/*
 * Copyright ©2026 Soham Pardeshi. All rights reserved.
 * Permission is hereby granted to students registered for University of
 * Washington CSE 333 for use solely during Summer Quarter 2026 for
 * purposes of the course. No other use, copying, distribution, or
 * modification is permitted without prior written consent. Copyrights
 * for third-party components of this work must be honored. Instructors
 * interested in reusing these course materials should contact the author.
 */

#include <arpa/inet.h>
#include <errno.h>
#include <netdb.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <iostream>

#include "./SocketUtils.h"

void PrintOut(int fd, struct sockaddr *addr, size_t) {
  std::cout << "Socket [" << fd << "] is bound to:" << std::endl;
  if (addr->sa_family == AF_INET) {
    // Print out the IPv6 address and port
    char astring[INET_ADDRSTRLEN];
    struct sockaddr_in *in4 = reinterpret_cast<struct sockaddr_in *>(addr);
    inet_ntop(AF_INET, &(in4->sin_addr), astring, INET_ADDRSTRLEN);
    std::cout << " IPv4 address " << astring;
    std::cout << " and port " << htons(in4->sin_port) << std::endl;
  } else if (addr->sa_family == AF_INET6) {
    // Print out the IPV4 address and port
    char astring[INET6_ADDRSTRLEN];
    struct sockaddr_in6 *in6 = reinterpret_cast<struct sockaddr_in6 *>(addr);
    inet_ntop(AF_INET6, &(in6->sin6_addr), astring, INET6_ADDRSTRLEN);
    std::cout << " IPv6 address " << astring;
    std::cout << " and port " << htons(in6->sin6_port) << std::endl;
  } else {
    std::cout << " ???? address and port ????" << std::endl;
  }
}

void PrintReverseDNS(struct sockaddr *addr, size_t addrlen) {
  char hostname[1024];  // ought to be big enough.
  if (getnameinfo(addr, addrlen, hostname, 1024, NULL, 0, 0) != 0) {
    snprintf(hostname, sizeof(hostname), "[reverse DNS failed]");
  }
  std::cout << " DNS name: " << hostname << std::endl;
}

void PrintServerSide(int client_fd, int sock_family) {
  char hname[1024];
  hname[0] = '\0';

  std::cout << "Server side interface is ";
    if (sock_family == AF_INET) {
    // The server is using an IPv4 address.
    struct sockaddr_in srvr;
    socklen_t srvrlen = sizeof(srvr);
    char addrbuf[INET_ADDRSTRLEN];
    getsockname(client_fd, (struct sockaddr *) &srvr, &srvrlen);
    inet_ntop(AF_INET, &srvr.sin_addr, addrbuf, INET_ADDRSTRLEN);
    std::cout << addrbuf;
    // Get the server's dns name, or return it's IP address as
    // a substitute if the dns lookup fails.
    getnameinfo((const struct sockaddr *) &srvr,
                srvrlen, hname, 1024, NULL, 0, 0);
    std::cout << " [" << hname << "]" << std::endl;
  } else {
    // The server is using an IPv6 address.
    struct sockaddr_in6 srvr;
    socklen_t srvrlen = sizeof(srvr);
    char addrbuf[INET6_ADDRSTRLEN];
    getsockname(client_fd, (struct sockaddr *) &srvr, &srvrlen);
    inet_ntop(AF_INET6, &srvr.sin6_addr, addrbuf, INET6_ADDRSTRLEN);
    std::cout << addrbuf;
    // Get the server's dns name, or return it's IP address as
    // a substitute if the dns lookup fails.
    getnameinfo((const struct sockaddr *) &srvr,
                srvrlen, hname, 1024, NULL, 0, 0);
    std::cout << " [" << hname << "]" << std::endl;
  }
}

int Listen(char *portnum, int *sock_family) {
  // Populate the "hints" addrinfo structure for getaddrinfo().
  // ("man addrinfo")
  struct addrinfo hints;
  memset(&hints, 0, sizeof(struct addrinfo));
  hints.ai_family = AF_UNSPEC;      // allow IPv4 or IPv6
  hints.ai_socktype = SOCK_STREAM;  // stream
  hints.ai_flags = AI_PASSIVE;      // use wildcard "INADDR_ANY"
  hints.ai_protocol = IPPROTO_TCP;  // tcp protocol
  hints.ai_canonname = NULL;
  hints.ai_addr = NULL;
  hints.ai_next = NULL;

  // Use argv[1] as the string representation of our portnumber to
  // pass in to getaddrinfo().  getaddrinfo() returns a list of
  // address structures via the output parameter "result".
  struct addrinfo *result;
  int res = getaddrinfo(NULL, portnum, &hints, &result);

  // Did addrinfo() fail?
  if (res != 0) {
    std::cerr << "getaddrinfo() failed: ";
    std::cerr << gai_strerror(res) << std::endl;
    return -1;
  }

  // Loop through the returned address structures until we are able
  // to create a socket and bind to one.  The address structures are
  // linked in a list through the "ai_next" field of result.
  int listen_fd = -1;
  for (struct addrinfo *rp = result; rp != NULL; rp = rp->ai_next) {
    listen_fd = socket(rp->ai_family,
                       rp->ai_socktype,
                       rp->ai_protocol);
    if (listen_fd == -1) {
      // Creating this socket failed.  So, loop to the next returned
      // result and try again.
      std::cerr << "socket() failed: " << strerror(errno) << std::endl;
      listen_fd = -1;
      continue;
    }

    // Configure the socket; we're setting a socket "option."  In
    // particular, we set "SO_REUSEADDR", which tells the TCP stack
    // so make the port we bind to available again as soon as we
    // exit, rather than waiting for a few tens of seconds to recycle it.
    int optval = 1;
    setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR,
               &optval, sizeof(optval));

    // Try binding the socket to the address and port number returned
    // by getaddrinfo().
    if (bind(listen_fd, rp->ai_addr, rp->ai_addrlen) == 0) {
      // Bind worked!  Print out the information about what
      // we bound to.
      PrintOut(listen_fd, rp->ai_addr, rp->ai_addrlen);

      // Return to the caller the address family.
      *sock_family = rp->ai_family;
      break;
    }

    // The bind failed.  Close the socket, then loop back around and
    // try the next address/port returned by getaddrinfo().
    close(listen_fd);
    listen_fd = -1;
  }

  // Free the structure returned by getaddrinfo().
  freeaddrinfo(result);

  // If we failed to bind, return failure.
  if (listen_fd <= 0)
    return listen_fd;

  // Success. Tell the OS that we want this to be a listening socket.
  if (listen(listen_fd, SOMAXCONN) != 0) {
    std::cerr << "Failed to mark socket as listening: ";
    std::cerr << strerror(errno) << std::endl;
    close(listen_fd);
    return -1;
  }

  // Return to the client the listening file descriptor.
  return listen_fd;
}

unsigned int WrappedWrite(int fd, unsigned char *buf, unsigned int writelen) {
  unsigned int written_so_far = 0;

  while (written_so_far < writelen) {
    int res = write(fd, buf + written_so_far, writelen - written_so_far);
    if (res == -1) {
      if ((errno == EAGAIN) || (errno == EINTR))
        continue;
      break;
    }
    if (res == 0)
      break;
    written_so_far += res;
  }
  return written_so_far;
}