/*
 * This file is part of blabouncer (https://www.blatech.co.uk/l_bratch/blabouncer).
 * Copyright (C) 2019 Luke Bratch <luke@bratch.co.uk>.
 *
 * Blabouncer 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, version 3.
 *
 * Blabouncer 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 blabouncer. If not, see <http://www.gnu.org/licenses/>.
*/

#include "functions.h"

// Global debug control
extern int debug;
extern char debugpath[PATH_MAX];
extern int background;

// Internal function just to replace nick in server greeting strings
// (as in ":servername 00x oldnick :Blablabla" -> ":servername 00x newnick :Blablabla")
void updategreetingnick(char *greeting, char *greetingnum, char *newnick, char *oldnick) {
  debugprint(DEBUG_FULL, "updategreetingnick(): '%s' '%s' '%s' '%s'.\n", greeting, greetingnum, newnick, oldnick);

  // Find the position of the old nick in the current greeting
  char searchstr[MAXDATASIZE];
  snprintf(searchstr, MAXDATASIZE, " %s %s :", greetingnum, oldnick);
  char *ret;
  ret = strstr(greeting, searchstr);

  // If ret not found, try again without the colon (e.g. for greeting 004)
  if (ret == NULL) {
    snprintf(searchstr, MAXDATASIZE, " %s %s ", greetingnum, oldnick);
    ret = strstr(greeting, searchstr);
  }

  // Perhaps the new nick is already present (seen for instance when connecting to another bouncer like Miau)
  if (ret == NULL) {
    snprintf(searchstr, MAXDATASIZE, " %s %s ", greetingnum, newnick);
    ret = strstr(greeting, searchstr);
    if (ret != NULL) {
      debugprint(DEBUG_FULL, "updategreetingnick(): newnick is already present, returning.\n");
      return;
    }
  }

  // If ret *still* not found, abandon ship
  if (ret == NULL) {
    debugprint(DEBUG_CRIT, "Error updating greeting string, substring not found.  Exiting!\n");
    printf("Error updating greeting string, substring not found.  Exiting!\n");
    exit(1);
  }

  int pos = ret - greeting + 5; // +5 for " 001 "

  // Copy the start of the old greeting into a new string
  char greetingtmp[MAXDATASIZE];
  strncpy(greetingtmp, greeting, pos);
  // Terminate it
  greetingtmp[pos] = '\0';

  // Now smash everything (start of old greeting + new nick + remainder of old greeting)
  // together into the new greeting, put in a new temporary string
  char greetingtmp2[MAXDATASIZE];
  if (!snprintf(greetingtmp2, MAXDATASIZE, "%s%s %s", greetingtmp, newnick, greeting + pos + strlen(oldnick) + 1)) {
    fprintf(stderr, "Error while preparing new greeting string!\n");
    debugprint(DEBUG_CRIT, "Error while preparing new greeting string!\n");
    exit(1);
  }

  // And finally copy back to source string
  strcpy(greeting, greetingtmp2);

  debugprint(DEBUG_FULL, "updategreetingnick(): Built new greeting '%s' '%s', length '%ld'.\n", greetingnum, greeting, strlen(greeting));
}

// Write debug string to file.
// Debug level is provided by level, set to one of DEBUG_CRIT, DEBUG_SOME or DEBUG_FULL.
// Debug is only written if the global int "debug" is greater than or equal to the level.
void debugprint(int level, char *format, ...) {
  // Stop here if the user's debug level is less than the level of the current message
  if (debug < level) return;

  if (strlen(debugpath) < 1) {
    // debugpath isn't set, we can't do anything here
    return;
  }

  va_list args;
  va_start(args, format);

  FILE *fp;
  int bytes = 0;
  fp = fopen(debugpath, "a");

  if (fp == NULL) {
    printf("Couldn't open debugpath '%s'!\n", debugpath);
    return;
  }

  if ((bytes = vfprintf(fp, format, args)) < 0) {
    debugprint(DEBUG_CRIT, "error: could not write to debug file.\n");
  }
  fclose(fp);

  va_end(args);
}

// Get stdin line with buffer overrun protection
int getstdin(char *prompt, char *buff, size_t sz) {
  int ch, extra;

  // Print optional prompt
  if (prompt != NULL) {
    printf ("%s", prompt);
    fflush (stdout);
  }

  // Get the intput from stdin
  if (fgets (buff, sz, stdin) == NULL) {
    return NO_INPUT;
  }

  // If it was too long, there'll be no newline. In that case, we flush
  // to end of line so that excess doesn't affect the next call.
  if (buff[strlen(buff) - 1] != '\n') { // strlen of the actually entered line, not the original array size
    extra = 0;
    while (((ch = getchar()) != '\n') && (ch != EOF)) {
      extra = 1;
    }
    return (extra == 1) ? TOO_LONG : OK;
  }

  // Otherwise remove newline and give string back to caller.
  buff[strlen(buff) - 1] = '\0';
  return OK;
}

// Append CR-LF to the end of a string (after cleaning up any existing trailing CR or LF)
void appendcrlf(char *string) {
  // Make sure it doesn't already end with CR or LF
  // (But only if string is at least two characters long already)
  if (strlen(string) >= 2) {
    while (string[strlen(string) - 1] == '\r' || string[strlen(string) - 1] == '\n') {
      string[strlen(string) - 1] = '\0';
    }
  }

  int startlen = strlen(string);
  string[startlen] = '\r'; // Add CR
  string[startlen + 1] = '\n'; // Add LF
  string[startlen + 2] = '\0'; // Finish with null terminator
}

// Remove leading colon ':' which is the starting character of a prefix in an IRC message
void stripprefix(char *string) {
  // Make a copy to work with
  char string2[strlen(string)];

  debugprint(DEBUG_FULL, "stripprefix(): starting with '%s', strlen: %zd.\n", string, strlen(string));

  // Don't bother if this isn't a prefix with a leading ':'
  if (string[0] != ':') {
    debugprint(DEBUG_FULL, "stripprefix(): no leading ':', returning.\n");
    return;
  }

  // Copy the old string into a new one, but...
  for (size_t i = 1; i < strlen(string); i++) {
    string2[i - 1] = string[i];
  }

  // Copy result back to original string
  strncpy(string, string2, strlen(string) - 1);

  // Finish with null terminator
  string[strlen(string) - 1] = '\0';

  debugprint(DEBUG_FULL, "stripprefix(): finishing with '%s', strlen: %zd.\n", string, strlen(string));
}

// Extract final parameter from IRC message, removing the leading colon ':'
// e.g. given this string:
// ":irc.tghost.co.uk 332 blabounce #test :This is a test topic!"
// We want to end up with:
// "This is a test topic!"
void extractfinalparameter(char *string) {
  // Make a copy to work with
  char string2[strlen(string)];

  // Position of colon
  int colonpos = -1;

  debugprint(DEBUG_FULL, "extractfinalparameter(): starting with '%s', strlen: %zd.\n", string, strlen(string));

  // Strip the colon at position 0 if there is one
  stripprefix(string);

  // Find the colon
  for (size_t i = 0; i < strlen(string); i++) {
    if (string[i] == ':') {
      debugprint(DEBUG_FULL, "Found colon at position %zd!\n", i);
      colonpos = i;
      break;
    }
  }

  if (colonpos == -1) {
    debugprint(DEBUG_FULL, "no colon found, returning\n");
    return;
  }

  // Build a new string starting from the next position after the colon
  int counter = 0;
  for (size_t i = colonpos + 1; i < strlen(string); i++) {
    string2[counter] = string[i];
    counter++;
  }

  // Copy result back to original string
  strncpy(string, string2, counter);

  // Finish with null terminator
  string[counter] = '\0';

  debugprint(DEBUG_FULL, "extractfinalparameter(): finishing with '%s', strlen: %zd.\n", string, strlen(string));
}

// Extract the IRC nick from a prefix
// e.g. given this string:
// ":foo!bar@baz"
// We want to end up with:
// "foo"
void extractnickfromprefix(char *string) {
  // Position of bang
  int bangpos = -1;

  debugprint(DEBUG_FULL, "extractnickfromprefix(): starting with '%s', strlen: %zd.\n", string, strlen(string));

  // Strip the colon at position 0 if there is one
  stripprefix(string);

  // Find the bang
  for (size_t i = 0; i < strlen(string); i++) {
    if (string[i] == '!') {
      debugprint(DEBUG_FULL, "Found bang at position %zd!\n", i);
      bangpos = i;
      break;
    }
  }

  if (bangpos == -1) {
    debugprint(DEBUG_FULL, "no bang found, returning\n");
    return;
  }

  // Terminate the string at whatever position we found the bang
  string[bangpos] = '\0';

  debugprint(DEBUG_FULL, "extractnickfromprefix(): finishing with '%s', strlen: %zd.\n", string, strlen(string));
}

// Update an existing nickuserhost string with a new nick
void updatenickuserhost(char *nickuserhost, char *nick) {
  debugprint(DEBUG_FULL, "updatenickuserhost(): updating '%s' with '%s'.\n", nickuserhost, nick);

  // Position of bang
  int bangpos = -1;

  // Find the bang
  for (size_t i = 0; i < strlen(nickuserhost); i++) {
    if (nickuserhost[i] == '!') {
      debugprint(DEBUG_FULL, "Found bang at position %ld!\n", i);
      bangpos = i;
      break;
    }
  }

  if (bangpos == -1) {
    debugprint(DEBUG_FULL, "No bang found in existing nickuserhost, quitting!\n");
    return;
  }

  // Make a new string combining the nick nick and the old nickuserhost + the offset of the bang
  char newstr[MAXDATASIZE];
  snprintf(newstr, MAXDATASIZE, "%s%s", nick, nickuserhost + bangpos);
  newstr[strlen(nickuserhost) - bangpos + strlen(nick)] = '\0';

  // Copy back to source string
  strcpy(nickuserhost, newstr);

  debugprint(DEBUG_FULL, "updatenickuserhost(): new nickuserhost '%s', length '%ld'.\n", nickuserhost, strlen(nickuserhost));
}

// Update existing greeting strings with a new nickuserhost and new nick
void updategreetings(char *greeting001, char *greeting002, char *greeting003, char *greeting004, char *greeting005a, char *greeting005b,
                     char *greeting005c, char *newnickuserhost, char *oldnickuserhost, char *newnick, char *oldnick) {
  debugprint(DEBUG_FULL, "updategreetings(): updating greetings with new nickuserhost '%s' and nick '%s'.\n", newnickuserhost, newnick);

  // nickuserhost and greeting001's final component first
  // (final component as in ":servername 001 nick :Blablabla final!com@ponent"

  // Make copies of the nickuserhosts to work with
  char newnickuserhostcpy[MAXDATASIZE];
  strcpy(newnickuserhostcpy, newnickuserhost);
  stripprefix(newnickuserhostcpy);
  char oldnickuserhostcpy[MAXDATASIZE];
  strcpy(oldnickuserhostcpy, oldnickuserhost);
  stripprefix(oldnickuserhostcpy);

  // Find the position of the old nickuserhost in the current greeting 001
  char *ret;
  ret = strstr(greeting001, oldnickuserhostcpy);
  int pos = ret - greeting001;

  // Terminate greeting001 where the nickuserhost begins
  greeting001[pos] = '\0';

  // Stick the new nickuserhost in place in a temporary greeting 001 string
  char greetingtmp[MAXDATASIZE];
  snprintf(greetingtmp, MAXDATASIZE, "%s%s", greeting001, newnickuserhostcpy);

  // Terminate it
  greetingtmp[pos + strlen(newnickuserhostcpy)] = '\0';

  // Copy back to source greeting 001
  strcpy(greeting001, greetingtmp);

  debugprint(DEBUG_FULL, "updategreetings(): new greeting 001 '%s', length '%ld'.\n", greeting001, strlen(greeting001));

  // Get the new nick

  char newnickcpy[MAXDATASIZE];
  strcpy(newnickcpy, newnick);
  extractnickfromprefix(newnickcpy);

  // greeting nicks next
  // (as in ":servername 00x oldnick :Blablabla" -> ":servername 00x newnick :Blablabla")
  updategreetingnick(greeting001, "001", newnickcpy, oldnick);
  updategreetingnick(greeting002, "002", newnickcpy, oldnick);
  updategreetingnick(greeting003, "003", newnickcpy, oldnick);
  updategreetingnick(greeting004, "004", newnickcpy, oldnick);
  if (greeting005a[0]) {
    updategreetingnick(greeting005a, "005", newnickcpy, oldnick);
  }
  if (greeting005b[0]) {
    updategreetingnick(greeting005b, "005", newnickcpy, oldnick);
  }
  if (greeting005c[0]) {
    updategreetingnick(greeting005c, "005", newnickcpy, oldnick);
  }
}