/*
 * Copyright (C) 2019 Weber Yann
 * 
 * This file is part of PyFCGI.
 * 
 * PyFCGI is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 * 
 * PyFCGI is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with PyFCGI.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef __LOGGER_H___
#define __LOGGER_H___

#include "config.h"
#include <syslog.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>

/**@file logger.h
 * @brief PyFCGI logging facility
 * @ingroup conf_logger
 */
/**@defgroup conf_logger Logging configuration
 * @ingroup conf_internal
 */

/**@defgroup log_facility Logger custom facilities */
/**@ingroup log_facility */
#define LOG_GLOBAL 0
/**@ingroup log_facility */
#define LOG_ACCESS 1
/**@ingroup log_facility */
#define LOG_INTERN 2
/**@ingroup log_facility */
#define LOG_WORKER 4
/**@ingroup log_facility */
#define LOG_MASTER 8

#define PYFCGI_LOGGER_MAX 64
#define PYFCGI_LOGGER_FMT_MAX PYFCGI_LOGGER_MAX
#define PYFCGI_LOGGER_FIELD_MAX 24
#define PYFCGI_LOGGER_FMT_PARSE_ERRSZ 64
/**@brief The size of the @ref struct pyfcgi_logger_format_t.buf allocated to
 * the message field */
#define PYFCGI_LOGGER_MSG_BUF_SZ 64

#define PYFCGI_LOG_DTM_LEN 25
#define PYFCGI_LOG_LVL_LEN 7
#define PYFCGI_LOG_TYP_LEN 7
#define PYFCGI_LOG_PID_LEN 6
#define PYFCGI_LOG_PID_FMT "%6d"

#define SYSLOG_syslog syslog
#define SYSLOG_vsyslog vsyslog
#define SYSLOG_EMERG   LOG_EMERG
#define SYSLOG_ALERT   LOG_ALERT
#define SYSLOG_CRIT    LOG_CRIT
#define SYSLOG_ERR     LOG_ERR
#define SYSLOG_WARNING LOG_WARNING
#define SYSLOG_NOTICE  LOG_NOTICE
#define SYSLOG_INFO    LOG_INFO
#define SYSLOG_DEBUG   LOG_DEBUG

#undef LOG_EMERG
#undef LOG_ALERT
#undef LOG_CRIT
#undef LOG_ERR
#undef LOG_WARNING
#undef LOG_NOTICE
#undef LOG_INFO
#undef LOG_DEBUG

/* This way we can mimic syslog and the or'ed level | facility */
//#define LOG_EMERG (1 << 4)
#define LOG_EMERG (2 << 4)
#define LOG_ALERT (2 << 4)
#define LOG_CRIT (3 << 4)
#define LOG_ERR (4 << 4)
#define LOG_WARNING (5 << 4)
#define LOG_NOTICE (6 << 4)
#define LOG_INFO (7 << 4)
#define LOG_DEBUG (8 << 4)

/**@brief Convert a PyFCGI loglevel in a syslog one */
#define PYFCGI_SYSLOG_LVL(lvl) (((lvl & 0xF0) >> 4)-1)

/**@brief Macro checking if syslog is activated and log a message
 * @params int lvl the PyFCGI log level
 * @param char* fmt the message format
 * @see _vsyslog syslog
 */
#define _syslog(lvl, ...) if(conf->flags & PYFCGI_LOG_FSYSLOG) { \
	syslog(PYFCGI_SYSLOG_LVL(lvl), __VA_ARGS__);\
}
#define _vsyslog(lvl, fmt, ap) if(conf->flags & PYFCGI_LOG_FSYSLOG) { \
	vsyslog(PYFCGI_SYSLOG_LVL(lvl), fmt, ap);\
}

/**@brief Macro checking if syslog is activated and log a message using PyFCGI
 * loglevels
 * @params int lvl the PyFCGI log level
 * @param char* fmt the message format
 * @see vsyslog _syslog
 */


/**@defgroup conf_logger_flags Logger confifurations flags
 * @ingroup conf_logger */
/**@ingroup cong_logger_flags */
#define PYFCGI_LOG_FSYSLOG 1
/**@brief Indicate if the logger should try to reopen on failure
 * @warn not implemented
 * @ingroup cong_logger_flags */
#define PYFCGI_LOG_FRETRY 2
/**@brief Exit if failure
 * @warn not implemented
 * @ingroup cong_logger_flags */
#define PYFCGI_LOG_FEXIT_ONFAIL 4

#define PYFCGI_LOGGER_FMT_DEFAULT "{datetime} {ident}[{pid}] {level} {msg}"
#define PYFCGI_LOGGER_TIME_FMT_DEFAULT "%F %T%z"


/**@brief Log level mask
 * @ingroup conf_logger
 * Allow selection of loglevels using a bitwise mask 1 << LEVEL
 */
typedef unsigned char logmask_t;
typedef unsigned char loglvl_t;
typedef struct pyfcgi_logger_s pyfcgi_logger_t;
typedef struct pyfcgi_logger_format_s pyfcgi_logger_format_t;
typedef struct pyfcgi_logger_fmt_field_s pyfcgi_logger_fmt_field_t;
typedef union pyfcgi_logger_fmt_field_u pyfcgi_logger_fmt_value_t;
typedef enum pyfcgi_logger_field_type pyfcgi_logger_field_type_e;
typedef struct strftime_args_s strftime_args_t;
typedef struct ident_args_s ident_args_t;
typedef union pyfcgi_logger_field_args pyfcgi_logger_field_args_u;


static const char* PYFCGI_LOGGER_LVLNAME[] __attribute__((unused)) = {
	" Emerge",
	"  Alert",
	" Critic",
	"  Error",
	"Warning",
	" Notice",
	"   Info",
	"  Debug"};

static const char* PYFCGI_LOGGER_TYPNAME[] __attribute__((unused)) =
	{"Global", "Access", "Internal", "Worker", "Master"} ;


/**@defgroup conf_logger_format Logline format
 * @ingroup conf_logger
 * A small description langage allows to describe wanted logline format.
 * A format is a string with special markup indicating fields. Fields markup
 * are surrounded by '{' and '}' chr. This markup can be divided in multiple
 * subfields separated by ':' chr, but the first field is always the field
 * name.
 *
 * Valid fields are :
 * - {datetime:SIZE:FMT} defines a format and a constant length for date
 * string. By default %F %T%z ISO 8601 date format  + time + tz
 * see @ref PYFCGI_LOGGER_TIME_FMT_DEFAULT
 * - {level} the loglevel (with a constant length of 7)
 * - {facility} the log facility (constant length od 6)
 * - {pid:SIZE} PID with a constant length for pid field
 * - {ident} the defined ident (size is processed when set)
 * - {msg} the log message (can only appears once)
 *
 * @note You can escape '{' and '}' by using '{{' and '}}'
 * @note There is a maximum of 24 fields by format (see 
 * @note All fields can be abbreviate to one character
 * @ref PYFCGI_LOGGER_FIELD_MAX )
 */

struct strftime_args_s
{
	//char **s; // field.buf_ptr
	//size_t max; // field.len
	char *format;
	//const struct tm *tm; // fecthed each time
};

struct ident_args_s
{
	size_t len;
};

union pyfcgi_logger_field_args
{
	strftime_args_t datetime;
	ident_args_t ident;
};

/**@brief Logger format field's type
 * @ingroup conf_logger_format */
enum pyfcgi_logger_field_type
{
	pyfcgi_logger_field_null = 0,
	pyfcgi_logger_field_const = -1,
	pyfcgi_logger_field_datetime = 1,
	pyfcgi_logger_field_level = 2,
	pyfcgi_logger_field_facility = 3,
	pyfcgi_logger_field_pid = 4,
	pyfcgi_logger_field_ppid = 5,
	pyfcgi_logger_field_ident = 6,
	pyfcgi_logger_field_msg = 7,
};

/**@brief Logger format field data
 * @ingroup conf_logger_format */
struct pyfcgi_logger_fmt_field_s
{
	pyfcgi_logger_field_type_e type;

	short known_length;
	size_t len;

	/** @brief pointer on value (interpreted given field type) */
	void *val;
	pyfcgi_logger_field_args_u args;
	/**@brief Points in prefix or sufix buffer */
	char *buf_ptr;
	/**@brief Field offset in msg buffer (prefix or sufix) */
	size_t buf_off;
	/**@brief 1 if in suffix else 0 */
	short suff;
};

/**@brief Logger format data
 * @ingroup conf_logger_format */
struct pyfcgi_logger_format_s
{
	/**@brief String copy of the format */
	char *fmt;
	/**@brief Stores data about fields */
	pyfcgi_logger_fmt_field_t fields[PYFCGI_LOGGER_FIELD_MAX];
	/**@brief field count */
	int nfield;
	/**@brief Preallocated buffer for prefix & suffix */
	char *buf;
	size_t buflen[2];
	/**@brief Message prefix */
	char *prefix;
	/**@brief Message suffix */
	char *suffix;

	char *_msg;
	size_t _msglen;
};

/**@brief Informations on a logger
 * @ingroup conf_logger
 */
struct pyfcgi_logger_s
{
	char *filename;
	int fd;
	logmask_t loglvl;
	logmask_t logtyp;

	size_t fmt_id;
};

/**@brief Logger configuration
 * @ingroup conf_logger
 */
struct pyfcgi_conf_logger_s
{
	/**@brief Or combination of @ref PYFCGI_LOG_SYSLOG or
	 * @ref PYFCGI_LOG_RETRY */
	short flags;
	char *syslog_ident;
	int syslog_facility;
	logmask_t syslog_loglvl;
	logmask_t syslog_logtyp;

	/**@brief PyFCGI internal ident, prefixes all log messages */
	char *ident;
	logmask_t facility;

	pyfcgi_logger_t loggers[PYFCGI_LOGGER_MAX];
	unsigned char logger_sz;

	pyfcgi_logger_format_t formats[PYFCGI_LOGGER_MAX];
	//char **format;
	unsigned char format_sz;

	/**@brief Buffer for message field formating */
	char *msg_buf;
	size_t msg_buf_sz;

	/**@brief Internal pipe to tee(2) the message on loggers (USELESS)*/
	int pipes[2];
};
#include "conf.h"

/**@brief Initiliaze logger conf */
int pyfcgi_logger_init();

/**@brief Stop & free the logger
 * @note also free formats
 */
int pyfcgi_logger_stop();

/**@brief Enable syslog logging with given ident
 * @param char* ident if NULL use current ident
 */
void pyfcgi_logger_enable_syslog(char*);

/**@brief Stop & free an individual logger */
void _pyfcgi_logger_free(pyfcgi_logger_t*);

/**@brief Add a new logger
 * @param char* filename
 * @param logmask_t loglvl a mask indicating wich loglevels should be logged
 * @param logmask_t typemask a mask indicating wich facility should be logged
 * @param char* log format (or NULL for default format)
 */
int pyfcgi_logger_add(const char*, logmask_t, logmask_t, const char*);

/**@brief Add a new format
 * @param char *format
 * @param size_t* idx if not NULL, will contain the format index
 * @return 0 if OK
 */
int pyfcgi_logger_format_add(const char*, size_t*);

/**@brief Parse a format string and populate corresponding 
 * @ref struct pyfgci_logger_format_s
 * @param const char* fmt string
 * @param pyfcgi_logger_format_t* fmt_data
 * @return 0 if no errors
 */
int pyfcgi_logger_parse_format(const char*, pyfcgi_logger_format_t*);

/**@brief Initialize a pyfcgi_logger_format_t.buf attribute (to init the
 * prefix & sufix attributes.
 * @note have to be called when ident is updated
 * @param pyfcgi_logger_format_t* fmt
 * @note called by @ref pyfcgi_logger_add_format but should be called
 * by @ref pyfcgi_logger_parse_format
 */
int pyfcgi_logger_format_bufinit(pyfcgi_logger_format_t*);

/**@brief Parse a field string and populate corresponding
 * @ret struct pyfcgi_logger_field_s
 * @param const char ** ptr on current format pointer
 * @param char * if not NULL and parse error occurs, this string
 * will be set
 * @return 0 if no errors and 1 if parse error
 */
int pyfcgi_logger_parse_field(const char**, const char *,
                              pyfcgi_logger_fmt_field_t*,
                              char[PYFCGI_LOGGER_FMT_PARSE_ERRSZ]);

/**@brief Free allocated memory in given field
 * @param pyfcgi_logger_fmt_field_t* field to free
 */
void pyfcgi_logger_field_free(pyfcgi_logger_fmt_field_t*);

/**@brief Given a field pointer return the size option incrementing
 * ptr
 * @warning do not check if the next character is OK, the caller has to
 * do it
 * @param char** pointer on format
 * @param size_t* size if found will be set to size option. if not found set to
 * 0
 * @return 0 if no error
 */
int pyfcgi_logger_parse_field_sz(const char**, size_t*);

/**@brief Alloc memory by parsing & strdup the strftime format found
 * in field. If not found use default format
 * @note set the @ref struct pyfcgi_logger_fmt_field_s.args field
 * @param const char** ptr
 * @param char** format
 * @return 
 */
int pyfcgi_logger_parse_field_dtfmt(const char**, char**);

/**@brief Return a str repr of given loglevel
 * @warning returned pointer must NOT be freed or modified
 * @return The loglevel name or NULL if error
 */
const char* pyfcgi_logger_value_level(short);
const char* pyfcgi_logger_value_facility(short);

/**@brief Open a logger
 * @param pyfcgi_logger_t
 * @return 0 if no errors
 */
int pyfcgi_logger_open(pyfcgi_logger_t*);

/**@brief Set programm identity for logger
 * @note ident is global to a process
 * @note this function triggers the refresh of the loggers internal
 * buffers if needed (see @ref pyfcgi_logger_format_bufinit() )
 * @param const char* new_ident
 * @return 0 if no error
 */
int pyfcgi_logger_set_ident(const char*);

/**@brief Format a message using a @ref struct pyfcgi_logger_format_s
 * @note alloc and write the logline in the attribute _msg
 * @param pyfcgi_logger_format_t the pyfcgi logger format structure
 * @param loglvl_t the loglevel (see @ref pyfcgi_log() )
 * @param char* message the message sent by user
 * @param size_t len the message len
 * @return NULL if error
 */
char* vpyfcgi_logger_format_message(pyfcgi_logger_format_t *fmt,
	loglvl_t lvl, const char* message, size_t len);

int pyfcgi_log(loglvl_t, const char*, ...);
int vpyfcgi_log(loglvl_t, const char*, va_list);

#endif