/*
 * This file is part of the EasyLogger Library.
 *
 * Copyright (c) 2015-2019, Qintl, <qintl_linux@163.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * 'Software'), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * Function: Save log to file.
 * Created on: 2019-01-05
 */

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

#include <file/elog_file.h>
#include <file/elog_file_cfg.h>

/* initialize OK flag */
static bool init_ok = false;
static FILE *fp = NULL;
static int fd = -1;
static ElogFileCfg local_cfg;

ElogErrCode elog_file_init(void)
{
    ElogErrCode result = ELOG_NO_ERR;
    ElogFileCfg cfg;

    if (init_ok)
        goto __exit;

    elog_file_port_init();

    cfg.name = ELOG_FILE_NAME;
    cfg.max_size = ELOG_FILE_MAX_SIZE;
    cfg.max_rotate = ELOG_FILE_MAX_ROTATE;

    elog_file_config(&cfg);

    init_ok = true;
__exit:
    return result;
}

void elog_file_write(const char *log, size_t size)
{
    ELOG_ASSERT(init_ok);
    ELOG_ASSERT(log);
    struct stat statbuf;

    statbuf.st_size = 0;
    fstat(fd, &statbuf);

    if (unlikely(statbuf.st_size > local_cfg.max_size)) {
        if (local_cfg.max_rotate > 0) {
            elog_file_rotate();
        } else {
            return;
        }
    }

    elog_file_port_lock();

    fwrite(log, size, 1, fp);

#ifdef ELOG_FILE_FLUSH_CAHCE_ENABLE
    fflush(fp);
    fsync(fd);
#endif

    elog_file_port_unlock();
}

void elog_file_deinit(void)
{
    ELOG_ASSERT(init_ok);

    elog_file_port_deinit();
    fclose(fp);
}

void elog_file_config(ElogFileCfg *cfg)
{
    if (fp) {
        fclose(fp);
    }

    elog_file_port_lock();

    local_cfg.name = cfg->name;
    local_cfg.max_size = cfg->max_size;
    local_cfg.max_rotate = cfg->max_rotate;

    fp = fopen(local_cfg.name, "a+");
    if (fp)
        fd = fileno(fp);
    else
        fd = -1;

    elog_file_port_unlock();
}

void elog_file_rotate(void)
{
    if (local_cfg.max_rotate <= 0) return;

    elog_file_port_lock();

    if (fp) {
        fclose(fp);
        fp = NULL;
    }

    /* mv xxx.log.n-1 => xxx.log.n, and xxx.log => xxx.log.0 */
    size_t base = strlen(local_cfg.name);
    char* oldpath = (char*)malloc(base + 10); // use c99 variable length array or alloca(3) instead?
    char* newpath = (char*)malloc(base + 10);
    memcpy(oldpath, local_cfg.name, base);
    memcpy(newpath, local_cfg.name, base);
    int n;
    for (n = local_cfg.max_rotate - 1; n >= 0; --n) {
        sprintf(oldpath + base, n ? ".%d" : "", n-1);
        sprintf(newpath + base, ".%d", n);
        rename(oldpath, newpath);
    }
    free(oldpath);
    free(newpath);

    fp = fopen(local_cfg.name, "a+");
    if (fp)
        fd = fileno(fp);
    else
        fd = -1;

    elog_file_port_unlock();
}