#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <fcntl.h>
#include <sys/time.h>
#include <time.h>
#include "util.h"
#include <stdbool.h>
#include <unistd.h>
#include <signal.h>

#define MAX_THREADS 100
#define MAX_queue_len 100
#define MAX_CE 100
#define INVALID -1
#define BUFF_SIZE 1024

/*
  THE CODE STRUCTURE GIVEN BELOW IS JUST A SUGGESTION. FEEL FREE TO MODIFY AS NEEDED
*/

// structs:
typedef struct request_queue {
   int fd;
   char *request;
} request_t;

typedef struct cache_entry {
    int len;
    char *request;
    char *content;
} cache_entry_t;

/* ******************** Dynamic Pool Code  [Extra Credit A] **********************/
// Extra Credit: This function implements the policy to change the worker thread pool dynamically
// depending on the number of requests
void * dynamic_pool_size_update(void *arg) {
  while(1) {
    // Run at regular intervals
    // Increase / decrease dynamically based on your policy
  }
}
/**********************************************************************************/

/* ************************ Cache Code [Extra Credit B] **************************/

// Function to check whether the given request is present in cache
int getCacheIndex(char *request){
  /// return the index if the request is present in the cache
  return 0;
}

// Function to add the request and its file content into the cache
void addIntoCache(char *mybuf, char *memory , int memory_size){
  // It should add the request at an index according to the cache replacement policy
  // Make sure to allocate/free memory when adding or replacing cache entries
}

// clear the memory allocated to the cache
void deleteCache(){
  // De-allocate/free the cache memory
}

// Function to initialize the cache
void initCache(){
  // Allocating memory and initializing the cache array
}

/**********************************************************************************/

/* ************************************ Utilities ********************************/
// Function to get the content type from the request
char* getContentType(char * mybuf) {
  // Should return the content type based on the file type in the request
  // (See Section 5 in Project description for more details)
  char* ext = strrchr(mybuf, '.');

  if (ext == NULL) {
      printf("Filetype not found. Exiting\n");
      exit(-1);
  }
  else if ((!strcmp((ext + 1), "htm")) || (!strcmp((ext + 1), "html"))) {
    return "text/html";
  }
  else if (!strcmp((ext + 1), "jpg")) {
    return "image/jpeg";
  }
  else if (!strcmp((ext + 1), "gif")) {
    return "image/gif";
  }
  else {
    return "text/plain";
  }
}

// Function to open and read the file from the disk into the memory
// Add necessary arguments as needed
int readFromDisk(/*necessary arguments*/) {
    // Open and read the contents of file given the request
    
}

/**********************************************************************************/

// Function to receive the request from the client and add to the queue
void * dispatch(void *arg) {

  while (1) {

    // Accept client connection

    // Get request from the client

    // Add the request into the queue

   }
   return NULL;
}

/**********************************************************************************/

// Function to retrieve the request from the queue, process it and then return a result to the client
void * worker(void *arg) {

   while (1) {

    // Get the request from the queue

    // Get the data from the disk or the cache (extra credit B)

    // Log the request into the file and terminal

    // return the result
  }
  return NULL;
}

/**********************************************************************************/

//Flag for when server needs to die nicely
static volatile sig_atomic_t exitFlag = 0;

//Sets exit flag so process can die happily and not sad.
static void eggs(int signo) {
  exitFlag |= 1;
}
int main(int argc, char **argv) {

  // Error check on number of arguments
  if(argc != 8){
    printf("usage: %s port path num_dispatcher num_workers dynamic_flag queue_length cache_size\n", argv[0]);
    return -1;
  }

  // Get the input args

  //Port
  int port = atoi(argv[3]);

  //Webroot path
  char* path = argv[4];

  //(static) number of dispatchers
  int dispatchers = atoi(argv[5]);

  //(static) number of workers
  int workers = atoi(argv[6]);

  //Dynamic worker flag
  int dynFlag = atoi(argv[7]);

  //Queue Length
  int qLen = atoi(argv[8]);

  //Max cache size
  int cSiz = atoi(argv[9]);

 /* -- ERROR CHECKING -- */
  if (port < 1025 || port > 65535) {
    printf("Invalid port. Port must be greater than 1024 or less than 65536.\n");
    return -1;
  }
  if (dispatchers > MAX_THREADS || dispatchers < 1) {
    printf("Number of dispatchers is invalid. It must be greater than 0 or less than 101.\n");
    return -1;
  }
  if (workers > MAX_THREADS || workers < 1) {
    printf("Number of dispatchers is invalid. It must be greater than 0 or less than 101.\n");
    return -1;
  }
  if (qLen > MAX_queue_len || qLen <= 0) {
    printf("Queue length is invalid.\n");
    return -1;
  }
  /* -- END ERROR CHECKING -- */

  // Change SIGINT action for grace termination
  struct sigaction act;
  act.sa_handler = eggs;
  act.sa_flags = 0;
  if (sigemptyset(&act.sa_mask) == -1 ||
      sigaction(SIGINT, &act, NULL) == -1) {
        perror("SIGINT Handler Error");
        return -1;
  }
  // Open log file
  FILE* logfile = fopen("webserver_log", "a");

  // Change the current working directory to server root directory
  if (chdir(path) == -1) {
    perror("Directory Change error");
    return -1;
  }
  // Initialize cache (extra credit B)
  cache_entry_t *dynQ;
  if (cSiz != 0) {
    //Should the queue start this large?
    dynQ =  (cache_entry_t*) malloc(cSiz * sizeof(cache_entry_t));
    if (dynQ == NULL) {
      printf("malloc cannot allocate the initial requested memory.\n");
    }
  } 

  // Start the server
  init(port);
  // Create dispatcher threads (make detachable????)
  pthread_t dThreads[dispatchers];
  for (int i=0; i<dispatchers; i++) {
    pthread_create(&dThreads[i], NULL, dispatch, NULL); // DEBUG! figure out last arg
  }
  //Create workers (make detachable?????)
  pthread_t wThreads[workers];
  for (int i = 0; i < workers; i++) {
    pthread_create(&wThreads[i], NULL, worker, NULL); //TODO: Worker arguments
  }
  // Create dynamic pool manager thread (extra credit A)
  if (dynFlag) {
    pthread_t pThread;
    pthread_create(&pThread, NULL, dynamic_pool_size_update, NULL); //TODO: possible arguments
  }

 
  //Server loop (RUNS FOREVER)
  while (1) {
    //TODO: Add something else?

    // Terminate server gracefully
    if (exitFlag){
      printf("SIGINT caught, exiting now.\nWorker threads now being killed.\n");
      // Print the number of pending requests in the request queue
      /*TODO*/
      //Kill all dispatch and worker threads
      for (int j=0; j<dispatchers; j++) {
        if (pthread_cancel(dThreads[j]) != 0) {
          printf("Thread ID %ld refused to die.\nThis may or may not be disasterous.\n", dThreads[j]);
          continue;
        }
      }
      printf("All dispatcher threads have been killed. Now killing worker threads.");
      for (int j=0; j<workers;j++) {
        if(pthread_cancel(wThreads[j]) != 0) {
          printf("Thread ID %ld refused to die.\nThis could be disasterous.\n", wThreads[j]);
          continue;
        }
      }
      // close log file
      if (fclose(logfile) != 0) {
        perror("fclose error");
        return -6;
      }
      // Remove cache (extra credit B)
      if (cSiz != 0)
        free(dynQ);
      printf("All threads have been successfully killed and cache has successfully been cleared.\nExiting now.\n");
      return 0;
    }
  }
  printf("This should never be printed.");
  return 42;
}