/**
 * Utilities for the quality of service module mod_qos.
 *
 * See http://mod-qos.sourceforge.net/ for further
 * details.
 *
 * Copyright (C) 2020 Pascal Buchbinder
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

static const char revision[] = "$Id: qs_util.c 2595 2020-01-03 06:19:53Z pbuchbinder $";

#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdarg.h>
#include <fcntl.h>
#include <dirent.h>
#include <unistd.h>
#include <errno.h>
#include <pwd.h>

#include "qs_util.h"

/* mutex for counter access */
static pthread_mutex_t m_qs_lock_cs;
/* online/offline mode */
static int m_qs_offline = 0;
/* internal clock for offline analysis
 * stores time in seconds */
static time_t m_qs_virtualSystemTime = 0;

/* ----------------------------------
 * functions
 * ---------------------------------- */

/**
 * man:
 * - escape special chars, like "\" and "-"
 * - wipe leading spaces
 * - wipe tailing LF
 */
void qs_man_print(int man, const char *fmt, ...) {
  char bufin[4096];
  char bufout[4096];
  va_list args;
  int i = 0;
  int j = 0;
  memset(bufin, 0, 4096);
  va_start(args, fmt);
  vsprintf(bufin, fmt, args);
  if(man) {
    // wipe leading spaces
    //    while(bufin[i] == ' ' && bufin[i+1] == ' ') {
    while(bufin[i] == ' ') {
      i++;
    }
  }
  while(bufin[i] && j < 4000) {
    // escape "\\" and "-" for man page
    if(man && (bufin[i] == '\\' || bufin[i] == '-')) {
      bufout[j] = '\\';
      j++;
    }
    if(bufin[i] == '\n') {
      if(man) {
	// skip LF for man page
	i++;
      } else {
	// keep LF
	bufout[j] = bufin[i];
	i++;
	j++;
      }
    } else {
      // standard char
      bufout[j] = bufin[i];
      i++;
      j++;
    }
  }
  bufout[j] = '\0';
  printf("%s", bufout);
  if(man) {
    printf(" ");
  }
}

// escape only
void qs_man_println(int man, const char *fmt, ...) {
  char bufin[4096];
  char bufout[4096];
  va_list args;
  int i = 0;
  int j = 0;
  memset(bufin, 0, 4096);
  va_start(args, fmt);
  vsprintf(bufin, fmt, args);
  while(bufin[i] && j < 4000) {
    // escape "\\" and "-" for man page
    if(man && (bufin[i] == '\\' || bufin[i] == '-')) {
      bufout[j] = '\\';
      j++;
    }
    // standard char
    bufout[j] = bufin[i];
    i++;
    j++;
  }
  bufout[j] = '\0';
  printf("%s", bufout);
}

char *qs_CMD(const char *cmd) {
  char *buf = calloc(1024, 1);
  int i = 0;
  while(cmd[i] && i < 1023) {
    buf[i] = toupper(cmd[i]);
    i++;
  }
  buf[i] = '\0';
  return buf;
}

/* io --------------------------------------------------------- */
/*
 * reads a line from stdin
 *
 * @param s Buffer to write line to
 * @param n Length of the buffer
 * @return 0 on EOF, or 1 if there is more data to read
 */
int qs_getLine(char *s, int n) {
  int i = 0;
  while (1) {
    s[i] = (char)getchar();
    if(s[i] == EOF) return 0;
    if (s[i] == CR) {
      s[i] = getchar();
    }
    if ((s[i] == 0x4) || (s[i] == LF) || (i == (n - 1))) {
      s[i] = '\0';
      return 1;
    }
    ++i;
  }
}

/*
 * reads a line from file
 *
 * @param s Buffer to write line to
 * @param n Length of the buffer
 * @return 0 on EOF, or 1 if there is more data to read
 */
int qs_getLinef(char *s, int n, FILE *f) {
  register int i = 0;
  while (1) {
    s[i] = (char) fgetc(f);
    if (s[i] == CR) {
      s[i] = fgetc(f);
    }
    if ((s[i] == 0x4) || (s[i] == LF) || (i == (n - 1))) {
      s[i] = '\0';
      return (feof(f) ? 1 : 0);
    }
    ++i;
  }
}

/* time ------------------------------------------------------- */
/*
 * We implement our own time which is either
 * the system time (real time) or the time from
 * the access log lines (offline) if m_qs_offline
 * has been set (use qs_set2OfflineMode() to enable
 * the offline mode).
 *
 * @param tme Set to the time since the Epoch in seconds.
 */
void qs_time(time_t *tme) {
  if(m_qs_offline) {
    /* use virtual time from the access log */
    *tme = m_qs_virtualSystemTime;
  } else {
    time(tme);
  }
}

/**
 * Sets time measurement (qs_time()) to offline mode.
 */
void qs_set2OfflineMode() {
  m_qs_offline = 1;
}

/* 
 * Updates the virtual time.
 */
void qs_setTime(time_t tme) {
  m_qs_virtualSystemTime = tme;
}

/* synchronisation -------------------------------------------- */
/*
 * locks all counter
 */
void qs_csLock() {
  pthread_mutex_lock(&m_qs_lock_cs);
}

/*
 * unlocks all counter
 */
void qs_csUnLock() {
  pthread_mutex_unlock(&m_qs_lock_cs);
}

/*
 * init locks
 */
void qs_csInitLock() {
  pthread_mutex_init(&m_qs_lock_cs, NULL);
}

/* logs ------------------------------------------------------- */

/**
 * Keeps only the specified number of files
 *
 * @param file_name Absolute file name
 * @param generations Number of files to keep
 */
void qs_deleteOldFiles(const char *file_name, int generations) {
  DIR *dir;
  char dirname[QS_HUGE_STR];
  char *p;
  memset(dirname, 0, QS_HUGE_STR);
  if(strlen(file_name) > (QS_HUGE_STR - 12)) {
    // invalid file length
    return;
  }
  if(strrchr(file_name, '/') == NULL) {
    sprintf(dirname, "./%s", file_name);
  } else {
    strcpy(dirname, file_name);
  }
  p = strrchr(dirname, '/');
  p[0] = '\0'; p++;
  dir = opendir(dirname);
  if(dir) {
    int num = 0;
    struct dirent *de;
    char filename[QS_HUGE_STR];
    snprintf(filename, sizeof(filename), "%s.20", p);
    /* determine how many files to delete */
    while((de = readdir(dir)) != 0) {
      if(de->d_name && (strncmp(de->d_name, filename, strlen(filename)) == 0)) {
	num++;
      }
    }
    /* delete the oldest files (assumes they are ordered by their creation date) */
    while(num > generations) {
      char old[QS_HUGE_STR];
      old[0] = '\0';
      rewinddir(dir);
      while((de = readdir(dir)) != 0) {
	if(de->d_name && (strncmp(de->d_name, filename, strlen(filename)) == 0)) {
	  if(strcmp(old, de->d_name) > 0) {
	    snprintf(old, sizeof(old), "%s", de->d_name);
	  } else {
	    if(old[0] == '\0') {
	      snprintf(old, sizeof(old), "%s", de->d_name);
	    }
	  }
	}
      }
      {
	/* build abs path and delete it */
	char unl[QS_HUGE_STR];
	snprintf(unl, sizeof(unl), "%s/%s", dirname, old);
	unlink(unl);
      }
      num--;
    }
    closedir(dir);
  }
}

/* user ------------------------------------------------------- */
void qs_setuid(const char *username, const char *cmd) {
  if(username && getuid() == 0) {
    struct passwd *pwd = getpwnam(username);
    uid_t uid, gid;
    if(pwd == NULL) {
      fprintf(stderr, "[%s] failed to switch user: unknown user id '%s'\n", cmd, username);
      exit(1);
    }
    uid = pwd->pw_uid;
    gid = pwd->pw_gid;
    setgid(gid);
    setuid(uid);
    if(getuid() != uid) {
      fprintf(stderr, "[%s] setuid failed (%s,%d)\n", cmd, username, uid);
      exit(1);
    }
    if(getgid() != gid) {
      fprintf(stderr, "[%s] setgid failed (%d)\n", cmd, gid);
      exit(1);
    }
  }
}