/**
 * @file log.h
 * @author Radek Krejci <rkrejci@cesnet.cz>
 * @brief Logger manipulation routines and error definitions.
 *
 * Copyright (c) 2015 - 2018 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_LOG_H_
#define LY_LOG_H_

#ifdef __cplusplus
extern "C" {
#endif

/* dummy context structure */
struct ly_ctx;

/**
 * @defgroup log Logger
 * @{
 *
 * Publicly visible functions and values of the libyang logger. For more
 * information, see \ref howtologger.
 */

/**
 * @typedef LY_LOG_LEVEL
 * @brief Verbosity levels of the libyang logger.
 */
typedef enum
{
    LY_LLERR = 0, /**< Print only error messages, default value. */
    LY_LLWRN = 1, /**< Print error and warning messages. */
    LY_LLVRB = 2, /**< Besides errors and warnings, print some other verbose messages. */
    LY_LLDBG = 3 /**< Print all messages including some development debug messages (be careful,
     without subsequently calling ly_verb_dbg() no debug messages will be printed!). */
} LY_LOG_LEVEL;

/**
 * @brief Set logger verbosity level.
 * @param[in] level Verbosity level.
 * @return Previous verbosity level.
 */
LY_LOG_LEVEL ly_verb (LY_LOG_LEVEL level);

/**
 * @defgroup logopts Logging options
 * @ingroup logger
 *
 * Logging option bits of libyang.
 *
 * @{
 */
#define LY_LOLOG        0x01 /**< Log messages normally, using callback if set. If not set, messages will
                                  not be printed by libyang. */
#define LY_LOSTORE      0x02 /**< Store any generated errors or warnings, never verbose or debug messages.
                                  Note that if #LY_LOLOG is not set then verbose and debug messages are always lost. */
#define LY_LOSTORE_LAST 0x06 /**< Store any generated errors or warnings but only the last message, always overwrite
                                  the previous one. */

/**
 * @}
 */

/**
 * @brief Set additional logger options. Default is #LY_LOLOG | #LY_LOSTORE_LAST.
 *
 * @param[in] opts Bitfield of @ref logopts.
 * @return Previous logger options.
 */
int ly_log_options (int opts);

#ifndef NDEBUG

/**
 * @defgroup dbggroup Debug message groups
 * @ingroup log
 *
 * Selected displayed debug message groups.
 *
 * @{
 */

#define LY_LDGDICT  0x01 /**< Dictionary additions and deletions. */
#define LY_LDGYANG  0x02 /**< YANG parser messages. */
#define LY_LDGYIN   0x04 /**< YIN parser messages. */
#define LY_LDGXPATH 0x08 /**< XPath parsing end evaluation. */
#define LY_LDGDIFF  0x10 /**< Diff processing and creation. */

/**
 * @}
 */

/**
 * @brief Enable specific debugging messages (independent of log level).
 * @param[in] dbg_groups Bitfield of enabled debug message groups (see @ref dbggroup).
 */
void ly_verb_dbg (int dbg_groups);

#endif

/**
 * @brief Set logger callback.
 *
 * !IMPORTANT! If an error has a specific error-app-tag defined in the model, it will NOT be set
 *             at the time of calling this callback. It will be set right after, so to retrieve it
 *             it must be checked afterwards with ly_errapptag().
 *
 * @param[in] clb Logging callback.
 * @param[in] path flag to resolve and provide path as the third parameter of the callback function. In case of
 *            validation and some other errors, it can be useful to get the path to the problematic element. Note,
 *            that according to the tree type and the specific situation, the path can slightly differs (keys
 *            presence) or it can be NULL, so consider it as an optional parameter. If the flag is 0, libyang will
 *            not bother with resolving the path.
 */
void ly_set_log_clb (void(*clb) (LY_LOG_LEVEL level, const char *msg, const char *path), int path);

/**
 * @brief Get logger callback.
 * @return Logger callback (can be NULL).
 */
void (*ly_get_log_clb (void)) (LY_LOG_LEVEL, const char *, const char *);

/** @} log */

/**
 * @defgroup errors Error information
 * @{
 */

/**
 * @typedef LY_ERR
 * @brief libyang's error codes returned by the libyang functions.
 */
typedef enum
{
    LY_SUCCESS = 0, /**< no error, not set by functions, included just to complete #LY_ERR enumeration */
    LY_EMEM,        /**< Memory allocation failure */
    LY_ESYS,        /**< System call failure */
    LY_EINVAL,      /**< Invalid value */
    LY_EEXIST,      /**< Item already exists */
    LY_ENOTFOUND,   /**< Item does not exists */
    LY_EINT,        /**< Internal error */
    LY_EVALID,      /**< Validation failure */
    LY_EPLUGIN,     /**< Error reported by a plugin */
    LY_EDENIED,     /**< Operation is not allowed */
    LY_EOTHER       /**< Unknown error */
} LY_ERR;

/**
 * @typedef LY_VECODE
 * @brief libyang's codes of validation error. Whenever ly_errno is set to LY_EVALID, the ly_vecode is also set
 * to the appropriate LY_VECODE value.
 * @ingroup logger
 */
typedef enum {
    LYVE_SUCCESS = 0,  /**< no error */
    LYVE_SYNTAX,       /**< generic syntax error */
    LYVE_SYNTAX_YANG,  /**< YANG-related syntax error */
    LYVE_REFERENCE,    /**< invalid referencing or using an item */
    LYVE_XPATH,        /**< invalid XPath expression */
    LYVE_SEMANTICS     /**< generic semantic error */
} LY_VECODE;

/**
 * @brief Libyang full error structure.
 */
struct ly_err_item {
    LY_LOG_LEVEL level;
    LY_ERR no;
    LY_VECODE vecode;
    char *msg;
    char *path;
    char *apptag;
    struct ly_err_item *next;
    struct ly_err_item *prev; /* first item's prev points to the last item */
};

/**
 * @brief Get the last (thread, context-specific) validation error code.
 *
 * This value is set only if ly_errno is #LY_EVALID.
 *
 * @param[in] ctx Relative context.
 * @return Validation error code.
 */
LY_VECODE ly_vecode(const struct ly_ctx *ctx);

/**
 * @brief Get the last (thread, context-specific) error code.
 *
 * @param[in] ctx Relative context.
 * @return LY_ERR value of the last error code.
 */
LY_ERR ly_errcode(const struct ly_ctx *ctx);

/**
 * @brief Get the last (thread, context-specific) error message. If the coresponding module defined
 * a specific error message, it will be used instead the default one.
 *
 * Sometimes, the error message is extended with path of the element where the problem is.
 * The path is available via ly_errpath().
 *
 * @param[in] ctx Relative context.
 * @return Text of the last error message, empty string if there is no error.
 */
const char *ly_errmsg(const struct ly_ctx *ctx);

/**
 * @brief Get the last (thread, context-specific) path of the element where was an error.
 *
 * The path always corresponds to the error message available via ly_errmsg(), so
 * whenever a subsequent error message is printed, the path is erased or rewritten.
 * The path reflects the type of the processed tree - data path for data tree functions
 * and schema path in case of schema tree functions. In case of processing YIN schema
 * or XML data, the path can be just XML path. In such a case, the corresponding
 * ly_vecode (value 1-3) is set.
 *
 * @param[in] ctx Relative context.
 * @return Path of the error element, empty string if error path does not apply to the last error.
 */
const char *ly_errpath(const struct ly_ctx *ctx);

/**
 * @brief Get the last (thread, context-specific) error-app-tag if there was a specific one defined
 * in the module for the last error.
 *
 * The app-tag always corresponds to the error message available via ly_errmsg(), so
 * whenever a subsequent error message is printed, the app-tag is erased or rewritten.
 *
 * @param[in] ctx Relative context.
 * @return Error-app-tag of the last error, empty string if the error-app-tag does not apply to the last error.
 */
const char *ly_errapptag(const struct ly_ctx *ctx);

/**
 * @brief Get the first (thread, context-specific) generated error structure.
 *
 * @param[in] ctx Relative context.
 * @return First error structure (can be NULL), do not modify!
 */
struct ly_err_item *ly_err_first(const struct ly_ctx *ctx);

/**
 * @brief Print the error structure as if just generated.
 *
 * @param[in] eitem Error item structure to print.
 */
void ly_err_print(struct ly_err_item *eitem);

/**
 * @brief Free error structures from a context.
 *
 * If \p eitem is not set, free all the error structures.
 *
 * @param[in] ctx Relative context.
 * @param[in] eitem Oldest error structure to remove, optional.
 */
void ly_err_clean(struct ly_ctx *ctx, struct ly_err_item *eitem);

/** @} errors */

#ifdef __cplusplus
}
#endif

#endif /* LY_LOG_H_ */