/*
 * Copyright (c) 2021 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#define LOG_MODULE_NAME net_lwm2m_senml_json
#define LOG_LEVEL CONFIG_LWM2M_LOG_LEVEL

#include <logging/log.h>
LOG_MODULE_REGISTER(LOG_MODULE_NAME);

#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <inttypes.h>
#include <ctype.h>
#include <sys/base64.h>
#include <sys/slist.h>

#include "lwm2m_object.h"
#include "lwm2m_rw_senml_json.h"
#include "lwm2m_rw_plain_text.h"
#include "lwm2m_engine.h"
#include "lwm2m_util.h"

#define T_OBJECT_BEGIN BIT(0)
#define T_OBJECT_END BIT(1)
#define T_STRING_BEGIN BIT(2)
#define T_STRING_END BIT(3)
#define T_VALUE BIT(4)

#define SENML_JSON_BASE_NAME_ATTRIBUTE 0
#define SENML_JSON_BASE_TIME_ATTRIBUTE 1
#define SENML_JSON_NAME_ATTRIBUTE 2
#define SENML_JSON_TIME_ATTRIBUTE 3
#define SENML_JSON_FLOAT_VALUE_ATTRIBUTE 4
#define SENML_JSON_BOOLEAN_VALUE_ATTRIBUTE 5
#define SENML_JSON_OBJ_LINK_VALUE_ATTRIBUTE 6
#define SENML_JSON_OPAQUE_VALUE_ATTRIBUTE 7
#define SENML_JSON_STRING_VALUE_ATTRIBUTE 8
#define SENML_JSON_STRING_BLOCK_DATA 9
#define SENML_JSON_UNKNOWN_ATTRIBUTE 255

#define OBJECT_SEPARATOR(f) ((f & WRITER_OUTPUT_VALUE) ? "," : "")

#define TOKEN_BUF_LEN 64
#define BASE64_OUTPUT_MIN_LENGTH 4
#define BASE64_MODULO_LENGTH(x) (x % BASE64_OUTPUT_MIN_LENGTH)
#define BASE64_BYTES_TO_MODULO(x) (BASE64_OUTPUT_MIN_LENGTH - x)

struct json_out_formatter_data {
	/* flags */
	uint8_t writer_flags;

	/* base name */
	struct lwm2m_obj_path base_name;
	/* Add Base name */
	bool add_base_name_to_start;
};

struct json_in_formatter_data {
	/* name info */
	uint16_t name_offset;
	uint16_t name_len;

	/* value info */
	uint16_t value_offset;
	/* Value length */
	uint16_t value_len;

	/* state */
	uint16_t offset;

	/* flags */
	uint8_t json_flags;
};

/* some temporary buffer space for format conversions */
static char json_buffer[TOKEN_BUF_LEN];

static void json_add_char(struct lwm2m_input_context *in, struct json_in_formatter_data *fd)
{
	if ((fd->json_flags & T_VALUE) ||
	    ((fd->json_flags & T_STRING_BEGIN) && !(fd->json_flags & T_STRING_END))) {
		if (fd->json_flags & T_VALUE) {
			fd->value_len++;
			if (fd->value_len == 1U) {
				fd->value_offset = fd->offset;
			}
		} else {
			fd->name_len++;
			if (fd->name_len == 1U) {
				fd->name_offset = fd->offset;
			}
		}
	}
}

static struct lwm2m_senml_json_context *seml_json_context_get(struct lwm2m_block_context *block_ctx)
{
	if (block_ctx) {
		return &block_ctx->senml_json_ctx;
	}

	return NULL;
}

static int json_atribute_decode(struct lwm2m_input_context *in, struct json_in_formatter_data *fd)
{
	uint8_t attrbute_name[3];

	if (fd->name_len == 0 || fd->name_len > 3) {
		if (fd->name_len == 0 && in->block_ctx && (fd->json_flags & T_VALUE) &&
		    (fd->json_flags & T_STRING_END)) {
			return SENML_JSON_STRING_BLOCK_DATA;
		}
		return SENML_JSON_UNKNOWN_ATTRIBUTE;
	}

	if (buf_read(attrbute_name, fd->name_len, CPKT_BUF_READ(in->in_cpkt), &fd->name_offset) <
	    0) {
		LOG_ERR("Error parsing attribute name!");
		return SENML_JSON_UNKNOWN_ATTRIBUTE;
	}

	if (fd->name_len == 1) {
		if (attrbute_name[0] == 'n') {
			return SENML_JSON_NAME_ATTRIBUTE;
		} else if (attrbute_name[0] == 't') {
			return SENML_JSON_TIME_ATTRIBUTE;
		} else if (attrbute_name[0] == 'v') {
			return SENML_JSON_FLOAT_VALUE_ATTRIBUTE;
		}

	} else if (fd->name_len == 2) {
		if (attrbute_name[0] == 'b') {
			if (attrbute_name[1] == 'n') {
				return SENML_JSON_BASE_NAME_ATTRIBUTE;
			} else if (attrbute_name[1] == 't') {
				return SENML_JSON_BASE_TIME_ATTRIBUTE;
			}
		} else if (attrbute_name[0] == 'v') {
			if (attrbute_name[1] == 'b') {
				return SENML_JSON_BOOLEAN_VALUE_ATTRIBUTE;
			} else if (attrbute_name[1] == 'd') {
				return SENML_JSON_OPAQUE_VALUE_ATTRIBUTE;
			} else if (attrbute_name[1] == 's') {
				return SENML_JSON_STRING_VALUE_ATTRIBUTE;
			}
		}
	} else if (fd->name_len == 3) {
		if (attrbute_name[0] == 'v' && attrbute_name[1] == 'l' && attrbute_name[2] == 'o') {
			return SENML_JSON_OBJ_LINK_VALUE_ATTRIBUTE;
		}
	}

	return SENML_JSON_UNKNOWN_ATTRIBUTE;
}

/* Parse SenML attribute & value pairs  */
static int json_next_token(struct lwm2m_input_context *in, struct json_in_formatter_data *fd)
{
	uint8_t cont, c = 0;
	bool escape = false;
	struct lwm2m_senml_json_context *block_ctx;

	(void)memset(fd, 0, sizeof(*fd));
	cont = 1U;
	block_ctx = seml_json_context_get(in->block_ctx);

	if (block_ctx && block_ctx->json_flags) {
		/* Store from last sequence */
		fd->json_flags = block_ctx->json_flags;
		block_ctx->json_flags = 0;
	}

	/* We will be either at start, or at a specific position */
	while (in->offset < in->in_cpkt->offset && cont) {
		fd->offset = in->offset;
		if (buf_read_u8(&c, CPKT_BUF_READ(in->in_cpkt), &in->offset) < 0) {
			break;
		}

		if (c == '\\') {
			escape = true;
			/* Keep track of the escape codes */
			json_add_char(in, fd);
			continue;
		}

		switch (c) {
		case '[':
			if (!escape) {
				fd->json_flags |= T_OBJECT_BEGIN;
				cont = 0U;
			} else {
				json_add_char(in, fd);
			}
			break;

		case '}':
		case ']':
			if (!escape) {
				fd->json_flags |= T_OBJECT_END;
				cont = 0U;
			} else {
				json_add_char(in, fd);
			}
			break;

		case '{':
			if (!escape) {
				fd->json_flags |= T_OBJECT_BEGIN;
			} else {
				json_add_char(in, fd);
			}

			break;

		case ',':
			if (!escape) {
				cont = 0U;
			} else {
				json_add_char(in, fd);
			}

			break;

		case '"':
			if (!escape) {
				if (fd->json_flags & T_STRING_BEGIN) {
					fd->json_flags &= ~T_STRING_BEGIN;
					fd->json_flags |= T_STRING_END;
				} else {
					fd->json_flags &= ~T_STRING_END;
					fd->json_flags |= T_STRING_BEGIN;
				}
			} else {
				json_add_char(in, fd);
			}

			break;

		case ':':
			if (!escape) {
				fd->json_flags &= ~T_STRING_END;
				fd->json_flags |= T_VALUE;
			} else {
				json_add_char(in, fd);
			}

			break;

		/* ignore whitespace */
		case ' ':
		case '\n':
		case '\t':
			if (!(fd->json_flags & T_STRING_BEGIN)) {
				break;
			}

			__fallthrough;

		default:
			json_add_char(in, fd);
		}

		if (escape) {
			escape = false;
		}
	}

	/* OK if cont == 0 otherwise we failed */
	return (cont == 0U);
}

static int put_begin(struct lwm2m_output_context *out, struct lwm2m_obj_path *path)
{
	int res;
	struct json_out_formatter_data *fd;

	fd = engine_get_out_user_data(out);
	if (!fd) {
		return -EINVAL;
	}

	res = buf_append(CPKT_BUF_WRITE(out->out_cpkt), "[", 1);
	if (res < 0) {
		return res;
	}

	/* Init base level state for skip first object instance compare */
	fd->base_name.level = LWM2M_PATH_LEVEL_NONE;
	return 1;
}

static int put_end(struct lwm2m_output_context *out, struct lwm2m_obj_path *path)
{
	struct json_out_formatter_data *fd;
	int res;

	fd = engine_get_out_user_data(out);
	if (!fd) {
		return -EINVAL;
	}

	res = buf_append(CPKT_BUF_WRITE(out->out_cpkt), "]", 1);
	if (res < 0) {
		return res;
	}

	return 1;
}

static int put_begin_oi(struct lwm2m_output_context *out, struct lwm2m_obj_path *path)
{
	struct json_out_formatter_data *fd;
	bool update_base_name = false;

	fd = engine_get_out_user_data(out);
	if (!fd) {
		return -EINVAL;
	}

	if (fd->base_name.level == LWM2M_PATH_LEVEL_NONE) {
		update_base_name = true;

	} else if (fd->base_name.obj_id != path->obj_id ||
		   fd->base_name.obj_inst_id != path->obj_inst_id) {
		update_base_name = true;
	}

	if (update_base_name) {
		fd->base_name.level = LWM2M_PATH_LEVEL_OBJECT_INST;
		fd->base_name.obj_id = path->obj_id;
		fd->base_name.obj_inst_id = path->obj_inst_id;
	}

	fd->add_base_name_to_start = update_base_name;

	return 0;
}

static int put_begin_ri(struct lwm2m_output_context *out, struct lwm2m_obj_path *path)
{
	struct json_out_formatter_data *fd;

	fd = engine_get_out_user_data(out);
	if (!fd) {
		return -EINVAL;
	}

	fd->writer_flags |= WRITER_RESOURCE_INSTANCE;
	return 0;
}

static int put_end_ri(struct lwm2m_output_context *out, struct lwm2m_obj_path *path)
{
	struct json_out_formatter_data *fd;

	fd = engine_get_out_user_data(out);
	if (!fd) {
		return -EINVAL;
	}

	fd->writer_flags &= ~WRITER_RESOURCE_INSTANCE;
	return 0;
}

static int put_char(struct lwm2m_output_context *out, char c)
{
	int res;

	res = buf_append(CPKT_BUF_WRITE(out->out_cpkt), &c, sizeof(c));
	if (res < 0) {
		return res;
	}

	return 1;
}

static int put_json_prefix(struct lwm2m_output_context *out, struct lwm2m_obj_path *path,
			      const char *format)
{
	struct json_out_formatter_data *fd;
	char *sep;
	int len = 0, t_length;

	fd = engine_get_out_user_data(out);

	/* Add separator after first added resource */
	sep = OBJECT_SEPARATOR(fd->writer_flags);

	if (fd->add_base_name_to_start) {
		t_length = snprintk(json_buffer, sizeof(json_buffer), "%s{\"bn\":\"/%u/%u/\",", sep,
				  path->obj_id, path->obj_inst_id);
	} else {
		t_length = snprintk(json_buffer, sizeof(json_buffer), "%s{", sep);
	}

	if (t_length < 0) {
		return t_length;
	}

	len = t_length;

	/* Add Name and value format */
	if (fd->writer_flags & WRITER_RESOURCE_INSTANCE) {
		t_length = snprintk(json_buffer + len, sizeof(json_buffer) - len,
				    "\"n\":\"%u/%u\",%s:", path->res_id, path->res_inst_id, format);
	} else {
		t_length = snprintk(json_buffer + len, sizeof(json_buffer) - len,
				    "\"n\":\"%u\",%s:", path->res_id, format);
	}

	if (t_length < 0) {
		return t_length;
	}
	len += t_length;

	/* Write Json Prefix to message */
	if (buf_append(CPKT_BUF_WRITE(out->out_cpkt), json_buffer, len)) {
		return -ENOMEM;
	}
	fd->add_base_name_to_start = false;

	return len;
}

static int put_json_postfix(struct lwm2m_output_context *out)
{
	int len;
	struct json_out_formatter_data *fd;

	fd = engine_get_out_user_data(out);

	len = put_char(out, '}');

	if (len < 0) {
		return len;
	}

	fd->writer_flags |= WRITER_OUTPUT_VALUE;
	return len;
}

static int put_s32(struct lwm2m_output_context *out, struct lwm2m_obj_path *path, int32_t value)
{
	int res, len;

	if (!out->out_cpkt || !engine_get_out_user_data(out)) {
		return -EINVAL;
	}

	res = put_json_prefix(out, path, "\"v\"");
	if (res < 0) {
		return res;
	}
	len = res;

	res = plain_text_put_format(out, "%d", value);
	if (res < 0) {
		return res;
	}
	len += res;

	res = put_json_postfix(out);
	if (res < 0) {
		return res;
	}
	len += res;

	return len;
}

static int put_s16(struct lwm2m_output_context *out, struct lwm2m_obj_path *path, int16_t value)
{
	return put_s32(out, path, (int32_t)value);
}

static int put_s8(struct lwm2m_output_context *out, struct lwm2m_obj_path *path, int8_t value)
{
	return put_s32(out, path, (int32_t)value);
}

static int put_s64(struct lwm2m_output_context *out, struct lwm2m_obj_path *path, int64_t value)
{
	int res, len;

	if (!out->out_cpkt || !engine_get_out_user_data(out)) {
		return -EINVAL;
	}

	res = put_json_prefix(out, path, "\"v\"");

	if (res < 0) {
		return res;
	}
	len = res;

	res = plain_text_put_format(out, "%lld", value);
	if (res < 0) {
		return res;
	}
	len += res;

	res = put_json_postfix(out);
	if (res < 0) {
		return res;
	}
	len += res;

	return len;
}

static int write_string_buffer(struct lwm2m_output_context *out, char *buf, size_t buflen)
{
	int res, len;

	res = put_char(out, '"');
	if (res < 0) {
		return res;
	}
	len = res;

	for (size_t i = 0; i < buflen; ++i) {
		/* Escape special characters */
		/* TODO: Handle UTF-8 strings */
		if (buf[i] < '\x20') {
			res = snprintk(json_buffer, sizeof(json_buffer), "\\x%x", buf[i]);
			if (res < 0) {
				return res;
			}

			if (buf_append(CPKT_BUF_WRITE(out->out_cpkt), json_buffer, res) < 0) {
				return -ENOMEM;
			}
			len += res;

			continue;
		} else if (buf[i] == '"' || buf[i] == '\\') {
			res = put_char(out, '\\');
			if (res < 0) {
				return res;
			}
			len += res;
		}
		res = put_char(out, buf[i]);
		if (res < 0) {
			return res;
		}
		len += res;
	}

	res = put_char(out, '"');
	if (res < 0) {
		return res;
	}
	len += res;

	return len;
}

static int put_string(struct lwm2m_output_context *out, struct lwm2m_obj_path *path, char *buf,
			 size_t buflen)
{
	int res, len;

	if (!out->out_cpkt || !engine_get_out_user_data(out)) {
		return -EINVAL;
	}

	res = put_json_prefix(out, path, "\"vs\"");
	if (res < 0) {
		return res;
	}
	len = res;

	res = write_string_buffer(out, buf, buflen);

	if (res < 0) {
		return res;
	}
	len += res;

	res = put_json_postfix(out);
	if (res < 0) {
		return res;
	}
	len += res;

	return len;
}

static int put_float(struct lwm2m_output_context *out, struct lwm2m_obj_path *path,
			     double  *value)
{
	int res, len;

	if (!out->out_cpkt || !engine_get_out_user_data(out)) {
		return -EINVAL;
	}
	res = put_json_prefix(out, path, "\"v\"");

	if (res < 0) {
		return res;
	}
	len = res;

	res = plain_text_put_float(out, path, value);
	if (res < 0) {
		return res;
	}
	len += res;

	res = put_json_postfix(out);
	if (res < 0) {
		return res;
	}
	len += res;

	return len;
}

static int put_bool(struct lwm2m_output_context *out, struct lwm2m_obj_path *path, bool value)
{
	int res, len;

	if (!out->out_cpkt || !engine_get_out_user_data(out)) {
		return -EINVAL;
	}

	res = put_json_prefix(out, path, "\"vb\"");
	if (res < 0) {
		return res;
	}
	len = res;

	res = plain_text_put_format(out, "%s", value ? "true" : "false");
	if (res < 0) {
		return res;
	}
	len += res;

	res = put_json_postfix(out);
	if (res < 0) {
		return res;
	}
	len += res;

	return len;
}

static int put_opaque(struct lwm2m_output_context *out, struct lwm2m_obj_path *path, char *buf,
			 size_t buflen)
{
	int res, len;
	size_t temp_length;

	if (!out->out_cpkt || !engine_get_out_user_data(out)) {
		return -EINVAL;
	}
	res = put_json_prefix(out, path, "\"vd\"");
	if (res < 0) {
		return res;
	}
	len = res;

	res = put_char(out, '"');
	if (res < 0) {
		return res;
	}
	len += res;

	if (base64_encode(CPKT_BUF_W_PTR(out->out_cpkt), CPKT_BUF_W_SIZE(out->out_cpkt),
			  &temp_length, buf, buflen)) {
		/* No space available for base64 data */
		return -ENOMEM;
	}
	len += temp_length;

	res = put_char(out, '"');
	if (res < 0) {
		return res;
	}
	len += res;

	res = put_json_postfix(out);
	if (res < 0) {
		return res;
	}
	len += res;

	return len;
}

static int put_objlnk(struct lwm2m_output_context *out, struct lwm2m_obj_path *path,
			 struct lwm2m_objlnk *value)
{
	int res, len;

	if (!out->out_cpkt || !engine_get_out_user_data(out)) {
		return -EINVAL;
	}

	res = put_json_prefix(out, path, "\"vlo\"");
	if (res < 0) {
		return res;
	}
	len = res;

	res = plain_text_put_format(out, "\"%u:%u\"", value->obj_id, value->obj_inst);
	if (res < 0) {
		return res;
	}
	len += res;

	res = put_json_postfix(out);
	if (res < 0) {
		return res;
	}
	len += res;

	return len;
}

static int read_int(struct lwm2m_input_context *in, int64_t *value, bool accept_sign)
{
	struct json_in_formatter_data *fd;
	uint8_t *buf;
	size_t i = 0;
	bool neg = false;
	char c;

	/* initialize values to 0 */
	*value = 0;

	fd = engine_get_in_user_data(in);
	if (!fd) {
		return -EINVAL;
	}

	if (fd->value_len == 0) {
		return -ENODATA;
	}

	buf = in->in_cpkt->data + fd->value_offset;
	while (*(buf + i) && i < fd->value_len) {
		c = *(buf + i);
		if (c == '-' && accept_sign && i == 0) {
			neg = true;
		} else if (isdigit(c)) {
			*value = *value * 10 + (c - '0');
		} else {
			/* anything else stop reading */
			break;
		}

		i++;
	}

	if (neg) {
		*value = -*value;
	}

	return i;
}

static int get_s64(struct lwm2m_input_context *in, int64_t *value)
{
	return read_int(in, value, true);
}

static int get_s32(struct lwm2m_input_context *in, int32_t *value)
{
	int64_t tmp = 0;
	int len = 0;

	len = read_int(in, &tmp, true);
	if (len > 0) {
		*value = (int32_t)tmp;
	}

	return len;
}

static int get_string(struct lwm2m_input_context *in, uint8_t *buf, size_t buflen)
{
	struct json_in_formatter_data *fd;
	int ret;

	fd = engine_get_in_user_data(in);
	if (!fd) {
		return -EINVAL;
	}

	if (fd->value_len > buflen) {
		LOG_WRN("Buffer too small to accommodate string, truncating");
		fd->value_len = buflen - 1;
	}

	ret = buf_read(buf, fd->value_len, CPKT_BUF_READ(in->in_cpkt), &fd->value_offset);

	if (ret < 0) {
		return ret;
	}
	/* add NULL */
	buf[fd->value_len] = '\0';

	return fd->value_len;
}

static int get_float(struct lwm2m_input_context *in, double *value)
{
	struct json_in_formatter_data *fd;

	int i = 0, len = 0;
	bool has_dot = false;
	uint8_t tmp, buf[24];
	uint8_t *json_buf;

	fd = engine_get_in_user_data(in);
	if (!fd) {
		return -EINVAL;
	}

	json_buf = in->in_cpkt->data + fd->value_offset;
	while (*(json_buf + len) && len < fd->value_len) {
		tmp = *(json_buf + len);

		if ((tmp == '-' && i == 0) || (tmp == '.' && !has_dot) || isdigit(tmp)) {
			len++;

			/* Copy only if it fits into provided buffer - we won't
			 * get better precision anyway.
			 */
			if (i < sizeof(buf) - 1) {
				buf[i++] = tmp;
			}

			if (tmp == '.') {
				has_dot = true;
			}
		} else {
			break;
		}
	}

	buf[i] = '\0';

	if (lwm2m_atof(buf, value) != 0) {
		LOG_ERR("Failed to parse float value");
	}

	return len;
}

static int get_bool(struct lwm2m_input_context *in, bool *value)
{
	struct json_in_formatter_data *fd;

	fd = engine_get_in_user_data(in);
	if (!fd) {
		return -EINVAL;
	}

	if (fd->value_len == 0) {
		return -ENODATA;
	}

	if (strncmp(in->in_cpkt->data + fd->value_offset, "true", 4) == 0) {
		*value = true;
	} else if (strncmp(in->in_cpkt->data + fd->value_offset, "false", 5) == 0) {
		*value = false;
	}

	return fd->value_len;
}

static void base64_url_safe_decode(uint8_t *data_buf, size_t buf_len)
{
	uint8_t *ptr = data_buf;

	for (size_t i = 0; i < buf_len; i++) {
		if (*ptr == '-') {
			/* replace '-' with "+" */
			*ptr = '+';
		} else if (*ptr == '_') {
			/* replace '_' with "/" */
			*ptr = '/';
		}
		ptr++;
	}
}

static int store_padded_modulo(uint16_t *padded_length, uint8_t *padded_buf, uint8_t *data_tail,
			       uint16_t data_length)
{
	uint16_t padded_len = BASE64_MODULO_LENGTH(data_length);

	if (data_length < padded_len) {
		return -ENODATA;
	}
	*padded_length = padded_len;

	if (padded_len) {
		uint8_t *tail_ptr;

		tail_ptr = data_tail - padded_len;
		memcpy(padded_buf, tail_ptr, padded_len);
		for (size_t i = padded_len; i < BASE64_OUTPUT_MIN_LENGTH; i++) {
			padded_buf[i] = '=';
		}
	}
	return 0;
}

static int store_modulo_data(struct lwm2m_senml_json_context *block_ctx, uint8_t *data_ptr,
			       uint16_t data_length)
{
	block_ctx->base64_buf_len = BASE64_MODULO_LENGTH(data_length);
	if (data_length < block_ctx->base64_buf_len) {
		return -ENODATA;
	}

	if (block_ctx->base64_buf_len) {
		uint8_t *data_tail_ptr;

		data_tail_ptr = data_ptr + (data_length - block_ctx->base64_buf_len);
		memcpy(block_ctx->base64_mod_buf, data_tail_ptr, block_ctx->base64_buf_len);
	}
	return 0;
}

static int get_opaque(struct lwm2m_input_context *in, uint8_t *value, size_t buflen,
			 struct lwm2m_opaque_context *opaque, bool *last_block)
{
	struct json_in_formatter_data *fd;
	struct lwm2m_senml_json_context *block_ctx;
	int in_len, ret;
	uint8_t module_buf[BASE64_OUTPUT_MIN_LENGTH];
	uint16_t padded_length = 0;
	uint8_t padded_buf[BASE64_OUTPUT_MIN_LENGTH];
	size_t buffer_base64_length;

	block_ctx = seml_json_context_get(in->block_ctx);

	fd = engine_get_in_user_data(in);
	if (!fd) {
		return -EINVAL;
	}

	uint8_t *data_ptr = in->in_cpkt->data + fd->value_offset;

	/* Decode from url safe to normal */
	base64_url_safe_decode(data_ptr, fd->value_len);

	if (opaque->remaining == 0) {
		size_t original_size = fd->value_len;
		size_t base64_length;

		if (block_ctx) {
			if (block_ctx->base64_buf_len) {
				size_t b_to_module;

				b_to_module = BASE64_BYTES_TO_MODULO(block_ctx->base64_buf_len);

				if (fd->value_len < b_to_module) {
					return -ENODATA;
				}

				fd->value_len -= b_to_module;
				memcpy(module_buf, block_ctx->base64_mod_buf,
				       block_ctx->base64_buf_len);
				memcpy(module_buf + block_ctx->base64_buf_len, data_ptr,
				       b_to_module);

				if (base64_decode(module_buf, BASE64_OUTPUT_MIN_LENGTH,
						  &buffer_base64_length, module_buf,
						  BASE64_OUTPUT_MIN_LENGTH) < 0) {
					return -ENODATA;
				}

				if (in->block_ctx->last_block) {
					ret = store_padded_modulo(&padded_length, padded_buf,
								  data_ptr + original_size,
								  fd->value_len);
					if (ret) {
						return ret;
					}
					fd->value_len -= padded_length;

				} else {
					ret = store_modulo_data(block_ctx, data_ptr,
								  fd->value_len);
					if (ret) {
						return ret;
					}

					fd->value_len -= block_ctx->base64_buf_len;
				}

				/* Decode rest of data and do memmove */
				if (base64_decode(data_ptr, original_size, &base64_length,
						  data_ptr + b_to_module, fd->value_len) < 0) {
					return -ENODATA;
				}
				fd->value_len = base64_length;
				/* Move decoded data by module result size from front */
				memmove(data_ptr + buffer_base64_length, data_ptr, fd->value_len);
				memcpy(data_ptr, module_buf, buffer_base64_length);
				fd->value_len += buffer_base64_length;
			} else {
				if (in->block_ctx->last_block) {
					ret = store_padded_modulo(&padded_length, padded_buf,
								  data_ptr + original_size,
								  original_size);
					if (ret) {
						return ret;
					}
					fd->value_len -= padded_length;

				} else {
					ret = store_modulo_data(block_ctx, data_ptr,
								  fd->value_len);
					if (ret) {
						return ret;
					}

					fd->value_len -= block_ctx->base64_buf_len;
				}

				if (base64_decode(data_ptr, original_size, &base64_length, data_ptr,
						  fd->value_len) < 0) {
					return -ENODATA;
				}
				fd->value_len = base64_length;
			}

			if (padded_length) {
				if (base64_decode(padded_buf, BASE64_OUTPUT_MIN_LENGTH,
						  &buffer_base64_length, padded_buf,
						  BASE64_OUTPUT_MIN_LENGTH) < 0) {
					return -ENODATA;
				}
				/* Add padded tail */
				memcpy(data_ptr + fd->value_len, padded_buf, buffer_base64_length);
				fd->value_len += buffer_base64_length;
			}
			/* Set zero because total length is unknown */
			opaque->len = 0;
		} else {
			ret = store_padded_modulo(&padded_length, padded_buf,
						  data_ptr + original_size, original_size);
			if (ret) {
				return ret;
			}

			if (base64_decode(data_ptr, fd->value_len, &base64_length, data_ptr,
					  fd->value_len) < 0) {
				return -ENODATA;
			}

			fd->value_len = base64_length;
			if (padded_length) {
				if (base64_decode(padded_buf, BASE64_OUTPUT_MIN_LENGTH,
						  &buffer_base64_length, padded_buf,
						  BASE64_OUTPUT_MIN_LENGTH) < 0) {
					return -ENODATA;
				}
				/* Add padded tail */
				memcpy(data_ptr + fd->value_len, padded_buf, buffer_base64_length);
				fd->value_len += buffer_base64_length;
			}
			opaque->len = fd->value_len;
		}
		opaque->remaining = fd->value_len;
	}

	in_len = opaque->remaining;

	if (in_len > buflen) {
		in_len = buflen;
	}

	if (in_len > fd->value_len) {
		in_len = fd->value_len;
	}

	opaque->remaining -= in_len;
	if (opaque->remaining == 0U) {
		*last_block = true;
	}
	/* Copy data to buffer */
	memcpy(value, data_ptr, in_len);

	return in_len;
}

static int get_objlnk(struct lwm2m_input_context *in, struct lwm2m_objlnk *value)
{
	int64_t tmp;
	int len, total_len;
	uint16_t value_offset;
	struct json_in_formatter_data *fd;

	fd = engine_get_in_user_data(in);
	if (!fd) {
		return -EINVAL;
	}

	/* Store the original value offset. */
	value_offset = fd->value_offset;

	len = read_int(in, &tmp, false);
	if (len <= 0) {
		return -ENODATA;
	}

	total_len = len;
	value->obj_id = (uint16_t)tmp;

	len++;  /* +1 for ':' delimiter. */
	fd->value_offset += len;

	len = read_int(in, &tmp, false);
	if (len <= 0) {
		return -ENODATA;
	}

	total_len += len;
	value->obj_inst = (uint16_t)tmp;

	/* Restore the original value offset. */
	fd->value_offset = value_offset;

	return total_len;
}

const struct lwm2m_writer senml_json_writer = {
	.put_begin = put_begin,
	.put_end = put_end,
	.put_begin_oi = put_begin_oi,
	.put_begin_ri = put_begin_ri,
	.put_end_ri = put_end_ri,
	.put_s8 = put_s8,
	.put_s16 = put_s16,
	.put_s32 = put_s32,
	.put_s64 = put_s64,
	.put_string = put_string,
	.put_float = put_float,
	.put_bool = put_bool,
	.put_opaque = put_opaque,
	.put_objlnk = put_objlnk,
};

const struct lwm2m_reader senml_json_reader = {
	.get_s32 = get_s32,
	.get_s64 = get_s64,
	.get_string = get_string,
	.get_float = get_float,
	.get_bool = get_bool,
	.get_opaque = get_opaque,
	.get_objlnk = get_objlnk,
};

void lwm2m_senml_json_context_init(struct lwm2m_senml_json_context *ctx)
{
	ctx->base_name_stored = false;
	ctx->full_name_true = false;
	ctx->base64_buf_len = 0;
	ctx->json_flags = 0;
}

int do_read_op_senml_json(struct lwm2m_message *msg)
{
	struct lwm2m_obj_path_list temp;
	sys_slist_t lwm2m_path_list;
	int ret;
	struct json_out_formatter_data fd;

	(void)memset(&fd, 0, sizeof(fd));
	engine_set_out_user_data(&msg->out, &fd);
	/* Init list */
	sys_slist_init(&lwm2m_path_list);
	/* Init message here ready for response */
	temp.path = msg->path;
	/* Add one entry to list */
	sys_slist_append(&lwm2m_path_list, &temp.node);

	ret = lwm2m_perform_read_op(msg, LWM2M_FORMAT_APP_SEML_JSON);
	engine_clear_out_user_data(&msg->out);

	return ret;
}

static int lwm2m_senml_write_operation(struct lwm2m_message *msg, struct json_in_formatter_data *fd)
{
	struct lwm2m_engine_obj_field *obj_field = NULL;
	struct lwm2m_engine_obj_inst *obj_inst = NULL;
	struct lwm2m_engine_res *res = NULL;
	struct lwm2m_engine_res_inst *res_inst = NULL;
	uint8_t created;
	int ret = 0;

	/* handle resource value */
	/* reset values */
	created = 0U;

	/* if valid, use the return value as level */

	ret = lwm2m_get_or_create_engine_obj(msg, &obj_inst, &created);
	if (ret < 0) {
		return ret;
	}

	ret = lwm2m_engine_validate_write_access(msg, obj_inst, &obj_field);
	if (ret < 0) {
		return ret;
	}

	ret = lwm2m_engine_get_create_res_inst(&msg->path, &res, &res_inst);
	if (ret < 0) {
		return -ENOENT;
	}

	/* Write the resource value */
	ret = lwm2m_write_handler(obj_inst, res, res_inst, obj_field, msg);
	return ret;
}

int do_write_op_senml_json(struct lwm2m_message *msg)
{
	struct json_in_formatter_data fd;
	int ret = 0;
	uint8_t name[MAX_RESOURCE_LEN + 1];
	uint8_t base_name[MAX_RESOURCE_LEN + 1] = {0};
	uint8_t full_name[MAX_RESOURCE_LEN + 1] = {0};
	struct lwm2m_obj_path resource_path;
	bool path_valid = false;
	bool data_value = false;
	struct lwm2m_senml_json_context *block_ctx;

	(void)memset(&fd, 0, sizeof(fd));
	engine_set_in_user_data(&msg->in, &fd);

	block_ctx = seml_json_context_get(msg->in.block_ctx);

	if (block_ctx && block_ctx->json_flags) {
		int name_length;

		/* Re-load Base name and Name data from context block */
		if (block_ctx->base_name_stored) {
			/* base name path generate to string */
			name_length = lwm2m_path_to_string(base_name, sizeof(base_name),
								&block_ctx->base_name_path,
								block_ctx->base_name_path.level);

			if (name_length <= 0) {
				ret = -EINVAL;
				goto end_of_operation;
			}

			if (block_ctx->base_name_path.level >= LWM2M_PATH_LEVEL_RESOURCE &&
			    !block_ctx->full_name_true) {
				memcpy(full_name, base_name, MAX_RESOURCE_LEN + 1);
				ret = lwm2m_string_to_path(full_name, &resource_path, '/');
				if (ret < 0) {
					ret = -EINVAL;
					goto end_of_operation;
				}
				path_valid = true;
			}
		}

		if (block_ctx->full_name_true) {
			/* full name path generate to string */
			name_length = lwm2m_path_to_string(full_name, sizeof(full_name),
								&block_ctx->base_name_path,
								block_ctx->resource_path_level);

			if (name_length <= 0) {
				ret = -EINVAL;
				goto end_of_operation;
			}

			ret = lwm2m_string_to_path(full_name, &resource_path, '/');
			if (ret < 0) {
				ret = -EINVAL;
				goto end_of_operation;
			}
			path_valid = true;
		}
	}

	/* Parse Attribute value pair */
	while (json_next_token(&msg->in, &fd)) {
		if (!(fd.json_flags & T_VALUE)) {
			continue;
		}

		data_value = false;

		switch (json_atribute_decode(&msg->in, &fd)) {
		case SENML_JSON_BASE_NAME_ATTRIBUTE:
			if (fd.value_len > MAX_RESOURCE_LEN) {
				LOG_ERR("Base name too long %u", fd.value_len);
				ret = -EINVAL;
				goto end_of_operation;
			}

			if (buf_read(base_name, fd.value_len, CPKT_BUF_READ(msg->in.in_cpkt),
				     &fd.value_offset) < 0) {
				LOG_ERR("Error parsing base name!");
				ret = -EINVAL;
				goto end_of_operation;
			}

			base_name[fd.value_len] = '\0';
			/* Relative name is optional - preinitialize full name with base name */
			snprintk(full_name, sizeof(full_name), "%s", base_name);
			ret = lwm2m_string_to_path(full_name, &resource_path, '/');
			if (ret < 0) {
				LOG_ERR("Relative name too long");
				ret = -EINVAL;
				goto end_of_operation;
			}

			if (resource_path.level) {
				path_valid = true;
			}

			if (block_ctx) {
				block_ctx->base_name_path = resource_path;
				block_ctx->base_name_stored = true;
			}

			break;
		case SENML_JSON_NAME_ATTRIBUTE:

			/* handle resource name */
			if (fd.value_len > MAX_RESOURCE_LEN) {
				LOG_ERR("Relative name too long");
				ret = -EINVAL;
				goto end_of_operation;
			}

			/* get value for relative path */
			if (buf_read(name, fd.value_len, CPKT_BUF_READ(msg->in.in_cpkt),
				     &fd.value_offset) < 0) {
				LOG_ERR("Error parsing relative path!");
				ret = -EINVAL;
				goto end_of_operation;
			}

			name[fd.value_len] = '\0';

			/* combine base_name + name */
			snprintk(full_name, sizeof(full_name), "%s%s", base_name, name);
			ret = lwm2m_string_to_path(full_name, &resource_path, '/');
			if (ret < 0) {
				LOG_ERR("Relative name too long");
				ret = -EINVAL;
				goto end_of_operation;
			}

			if (block_ctx) {
				/* Store Resource data Path to base name path but
				 * store separately path level
				 */
				uint8_t path_level = block_ctx->base_name_path.level;

				block_ctx->base_name_path = resource_path;
				block_ctx->resource_path_level = resource_path.level;
				block_ctx->base_name_path.level = path_level;
				block_ctx->full_name_true = true;
			}
			path_valid = true;
			break;

		case SENML_JSON_FLOAT_VALUE_ATTRIBUTE:
		case SENML_JSON_BOOLEAN_VALUE_ATTRIBUTE:
		case SENML_JSON_OBJ_LINK_VALUE_ATTRIBUTE:
		case SENML_JSON_OPAQUE_VALUE_ATTRIBUTE:
		case SENML_JSON_STRING_VALUE_ATTRIBUTE:
		case SENML_JSON_STRING_BLOCK_DATA:
			data_value = true;
			break;

		case SENML_JSON_UNKNOWN_ATTRIBUTE:
			LOG_ERR("Unknown attribute");
			ret = -EINVAL;
			goto end_of_operation;

		default:
			break;
		}

		if (data_value && path_valid) {
			/* parse full_name into path */
			if (block_ctx) {
				/* Store json Flags */
				block_ctx->json_flags = fd.json_flags;
			}

			msg->path = resource_path;
			ret = lwm2m_senml_write_operation(msg, &fd);

			if (ret < 0) {
				break;
			}
		}
	}
	/* Do we have a data value which is part of the CoAP blocking process */
	if ((fd.json_flags & T_VALUE) && !(fd.json_flags & T_OBJECT_END) && !data_value &&
	    block_ctx && fd.value_len) {
		if (!path_valid) {
			LOG_ERR("No path available for Coap Block sub sequency");
			ret = -EINVAL;
			goto end_of_operation;
		}
		/* Store Json File description flags */
		block_ctx->json_flags = fd.json_flags;
		msg->path = resource_path;
		ret = lwm2m_senml_write_operation(msg, &fd);
	}

end_of_operation:
	engine_clear_in_user_data(&msg->in);

	return ret;
}

static uint8_t json_parse_composite_read_paths(struct lwm2m_message *msg,
					       sys_slist_t *lwm2m_path_list,
					       sys_slist_t *lwm2m_path_free_list)
{
	struct json_in_formatter_data fd;
	struct lwm2m_obj_path path;
	bool path_valid;
	int ret;
	uint8_t name[MAX_RESOURCE_LEN];
	uint8_t base_name[MAX_RESOURCE_LEN + 1] = {0};
	uint8_t full_name[MAX_RESOURCE_LEN + 1] = {0};
	uint8_t valid_path_cnt = 0;

	while (json_next_token(&msg->in, &fd)) {
		if (!(fd.json_flags & T_VALUE)) {
			continue;
		}

		path_valid = false;
		switch (json_atribute_decode(&msg->in, &fd)) {
		case SENML_JSON_BASE_NAME_ATTRIBUTE:
			if (fd.value_len >= sizeof(base_name)) {
				LOG_ERR("Base name too long");
				break;
			}

			if (buf_read(base_name, fd.value_len, CPKT_BUF_READ(msg->in.in_cpkt),
				     &fd.value_offset) < 0) {
				LOG_ERR("Error parsing base name!");
				break;
			}

			base_name[fd.value_len] = '\0';

			/* Relative name is optional - preinitialize full name with base name */
			snprintk(full_name, sizeof(full_name), "%s", base_name);

			if (fd.json_flags & T_OBJECT_END) {
				path_valid = true;
			}
			break;

		case SENML_JSON_NAME_ATTRIBUTE:

			/* handle resource name */
			if (fd.value_len >= MAX_RESOURCE_LEN) {
				LOG_ERR("Relative name too long");
				break;
			}

			/* get value for relative path */
			if (buf_read(name, fd.value_len, CPKT_BUF_READ(msg->in.in_cpkt),
				     &fd.value_offset) < 0) {
				LOG_ERR("Error parsing relative path!");
				break;
			}

			name[fd.value_len] = '\0';

			/* combine base_name + name */
			snprintk(full_name, sizeof(full_name), "%s%s", base_name, name);
			path_valid = true;
			break;

		default:
			break;
		}

		if (path_valid) {
			ret = lwm2m_string_to_path(full_name, &path, '/');
			if (ret == 0) {
				if (lwm2m_engine_add_path_to_list(
					    lwm2m_path_list, lwm2m_path_free_list, &path) == 0) {
					valid_path_cnt++;
				}
			}
		}
	}
	return valid_path_cnt;
}

int do_composite_read_op_senml_json(struct lwm2m_message *msg)
{
	int ret;
	struct json_out_formatter_data fd;
	struct lwm2m_obj_path_list path_list_buf[CONFIG_LWM2M_COMPOSITE_PATH_LIST_SIZE];
	sys_slist_t path_list;
	sys_slist_t free_list;
	uint8_t path_list_size;

	/* Init list */
	lwm2m_engine_path_list_init(&path_list, &free_list, path_list_buf,
				    CONFIG_LWM2M_COMPOSITE_PATH_LIST_SIZE);

	/* Parse Path's from SenML JSO payload */
	path_list_size = json_parse_composite_read_paths(msg, &path_list, &free_list);
	if (path_list_size == 0) {
		LOG_ERR("No Valid Url at msg");
		return -ESRCH;
	}

	/* Clear path which are part are part of recursive path /1 will include /1/0/1 */
	lwm2m_engine_clear_duplicate_path(&path_list, &free_list);

	(void)memset(&fd, 0, sizeof(fd));
	engine_set_out_user_data(&msg->out, &fd);

	ret = lwm2m_perform_composite_read_op(msg, LWM2M_FORMAT_APP_SEML_JSON, &path_list);
	engine_clear_out_user_data(&msg->out);

	return ret;
}

int do_send_op_senml_json(struct lwm2m_message *msg, sys_slist_t *lwm2m_path_list)
{
	struct json_out_formatter_data fd;
	int ret;

	(void)memset(&fd, 0, sizeof(fd));
	engine_set_out_user_data(&msg->out, &fd);

	ret = lwm2m_perform_composite_read_op(msg, LWM2M_FORMAT_APP_SEML_JSON, lwm2m_path_list);
	engine_clear_out_user_data(&msg->out);

	return ret;
}

int do_composite_observe_parse_path_senml_json(struct lwm2m_message *msg,
					       sys_slist_t *lwm2m_path_list,
					       sys_slist_t *lwm2m_path_free_list)
{
	uint8_t list_size;
	uint16_t original_offset;

	original_offset = msg->in.offset;
	/* Parse Path's from SenML JSON payload */
	list_size = json_parse_composite_read_paths(msg, lwm2m_path_list, lwm2m_path_free_list);
	if (list_size == 0) {
		LOG_ERR("No Valid Url at msg");
		return -ESRCH;
	}

	msg->in.offset = original_offset;
	return 0;
}