/*
 * SCSI stream command processing backing store
 *
 * Copyright (C) 2008 Mark Harvey markh794@gmail.com
 *
 * This program 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, version 2 of the
 * License.
 *
 * This program 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <linux/fs.h>
#include <sys/epoll.h>

#include "list.h"
#include "util.h"
#include "tgtd.h"
#include "scsi.h"
#include "bs_thread.h"

#include "media.h"
#include "bs_ssc.h"
#include "ssc.h"
#include "libssc.h"

#define SENSE_FILEMARK	0x80
#define SENSE_EOM	0x40
#define SENSE_ILI	0X20

static void ssc_sense_data_build(struct scsi_cmd *cmd, uint8_t key,
				 uint16_t asc, uint8_t *info, int info_len)
{
	/* TODO: support descriptor format */

	sense_data_build(cmd, key, asc);
	if (info_len) {
		memcpy(cmd->sense_buffer + 3, info, 4);
		cmd->sense_buffer[0] |= 0x80;
	}
}

static inline uint32_t ssc_get_block_length(struct scsi_lu *lu)
{
	return get_unaligned_be24(lu->mode_block_descriptor + 5);
}

/* I'm sure there is a more efficent method then this */
static int32_t be24_to_2comp(uint8_t *c)
{
	int count;
	count = (c[0] << 16) | (c[1] << 8) | c[2];
	if (c[0] & 0x80)
		count += (0xff << 24);
	return count;
}

static int skip_next_header(struct scsi_lu *lu)
{
	struct ssc_info *ssc = dtype_priv(lu);
	struct blk_header_info *h = &ssc->c_blk;

	return ssc_read_blkhdr(lu->fd, h, h->next);
}

static int skip_prev_header(struct scsi_lu *lu)
{
	ssize_t rd;
	struct ssc_info *ssc = dtype_priv(lu);
	struct blk_header_info *h = &ssc->c_blk;

	rd = ssc_read_blkhdr(lu->fd, h, h->prev);
	if (rd)
		return 1;
	if (h->blk_type == BLK_BOT)
		return skip_next_header(lu);
	return 0;
}

static int resp_rewind(struct scsi_lu *lu)
{
	int fd;
	ssize_t rd;
	struct ssc_info *ssc = dtype_priv(lu);
	struct blk_header_info *h = &ssc->c_blk;

	fd = lu->fd;

	dprintf("*** Backing store fd: %s %d %d ***\n", lu->path, lu->fd, fd);

	rd = ssc_read_blkhdr(fd, h, 0);
	if (rd) {
		eprintf("fail to read the first block header\n");
		return 1;
	}

	return skip_next_header(lu);
}

static unsigned long current_size(struct scsi_cmd *cmd)
{
	struct ssc_info *ssc = dtype_priv(cmd->dev);
	return ssc->c_blk.curr;
}

static int append_blk(struct scsi_cmd *cmd, uint8_t *data,
		      int size, int orig_sz, int type)
{
	int fd;
	struct ssc_info *ssc = dtype_priv(cmd->dev);
	struct blk_header_info c, *curr = &c;
	struct blk_header_info e, *eod = &e;
	ssize_t ret;

	fd = cmd->dev->fd;
	*curr = ssc->c_blk;

	dprintf("B4 update     : prev/curr/next"
		" <%" PRId64 "/%" PRId64 "/%" PRId64 "> type: %d,"
		" num: %" PRIx64 ", ondisk sz: %d, about to write %d\n",
		curr->prev, curr->curr, curr->next,
		curr->blk_type, curr->blk_num,
		curr->ondisk_sz, size);

	curr->next = curr->curr + size + SSC_BLK_HDR_SIZE;
	curr->blk_type = type;
	curr->ondisk_sz = size;
	curr->blk_sz = orig_sz;
	eod->prev = curr->curr;
	eod->curr = curr->next;
	eod->next = curr->next;
	eod->ondisk_sz = 0;
	eod->blk_sz = 0;
	eod->blk_type = BLK_EOD;
	eod->blk_num = curr->blk_num + 1;

	memcpy(&ssc->c_blk, eod, sizeof(*eod));

	dprintf("After update  : prev/curr/next <%" PRId64 "/%" PRId64
		"/%" PRId64 "> type: %d, num: %" PRIx64 ", ondisk sz: %d\n",
		curr->prev, curr->curr, curr->next, curr->blk_type,
		curr->blk_num, curr->ondisk_sz);

	dprintf("EOD blk header: prev/curr/next <%" PRId64 "/%" PRId64
		"/%" PRId64 "> type: %d, num: %" PRIx64 ", ondisk sz: %d\n",
		eod->prev, eod->curr, eod->next, eod->blk_type, eod->blk_num,
		eod->ondisk_sz);

	/* Rewrite previous header with updated positioning info */
	ret = ssc_write_blkhdr(fd, curr, curr->curr);
	if (ret) {
		eprintf("Rewrite of blk header failed: %m\n");
		sense_data_build(cmd, MEDIUM_ERROR, ASC_WRITE_ERROR);
		return SAM_STAT_CHECK_CONDITION;
	}
	/* Write new EOD blk header */
	ret = ssc_write_blkhdr(fd, eod, eod->curr);
	if (ret) {
		eprintf("Write of EOD blk header failed: %m\n");
		sense_data_build(cmd, MEDIUM_ERROR, ASC_WRITE_ERROR);
		return SAM_STAT_CHECK_CONDITION;
	}

	/* Write any data */
	if (size) {
		ret = pwrite(fd, data, size,
			     (off_t)curr->curr + SSC_BLK_HDR_SIZE);
		if (ret != size) {
			eprintf("Write of data failed: %m\n");
			sense_data_build(cmd, MEDIUM_ERROR, ASC_WRITE_ERROR);
			return SAM_STAT_CHECK_CONDITION;
		}
	}
	/* Write new EOD blk header */

	fsync(fd);

	return SAM_STAT_GOOD;
}

static int space_filemark_reverse(struct scsi_cmd *cmd, int32_t count)
{
	struct ssc_info *ssc = dtype_priv(cmd->dev);
	struct blk_header_info *h = &ssc->c_blk;

	count *= -1;

again:
	if (!h->prev) {
		sense_data_build(cmd, NO_SENSE, ASC_BOM);
		return SAM_STAT_CHECK_CONDITION;
	}

	if (h->blk_type == BLK_FILEMARK)
		count--;

	if (skip_prev_header(cmd->dev)) {
		sense_data_build(cmd, MEDIUM_ERROR,
				 ASC_MEDIUM_FORMAT_CORRUPT);
		return SAM_STAT_CHECK_CONDITION;
	}

	if (count > 0)
		goto again;

	return SAM_STAT_GOOD;
}

static int space_filemark_forward(struct scsi_cmd *cmd, int32_t count)
{
	struct ssc_info *ssc = dtype_priv(cmd->dev);
	struct blk_header_info *h = &ssc->c_blk;

again:
	if (h->blk_type == BLK_EOD) {
		sense_data_build(cmd, NO_SENSE, ASC_END_OF_DATA);
		return SAM_STAT_CHECK_CONDITION;
	}

	if (h->blk_type == BLK_FILEMARK)
		count--;

	if (skip_next_header(cmd->dev)) {
		sense_data_build(cmd, MEDIUM_ERROR,
				 ASC_MEDIUM_FORMAT_CORRUPT);
		return SAM_STAT_CHECK_CONDITION;
	}

	if (count > 0)
		goto again;

	return SAM_STAT_GOOD;
}

static int space_filemark(struct scsi_cmd *cmd, int32_t count)
{
	struct ssc_info *ssc = dtype_priv(cmd->dev);
	struct blk_header_info *h = &ssc->c_blk;
	int result;

	dprintf("*** space %d filemarks, %" PRIu64 "\n", count, h->curr);

	if (count > 0)
		result = space_filemark_forward(cmd, count);
	else if (count < 0)
		result = space_filemark_reverse(cmd, count);
	else
		result = SAM_STAT_GOOD;

	dprintf("%" PRIu64 "\n", h->curr);

	return result;
}

static int space_blocks(struct scsi_cmd *cmd, int32_t count)
{
	struct ssc_info *ssc = dtype_priv(cmd->dev);
	struct blk_header_info *h = &ssc->c_blk;

	dprintf("*** space %d blocks, %" PRIu64 "\n", count, h->curr);

	while (count != 0) {
		if (count > 0) {
			if (skip_next_header(cmd->dev)) {
				sense_data_build(cmd, MEDIUM_ERROR,
						ASC_MEDIUM_FORMAT_CORRUPT);
				return SAM_STAT_CHECK_CONDITION;
			}
			if (h->blk_type == BLK_EOD) {
				sense_data_build(cmd, NO_SENSE,
						ASC_END_OF_DATA);
				return SAM_STAT_CHECK_CONDITION;
			}
			count--;
		} else {
			if (skip_prev_header(cmd->dev)) {
				sense_data_build(cmd, MEDIUM_ERROR,
						ASC_MEDIUM_FORMAT_CORRUPT);
				return SAM_STAT_CHECK_CONDITION;
			}
			if (h->blk_type == BLK_BOT) {
				/* Can't leave at BOT */
				skip_next_header(cmd->dev);

				sense_data_build(cmd, NO_SENSE, ASC_BOM);
				return SAM_STAT_CHECK_CONDITION;
			}
			count++;
		}
	}
	dprintf("%" PRIu64 "\n", h->curr);
	return SAM_STAT_GOOD;
}

static int resp_var_read(struct scsi_cmd *cmd, uint8_t *buf, uint32_t length,
			 int *transferred)
{
	struct ssc_info *ssc = dtype_priv(cmd->dev);
	struct blk_header_info *h = &ssc->c_blk;
	int ret = 0, result = SAM_STAT_GOOD;

	length = min(length, get_unaligned_be24(&cmd->scb[2]));
	*transferred = 0;

	if (length != h->blk_sz) {
		uint8_t info[4];
		int val = length - h->blk_sz;

		put_unaligned_be32(val, info);

		if (h->blk_type == BLK_EOD)
			sense_data_build(cmd, 0x40 | BLANK_CHECK,
					 NO_ADDITIONAL_SENSE);
		else
			ssc_sense_data_build(cmd, NO_SENSE | 0x20,
					     NO_ADDITIONAL_SENSE,
					     info, sizeof(info));

		if (length > h->blk_sz)
			scsi_set_in_resid_by_actual(cmd, length - h->blk_sz);
		else
			scsi_set_in_resid_by_actual(cmd, 0);

		length = min(length, h->blk_sz);

		result = SAM_STAT_CHECK_CONDITION;

		if (!length)
			goto out;
	}

	ret = pread(cmd->dev->fd, buf, length, h->curr + SSC_BLK_HDR_SIZE);
	if (ret != length) {
		sense_data_build(cmd, MEDIUM_ERROR, ASC_READ_ERROR);
		result = SAM_STAT_CHECK_CONDITION;
		goto out;
	}
	*transferred = length;

	ret = skip_next_header(cmd->dev);
	if (ret) {
		sense_data_build(cmd, MEDIUM_ERROR, ASC_MEDIUM_FORMAT_CORRUPT);
		result = SAM_STAT_CHECK_CONDITION;
	}
out:
	return result;
}

static int resp_fixed_read(struct scsi_cmd *cmd, uint8_t *buf, uint32_t length,
			   int *transferred)
{
	struct ssc_info *ssc = dtype_priv(cmd->dev);
	struct blk_header_info *h = &ssc->c_blk;
	int i, ret, result = SAM_STAT_GOOD;
	int count;
	ssize_t residue;
	int fd;
	uint32_t block_length = ssc_get_block_length(cmd->dev);

	count = get_unaligned_be24(&cmd->scb[2]);
	fd = cmd->dev->fd;
	ret = 0;

	for (i = 0; i < count; i++) {
		if (h->blk_type == BLK_FILEMARK) {
			uint8_t info[4];

			eprintf("Oops - found filemark\n");
			put_unaligned_be32(count - i, info);
			ssc_sense_data_build(cmd, NO_SENSE | SENSE_FILEMARK,
					     ASC_MARK, info, sizeof(info));
			skip_next_header(cmd->dev);
			result = SAM_STAT_CHECK_CONDITION;
			goto out;
		}

		if (block_length != h->blk_sz) {
			eprintf("block size mismatch %d vs %d\n",
				block_length, h->blk_sz);
			sense_data_build(cmd, MEDIUM_ERROR,
						ASC_MEDIUM_FORMAT_CORRUPT);
			result = SAM_STAT_CHECK_CONDITION;
			goto out;
		}

		residue = pread(fd, buf, block_length,
				h->curr + SSC_BLK_HDR_SIZE);
		if (block_length != residue) {
			eprintf("Could only read %d bytes, not %d\n",
					(int)residue, block_length);
			sense_data_build(cmd, MEDIUM_ERROR, ASC_READ_ERROR);
			result = SAM_STAT_CHECK_CONDITION;
			goto out;
		}
		ret += block_length;
		buf += block_length;

		if (skip_next_header(cmd->dev)) {
			eprintf("Could not read next header\n");
			sense_data_build(cmd, MEDIUM_ERROR,
						ASC_MEDIUM_FORMAT_CORRUPT);
			result = SAM_STAT_CHECK_CONDITION;
			goto out;
		}
	}

	*transferred = ret;
out:
	return result;
}

static void tape_rdwr_request(struct scsi_cmd *cmd)
{
	struct ssc_info *ssc = dtype_priv(cmd->dev);
	struct blk_header_info *h = &ssc->c_blk;
	int ret, code;
	uint32_t length, i, transfer_length, residue;
	int result = SAM_STAT_GOOD;
	uint8_t *buf;
	int32_t count;
	int8_t fixed;
	int8_t sti;
	uint32_t block_length = ssc_get_block_length(cmd->dev);

	ret = 0;
	length = 0;
	i = 0;
	transfer_length = 0;
	residue = 0;
	code = 0;
	ssc = dtype_priv(cmd->dev);

	switch (cmd->scb[0]) {
	case REZERO_UNIT:
		dprintf("**** Rewind ****\n");
		if (resp_rewind(cmd->dev)) {
			sense_data_build(cmd,
				MEDIUM_ERROR, ASC_SEQUENTIAL_POSITION_ERR);
			result = SAM_STAT_CHECK_CONDITION;
		}
		break;

	case WRITE_FILEMARKS:
		ret = get_unaligned_be24(&cmd->scb[2]);
		dprintf("*** Write %d filemark%s ***\n", ret,
			((ret > 1) || (ret < 0)) ? "s" : "");

		for (i = 0; i < ret; i++)
			append_blk(cmd, scsi_get_out_buffer(cmd), 0,
					0, BLK_FILEMARK);

		break;

	case READ_6:
		fixed = cmd->scb[1] & 1;
		sti = cmd->scb[1] & 2;

		if (fixed && sti) {
			sense_data_build(cmd, ILLEGAL_REQUEST,
						ASC_INVALID_FIELD_IN_CDB);
			result = SAM_STAT_CHECK_CONDITION;
			break;
		}

		length = scsi_get_in_length(cmd);
		count = get_unaligned_be24(&cmd->scb[2]);
		buf = scsi_get_in_buffer(cmd);

		dprintf("*** READ_6: length %d, count %d, fixed block %s,"
			" %" PRIu64 " %d\n", length, count,
			(fixed) ? "Yes" : "No", h->curr, sti);
		if (fixed)
			result = resp_fixed_read(cmd, buf, length, &ret);
		else
			result = resp_var_read(cmd, buf, length, &ret);

		eprintf("Executed READ_6, Read %d bytes, %" PRIu64 "\n",
			ret, h->curr);
		break;

	case WRITE_6:
		fixed = cmd->scb[1] & 1;

		buf = scsi_get_out_buffer(cmd);
		count = get_unaligned_be24(&cmd->scb[2]);
		length = scsi_get_out_length(cmd);

		if (!fixed) {
			block_length = length;
			count = 1;
		}

		for (i = 0, ret = 0; i < count; i++) {
			if (append_blk(cmd, buf, block_length,
				       block_length, BLK_UNCOMPRESS_DATA)) {
				sense_data_build(cmd, MEDIUM_ERROR,
						ASC_WRITE_ERROR);
				result = SAM_STAT_CHECK_CONDITION;
				break;
			}
			buf += block_length;
			ret += block_length;
		}

		dprintf("*** WRITE_6 count: %d, length: %d, ret: %d, fixed: %s,"
			" ssc->blk_sz: %d\n",
			count, length, ret, (fixed) ? "Yes" : "No",
			block_length);

		/* Check for end of media */
		if (current_size(cmd) > ssc->mam.max_capacity) {
			sense_data_build(cmd, NO_SENSE|SENSE_EOM,
						NO_ADDITIONAL_SENSE);
			result = SAM_STAT_CHECK_CONDITION;
			break;
		}

		if (ret != length) {
			sense_data_build(cmd, MEDIUM_ERROR, ASC_WRITE_ERROR);
			result = SAM_STAT_CHECK_CONDITION;
		}
		break;

	case SPACE:
		code = cmd->scb[1] & 0xf;
		count = be24_to_2comp(&cmd->scb[2]);

		if (code == 0) {	/* Logical Blocks */
			result = space_blocks(cmd, count);
			break;
		} else if (code == 1) { /* Filemarks */
			result = space_filemark(cmd, count);
			break;
		} else if (code == 3) { /* End of data */
			while (h->blk_type != BLK_EOD)
				if (skip_next_header(cmd->dev)) {
					sense_data_build(cmd, MEDIUM_ERROR,
						ASC_MEDIUM_FORMAT_CORRUPT);
					result = SAM_STAT_CHECK_CONDITION;
					break;
				}
		} else { /* Unsupported */
			sense_data_build(cmd, ILLEGAL_REQUEST,
						ASC_INVALID_FIELD_IN_CDB);
			result = SAM_STAT_CHECK_CONDITION;
		}
		break;

	case READ_POSITION:
	{
		int service_action = cmd->scb[1] & 0x1f;
		uint8_t *data = scsi_get_in_buffer(cmd);
		int len = scsi_get_in_length(cmd);

		dprintf("Size of in_buffer = %d\n", len);
		dprintf("Sizeof(buf): %Zd\n", sizeof(buf));
		dprintf("service action: 0x%02x\n", service_action);

		if (service_action == 0) {	/* Short form - block ID */
			memset(data, 0, 20);
			data[0] = 20;
		} else if (service_action == 1) { /* Short form - vendor uniq */
			memset(data, 0, 20);
			data[0] = 20;
		} else if (service_action == 6) { /* Long form */
			memset(data, 0, 32);
			data[0] = 32;
		} else {
			sense_data_build(cmd, ILLEGAL_REQUEST,
						ASC_INVALID_FIELD_IN_CDB);
			result = SAM_STAT_CHECK_CONDITION;
		}
		break;
	}
	default:
		eprintf("Unknown op code - should never see this\n");
		sense_data_build(cmd, ILLEGAL_REQUEST, ASC_INVALID_OP_CODE);
		result = SAM_STAT_CHECK_CONDITION;
		break;
	}

	dprintf("io done %p %x %d %u\n", cmd, cmd->scb[0], ret, length);

	scsi_set_result(cmd, result);

	if (result != SAM_STAT_GOOD)
		eprintf("io error %p %x %d %d %" PRIu64 ", %m\n",
			cmd, cmd->scb[0], ret, length, cmd->offset);
}

static int bs_ssc_init(struct scsi_lu *lu)
{
	struct bs_thread_info *info = BS_THREAD_I(lu);
	return bs_thread_open(info, tape_rdwr_request, 1);
}

static int bs_ssc_open(struct scsi_lu *lu, char *path, int *fd, uint64_t *size)
{
	struct ssc_info *ssc;
	char *cart = NULL;
	ssize_t rd;
	int ret;
	struct blk_header_info *h;

	ssc = dtype_priv(lu);

	*fd = backed_file_open(path, O_RDWR | O_LARGEFILE, size);
	if (*fd < 0) {
		eprintf("Could not open %s %m\n", path);
		return *fd;
	}
	eprintf("Backing store %s, %d\n", path, *fd);

	if (*size < SSC_BLK_HDR_SIZE + sizeof(struct MAM)) {
		eprintf("backing file too small - not correct media format\n");
		return -1;
	}

	h = &ssc->c_blk;
	/* Can't call 'resp_rewind() at this point as lu data not
	 * setup */
	rd = ssc_read_blkhdr(*fd, h, 0);
	if (rd) {
		eprintf("Failed to read complete blk header: %d %m\n", (int)rd);
		return -1;
	}

	ret = ssc_read_mam_info(*fd, &ssc->mam);
	if (ret) {
		eprintf("Failed to read MAM: %d %m\n", (int)rd);
		return -1;
	}

	rd = ssc_read_blkhdr(*fd, h, h->next);
	if (rd) {
		eprintf("Failed to read complete blk header: %d %m\n", (int)rd);
		return -1;
	}

	switch (ssc->mam.medium_type) {
	case CART_CLEAN:
		cart = "Cleaning cartridge";
		break;
	case CART_DATA:
		cart = "data cartridge";
		break;
	case CART_WORM:
		cart = "WORM cartridge";
		break;
	default:
		cart = "Unknown cartridge type";
		break;
	}

	dprintf("Media size: %d, media type: %s\n", h->blk_sz, cart);
	return 0;
}

static void bs_ssc_exit(struct scsi_lu *lu)
{
	struct bs_thread_info *info = BS_THREAD_I(lu);
	bs_thread_close(info);
}

static void bs_ssc_close(struct scsi_lu *lu)
{
	struct ssc_info *ssc;
	ssc = dtype_priv(lu);
	dprintf("##### Close #####\n");
	close(lu->fd);
}

static int bs_ssc_cmd_done(struct scsi_cmd *cmd)
{
	return 0;
}

static struct backingstore_template ssc_bst = {
	.bs_name		= "ssc",
	.bs_datasize		= sizeof(struct bs_thread_info),
	.bs_init		= bs_ssc_init,
	.bs_exit		= bs_ssc_exit,
	.bs_open		= bs_ssc_open,
	.bs_close		= bs_ssc_close,
	.bs_cmd_submit		= bs_thread_cmd_submit,
	.bs_cmd_done		= bs_ssc_cmd_done,
};

__attribute__((constructor)) static void bs_ssc_constructor(void)
{
	register_backingstore_template(&ssc_bst);
}
