((block_group_count - 1) * inodes_per_group))
				* inode_table_item_size;
	}

	uint32_t inode_table_blocks = inode_table_bytes / block_size;

	if (inode_table_bytes % block_size) {
		inode_table_blocks++;
	}

	goal = inode_table_first_block + inode_table_blocks;

	ext4_filesystem_put_block_group_ref(bg_ref);

	return goal;
}

int ext4_balloc_alloc_block(ext4_filesystem_t *fs, ext4_inode_ref_t *inode_ref, uint32_t *fblock)
{
	int rc;
	uint32_t allocated_block = 0;

	uint32_t bitmap_block_addr;
	block_t *bitmap_block;
	uint32_t rel_block_idx = 0;

	// Find GOAL
	uint32_t goal = ext4_balloc_find_goal(fs, inode_ref);
	if (goal == 0) {
		// TODO
		EXT4FS_DBG("ERRORR (goal == 0)");
		return ENOSPC;
	}

	// Load block group number for goal and relative index
	uint32_t block_group = ext4_balloc_get_bgid_of_block(fs->superblock, goal);
	uint32_t index_in_group = ext4_balloc_blockaddr2_index_in_group(fs->superblock, goal);


	ext4_block_group_ref_t *bg_ref;
	rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
	if (rc != EOK) {
		EXT4FS_DBG("initial BG ref not loaded");
		return rc;
	}

	uint32_t first_in_group =
			ext4_balloc_get_first_data_block_in_group(fs->superblock,
					bg_ref->block_group, block_group);

	uint32_t first_in_group_index = ext4_balloc_blockaddr2_index_in_group(
			fs->superblock, first_in_group);

	if (index_in_group < first_in_group_index) {
		index_in_group = first_in_group_index;
	}

	// Load bitmap
	bitmap_block_addr = ext4_block_group_get_block_bitmap(bg_ref->block_group,
			fs->superblock);

	rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
	if (rc != EOK) {
		ext4_filesystem_put_block_group_ref(bg_ref);
		EXT4FS_DBG("initial bitmap not loaded");
		return rc;
	}

	// Check if goal is free
	if (ext4_bitmap_is_free_bit(bitmap_block->data, index_in_group)) {
		ext4_bitmap_set_bit(bitmap_block->data, index_in_group);
		bitmap_block->dirty = true;
		rc = block_put(bitmap_block);
		if (rc != EOK) {
			// TODO error
			EXT4FS_DBG("goal check: error in saving initial bitmap \%d", rc);
			ext4_filesystem_put_block_group_ref(bg_ref);
			return rc;
		}

		allocated_block = goal;
		goto success;

	}

	uint32_t blocks_in_group = ext4_superblock_get_blocks_in_group(fs->superblock, block_group);

	uint32_t end_idx = (index_in_group + 63) & ~63;
	if (end_idx > blocks_in_group) {
		end_idx = blocks_in_group;
	}

	// Try to find free block near to goal
	for (uint32_t tmp_idx = index_in_group + 1; tmp_idx < end_idx; ++tmp_idx) {
		if (ext4_bitmap_is_free_bit(bitmap_block->data, tmp_idx)) {

			ext4_bitmap_set_bit(bitmap_block->data, tmp_idx);
			bitmap_block->dirty = true;
			rc = block_put(bitmap_block);
			if (rc != EOK) {
				// TODO error
				EXT4FS_DBG("near blocks: error in saving initial bitmap \%d", rc);
			}

			allocated_block = ext4_balloc_index_in_group2blockaddr(
					fs->superblock, tmp_idx, block_group);

			goto success;
		}

	}

	// Find free BYTE in bitmap
	rc = ext4_bitmap_find_free_byte_and_set_bit(bitmap_block->data, index_in_group, &rel_block_idx, blocks_in_group);
	if (rc == EOK) {
		bitmap_block->dirty = true;
		rc = block_put(bitmap_block);
		if (rc != EOK) {
			// TODO error
			EXT4FS_DBG("free byte: error in saving initial bitmap \%d", rc);
		}

		allocated_block = ext4_balloc_index_in_group2blockaddr(
				fs->superblock, rel_block_idx, block_group);

		goto success;
	}

	// Find free bit in bitmap
	rc = ext4_bitmap_find_free_bit_and_set(bitmap_block->data, index_in_group, &rel_block_idx, blocks_in_group);
	if (rc == EOK) {
		bitmap_block->dirty = true;
		rc = block_put(bitmap_block);
		if (rc != EOK) {
			// TODO error
			EXT4FS_DBG("free bit: error in saving initial bitmap \%d", rc);
		}

		allocated_block = ext4_balloc_index_in_group2blockaddr(
				fs->superblock, rel_block_idx, block_group);

		goto success;
	}

	block_put(bitmap_block);
	ext4_filesystem_put_block_group_ref(bg_ref);

	// Try other block groups
	uint32_t block_group_count = ext4_superblock_get_block_group_count(fs->superblock);

	uint32_t bgid = (block_group + 1) % block_group_count;
	uint32_t count = block_group_count;

	while (count > 0) {
		rc = ext4_filesystem_get_block_group_ref(fs, bgid, &bg_ref);
		if (rc != EOK) {
			EXT4FS_DBG("errrrrrrrrrrr");
			return rc;
		}

		// Load bitmap
		bitmap_block_addr = ext4_block_group_get_block_bitmap(
				bg_ref->block_group, fs->superblock);

		rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
		if (rc != EOK) {
			ext4_filesystem_put_block_group_ref(bg_ref);
			EXT4FS_DBG("errrrrrrrrrr");
			return rc;
		}

		first_in_group = ext4_balloc_get_first_data_block_in_group(
				fs->superblock, bg_ref->block_group, bgid);
		index_in_group = ext4_balloc_blockaddr2_index_in_group(fs->superblock,
						first_in_group);
		blocks_in_group = ext4_superblock_get_blocks_in_group(fs->superblock, bgid);

		first_in_group_index = ext4_balloc_blockaddr2_index_in_group(
			fs->superblock, first_in_group);

		if (index_in_group < first_in_group_index) {
			index_in_group = first_in_group_index;
		}


		rc = ext4_bitmap_find_free_byte_and_set_bit(bitmap_block->data, index_in_group, &rel_block_idx, blocks_in_group);
		if (rc == EOK) {
			bitmap_block->dirty = true;
			rc = block_put(bitmap_block);
			if (rc != EOK) {
				// TODO error
				EXT4FS_DBG("error in saving bitmap \%d", rc);
			}

			allocated_block = ext4_balloc_index_in_group2blockaddr(
					fs->superblock, rel_block_idx, bgid);

			goto success;
		}

		// Find free bit in bitmap
		rc = ext4_bitmap_find_free_bit_and_set(bitmap_block->data, index_in_group, &rel_block_idx, blocks_in_group);
		if (rc == EOK) {
			bitmap_block->dirty = true;
			rc = block_put(bitmap_block);
			if (rc != EOK) {
				// TODO error
				EXT4FS_DBG("error in saving bitmap \%d", rc);
			}

			allocated_block = ext4_balloc_index_in_group2blockaddr(
					fs->superblock, rel_block_idx, bgid);

			goto success;
		}


		// Next group
		block_put(bitmap_block);
		ext4_filesystem_put_block_group_ref(bg_ref);
		bgid = (bgid + 1) % block_group_count;
		count--;
	}

	return ENOSPC;

success:
	; 	// Empty command - because of syntax
	
	uint32_t block_size = ext4_superblock_get_block_size(fs->superblock);

	// Update superblock free blocks count
	uint32_t sb_free_blocks = ext4_superblock_get_free_blocks_count(fs->superblock);
	sb_free_blocks--;
	ext4_superblock_set_free_blocks_count(fs->superblock, sb_free_blocks);

	// Update inode blocks (different block size!) count
	uint64_t ino_blocks = ext4_inode_get_blocks_count(fs->superblock, inode_ref->inode);
	ino_blocks += block_size / EXT4_INODE_BLOCK_SIZE;
	ext4_inode_set_blocks_count(fs->superblock, inode_ref->inode, ino_blocks);
	inode_ref->dirty = true;

	// Update block group free blocks count
	uint32_t bg_free_blocks = ext4_block_group_get_free_blocks_count(
			bg_ref->block_group, fs->superblock);
	bg_free_blocks--;
	ext4_block_group_set_free_blocks_count(bg_ref->block_group,
			fs->superblock, bg_free_blocks);
	bg_ref->dirty = true;

	ext4_filesystem_put_block_group_ref(bg_ref);

	*fblock = allocated_block;
	return EOK;
}


/**
 * @}
 */