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

#define MAX_LEN 128
#define MAX_LINE_LEN 1024

int nb_threads = 4;

struct word_stat {
  char word[MAX_LEN];
  int count;
  struct word_stat* next;
};
struct word_stat * word_list = NULL;
pthread_mutex_t lock;

/* Update statistics on a word */
void update_word(const char* w) {
  /* First, search of word w in the linked list word_list
   * If found, we update thee word count and return
   */
  pthread_mutex_lock(&lock);
  struct word_stat* cur = word_list;
  while(cur) {
    if(strcmp(w, cur->word) == 0) {
      cur->count++;
      pthread_mutex_unlock(&lock);
      return;
    }

    cur = cur->next;
  }

  /* If w was not found in the list of word, we allocate a new word,
   * initialize it and add it to the list.
   */
  struct word_stat* new_word = malloc(sizeof(struct word_stat));
  strncpy(new_word->word, w, MAX_LEN);
  new_word->count = 1;
  new_word->next  = word_list;
  word_list = new_word;
  pthread_mutex_unlock(&lock);
}


void print_words() {
  struct word_stat* cur = word_list;
  while(cur) {
    printf("%s: %d\n", cur->word, cur->count);
    cur = cur->next;
  }
}

/* Remove punctuation and whitespaces from a string
 * Return the resulting string length
 */
int trim(char*str) {
  for(int i = 0; str[i]; i++) {
    /* replace all punctuation with space */
    char c=str[i];
    if(ispunct(c))
      str[i]=' ';
  }

  int j=0;
  for(int i = 0; str[i]; i++) {
    /* copy letters and remove spaces */
    if(! isspace(str[i])){
      str[j]=str[i];
      j++;
    }
  }
  str[j]='\0';
  return j;
}

void word_count(char* line) {
  char* saveptr;
  char* w = strtok_r(line, " ", &saveptr);
  /* Iterate over the words of the line */
  while(w) {
    if(trim(w))
      update_word(w); // update the word statistics

    // move to the next word of the line
    w = strtok_r(NULL, " ", &saveptr);
  }
}

int pipe_fd[2];

void* worker(void* arg) {
  char line[MAX_LINE_LEN];
  while(1) {
    read(pipe_fd[0], line, MAX_LINE_LEN);
    if(strlen(line) == 0)
      return NULL;
    word_count(line);
  }
  return NULL;
}

int main(int argc, char**argv) {
  if(argc < 2) {
    fprintf(stderr, "Usage: %s filename\n", argv[0]);
    return EXIT_FAILURE;
  }

  pthread_mutex_init(&lock, NULL);
  pipe(pipe_fd);
  pthread_t tids[nb_threads];
  for(int i=0; i< nb_threads; i++){
    pthread_create(&tids[i], NULL, worker, NULL);
  }

  char* filename = argv[1];
  char line[MAX_LINE_LEN];

  FILE* f = fopen(filename, "r");
  if(!f) {
    perror("File open failed");
    exit(EXIT_FAILURE);
  }

  while(fgets(line, MAX_LINE_LEN, f)) {
    write(pipe_fd[1], line, MAX_LINE_LEN);
  }

  fclose(f);

  for(int i=0; i< nb_threads; i++) {
    line[0]='\0';
    write(pipe_fd[1], line, MAX_LINE_LEN);
  }
  for(int i=0; i< nb_threads; i++) {
    pthread_join(tids[i], NULL);    
  }

  print_words();

  return EXIT_SUCCESS;
}