#ifndef _REENTRANT
#define _REENTRANT
#endif

#include <stdio.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "util.h"

//Global socket
int sockfd, new_socket;

/**********************************************
 * init
   - port is the number of the port you want the server to be
     started on
   - initializes the connection acception/handling system
   - YOU MUST CALL THIS EXACTLY ONCE (not once per thread,
     but exactly one time, in the main thread of your program)
     BEFORE USING ANY OF THE FUNCTIONS BELOW
   - if init encounters any errors, it will call exit().
************************************************/
void init(int port) {
  if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
    perror("Cannot create socket");
    exit(EXIT_FAILURE);
  }
  //Socket describer
  struct sockaddr_in addr;
  memset(&addr, 0, sizeof(addr));
  addr.sin_family = AF_INET;
  addr.sin_addr.s_addr = htonl(INADDR_ANY);
  addr.sin_port = htons(port);
  //Allow port to be released
  int enable = 1;
  if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char *)&enable, sizeof(int)) == -1) {
    perror("Cannot set socket option");
    exit(EXIT_FAILURE);
  }
  //Bind socket and open the port
  if (bind(sockfd, (struct sockaddr*) &addr, sizeof(addr)) == -1) {
    perror("Cannot bind socket");
    exit(EXIT_FAILURE);
  }
  //Enable listen
  if (listen(sockfd, 20) == -1) {
    perror("Cannot set listen queue");
    exit(EXIT_FAILURE);
  }
}

/**********************************************
 * accept_connection - takes no parameters
   - returns a file descriptor for further request processing.
     DO NOT use the file descriptor on your own -- use
     get_request() instead.
   - if the return value is negative, the request should be ignored.
***********************************************/
int accept_connection(void) {

  struct sockaddr_in address;
  int addrlen = sizeof(address);
  if ((new_socket = accept(sockfd, (struct sockaddr *)&address, (socklen_t*)&addrlen))<0) {
    perror("Accept");
    return -1;
  }
  return(new_socket);

}

/**********************************************
 * get_request
   - parameters:
      - fd is the file descriptor obtained by accept_connection()
        from where you wish to get a request
      - filename is the location of a character buffer in which
        this function should store the requested filename. (Buffer
        should be of size 1024 bytes.)
   - returns 0 on success, nonzero on failure. You must account
     for failures because some connections might send faulty
     requests. This is a recoverable error - you must not exit
     inside the thread that called get_request. After an error, you
     must NOT use a return_request or return_error function for that
     specific 'connection'.
************************************************/
int get_request(int fd, char *filename) {

  char buffer[2048] = "\0";
  char get[100], http[100];

  read(fd, buffer, 2048);
   
  if(sscanf(buffer, "%s %s %s", get, filename, http) < 2) { // Read HTTP Get request and parse 
    close(fd);
    return -1;    
  }
  else if (strcmp(get, "GET")) {
    close(fd);
    return -2;
  }
  else if (strlen(filename) > 1023) {
    close(fd);
    return -3;
  }
  for (int i=0; i<strlen(filename); i++) {
    if ((strstr(filename, "//")) != 0 || (strstr(filename, "..")) != 0) {
      close(fd);
      return -4;
    }
  }
  return 0;
}

/**********************************************
 * return_result
   - returns the contents of a file to the requesting client
   - parameters:
      - fd is the file descriptor obtained by accept_connection()
        to where you wish to return the result of a request
      - content_type is a pointer to a string that indicates the
        type of content being returned. possible types include
        "text/html", "text/plain", "image/gif", "image/jpeg" cor-
        responding to .html, .txt, .gif, .jpg files.
      - buf is a pointer to a memory location where the requested
        file has been read into memory (the heap). return_result
        will use this memory location to return the result to the
        user. (remember to use -D_REENTRANT for CFLAGS.) you may
        safely deallocate the memory after the call to
        return_result (if it will not be cached).
      - numbytes is the number of bytes the file takes up in buf
   - returns 0 on success, nonzero on failure.
************************************************/
int return_result(int fd, char *content_type, char *buf, int numbytes) {
  //Convert low IO to high IO
  FILE *fdstream = fdopen(fd, "w");
  if (fdstream == NULL) {
    printf("File stream conversion(?) failed.\n");
    close(fd);
    return -1;
  }
  //
  if (fprintf(fdstream, "HTTP/1.1 200 OK\nContent-Type: %s\nContent-Length: %d\nConnection: Close\n\n", content_type, numbytes) < 0) {
    close(fd);
    return -2;
  }
  if (fflush(fdstream) == EOF) {
    perror("Flush error");
    close(fd);
    return -3;
  } 
  if (fclose(fdstream) == EOF) {
    perror("Stream close error");
    close(fd);
    return -4;
  }
  if (write(fd, buf, numbytes) == -1) {
    perror("Return result: Write error");
    close(fd);
    return -5;
  }
  close(fd);
  return 0;
}

/**********************************************
 * return_error
   - returns an error message in response to a bad request
   - parameters:
      - fd is the file descriptor obtained by accept_connection()
        to where you wish to return the error
      - buf is a pointer to the location of the error text
   - returns 0 on success, nonzero on failure.
************************************************/
int return_error(int fd, char *buf) {
  //Convert low IO to high IO
  FILE *fdstream = fdopen(fd, "w");
  if (fdstream == NULL)
  {
    printf("File stream conversion(?) failed.\n");
    close(fd);
    return -1;
  }
  //
  if (fprintf(fdstream, "HTTP/1.1 404 Not Found\nContent-Length: %ld\nConnection: Close\n\n", strlen(buf)) < 0)
  {
    close(fd);
    return -2;
  }
  if (fflush(fdstream) == EOF)
  {
    perror("Flush error");
    close(fd);
    return -3;
  }
  if (fclose(fdstream) == EOF)
  {
    perror("Stream close error");
    close(fd);
    return -4;
  }
  if (write(fd, buf, strlen(buf)) == -1)
  {
    perror("Return result: Write error");
    close(fd);
    return -5;
  }
  close(fd);
  return 0;
}