#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>


const char* locations[] = {"Bali", "Mali", "Cook islands", "Bahamas", "Iceland"};
int location_count[] = {0, 0, 0, 0, 0};
int location_min[] = {2, 5, 5, 5, 5};
const char* transports[] = {"Airplane", "Ship", "Bus"};

const char* DATAFILENAME = "data.txt";
const char* TEMPFILENAME = "data_temp.txt";

int locations_len = sizeof(locations) / sizeof(locations[0]);
int transports_len = sizeof(transports) / sizeof(transports[0]);

char* people[1024][4];

// enum Transport{Airplane, Ship, Bus};

// struct PersonInfo{
//   char name[60];
//   char location[20];
//   char phoneNumber[20];
//   char transport[20];
//   // enum Transport transport;
// };

void printSeparator()
{
  printf("\n###############################\n\n");
}

int printAllData()
{
  printSeparator();

  FILE *fp = fopen(DATAFILENAME, "r");
  if(fp == NULL) {
    perror("Unable to open file!"); //TODO: create file if does not exist
    exit(1);
  }

  int chunkIndex = 0;
  char chunk[256];
  while(fgets(chunk, sizeof(chunk), fp) != NULL)
  {
    char *pt;
    pt = strtok (chunk, ",");

    char* personInfo[4];

    int n = 0;
    while (pt != NULL) {
      personInfo[n] = pt;
      pt = strtok(NULL, ",");
      n++;
    }

    printf("%d) name: %s, location: %s, phone number: %s, transport: %s\n", chunkIndex, personInfo[0], personInfo[1], personInfo[2], personInfo[3]);
    ++chunkIndex;
  }
  printSeparator();
  fclose(fp);
  return chunkIndex;
}

int getIntUserInput()
{
  int input;
  char ch;

  while (scanf("%d", &input) != 1)
  {
    while ((ch = getchar()) != '\n')
    {
      putchar(ch);
    }
    printf(" is not a number.\nPlease enter a number!\n");
  }
  return input;
}


int chooseLocationNum()
{
  int selectedLocationNum;

  printf("The available locations are the following:\n");

  printSeparator();
  for (int i = 0; i < locations_len; ++i)
  {
    printf("%d: %s\n", i, locations[i]);
  }
  printSeparator();

  while(true)
  {
    selectedLocationNum = getIntUserInput();
    if (selectedLocationNum >= 0 && selectedLocationNum < locations_len)
    {
      break;
    }

    printf("Invalid number!\nSelect the number of location you need information about!\n");
    printSeparator();
    for (int i = 0; i < locations_len; ++i)
    {
      printf("%d: %s\n", i, locations[i]);
    }
    printSeparator();
  }

  return selectedLocationNum;
}

int chooseTransportNum()
{
  int selectedTransportNum;

  printf("The available transports are the following:\n");

  printSeparator();
  for (int i = 0; i < transports_len; ++i)
  {
    printf("%d: %s\n", i, transports[i]);
  }
  printSeparator();

  while(true)
  {
    selectedTransportNum = getIntUserInput();
    if (selectedTransportNum >= 0 && selectedTransportNum < transports_len)
    {
      break;
    }

    printf("Invalid number!\nSelect the number of location you need information about!\n");
    printSeparator();
    for (int i = 0; i < transports_len; ++i)
    {
      printf("%d: %s\n", i, transports[i]);
    }
    printSeparator();
  }

  return selectedTransportNum;
}


int getChosenMenuPoint(void)
{
  printf("0) exit the program\n");
  printf("1) input data\n");
  printf("2) delete data\n");
  printf("3) modify existing data\n");
  printf("4) list data by location\n");
  printf("5) list all data\n");

  return getIntUserInput();
}

void enterNewData()
{
  const char* personInfo[4];

  char name[60];
  char location[20];
  char phoneNumber[20];
  char transport[20];

  printf("[Enter name]\n");
  getchar();
  scanf("%[^\n]", name);
  personInfo[0] = name;

  printf("[Enter location numer]\n");
  int chosenLocation = chooseLocationNum();
  personInfo[1] = locations[chosenLocation];
  location_count[chosenLocation] += 1;

  printf("[Enter phone number]\n");
  scanf("%s", phoneNumber);
  personInfo[2] = phoneNumber;

  printf("[Enter transport]\n");
  int chosenTransport = chooseTransportNum();
  personInfo[3] = transports[chosenTransport];

  char lineToAdd[1024];

  snprintf(lineToAdd, sizeof(lineToAdd), "%s,%s,%s,%s\n", personInfo[0], personInfo[1], personInfo[2], personInfo[3]);

  FILE *fp;
  fp = fopen(DATAFILENAME, "a");

  if(fp == NULL) {
    perror("Error opening file.");
    exit(1);
  }

  fprintf(fp, "%s", lineToAdd);
  fclose(fp);
}

int deleteData(const char* outputText)
{
  int maxLineIndex = printAllData() - 1;
  if (maxLineIndex == -1)
  {
    return -1;
  }
  printf("%s", outputText);
  int lineIndexToDelete;

  while(true)
  {
    lineIndexToDelete = getIntUserInput();
    if (lineIndexToDelete >= 0 && lineIndexToDelete <= maxLineIndex)
    {
      break;
    }

    printf("Invalid number!\nSelect a valid number!\n");
  }

  FILE *fp1, *fp2;
  char filename[100], c;

  // Open one file for reading
  fp1 = fopen(DATAFILENAME, "r");
  if (fp1 == NULL)
  {
      printf("Cannot open file %s \n", DATAFILENAME);
      exit(1);
  }

  // Open another file for writing
  fp2 = fopen(TEMPFILENAME, "w");
  if (fp2 == NULL)
  {
      printf("Cannot open file %s \n", TEMPFILENAME);
      exit(1);
  }

  int line_index = 0;
  while (true)
  {
    char ch = getc(fp1);
    if (ch == EOF)
    {
      break;
    }
    //except the line to be deleted
    if (line_index != lineIndexToDelete)
    {
      putc(ch, fp2);
    }
    if (ch == '\n')
    {
      line_index++;
    }
  }

  fclose(fp1);
  fclose(fp2);

  remove(DATAFILENAME);
  rename(TEMPFILENAME, DATAFILENAME);
  return 0;
}

void modifyData()
{
  if (deleteData("choose the index of the line you wanna modify!\n") != -1)
  {
    enterNewData();
  }
  else
  {
    printf("there is no data stored yet! Nothing to modify!\n");
  }

}

void listData(bool silent_init = false)
{
  int selectedLocationNum = -1;

  if (!silent_init)
  {
    printf("[Select the number of location you need information about]\n");

    selectedLocationNum = chooseLocationNum();

    printf("selected location is: %s.  The following people are stuck there:\n", locations[selectedLocationNum]);
    printSeparator();
  }

  FILE *fp = fopen(DATAFILENAME, "r");
  if(fp == NULL) {
    perror("Unable to open file!"); //TODO: create file if does not exist
    exit(1);
  }
   char chunk[256];
   while(fgets(chunk, sizeof(chunk), fp) != NULL)
   {
      char *pt;
      pt = strtok (chunk, ",");

      char* personInfo[4];

      int n = 0;
      while (pt != NULL) {
        personInfo[n] = pt;
        pt = strtok(NULL, ",");
        n++;
      }

      if (silent_init)
      {
        for (int i = 0; i < 5; ++i)
        {
          if (strcmp(personInfo[1], locations[i]) == 0)
          {
            location_count[i] += 1;
            break;
          }
        }
      }
      else if (strcmp(personInfo[1], locations[selectedLocationNum]) == 0)
      {
        printf("name: %s, location: %s, phone number: %s, transport: %s\n", personInfo[0], personInfo[1], personInfo[2], personInfo[3]);
      }
   }
   if (!silent_init)
   {
     printSeparator();
   }

   fclose(fp);
}

void rescue(int location_index)
{
  if (fork() == 0)
  {
    printf("[son] pid %d from [parent] pid %d\n",getpid(),getppid());
    exit(0);
  }
}

int main()
{
  if (access(DATAFILENAME, F_OK) == -1) {
    printf("file does not exist.. creating data.txt\n");

    FILE* fp = fopen(DATAFILENAME, "w");
    fclose(fp);
  }

  listData(true); //init number of stuck people per location
  for (int i = 0; i < 5; ++i)
  {
    if (location_count[i] >= location_min[i])
    {
      printf("Let's rescue some people from: %s!\n", locations[i]);
      rescue(i);
    }
  }

  int n = -1;
  while (n = getChosenMenuPoint()) //it will exit if n is 0
  {
    switch (n)
    {
      case 1:
        enterNewData();
        break;
      case 2:
        if (deleteData("choose the index of the line you wanna delete!\n") == -1)
        {
          printf("there is no data stored yet! Nothing to delete!\n");
        }
        break;
      case 3:
        modifyData();
        break;
      case 4:
        listData();
        break;
      case 5:
        printAllData();
      break;
      case 6:
        for (int i = 0; i < 5; ++i)
        {
          printf("%d, ", location_count[i]);
        }
        printf("\n");
      default:
        printf("Please input a valid menu point number!\n");
        break;
    }
  }

  return 0;
}