/*
 * Copyright (C) 2018 Red Hat, Inc. All rights reserved.
 *
 * This file is part of LVM2.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License v.2.
 *
 * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#define _GNU_SOURCE

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

#include "bcache.h"
#include "framework.h"
#include "units.h"

//----------------------------------------------------------------

#define T_BLOCK_SIZE 4096
#define NR_BLOCKS 64
#define INIT_PATTERN 123

struct fixture {
	int fd;
	char fname[32];
	struct bcache *cache;
};

static inline uint8_t _pattern_at(uint8_t pat, uint8_t byte)
{
	return pat + byte;
}

static uint64_t byte(block_address b, uint64_t offset)
{
	return b * T_BLOCK_SIZE + offset;
}

static void *_fix_init(void)
{
        uint8_t buffer[T_BLOCK_SIZE];
        struct io_engine *engine;
        struct fixture *f = malloc(sizeof(*f));
        unsigned b, i;

        T_ASSERT(f);

        snprintf(f->fname, sizeof(f->fname), "unit-test-XXXXXX");
	f->fd = mkostemp(f->fname, O_RDWR | O_CREAT | O_EXCL);
	T_ASSERT(f->fd >= 0);

	for (b = 0; b < NR_BLOCKS; b++) {
        	for (i = 0; i < sizeof(buffer); i++)
                	buffer[i] = _pattern_at(INIT_PATTERN, byte(b, i));
		T_ASSERT(write(f->fd, buffer, T_BLOCK_SIZE) > 0);
	}
	close(f->fd);

	// reopen with O_DIRECT
	f->fd = open(f->fname, O_RDWR | O_DIRECT);
	T_ASSERT(f->fd >= 0);

	engine = create_async_io_engine();
	T_ASSERT(engine);

	f->cache = bcache_create(T_BLOCK_SIZE / 512, NR_BLOCKS, engine);
	T_ASSERT(f->cache);

        return f;
}

static void _fix_exit(void *fixture)
{
        struct fixture *f = fixture;

	bcache_destroy(f->cache);
	close(f->fd);
	unlink(f->fname);
        free(f);
}

//----------------------------------------------------------------

static void _verify_bytes(struct block *b, uint64_t base,
                          uint64_t offset, uint64_t len, uint8_t pat)
{
	unsigned i;

	for (i = 0; i < len; i++)
		T_ASSERT_EQUAL(((uint8_t *) b->data)[offset + i], _pattern_at(pat, base + offset + i));
}

static void _zero_bytes(struct block *b, uint64_t offset, uint64_t len)
{
	memset(((uint8_t *) b->data) + offset, 0, len);
}

static uint64_t _min(uint64_t lhs, uint64_t rhs)
{
	return rhs < lhs ? rhs : lhs;
}

static void _verify(struct fixture *f, uint64_t byte_b, uint64_t byte_e, uint8_t pat)
{
        int err;
	struct block *b;
	block_address bb = byte_b / T_BLOCK_SIZE;
	block_address be = (byte_e + T_BLOCK_SIZE - 1) / T_BLOCK_SIZE;
	uint64_t offset = byte_b % T_BLOCK_SIZE;
	uint64_t blen, len = byte_e - byte_b;

	// Verify via bcache_read_bytes
	{
        	unsigned i;
        	size_t len2 = byte_e - byte_b;
		uint8_t *buffer = malloc(len2);
		T_ASSERT(bcache_read_bytes(f->cache, f->fd, byte_b, len2, buffer));
		for (i = 0; i < len; i++)
        		T_ASSERT_EQUAL(buffer[i], _pattern_at(pat, byte_b + i));
	}

	// Verify again, driving bcache directly
	for (; bb != be; bb++) {
        	T_ASSERT(bcache_get(f->cache, f->fd, bb, 0, &b, &err));

		blen = _min(T_BLOCK_SIZE - offset, len);
        	_verify_bytes(b, bb * T_BLOCK_SIZE, offset, blen, pat);

        	offset = 0;
        	len -= blen;

        	bcache_put(b);
	}
}

static void _verify_zeroes(struct fixture *f, uint64_t byte_b, uint64_t byte_e)
{
        int err;
        unsigned i;
	struct block *b;
	block_address bb = byte_b / T_BLOCK_SIZE;
	block_address be = (byte_e + T_BLOCK_SIZE - 1) / T_BLOCK_SIZE;
	uint64_t offset = byte_b % T_BLOCK_SIZE;
	uint64_t blen, len = byte_e - byte_b;

	for (; bb != be; bb++) {
        	T_ASSERT(bcache_get(f->cache, f->fd, bb, 0, &b, &err));

		blen = _min(T_BLOCK_SIZE - offset, len);
		for (i = 0; i < blen; i++)
        		T_ASSERT(((uint8_t *) b->data)[offset + i] == 0);

        	offset = 0;
        	len -= blen;

        	bcache_put(b);
	}
}

static void _do_write(struct fixture *f, uint64_t byte_b, uint64_t byte_e, uint8_t pat)
{
        unsigned i;
        size_t len = byte_e - byte_b;
        uint8_t *buffer = malloc(len);
        T_ASSERT(buffer);

        for (i = 0; i < len; i++)
		buffer[i] = _pattern_at(pat, byte_b + i);

        T_ASSERT(bcache_write_bytes(f->cache, f->fd, byte_b, i, buffer));
	free(buffer);
}

static void _do_zero(struct fixture *f, uint64_t byte_b, uint64_t byte_e)
{
        int err;
	struct block *b;
	block_address bb = byte_b / T_BLOCK_SIZE;
	block_address be = (byte_e + T_BLOCK_SIZE - 1) / T_BLOCK_SIZE;
	uint64_t offset = byte_b % T_BLOCK_SIZE;
	uint64_t blen, len = byte_e - byte_b;

	for (; bb != be; bb++) {
        	T_ASSERT(bcache_get(f->cache, f->fd, bb, GF_DIRTY, &b, &err));

		blen = _min(T_BLOCK_SIZE - offset, len);
		_zero_bytes(b, offset, blen);

        	offset = 0;
        	len -= blen;

        	bcache_put(b);
	}
}

static void _reopen(struct fixture *f)
{
        struct io_engine *engine;

	bcache_destroy(f->cache);
	engine = create_async_io_engine();
	T_ASSERT(engine);

	f->cache = bcache_create(T_BLOCK_SIZE / 512, NR_BLOCKS, engine);
	T_ASSERT(f->cache);
}

//----------------------------------------------------------------

static uint8_t _random_pattern(void)
{
	return random();
}

static uint64_t _max_byte(void)
{
        return T_BLOCK_SIZE * NR_BLOCKS;
}

static void _rwv_cycle(struct fixture *f, uint64_t b, uint64_t e)
{
	uint8_t pat = _random_pattern();

	_verify(f, b, e, INIT_PATTERN);
	_do_write(f, b, e, pat); 
	_reopen(f);
	_verify(f, b < 128 ? 0 : b - 128, b, INIT_PATTERN);
	_verify(f, b, e, pat);
	_verify(f, e, _min(e + 128, _max_byte()), INIT_PATTERN);
}

static void _test_rw_first_block(void *fixture)
{
	_rwv_cycle(fixture, byte(0, 0), byte(0, T_BLOCK_SIZE));
}

static void _test_rw_last_block(void *fixture)
{
        uint64_t last_block = NR_BLOCKS - 1;
	_rwv_cycle(fixture, byte(last_block, 0),
                   byte(last_block, T_BLOCK_SIZE)); 
}

static void _test_rw_several_whole_blocks(void *fixture)
{
        _rwv_cycle(fixture, byte(5, 0), byte(10, 0));
}

static void _test_rw_within_single_block(void *fixture)
{
        _rwv_cycle(fixture, byte(7, 3), byte(7, T_BLOCK_SIZE / 2));
}

static void _test_rw_cross_one_boundary(void *fixture)
{
        _rwv_cycle(fixture, byte(13, 43), byte(14, 43));
}

static void _test_rw_many_boundaries(void *fixture)
{
        _rwv_cycle(fixture, byte(13, 13), byte(23, 13));
}

//----------------------------------------------------------------

static void _zero_cycle(struct fixture *f, uint64_t b, uint64_t e)
{
	_verify(f, b, e, INIT_PATTERN);
	_do_zero(f, b, e); 
	_reopen(f);
	_verify(f, b < 128 ? 0 : b - 128, b, INIT_PATTERN);
	_verify_zeroes(f, b, e);
	_verify(f, e, _min(e + 128, _max_byte()), INIT_PATTERN);
}

static void _test_zero_first_block(void *fixture)
{
	_zero_cycle(fixture, byte(0, 0), byte(0, T_BLOCK_SIZE));
}

static void _test_zero_last_block(void *fixture)
{
        uint64_t last_block = NR_BLOCKS - 1;
	_zero_cycle(fixture, byte(last_block, 0), byte(last_block, T_BLOCK_SIZE)); 
}

static void _test_zero_several_whole_blocks(void *fixture)
{
        _zero_cycle(fixture, byte(5, 0), byte(10, 0));
}

static void _test_zero_within_single_block(void *fixture)
{
        _zero_cycle(fixture, byte(7, 3), byte(7, T_BLOCK_SIZE / 2));
}

static void _test_zero_cross_one_boundary(void *fixture)
{
        _zero_cycle(fixture, byte(13, 43), byte(14, 43));
}

static void _test_zero_many_boundaries(void *fixture)
{
        _zero_cycle(fixture, byte(13, 13), byte(23, 13));
}

//----------------------------------------------------------------

#define T(path, desc, fn) register_test(ts, "/base/device/bcache/utils/" path, desc, fn)

static struct test_suite *_tests(void)
{
        struct test_suite *ts = test_suite_create(_fix_init, _fix_exit);
        if (!ts) {
                fprintf(stderr, "out of memory\n");
                exit(1);
        }

        T("rw-first-block", "read/write/verify the first block", _test_rw_first_block);
        T("rw-last-block", "read/write/verify the last block", _test_rw_last_block);
        T("rw-several-blocks", "read/write/verify several whole blocks", _test_rw_several_whole_blocks);
        T("rw-within-single-block", "read/write/verify within single block", _test_rw_within_single_block);
        T("rw-cross-one-boundary", "read/write/verify across one boundary", _test_rw_cross_one_boundary);
        T("rw-many-boundaries", "read/write/verify many boundaries", _test_rw_many_boundaries);

        T("zero-first-block", "zero the first block", _test_zero_first_block);
        T("zero-last-block", "zero the last block", _test_zero_last_block);
        T("zero-several-blocks", "zero several whole blocks", _test_zero_several_whole_blocks);
        T("zero-within-single-block", "zero within single block", _test_zero_within_single_block);
        T("zero-cross-one-boundary", "zero across one boundary", _test_zero_cross_one_boundary);
        T("zero-many-boundaries", "zero many boundaries", _test_zero_many_boundaries);

        return ts;
}

void bcache_utils_tests(struct dm_list *all_tests)
{
	dm_list_add(all_tests, &_tests()->list);
}