#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <errno.h>

#define MAX_LEN 100
#define MAX_NODE_LEN 1100000
#define MAX_EDGE_LEN 40000

typedef struct nodes {
  char email[MAX_LEN + 1];
} Node;

typedef struct edges {
  Node sender, receiver;
} Edge;

Node nodes_list[MAX_NODE_LEN + 1];
Edge edges_list[MAX_EDGE_LEN + 1];
Node in_degree_list[MAX_NODE_LEN + 1];

int compare(const void *a, const void *b) {
   const Node *a_node = a;
   const Node *b_node = b;
   return strcmp(a_node->email, b_node->email);
}

void list_emails(int size) {
  int i = 0;
  for (i = 0; i < size; i++) {
    printf("%s\n", nodes_list[i].email);
  }
}

void show_email_information(int size, char email[]) {
  Node temp;
  char temp_email[MAX_LEN + 1];
  char override[MAX_LEN + 1] = "";
  int in_count = 0;
  int out_count = 0;
  int in_degree = 0;
  int i = 0;
  int in_degree_index = 0;
  int result = 0;

  for (i = 0; i < size; i++) {
    if (strcmp(edges_list[i].receiver.email, email) == 0) {
      in_count++;
      result = search_in_degree_list(in_degree_index, edges_list[i].sender.email);
      if (result == 0) {
      strcpy(temp_email, override);
      strcpy(temp.email, override);
      strcpy(temp_email, edges_list[i].sender.email);
      strcpy(temp.email, temp_email);
      in_degree_list[in_degree_index] = temp;
      in_degree_index++;
      in_degree++;
      qsort(in_degree_list, in_degree_index, sizeof(Node), compare);
      }
    }
    if (strcmp(edges_list[i].sender.email, email) == 0) {
      out_count++;
    }
  }

  printf("%s in_count: %d out_count: %d in_degree: %d\n", email, in_count, out_count, in_degree);
}

int search(int size, char target_email[]) {
  int first = 0;
  int last = size - 1;
  int middle = (first + last) / 2;

  while (first <= last) {
    if (strcmp(nodes_list[middle].email, target_email) < 0) {
      first = middle + 1;
    } else if (strcmp(nodes_list[middle].email, target_email) == 0) {
      return 1;
      break;
    } else {
      last = middle - 1;
    }
    middle = (first + last) / 2;
  }

  if (first > last) {
    return 0;
  } else {
    return 9;
  }
}

int search_in_degree_list(int size, char target_email[]) {
  int first = 0;
  int last = size - 1;
  int middle = (first + last) / 2;

  while (first <= last) {
    if (strcmp(in_degree_list[middle].email, target_email) < 0) {
      first = middle + 1;
    } else if (strcmp(in_degree_list[middle].email, target_email) == 0) {
      return 1;
      break;
    } else {
      last = middle - 1;
    }
    middle = (first + last) / 2;
  }

  if (first > last) {
    return 0;
  } else {
    return 9;
  }
}

int main(int argc, char **argv) {
  FILE *stream;
  char input1[MAX_LEN + 1];
  char input2[MAX_LEN + 1];
  char filename[MAX_LEN + 1];
  char line[MAX_LEN + 1];
  char sender_username[MAX_LEN + 1];
  char sender_hostname[MAX_LEN + 1];
  char receiver_username[MAX_LEN + 1];
  char receiver_hostname[MAX_LEN + 1];
  char sender_email[MAX_LEN + 1];
  char receiver_email[MAX_LEN + 1];
  char override[MAX_LEN + 1] = "";
  int scanner = 0;

  Node sender;
  Node receiver;
  Edge edge;

  int nodes_list_index = 0;
  int edges_list_index = 0;

  int added = 0;
  int hold = 0;

  if (argc == 1) {
    printf("Enter file name: ");
    scanf("%s", filename);
    if (!(stream = fopen(filename, "r"))) {
      perror("Error opening file. Please try again and enter proper filename");
      exit(EXIT_FAILURE);
    }
  } else if (argc == 2) {
    stream = fopen(argv[1], "r");
    if (stream == NULL) {
      fprintf(stderr, "File %s open failed. Error %s\n", argv[1], strerror(errno));
      return EX_OSERR;
    }
  }

  while (fgets(line, MAX_LEN + 1, stream) != NULL) {
    if (sscanf(line, "%49[^@ ]@%49s -> %49[^@ ]@%49s", sender_username, sender_hostname, receiver_username, receiver_hostname) != 4) {
      continue;
    } else {
      strcpy(sender_email, override);
      strcpy(receiver_email, override);
      strcpy(sender_email, (strcat(strcat(sender_username, "@"), sender_hostname)));
      strcpy(receiver_email, (strcat(strcat(receiver_username, "@"), receiver_hostname)));
      if (nodes_list_index == 0) {
        strcpy(sender.email, sender_email);
        nodes_list[nodes_list_index] = sender;
        strcpy(receiver.email, receiver_email);
        nodes_list[nodes_list_index + 1] = receiver;
        edge.sender = sender;
        edge.receiver = receiver;
        edges_list[edges_list_index] = edge;
        nodes_list_index = nodes_list_index + 2;
        edges_list_index++;
        added = added + 2;
        qsort(nodes_list, added, sizeof(Node), compare);
      } else {
          if (search(added, sender_email) == 0) {
            strcpy(sender.email, override);
            strcpy(sender.email, sender_email);
            nodes_list[nodes_list_index] = sender;
            nodes_list_index++;
            added++;
            qsort(nodes_list, added, sizeof(Node), compare);
          }

          if (search(added, receiver_email) == 0) {
            strcpy(receiver.email, override);
            strcpy(receiver.email, receiver_email);
            nodes_list[nodes_list_index] = receiver;
            nodes_list_index++;
            added++;
            qsort(nodes_list, added, sizeof(Node), compare);
          }

         strcpy(sender.email, override);
         strcpy(receiver.email, override);
         strcpy(sender.email, sender_email);
         strcpy(receiver.email, receiver_email);
         edge.sender = sender;
         edge.receiver = receiver;
         edges_list[edges_list_index] = edge;
         edges_list_index++;
      }
     }
   } /* End of while */

  fclose(stream);

  while (hold == 0) {
    scanner = scanf("%s", input1);
    if (strcmp(input1, "list") == 0) {
      list_emails(added);
    } else if (strcmp(input1, "quit") == 0 || scanner == 0) {
      break;
    } else if (strcmp(input1, "show") == 0) {
      scanf(" %s", input2);
      show_email_information(edges_list_index, input2);
    }
  }
  return 0;
} /* End of main */