#include <limits.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include <bitops.h>
#include <flash.h>
#include <ftl.h>
#include <macros.h>

#include "gc.h"
#include "map.h"

int ftl_is_mapped(struct ftl_map *map, uint32_t va)
{
	if (trace_path(map, NULL, NULL, va) < 0)
		return 0;

	return 1;
}

size_t ftl_read(struct ftl_map *map, void *data, size_t len, uint32_t va)
{
	int ret;
	uint32_t offset, page;

	if (!data)
		return 0;

	if (ftl_sync(map) < 0)
		return 0;

	offset = va & ((1 << map->log2_page_size) - 1);
	va >>= map->log2_page_size;
	len = min(len, (1 << map->log2_page_size) - offset);

	if ((ret = trace_path(map, NULL, &page, va)) < 0) {
		memset(data, 0, len);
		return len;
	}

	return flash_read(map->dev, (page << map->log2_page_size) + offset, data,
		len);
}

static int ftl_start_transaction(struct ftl_map *map, uint32_t va)
{
	uint32_t page;
	int ret;

	if ((map->outstanding.flags & FTL_PRESENT) && map->outstanding.va == va)
		return 0;

	if (ftl_sync(map) < 0)
		return -1;

	if ((ret = trace_path(map, NULL, &page, va)) < 0 && ret != -ERR_NOT_FOUND)
		return -1;

	if (prepare_head(map) < 0)
		return -1;

	map->outstanding.flags |= FTL_PRESENT;
	map->outstanding.va = va;
	map->outstanding.page = page;

	if (ret == -ERR_NOT_FOUND) {
		map->outstanding.flags |= FTL_NO_MAPPING;
		++map->nused_pages;
	}

	map->offset = 0;

	return 0;
}

static int ftl_seek(struct ftl_map *map, uint32_t va)
{
	size_t len;
	uint32_t offset, dst, src;

	if (va >= ftl_get_capacity(map))
		return -1;

	offset = va & ((1 << map->log2_page_size) - 1);
	va >>= map->log2_page_size;

	if (ftl_start_transaction(map, va) < 0)
		return -1;

	if (offset < map->offset)
		return -1;

	if (offset == map->offset)
		return 0;

	dst = map->head << map->log2_page_size;
	src = map->outstanding.page << map->log2_page_size;
	len = offset - map->offset;

	if (map->outstanding.flags & FTL_NO_MAPPING)
		flash_write0(map->dev, dst, len);
	else
		flash_copy(map->dev, dst, src, len);

	map->offset += len;

	return 0;
}

size_t ftl_write(struct ftl_map *map, uint32_t va, const void *udata,
	size_t len)
{
	uint32_t dst;

	if (ftl_seek(map, va) < 0)
		return 0;

	dst = (map->head << map->log2_page_size) + map->offset;
	len = min(len, (1 << map->log2_page_size) - map->offset);

	if ((len = flash_write(map->dev, dst, udata, len)) == 0)
		return 0;

	map->offset += len;

	return len;
}

int ftl_sync(struct ftl_map *map)
{
	struct ftl_page_desc page_desc;
	size_t len;
	int ret;
	uint32_t dst, src;

	if (!(map->outstanding.flags & FTL_PRESENT))
		return 0;

	dst = (map->head << map->log2_page_size) + map->offset;
	src = (map->outstanding.page << map->log2_page_size) + map->offset;
	len = (1 << map->log2_page_size) - map->offset;

	if (map->outstanding.flags & FTL_NO_MAPPING)
		flash_write0(map->dev, dst, len);
	else
		flash_copy(map->dev, dst, src, len);

	page_desc.nused_pages = map->nused_pages;

	if ((ret = trace_path(map, &page_desc, NULL, map->outstanding.va)) < 0 &&
		ret != -ERR_NOT_FOUND)
		return -1;

	if (write_page_desc(map, &page_desc) < 0)
		return -1;

	map->offset = 0;
	map->outstanding.flags = 0;

	return 0;
}

int ftl_trim(struct ftl_map *map, uint32_t va)
{
	struct ftl_page_desc page_desc, alt_page_desc;
	size_t level, i;
	uint32_t alt_page, page;
	int ret;

	if (ftl_sync(map) < 0)
		return -1;

	if ((ret = trace_path(map, &page_desc, &page, va)) < 0) {
		if (ret == -ERR_NOT_FOUND)
			return 0;

		return ret;
	}

	for (i = 0; i < 32; ++i) {
		level = 32 - i - 1;

		if ((alt_page = page_desc.subtrees[level]) != UINT32_MAX)
			break;
	}

	if (i == 32) {
		map->root = UINT32_MAX;
		map->nused_pages = 0;

		memset(&page_desc, 0xff, sizeof page_desc);
		page_desc.nused_pages = 0;

		return write_upage(map, NULL, &page_desc);
	}

	if (read_page_desc(map, &alt_page_desc, alt_page) < 0)
		return -1;

	--map->nused_pages;

	page_desc.va = alt_page_desc.va;
	page_desc.nused_pages = map->nused_pages;
	page_desc.subtrees[level] = UINT32_MAX;

	for (i = level + 1; i < 32; ++i) {
		page_desc.subtrees[i] = alt_page_desc.subtrees[i];
	}

	if (flash_copy(map->dev, map->head << map->log2_page_size,
		alt_page << map->log2_page_size, 1 << map->log2_page_size) == 0)
		return -1;

	if (prepare_head(map) < 0)
		return -1;

	return write_page_desc(map, &page_desc);
}

/* Returns the amount of used pages with a unique virtual address multiplied by
 * the page size as the size of used space on the device.
 */
uint32_t ftl_get_size(const struct ftl_map *map)
{
	return map->nused_pages << map->log2_page_size;
}

/* The capacity of the device is the total amount of user pages minus a block
 * worth of user pages for garbage collection.
 */
uint32_t ftl_get_capacity(const struct ftl_map *map)
{
	return ((map->nblocks - 1) << map->log2_block_size) -
		((map->nblocks - 1) << map->log2_page_size);
}