#include <stdlib.h>
#include <stdio.h>
#include "cap_utils.h"
#include "packet.h"

#define MAX_PKTS_TO_CHECK_FOR_DROP 10

uint8_t are_packets_equal(struct buffer_packet bpread[]) {
  size_t s1 = bpread[0].ip.ap.fmt.headers.size, s2 = bpread[1].ip.ap.fmt.headers.size;
  if (s1 != s2) return 0;

  for (size_t idx = sizeof(bpread[0].ip.ap.fmt.headers) + sizeof(bpread[0].ip.ap.fmt.content.clear) - sizeof(char); idx < s1; idx++) {
    char e1 = (&bpread[0].ip.ap.raw)[idx], e2 = (&bpread[1].ip.ap.raw)[idx];
    if (e1 != e2) return 0;
  }

  return 1;
}

enum pkt_reconstruct_res { PREC_SAME, PREC_DROP, PREC_FAIL };
struct pkt_reconstruct {
  enum pkt_reconstruct_res r;
  int diff_0;
  int diff_1;
};

void reconstruct_action(struct cap_file cf[], struct pkt_reconstruct* pr) {
  struct buffer_packet bpread[2];
  pr->r = PREC_FAIL;
  for (int m1 = 0; m1 < MAX_PKTS_TO_CHECK_FOR_DROP; m1++) {
    for (int m2 = 0; m2 <= m1; m2++) {
      cap_npeek_bp(&cf[0], m1, &bpread[0]);
      cap_npeek_bp(&cf[1], m2, &bpread[1]);
      if(are_packets_equal(bpread)) {
        pr->r = m1 == 0 && m2 == 0 ? PREC_SAME : PREC_DROP;
        pr->diff_0 = m1;
        pr->diff_1 = m2;
        while (m1-- >= 0) cap_next_bp (&cf[0], &bpread[0]);
        while (m2-- >= 0) cap_next_bp (&cf[1], &bpread[1]);
        return;
      }

      cap_npeek_bp(&cf[0], m2, &bpread[0]);
      cap_npeek_bp(&cf[1], m1, &bpread[1]);
      if(are_packets_equal(bpread)) {
        pr->r = PREC_DROP;
        pr->diff_0 = m2;
        pr->diff_1 = m1;
        while (m2-- >= 0) cap_next_bp (&cf[0], &bpread[0]);
        while (m1-- >= 0) cap_next_bp (&cf[1], &bpread[1]);
        return;
      }
    }
  }
};

int main(int argc, char** argv) {
  setvbuf(stdout, NULL, _IONBF, 0);
  printf("~ capdiff ~\n");

  if (argc != 3) {
    fprintf(stderr, "Usage %s FILE.IN FILE.OUT\n", argv[0]);
    exit(EXIT_FAILURE);
  }
  uint8_t verbose = 0;

  struct cap_file cf[2];
  for (int i = 0; i < 2; i++) cap_load(&cf[i], argv[i+1]);

  if (cf[0].sz != cf[1].sz) {
    printf("[!!] %s has %ld entries, %s has %ld entries\n",
           argv[1],
           cf[0].sz/sizeof(struct buffer_packet),
           argv[2],
           cf[1].sz/sizeof(struct buffer_packet));
  } else if (verbose) {
    printf("[OK] %s and %s have %ld entries\n",
           argv[1],
           argv[2],
           cf[0].sz/sizeof(struct buffer_packet));
  }

  struct pkt_reconstruct pr;
  struct buffer_packet bpread[2];
  int c0 = 0, c1 = 0, stop = 0;
  while (c0 < cf[0].sz_obj && c1 < cf[1].sz_obj && !stop) {
    reconstruct_action(cf, &pr);
    c0 += pr.diff_0 + 1;
    c1 += pr.diff_1 + 1;
    switch (pr.r) {
    case PREC_SAME:
      // Nothing
      break;
    case PREC_DROP:
      fprintf(stderr, "[!!] packets (%d,%d) ", c0, c1);
      if (c0 > 0) fprintf(stderr, "%s dropped %d pkts ", cf[0].filename, pr.diff_0);
      if (c1 > 0) fprintf(stderr, "%s has dropped %d pkts ", cf[1].filename, pr.diff_1);
      fprintf(stderr, "\n");
      break;
    case PREC_FAIL:
      fprintf(stderr, "[!!] Unable to remap packets (%d, %d). We should stop\n", c0, c1);
      stop = 1;
      break;
    }
  }

  printf("parsed (%d,%d) packets\n", c0, c1);

  for (int i = 0; i < 2; i++) cap_unload (&cf[i]);
  return 0;
}