/**
 * @file mce-log.c
 * Logging functions for Mode Control Entity
 * <p>
 * Copyright (c) 2006 - 2007, 2010 Nokia Corporation and/or its subsidiary(-ies).
 * Copyright (c) 2012 - 2020 Jolla Ltd.
 * Copyright (c) 2020 Open Mobile Platform LLC.
 * <p>
 * @author David Weinehall <david.weinehall@nokia.com>
 * @author Simo Piiroinen <simo.piiroinen@jollamobile.com>
 *
 * mce is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License
 * version 2.1 as published by the Free Software Foundation.
 *
 * mce 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with mce.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifdef OSSOLOG_COMPILE

#include "mce-log.h"

#include <sys/time.h>

#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <fnmatch.h>

#include <glib/gprintf.h>

static unsigned int logverbosity = LL_WARN;	/**< Log verbosity */
static int logtype = MCE_LOG_STDERR;		/**< Output for log messages */
static char *logname = NULL;

/** Get process identity to use for logging
 *
 * Will default to "mce" before mce_log_open() and after mce_log_close().
 */
static const char *mce_log_name(void)
{
	return logname ?: "mce";
}

/** Get monotonic time as struct timeval */
static void monotime(struct timeval *tv)
{
	struct timespec ts;
	clock_gettime(CLOCK_BOOTTIME, &ts);
	TIMESPEC_TO_TIMEVAL(tv, &ts);
}
static void timestamp(struct timeval *tv)
{
	static struct timeval start, prev;
	struct timeval diff;
	monotime(tv);
	if( !timerisset(&start) )
		prev = start = *tv;
	timersub(tv, &prev, &diff);
	if( diff.tv_sec >= 4 ) {
		timersub(tv, &start, &diff);
		fprintf(stderr, "%s: T+%ld.%03ld %s\n\n",
			mce_log_name(),
			(long)diff.tv_sec, (long)(diff.tv_usec/1000),
			"END OF BURST");
		fflush(stderr);
		start = *tv;
	}
	prev = *tv;
	timersub(tv, &start, tv);
}

/** Make sure loglevel is in the supported range
 *
 * @param loglevel level to check
 *
 * @return log level clipped to LL_CRIT ... LL_DEBUG range
 */
static loglevel_t mce_log_level_clip(loglevel_t loglevel)
{
	if( loglevel <= LL_MINIMUM ) {
		loglevel = LL_MINIMUM;
	}
	else if( loglevel > LL_MAXIMUM ) {
		loglevel = LL_MAXIMUM;
	}
	return loglevel;
}

/** Get level indication tag to include in stderr logging
 *
 * @param loglevel level for the message
 *
 * @return level indication string
 */
static const char *mce_log_level_tag(loglevel_t loglevel)
{
	const char *res = "?";
	switch( loglevel ) {
	case LL_CRUCIAL:res = "T"; break;
	case LL_EXTRA:  res = "X"; break;
	case LL_CRIT:   res = "C"; break;
	case LL_ERR:    res = "E"; break;
	case LL_WARN:   res = "W"; break;
	case LL_NOTICE: res = "N"; break;
	case LL_INFO:   res = "I"; break;
	case LL_DEBUG:  res = "D"; break;
	default: break;
	}
	return res;
}

/** Looking at white (ascii) character predicate
 */
static inline bool mce_log_white_p(const char *str)
{
	int c = (unsigned char)*str;
	return (c > 0x00) && (c <= 0x20);
}

/** Looking at non-white (ascii) character predicate
 */
static inline bool mce_log_black_p(const char *str)
{
	int c = (unsigned char)*str;
	return c > 0x20;
}

/** Strip whitespace from log string, similarly to what syslog does
 */
static char *mce_log_strip_string(char *str)
{
	if( !str )
		goto EXIT;

	char *src = str;
	char *dst = str;

	// skip leading white space
	while( mce_log_white_p(src) ) ++src;

	for( ;; ) {
		// copy non-white as-is
		while( mce_log_black_p(src) ) *dst++ = *src++;

		// skip internal / trailing white space
		while( mce_log_white_p(src) ) ++src;

		if( !*src ) break;

		// compress internal whitespace to single space
		*dst++ = ' ';
	}
	*dst = 0;
EXIT:
	return str;
}

/* There is false positive warning during compilation:
 *
 * "function might be possible candidate for 'gnu_printf' format attribute"
 *
 * Instead of disabling the whole check via -Wno-suggest-attribute=format,
 * use pragmas locally to sweep the issue under carpet...
 */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"

void mce_log_unconditional_va(loglevel_t loglevel, const char *const file,
		    const char *const function, const char *const fmt, va_list va)
{
    gchar *msg = 0;

    g_vasprintf(&msg, fmt, va);

    if( file && function ) {
	gchar *tmp = g_strconcat(file, ": ", function, "(): ",
				 mce_log_strip_string(msg), NULL);
	g_free(msg), msg = tmp;
    }

    if (logtype == MCE_LOG_STDERR) {
	struct timeval tv;
	timestamp(&tv);
	fprintf(stderr, "%s: T+%ld.%03ld %s: %s\n",
		mce_log_name(),
		(long)tv.tv_sec, (long)(tv.tv_usec/1000),
		mce_log_level_tag(loglevel),
		msg);
	fflush(stderr);
    } else {
	/* Use NOTICE priority when reporting LL_EXTRA
	 * and LL_CRUCIAL logging */
	switch( loglevel ) {
	case LL_EXTRA:
	case LL_CRUCIAL:
	    loglevel = LL_NOTICE;
	    break;
	default:
	    break;
	}

	/* loglevels are subset of syslog priorities, so
	 * we can use loglevel as is for syslog priority */
	syslog(loglevel, "%s", msg);
    }

    g_free(msg);
}

#pragma GCC diagnostic pop

void mce_log_unconditional(loglevel_t loglevel, const char *const file,
		 const char *const function, const char *const fmt, ...)
{
    va_list va;
    va_start(va, fmt);
    mce_log_unconditional_va(loglevel, file, function, fmt, va);
    va_end(va);
}

/**
 * Log debug message with optional filename and function name attached
 *
 * @param loglevel The level of severity for this message
 * @param fmt The format string for this message
 * @param ... Input to the format string
 */
void mce_log_file(loglevel_t loglevel, const char *const file,
		  const char *const function, const char *const fmt, ...)
{
	loglevel = mce_log_level_clip(loglevel);

	if( mce_log_p_(loglevel, file, function) ) {
	    va_list va;
	    va_start(va, fmt);
	    mce_log_unconditional_va(loglevel, file, function, fmt, va);
	    va_end(va);
	}
}

/**
 * Set log verbosity
 * messages with loglevel higher than or equal to verbosity will be logged
 *
 * @param verbosity minimum level for log level
 */
void mce_log_set_verbosity(int verbosity)
{
	if( verbosity < LL_MINIMUM )
		verbosity = LL_MINIMUM;
	else if( verbosity > LL_MAXIMUM )
		verbosity = LL_MAXIMUM;

	logverbosity = verbosity;
}

/** Set log verbosity
 *
 * @return current verbosity level
 */
int mce_log_get_verbosity(void)
{
  return logverbosity;
}

/**
 * Open log
 *
 * @param name identifier to use for log messages
 * @param facility the log facility; normally LOG_USER or LOG_DAEMON
 * @param type log type to use; MCE_LOG_STDERR or MCE_LOG_SYSLOG
 */
void mce_log_open(const char *const name, const int facility, const int type)
{
	logtype = type;
	logname = g_strdup(name);

	if (logtype == MCE_LOG_SYSLOG)
		openlog(name, LOG_PID | LOG_NDELAY, facility);
}

/**
 * Close log
 */
void mce_log_close(void)
{
	/* Logging (to stderr) after this will use default identity */
	g_free(logname), logname = 0;

	/* Any further syslog() calls will automatically reopen */
	if (logtype == MCE_LOG_SYSLOG)
		closelog();
}

static GSList     *mce_log_patterns = 0;
static GHashTable *mce_log_functions = 0;

void mce_log_add_pattern(const char *pat)
{
	// NB these are never released by desing

	mce_log_patterns = g_slist_prepend(mce_log_patterns, strdup(pat));

	if( !mce_log_functions )
		mce_log_functions = g_hash_table_new_full(g_str_hash,
							  g_str_equal,
							  free, 0);
}

static bool mce_log_check_pattern(const char *func)
{
	gpointer hit = 0;

	if( !mce_log_functions )
		goto EXIT;

	if( (hit = g_hash_table_lookup(mce_log_functions, func)) )
		goto EXIT;

	hit = GINT_TO_POINTER(1);

	for( GSList *item = mce_log_patterns; item; item = item->next ) {
		const char *pat = item->data;
		if( fnmatch(pat, func, 0) != 0 )
			continue;
		hit = GINT_TO_POINTER(2);
		break;
	}
	g_hash_table_replace(mce_log_functions, strdup(func), hit);

EXIT:
	return GPOINTER_TO_INT(hit) > 1;
}

/**
 * Log level testing predicate
 *
 * For testing whether given level of logging is allowed
 * before spending cpu time for gathering parameters etc
 *
 * @param loglevel level of logging we might do
 *
 * @return 1 if logging at givel level is enabled, 0 if not
 */
int mce_log_p_(loglevel_t loglevel,
	       const char *const file,
	       const char *const func)
{
	if( mce_log_functions && file && func ) {
		char temp[256];
		snprintf(temp, sizeof temp, "%s:%s", file, func);
		if( mce_log_check_pattern(temp) )
			return true;
	}

	/* LL_EXTRA & LL_CRUCIAL are evaluated as WARNING level */
	switch( loglevel ) {
	case LL_EXTRA:
	case LL_CRUCIAL:
		loglevel = LL_WARN;;
		break;
	default:
		break;
	}

	return logverbosity >= loglevel;
}

#endif /* OSSOLOG_COMPILE */