/* Copyright Yann Weber <asmsh@yannweb.net>
   This file is part of asmsh.

   asmsh is free software: you can redistribute it and/or modify it under the
   terms of the GNU General Public License as published by the Free Software
   Foundation, either version 3 of the License, or any later version.
   
   asmsh 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 General Public License for more
   details.
   
   You should have received a copy of the GNU General Public License along
   with asmsh. If not, see <https://www.gnu.org/licenses/>.
*/
#include "logger.h"

asmsh_logger_t *_default_logger=NULL;

int asmsh_logger_setup(asmsh_logger_t *logger)
{
	if(logger)
	{
		_default_logger = logger;
		return 0;
	}
	_default_logger = asmsh_logger_new(ASMSH_WARN);

	return (_default_logger == NULL) ? -1 : 0;
}


asmsh_logger_t* asmsh_logger_new(asmsh_loglevel_t min_level)
{
	asmsh_logger_t *res;
	int err;

	if((res = malloc(sizeof(*res))) == NULL)
	{
		err = errno;
		dprintf(2, "Error allocating logger");
		errno = err;
		return NULL;
	}
	if((res->msgs = malloc(ASMSH_LOG_BUFFER_ALLOC)) == NULL)
	{
		err = errno;
		dprintf(2, "Error allocating logger's buffer");
		goto err_msgs;
	}
	res->min_level = min_level;
	res->msgs_sz = 0;
	res->msgs_alloc = ASMSH_LOG_BUFFER_ALLOC;
	res->nxt = res->msgs;
	res->fmt = asmsh_log_default_fmt;

	return res;

err_msgs:
	free(res);
	errno = err;
	return NULL;
}


void asmsh_logger_free(asmsh_logger_t* logger)
{
	if(logger->msgs) { free(logger->msgs); }
	free(logger);
}

int asmsh_logger_dprint_fmt(int fd, asmsh_logger_t *logger, asmsh_log_fmt_f *custom_fmt)
{
	const int BUF_ALLOC = 4096;
	char *buf;
	int bufsz, ret, res;
	asmsh_log_msg_t *cur;
	asmsh_log_fmt_f *fmt;

	fmt = custom_fmt?custom_fmt:logger->fmt;

	if((buf = malloc(BUF_ALLOC)) == NULL)
	{
		return -1;
	}
	bufsz = BUF_ALLOC;

	cur = (asmsh_log_msg_t*)logger->msgs;
	res = 0;
	while(cur != logger->nxt)
	{
		ret = fmt(cur, buf, bufsz);
		if(ret < 0)
		{
			perror("Unable to format log message");
			continue;
		}
		else if (ret == BUF_ALLOC)
		{
			buf[BUF_ALLOC-1] = '\0';
			for(int i=0; i<3; i++)
			{
				buf[BUF_ALLOC-(2+i)] = '.';
			}
		}
		res += dprintf(fd, buf); /// TODO use write & check result
		cur = cur->nxt;
	}
	free(buf);
	logger->nxt = logger->msgs;
	return res;
}

int asmsh_logger_strdup(asmsh_logger_t *logger, char **result, size_t *res_sz)
{
	const int BUF_ALLOC = 4096;
	size_t buf_sz;
	asmsh_log_msg_t *cur;
	char *buf_ptr;
	int ret;

	*res_sz = 0;
	buf_ptr = *result = malloc(buf_sz = BUF_ALLOC);
	if(*result == NULL)
	{
		perror("Enable to allocate buffer for log messages");
		return -1;
	}

	cur = (asmsh_log_msg_t*)logger->msgs;
	while(cur != logger->nxt)
	{
		ret = logger->fmt(cur, buf_ptr, buf_sz - *res_sz);
		if(ret == (*res_sz - buf_sz))
		{
			buf_sz += BUF_ALLOC;
			void *tmp = realloc(*result, buf_sz);
		}
		else
		{
			*res_sz += ret;
			cur = cur->nxt;
		}
	}
}

int asmsh_log(asmsh_logger_t *logger, asmsh_loglevel_t lvl, const char caller[],
		const char *msg)
{
	if(!logger)
	{
		logger = _default_logger = asmsh_logger_new(ASMSH_TRACE);
	}
	if(lvl < logger->min_level) { return 0; }

	size_t caller_len, msg_len, total_len;

	caller_len = strlen(caller);
	msg_len = strlen(msg);
	total_len = msg_len  + caller_len + 2 + sizeof(asmsh_log_msg_t);

	if(logger->msgs_alloc <= logger->msgs_sz + total_len)
	{
		void *tmp;
		logger->msgs_alloc += ASMSH_LOG_BUFFER_ALLOC;
		tmp = realloc(logger->msgs, logger->msgs_alloc);
		if(tmp <= 0)
		{
			return -1;
		}
		if(tmp != logger->msgs)
		{
			logger->nxt = tmp + ((void*)logger->nxt - (void*)logger->msgs);
		}
		logger->msgs = tmp;
	}
	if(logger->msgs_alloc <= logger->msgs_sz + total_len)
	{
		// still to short just after realloc, more than
		// ASMSH_LOG_BUFFER_ALLOC is needed, something seems
		// to be wrong
		errno = EMSGSIZE;
		return -1;
	}

	logger->msgs_sz += total_len;

	logger->nxt->level = lvl;
	if(time(&(logger->nxt->timestamp)) < 0)
	{
		return -1;
	}
	logger->nxt->caller = (char*)((logger->nxt)+1);
	logger->nxt->msg = logger->nxt->caller + caller_len + 1;

	strncpy(logger->nxt->caller, caller, caller_len+1);
	strncpy(logger->nxt->msg, msg, msg_len+1);

	logger->nxt->nxt = (asmsh_log_msg_t*)((void*)logger->nxt->msg+total_len);
	logger->nxt = logger->nxt->nxt;

	return 0;

}

const char * asmsh_loglevel_name(asmsh_loglevel_t lvl)
{
	switch(lvl)
	{
		case ASMSH_TRACE:
			return "TRACE";
		case ASMSH_DEBUG:
			return "DEBUG";
		case ASMSH_INFO:
			return "INFO";
		case ASMSH_WARN:
			return "WARN";
		case ASMSH_ERR:
			return "ERR";
		case ASMSH_FATAL:
			return "FATAL";
		default:
			return "UNKNW";
	}
}

int asmsh_log_default_fmt(asmsh_log_msg_t *msg, char *res, int sz)
{
	int ret;
	struct tm msg_tm;
	char dtstr[32];

	if(gmtime_r(&msg->timestamp, &msg_tm) == NULL)
	{
		strncpy(res, "DATETIME ERROR", sz);
		return -1;
	}

	if(strftime(dtstr, sizeof(dtstr), "%FT%H:%M:%S+00:00", &msg_tm) == 0)
	{
		strncpy(res, "DATETIME FMT ERROR", sz);
		return -1;
	}

	ret = snprintf(res, sz, "%s [%s](%s) : %s\n",
			dtstr, asmsh_loglevel_name(msg->level),
			msg->caller, msg->msg);
	return ret;
}


int asmsh_log_lvl_fmt(asmsh_log_msg_t *msg, char *res, int sz)
{
	int ret;

	ret = snprintf(res, sz, "%s: %s\n",
			asmsh_loglevel_name(msg->level),
			msg->msg);
	return ret;
}