/**
 * @file out_internal.h
 * @author Radek Krejci <rkrejci@cesnet.cz>
 * @author Michal Vasko
 * @brief Internal structures and functions for libyang
 *
 * Copyright (c) 2015-2025 CESNET, z.s.p.o.
 *
 * This source code is licensed under BSD 3-Clause License (the "License").
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://opensource.org/licenses/BSD-3-Clause
 */

#ifndef LY_OUT_INTERNAL_H_
#define LY_OUT_INTERNAL_H_

#include "out.h"

struct lyd_node;

/**
 * @brief Printer output structure specifying where the data are printed.
 */
struct ly_out {
    LY_OUT_TYPE type;     /**< type of the output to select the output method */

    union {
        int fd;          /**< file descriptor for LY_OUT_FD type */
        FILE *f;         /**< file structure for LY_OUT_FILE, LY_OUT_FDSTREAM and LY_OUT_FILEPATH types */

        struct {
            FILE *f;          /**< file stream from the original file descriptor, variable is mapped to the LY_OUT_FILE's f */
            int fd;           /**< original file descriptor, which was not used directly because of missing vdprintf() */
        } fdstream;      /**< structure for LY_OUT_FDSTREAM type, which is LY_OUT_FD when vdprintf() is missing */
        struct {
            FILE *f;          /**< file structure for LY_OUT_FILEPATH, variable is mapped to the LY_OUT_FILE's f */
            char *filepath;   /**< stored original filepath */
        } fpath;         /**< filepath structure for LY_OUT_FILEPATH */
        struct {
            char **buf;       /**< storage for the pointer to the memory buffer to store the output */
            size_t len;       /**< number of used bytes in the buffer */
            size_t size;      /**< allocated size of the buffer */
        } mem;           /**< memory buffer information for LY_OUT_MEMORY type */
        struct {
            ssize_t (*func)(void *arg, const void *buf, size_t count); /**< callback function */
            void *arg;        /**< optional argument for the callback function */
        } clb;           /**< printer callback for LY_OUT_CALLBACK type */
    } method;            /**< type-specific information about the output */

    /* LYB only */
    char *buffered;      /**< additional buffer for holes */
    size_t buf_len;      /**< number of used bytes in the additional buffer for holes */
    size_t buf_size;     /**< allocated size of the buffer for holes */
    size_t hole_count;   /**< hole counter */

    size_t printed;      /**< Total number of printed bytes */
    size_t func_printed; /**< Number of bytes printed by the last function */
};

/**
 * @brief Generic printer of the given format string into the specified output.
 *
 * Does not reset printed bytes. Adds to printed bytes.
 *
 * @param[in] out Output specification.
 * @param[in] format Format string to be printed.
 * @return LY_ERR value.
 */
LY_ERR ly_print_(struct ly_out *out, const char *format, ...);

/**
 * @brief Generic printer of the given string buffer into the specified output.
 *
 * Does not reset printed bytes. Adds to printed bytes.
 *
 * @param[in] out Output specification.
 * @param[in] buf Memory buffer with the data to print.
 * @param[in] len Length of the data to print in the @p buf.
 * @return LY_ERR value.
 */
LY_ERR ly_write_(struct ly_out *out, const char *buf, size_t len);

/**
 * @brief Create a hole in the output data that will be filled later.
 *
 * Adds printed bytes.
 *
 * @param[in] out Output specification.
 * @param[in] len Length of the created hole.
 * @param[out] position Position of the hole, value must be later provided to the ::ly_write_skipped() call.
 * @return LY_ERR value.
 */
LY_ERR ly_write_skip(struct ly_out *out, size_t len, size_t *position);

/**
 * @brief Write data into the hole at given position.
 *
 * Does not change printed bytes.
 *
 * @param[in] out Output specification.
 * @param[in] position Position of the hole to fill, the value was provided by ::ly_write_skip().
 * @param[in] buf Memory buffer with the data to print.
 * @param[in] len Length of the data to print in the @p buf. Not that the length must correspond
 * to the len value specified in the corresponding ::ly_write_skip() call.
 * @return LY_ERR value.
 */
LY_ERR ly_write_skipped(struct ly_out *out, size_t position, const char *buf, size_t len);

#endif /* LY_OUT_INTERNAL_H_ */
