#include <sys/timerfd.h>
#include "algo_utils.h"
#include "utils.h"
#include "url.h"
#include "proxy.h"
#include "timer.h"

// A Tor cell size is 512 bytes but handle only 498 bytes of data
#define TOR_CELL_SIZE 498

struct thunder_ctx {
  uint16_t recv_id;
  uint16_t emit_id;
  uint8_t selected_link;
  uint8_t total_links;
  uint8_t delta_t_per_link[64];
  uint64_t received_pkts_on_link[64];
  uint8_t blacklisted[64];
  size_t monit_pkt_size;
  struct timespec prev_link_time, prev_packet_time;
};

uint64_t compute_delta(struct timespec* prev_time, uint64_t max) {
  struct timespec curr;
  int secs, nsecs;
  uint64_t mili_sec;

  // 1. We compute the time difference
  if (clock_gettime(CLOCK_MONOTONIC, &curr) == -1){
    perror("clock_gettime error");
    exit(EXIT_FAILURE);
  }
  secs = curr.tv_sec - prev_time->tv_sec;
  nsecs = curr.tv_nsec - prev_time->tv_nsec;
  *prev_time = curr;
  mili_sec = secs * 1000 + nsecs / 1000000;
  if (mili_sec > max) mili_sec = max;

  return mili_sec;
}

void prepare(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
  struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
  struct thunder_ctx* thunderc = app_ctx->misc;

  thunderc->emit_id++;
  union abstract_packet metadata = {
    .fmt.headers.cmd = CMD_UDP_METADATA_THUNDER,
    .fmt.headers.size = sizeof(metadata.fmt.headers) + sizeof(metadata.fmt.content.udp_metadata_thunder),
    .fmt.headers.flags = 0,
    .fmt.content.udp_metadata_thunder.id = thunderc->emit_id,
  };
  buffer_append_ap (bp, &metadata);
}

void pad(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
  struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
  struct thunder_ctx* thunderc = app_ctx->misc;
  uint64_t ref = 0l + thunderc->emit_id;

  dup_buffer_toa (&app_ctx->br, bp, (void *)ref);

  // 1. Clean old buffers (we keep only thunderc->total_links buffer, keeping more would be useless)
  if (ref > thunderc->total_links && get_app_buffer (&app_ctx->br, (void *)(ref - thunderc->total_links))) {
    mv_buffer_atof (&app_ctx->br, (void *)(ref - thunderc->total_links));
  }

  // 2. Append abstract packets stored in our buffers
  uint64_t add_ref = ref;
  while(1) {
    if (add_ref < 1) break;
    add_ref--;
    struct buffer_packet *bp_iter = get_app_buffer (&app_ctx->br, (void *)add_ref);
    if (bp_iter == NULL) break;
    union abstract_packet *ap = buffer_first_ap (bp_iter);
    if (ap->fmt.headers.cmd != CMD_UDP_ENCAPSULATED || ap->fmt.headers.flags & FLAG_READ_NEXT) {
      fprintf(stderr, "Invalid buffer!\n");
      exit(EXIT_FAILURE);
    }

    if (buffer_full_size (bp) + ap->fmt.headers.size > TOR_CELL_SIZE - thunderc->monit_pkt_size) break;

    buffer_append_ap (bp, ap);
  }
}

int schedule(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
  struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
  struct thunder_ctx* thunderc = app_ctx->misc;
  struct evt_core_fdinfo *to_fdinfo = NULL;
  struct evt_core_cat* cat = evt_core_get_from_cat (ctx, "tcp-write");

  do {
    // 1. We choose the link
    thunderc->selected_link = (thunderc->selected_link + 1) % cat->socklist->len;

    // 2. We create the packet template
    union abstract_packet links = {
      .fmt.headers.cmd = CMD_LINK_MONITORING_THUNDER,
      .fmt.headers.size = thunderc->monit_pkt_size,
      .fmt.headers.flags = 0,
      .fmt.content.link_monitoring_thunder.links_status = {}
    };

    to_fdinfo = g_array_index(cat->socklist, struct evt_core_fdinfo*, thunderc->selected_link);

    // 3. We append the template to the buffer
    struct buffer_packet* bp_dup = dup_buffer_tow (&app_ctx->br, bp, to_fdinfo);
    union abstract_packet *new_ap = buffer_append_ap (bp_dup, &links);

    // 4. We compute the time difference
    uint64_t mili_sec = compute_delta (&thunderc->prev_link_time, 200);

    // 5. We create the array
    struct link_info *li = &new_ap->fmt.content.link_monitoring_thunder.links_status;
    for (int i = 0; i < thunderc->total_links; i++) {
      thunderc->delta_t_per_link[i] += mili_sec;
      li[i].delta_t = thunderc->delta_t_per_link[i];
    }
    li[thunderc->selected_link].delta_t = 0;

    main_on_tcp_write(ctx, to_fdinfo);
  } while (thunderc->blacklisted[thunderc->selected_link]);

  if (ctx->verbose > 1) fprintf(stderr, "    [algo_thunder] Packets sent\n");

  // Release the buffer
  mv_buffer_rtof (&app_ctx->br, fdinfo);

  return 0;
}

void algo_thunder_init(struct evt_core_ctx* ctx, struct algo_ctx* app_ctx, struct algo_params* ap) {
  app_ctx->misc = malloc(sizeof(struct thunder_ctx));
  if (app_ctx->misc == NULL) {
    perror("malloc failed in algo thunder init");
    exit(EXIT_FAILURE);
  }
  memset(app_ctx->misc, 0, sizeof(struct thunder_ctx));
  struct thunder_ctx* thunderc = app_ctx->misc;
  thunderc->selected_link = UINT8_MAX - 1;

  union abstract_packet links = {};
  thunderc->monit_pkt_size = sizeof(links.fmt.headers) + sizeof(links.fmt.content.link_monitoring_thunder) + sizeof(struct link_info) * (thunderc->total_links - 1);
}

void classify(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
  struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
  struct thunder_ctx* thunderc = app_ctx->misc;

  union abstract_packet* ap = buffer_first_ap (bp);
  while (ap != NULL && ap->fmt.headers.cmd != CMD_LINK_MONITORING_THUNDER) ap = ap_next(ap);
  if (ap == NULL) {
    fprintf(stderr, "Unable to find our packet\n");
    exit(EXIT_FAILURE);
  }

  int link_id = url_get_port_int(fdinfo->url) - 7500;
  thunderc->received_pkts_on_link[link_id]++;

  struct link_info *li = &ap->fmt.content.link_monitoring_thunder.links_status;
  for (int i = 0; i < thunderc->total_links; i++) {
    uint64_t expected = i <= link_id ? thunderc->received_pkts_on_link[link_id] : thunderc->received_pkts_on_link[link_id] - 1;
    if (thunderc->received_pkts_on_link[i] >= expected) continue; // Nothing to do, all packets have been received
    set_timeout ()
  }
}

void unpad() {

}

void adapt() {

}

int algo_thunder_on_stream(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
  classify(ctx, fdinfo, bp);
  unpad();
  adapt();
  return 0;
}

int algo_thunder_on_datagram(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
  prepare(ctx, fdinfo, bp);
  pad(ctx, fdinfo, bp);
  return schedule(ctx, fdinfo, bp);
}

int algo_thunder_on_err(struct evt_core_ctx *ctx, struct evt_core_fdinfo *fdinfo) {
  if (strstr(fdinfo->cat->name, "udp") != NULL) return 1;
  return 0;
}