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

#include <zephyr/types.h>
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include <sys/printk.h>
#include <sys/byteorder.h>
#include <zephyr.h>

#include <bluetooth/gatt.h>
#include <bluetooth/services/ots.h>
#include "ots_internal.h"
#include "ots_obj_manager_internal.h"

#include <logging/log.h>

LOG_MODULE_DECLARE(bt_ots, CONFIG_BT_OTS_LOG_LEVEL);

#define OLCP_PROC_TYPE_SIZE	1
#define OLCP_RES_MAX_SIZE	7

static enum bt_gatt_ots_olcp_res_code obj_manager_to_olcp_err_map(int err)
{
	switch (-err) {
	case EINVAL:
		return BT_GATT_OTS_OLCP_RES_OBJECT_ID_NOT_FOUND;
	case ENFILE:
		return BT_GATT_OTS_OLCP_RES_OUT_OF_BONDS;
	case ENOENT:
	default:
		return BT_GATT_OTS_OLCP_RES_NO_OBJECT;
	}
}

static enum bt_gatt_ots_olcp_res_code olcp_first_proc_execute(
	struct bt_ots *ots)
{
	int err;
	struct bt_gatt_ots_object *first_obj;

	err = bt_gatt_ots_obj_manager_first_obj_get(ots->obj_manager,
						    &first_obj);
	if (err) {
		return obj_manager_to_olcp_err_map(err);
	}

	ots->cur_obj = first_obj;

	return BT_GATT_OTS_OLCP_RES_SUCCESS;
}

static enum bt_gatt_ots_olcp_res_code olcp_last_proc_execute(
	struct bt_ots *ots)
{
	int err;
	struct bt_gatt_ots_object *last_obj;

	err = bt_gatt_ots_obj_manager_last_obj_get(ots->obj_manager,
						   &last_obj);
	if (err) {
		return obj_manager_to_olcp_err_map(err);
	}

	ots->cur_obj = last_obj;

	return BT_GATT_OTS_OLCP_RES_SUCCESS;
}

static enum bt_gatt_ots_olcp_res_code olcp_prev_proc_execute(
	struct bt_ots *ots)
{
	int err;
	struct bt_gatt_ots_object *prev_obj;

	if (!ots->cur_obj) {
		return BT_GATT_OTS_OLCP_RES_OPERATION_FAILED;
	}
	err = bt_gatt_ots_obj_manager_prev_obj_get(ots->obj_manager,
						   ots->cur_obj,
						   &prev_obj);
	if (err) {
		return obj_manager_to_olcp_err_map(err);
	}

	ots->cur_obj = prev_obj;

	return BT_GATT_OTS_OLCP_RES_SUCCESS;
}

static enum bt_gatt_ots_olcp_res_code olcp_next_proc_execute(
	struct bt_ots *ots)
{
	int err;
	struct bt_gatt_ots_object *next_obj;

	if (!ots->cur_obj) {
		return BT_GATT_OTS_OLCP_RES_OPERATION_FAILED;
	}
	err = bt_gatt_ots_obj_manager_next_obj_get(ots->obj_manager,
						   ots->cur_obj,
						   &next_obj);
	if (err) {
		return obj_manager_to_olcp_err_map(err);
	}

	ots->cur_obj = next_obj;

	return BT_GATT_OTS_OLCP_RES_SUCCESS;
}

static enum bt_gatt_ots_olcp_res_code olcp_goto_proc_execute(
	struct bt_ots *ots, uint64_t id)
{
	int err;
	struct bt_gatt_ots_object *id_obj;

	err = bt_gatt_ots_obj_manager_obj_get(ots->obj_manager,
					      id,
					      &id_obj);
	if (err) {
		return obj_manager_to_olcp_err_map(err);
	}

	ots->cur_obj = id_obj;

	return BT_GATT_OTS_OLCP_RES_SUCCESS;
}

static enum bt_gatt_ots_olcp_res_code olcp_proc_execute(
	struct bt_ots *ots, struct bt_gatt_ots_olcp_proc *proc)
{
	LOG_DBG("Executing OLCP procedure with 0x%02X Op Code", proc->type);

	switch (proc->type) {
	case BT_GATT_OTS_OLCP_PROC_FIRST:
		return olcp_first_proc_execute(ots);
	case BT_GATT_OTS_OLCP_PROC_LAST:
		return olcp_last_proc_execute(ots);
	case BT_GATT_OTS_OLCP_PROC_PREV:
		return olcp_prev_proc_execute(ots);
	case BT_GATT_OTS_OLCP_PROC_NEXT:
		return olcp_next_proc_execute(ots);
	case BT_GATT_OTS_OLCP_PROC_GOTO:
		return olcp_goto_proc_execute(ots, proc->goto_params.id);
	case BT_GATT_OTS_OLCP_PROC_ORDER:
	case BT_GATT_OTS_OLCP_PROC_REQ_NUM_OBJS:
	case BT_GATT_OTS_OLCP_PROC_CLEAR_MARKING:
	default:
		return BT_GATT_OTS_OLCP_RES_PROC_NOT_SUP;
	}
};

static enum bt_gatt_ots_olcp_res_code olcp_command_decode(
	const uint8_t *buf, struct bt_gatt_ots_olcp_proc *proc)
{
	memset(proc, 0, sizeof(*proc));

	proc->type = *buf++;

	switch (proc->type) {
	case BT_GATT_OTS_OLCP_PROC_FIRST:
	case BT_GATT_OTS_OLCP_PROC_LAST:
	case BT_GATT_OTS_OLCP_PROC_PREV:
	case BT_GATT_OTS_OLCP_PROC_NEXT:
		break;
	case BT_GATT_OTS_OLCP_PROC_GOTO:
		proc->goto_params.id = sys_get_le48(buf);
		break;
	default:
		LOG_WRN("OLCP unsupported procedure type");
		return BT_GATT_OTS_OLCP_RES_PROC_NOT_SUP;
	}

	return BT_GATT_OTS_OLCP_RES_SUCCESS;
}

static bool olcp_command_len_verify(enum bt_gatt_ots_olcp_proc_type type,
				    uint16_t len)
{
	uint16_t ref_len = OLCP_PROC_TYPE_SIZE;

	switch (type) {
	case BT_GATT_OTS_OLCP_PROC_FIRST:
	case BT_GATT_OTS_OLCP_PROC_LAST:
	case BT_GATT_OTS_OLCP_PROC_PREV:
	case BT_GATT_OTS_OLCP_PROC_NEXT:
	case BT_GATT_OTS_OLCP_PROC_REQ_NUM_OBJS:
	case BT_GATT_OTS_OLCP_PROC_CLEAR_MARKING:
		break;
	case BT_GATT_OTS_OLCP_PROC_GOTO:
		ref_len += BT_OTS_OBJ_ID_SIZE;
		break;
	case BT_GATT_OTS_OLCP_PROC_ORDER:
		ref_len += sizeof(uint8_t);
		break;
	default:
		return true;
	}

	return (len == ref_len);
}

static void olcp_ind_cb(struct bt_conn *conn,
		const struct bt_gatt_attr *attr,
		uint8_t err)
{
	LOG_DBG("Received OLCP Indication ACK with status: 0x%04X", err);
}

static int olcp_ind_send(const struct bt_gatt_attr *olcp_attr,
			 enum bt_gatt_ots_olcp_proc_type req_op_code,
			 enum bt_gatt_ots_olcp_res_code olcp_status)
{
	uint8_t olcp_res[OLCP_RES_MAX_SIZE];
	uint16_t olcp_res_len = 0;
	struct bt_ots *ots = (struct bt_ots *) olcp_attr->user_data;

	/* Encode OLCP Response */
	olcp_res[olcp_res_len++] = BT_GATT_OTS_OLCP_PROC_RESP;
	olcp_res[olcp_res_len++] = req_op_code;
	olcp_res[olcp_res_len++] = olcp_status;

	/* Prepare indication parameters */
	memset(&ots->olcp_ind.params, 0, sizeof(ots->olcp_ind.params));
	memcpy(&ots->olcp_ind.attr, olcp_attr, sizeof(ots->olcp_ind.attr));
	ots->olcp_ind.params.attr = olcp_attr;
	ots->olcp_ind.params.func = olcp_ind_cb;
	ots->olcp_ind.params.data = olcp_res;
	ots->olcp_ind.params.len  = olcp_res_len;

	LOG_DBG("Sending OLCP indication");

	return bt_gatt_indicate(NULL, &ots->olcp_ind.params);
}

ssize_t bt_gatt_ots_olcp_write(struct bt_conn *conn,
				   const struct bt_gatt_attr *attr,
				   const void *buf, uint16_t len,
				   uint16_t offset, uint8_t flags)
{
	struct bt_gatt_ots_object *old_obj;
	enum bt_gatt_ots_olcp_res_code olcp_status;
	struct bt_gatt_ots_olcp_proc olcp_proc;
	struct bt_ots *ots = (struct bt_ots *) attr->user_data;

	LOG_DBG("Object List Control Point GATT Write Operation");

	if (!ots->olcp_ind.is_enabled) {
		LOG_WRN("OLCP indications not enabled");
		return BT_GATT_ERR(BT_ATT_ERR_CCC_IMPROPER_CONF);
	}

	if (offset != 0) {
		LOG_ERR("Invalid offset of OLCP Write Request");
		return BT_GATT_ERR(BT_ATT_ERR_INVALID_OFFSET);
	}

	olcp_status = olcp_command_decode(buf, &olcp_proc);

	if (!olcp_command_len_verify(olcp_proc.type, len)) {
		LOG_ERR("Invalid length of OLCP Write Request for 0x%02X "
			"Op Code", olcp_proc.type);
		return BT_GATT_ERR(BT_ATT_ERR_INVALID_ATTRIBUTE_LEN);
	}

	old_obj = ots->cur_obj;
	if (olcp_status == BT_GATT_OTS_OLCP_RES_SUCCESS) {
		olcp_status = olcp_proc_execute(ots, &olcp_proc);
	}

	if (olcp_status != BT_GATT_OTS_OLCP_RES_SUCCESS) {
		LOG_WRN("OLCP Write error status: 0x%02X", olcp_status);
	} else if (old_obj != ots->cur_obj) {
		char id[BT_OTS_OBJ_ID_STR_LEN];

		bt_ots_obj_id_to_str(ots->cur_obj->id, id,
					      sizeof(id));
		LOG_DBG("Selecting a new Current Object with id: %s",
			log_strdup(id));

		if (ots->cb->obj_selected) {
			ots->cb->obj_selected(ots, conn, ots->cur_obj->id);
		}
	}

	olcp_ind_send(attr, olcp_proc.type, olcp_status);
	return len;
}

void bt_gatt_ots_olcp_cfg_changed(const struct bt_gatt_attr *attr,
				      uint16_t value)
{
	struct bt_gatt_ots_indicate *olcp_ind =
	    CONTAINER_OF((struct _bt_gatt_ccc *) attr->user_data,
			 struct bt_gatt_ots_indicate, ccc);

	LOG_DBG("Object List Control Point CCCD value: 0x%04X", value);

	olcp_ind->is_enabled = false;
	if (value == BT_GATT_CCC_INDICATE) {
		olcp_ind->is_enabled = true;
	}
}