/*
 * Copyright (c) 2020 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/settings/settings.h>
#include "dfu_slot.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <zephyr/sys/util.h>
#include <common/bt_str.h>

#define LOG_LEVEL CONFIG_BT_MESH_DFU_LOG_LEVEL
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(bt_mesh_dfu_slot);

#define SLOT_ENTRY_BUFLEN 25

#define DFU_SLOT_SETTINGS_PATH "bt/mesh-dfu/slot"

#define HEADER_SIZE offsetof(struct slot, slot.fwid)

#define PROP_HEADER "h"
#define PROP_FWID "id"
#define PROP_METADATA "m"

static sys_slist_t list;

static struct slot {
	uint32_t idx;
	struct bt_mesh_dfu_slot slot;
	sys_snode_t n;
} slots[CONFIG_BT_MESH_DFU_SLOT_CNT];

static uint32_t slot_index;

static char *slot_entry_encode(uint16_t idx, char buf[SLOT_ENTRY_BUFLEN],
			       const char *property)
{
	snprintf(buf, SLOT_ENTRY_BUFLEN, DFU_SLOT_SETTINGS_PATH "/%x/%s", idx,
		 property);

	return buf;
}

static bool slot_eq(const struct bt_mesh_dfu_slot *slot,
		    const uint8_t *fwid, size_t fwid_len)
{
	return (slot->fwid_len == fwid_len) &&
	       !memcmp(fwid, slot->fwid, fwid_len);
}

static bool is_slot_committed(struct slot *slot_to_check)
{
	struct slot *s;

	SYS_SLIST_FOR_EACH_CONTAINER(&list, s, n) {
		if (s == slot_to_check) {
			return true;
		}
	}

	return false;
}

static int slot_store(const struct slot *slot_to_store)
{
	uint16_t idx = ARRAY_INDEX(slots, slot_to_store);
	char buf[SLOT_ENTRY_BUFLEN];
	int err;

	err = settings_save_one(slot_entry_encode(idx, buf, PROP_HEADER),
				slot_to_store, HEADER_SIZE);
	if (err) {
		return err;
	}

	err = settings_save_one(slot_entry_encode(idx, buf, PROP_FWID),
				slot_to_store->slot.fwid, slot_to_store->slot.fwid_len);
	if (err) {
		return err;
	}

	err = settings_save_one(slot_entry_encode(idx, buf,
						  PROP_METADATA),
				slot_to_store->slot.metadata, slot_to_store->slot.metadata_len);

	return err;
}

static void slot_erase(struct slot *slot_to_erase)
{
	uint16_t idx = ARRAY_INDEX(slots, slot_to_erase);
	char buf[SLOT_ENTRY_BUFLEN];

	(void)settings_delete(slot_entry_encode(idx, buf, PROP_HEADER));
	(void)settings_delete(slot_entry_encode(idx, buf, PROP_FWID));
	(void)settings_delete(slot_entry_encode(idx, buf, PROP_METADATA));
}

static void slot_index_defrag(void)
{
	slot_index = 0;
	struct slot *s;

	SYS_SLIST_FOR_EACH_CONTAINER(&list, s, n) {
		s->idx = ++slot_index;
		slot_store(s);
	}
}

int bt_mesh_dfu_slot_count(void)
{
	int cnt = 0;
	sys_snode_t *n;

	SYS_SLIST_FOR_EACH_NODE(&list, n) {
		cnt++;
	}

	return cnt;
}

struct bt_mesh_dfu_slot *bt_mesh_dfu_slot_reserve(void)
{
	struct slot *slot = NULL;

	for (int i = 0; i < ARRAY_SIZE(slots); ++i) {
		if (slots[i].idx == 0) {
			slot = &slots[i];
			break;
		}
	}

	if (!slot) {
		LOG_WRN("No space");
		return NULL;
	}

	if (slot_index == UINT32_MAX) {
		slot_index_defrag();
	}

	slot->slot.fwid_len = 0;
	slot->slot.metadata_len = 0;
	slot->slot.size = 0;
	slot->idx = ++slot_index;

	LOG_DBG("Reserved slot #%u", slot - &slots[0]);

	return &slot->slot;
}

int bt_mesh_dfu_slot_info_set(struct bt_mesh_dfu_slot *dfu_slot, size_t size,
			      const uint8_t *metadata, size_t metadata_len)
{
	struct slot *slot = CONTAINER_OF(dfu_slot, struct slot, slot);

	if (metadata_len > CONFIG_BT_MESH_DFU_METADATA_MAXLEN) {
		return -EFBIG;
	}

	if (slot->idx == 0 || is_slot_committed(slot)) {
		return -EINVAL;
	}

	slot->slot.size = size;
	slot->slot.metadata_len = metadata_len;
	memcpy(slot->slot.metadata, metadata, metadata_len);
	return 0;
}

int bt_mesh_dfu_slot_fwid_set(struct bt_mesh_dfu_slot *dfu_slot,
			      const uint8_t *fwid, size_t fwid_len)
{
	struct slot *slot = CONTAINER_OF(dfu_slot, struct slot, slot);

	if (fwid_len > CONFIG_BT_MESH_DFU_FWID_MAXLEN) {
		return -EFBIG;
	}

	if (slot->idx == 0 || is_slot_committed(slot)) {
		return -EINVAL;
	}

	for (int i = 0; i < ARRAY_SIZE(slots); i++) {
		if (slots[i].idx != 0 &&
		    slot_eq(&slots[i].slot, fwid, fwid_len)) {
			return is_slot_committed(&slots[i]) ?
				-EEXIST : -EALREADY;
		}
	}

	slot->slot.fwid_len = fwid_len;
	memcpy(slot->slot.fwid, fwid, fwid_len);
	return 0;
}

int bt_mesh_dfu_slot_commit(struct bt_mesh_dfu_slot *dfu_slot)
{
	int err;
	struct slot *slot = CONTAINER_OF(dfu_slot, struct slot, slot);

	if (slot->idx == 0 ||
	    slot->slot.fwid_len == 0 ||
	    slot->slot.size == 0 ||
	    is_slot_committed(slot)) {
		return -EINVAL;
	}

	err = slot_store(slot);
	if (err) {
		LOG_WRN("Store failed (err: %d)", err);
		return err;
	}

	sys_slist_append(&list, &slot->n);

	LOG_DBG("Stored slot #%u: %s", ARRAY_INDEX(slots, slot),
		bt_hex(slot->slot.fwid, slot->slot.fwid_len));
	return 0;
}

void bt_mesh_dfu_slot_release(const struct bt_mesh_dfu_slot *dfu_slot)
{
	struct slot *slot = CONTAINER_OF(dfu_slot, struct slot, slot);

	if (is_slot_committed(slot)) {
		return;
	}

	slot->idx = 0;
}

int bt_mesh_dfu_slot_del(const struct bt_mesh_dfu_slot *dfu_slot)
{
	struct slot *slot = CONTAINER_OF(dfu_slot, struct slot, slot);

	if (!sys_slist_find_and_remove(&list, &slot->n)) {
		return -EINVAL;
	}

	int idx = ARRAY_INDEX(slots, slot);

	LOG_DBG("%u", idx);

	slot_erase(slot);
	slot->idx = 0;

	return 0;
}

void bt_mesh_dfu_slot_del_all(void)
{
	struct slot *s;
	SYS_SLIST_FOR_EACH_CONTAINER(&list, s, n) {
		slot_erase(s);
		s->idx = 0;
	}

	sys_slist_init(&list);
}

const struct bt_mesh_dfu_slot *bt_mesh_dfu_slot_at(uint16_t img_idx)
{
	struct slot *s;

	SYS_SLIST_FOR_EACH_CONTAINER(&list, s, n) {
		if (!img_idx--) {
			return &s->slot;
		}
	}

	return NULL;
}

int bt_mesh_dfu_slot_get(const uint8_t *fwid, size_t fwid_len, struct bt_mesh_dfu_slot **slot)
{
	struct slot *s;
	int idx = 0;

	SYS_SLIST_FOR_EACH_CONTAINER(&list, s, n) {
		if (slot_eq(&s->slot, fwid, fwid_len)) {
			if (slot) {
				*slot = &s->slot;
			}
			return idx;
		}
		idx++;
	}

	return -ENOENT;
}

int bt_mesh_dfu_slot_img_idx_get(const struct bt_mesh_dfu_slot *dfu_slot)
{
	struct slot *s;
	int idx = 0;

	SYS_SLIST_FOR_EACH_CONTAINER(&list, s, n) {
		if (&s->slot == dfu_slot) {
			return idx;
		}
		idx++;
	}

	return -ENOENT;
}

size_t bt_mesh_dfu_slot_foreach(bt_mesh_dfu_slot_cb_t cb, void *user_data)
{
	enum bt_mesh_dfu_iter iter;
	size_t cnt = 0;
	struct slot *s;

	SYS_SLIST_FOR_EACH_CONTAINER(&list, s, n) {
		cnt++;

		if (!cb) {
			continue;
		}

		iter = cb(&s->slot, user_data);
		if (iter != BT_MESH_DFU_ITER_CONTINUE) {
			break;
		}
	}

	return cnt;
}

static int slot_data_load(const char *key, size_t len_rd,
			  settings_read_cb read_cb, void *cb_arg)
{
	const char *prop;
	size_t len;
	uint16_t idx;

	idx = strtol(key, NULL, 16);

	if (idx >= ARRAY_SIZE(slots)) {
		return 0;
	}

	len = settings_name_next(key, &prop);

	if (!strncmp(prop, PROP_HEADER, len)) {
		if (read_cb(cb_arg, &slots[idx], HEADER_SIZE) > 0) {
			struct slot *s, *prev = NULL;

			SYS_SLIST_FOR_EACH_CONTAINER(&list, s, n) {
				if (s->idx > slots[idx].idx) {
					break;
				}

				prev = s;
			}

			if (prev == NULL) {
				sys_slist_prepend(&list, &slots[idx].n);
			} else {
				sys_slist_insert(&list, &prev->n, &slots[idx].n);
			}

			if (slots[idx].idx >= slot_index) {
				slot_index = slots[idx].idx + 1;
			}
		}
		return 0;
	}

	if (!strncmp(prop, PROP_FWID, len)) {
		if (read_cb(cb_arg, &slots[idx].slot.fwid,
			    sizeof(slots[idx].slot.fwid)) < 0) {
			slots[idx].idx = 0;
			sys_slist_find_and_remove(&list, &slots[idx].n);
			return 0;
		}

		slots[idx].slot.fwid_len = len_rd;
		return 0;
	}

	if (!strncmp(prop, PROP_METADATA, len)) {
		if (read_cb(cb_arg, &slots[idx].slot.metadata,
			    sizeof(slots[idx].slot.metadata)) < 0) {
			slots[idx].idx = 0;
			sys_slist_find_and_remove(&list, &slots[idx].n);
			return 0;
		}

		slots[idx].slot.metadata_len = len_rd;
		return 0;
	}

	return 0;
}

SETTINGS_STATIC_HANDLER_DEFINE(bt_mesh_dfu_slots, DFU_SLOT_SETTINGS_PATH, NULL,
			       slot_data_load, NULL, NULL);