/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2014 The libLTE Developers. See the
 * COPYRIGHT file at the top-level directory of this distribution.
 *
 * \section LICENSE
 *
 * This file is part of the libLTE library.
 *
 * libLTE is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * libLTE is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * A copy of the GNU Lesser General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <math.h>
#include <sys/time.h>
#include <unistd.h>

#include "liblte/phy/phy.h"

//#define DISABLE_UHD

#ifndef DISABLE_UHD
#include "liblte/cuhd/cuhd.h"
#endif

#define MHZ       1000000
#define SAMP_FREQ     1920000
#define RSSI_FS      1000000
#define FLEN       9600
#define FLEN_PERIOD    0.005

#define RSSI_DECIM    20

#define IS_SIGNAL(i) (10*log10f(rssi[i]) + 30 > rssi_threshold)

int band, earfcn=-1;
float find_threshold = 10.0;
int earfcn_start=-1, earfcn_end = -1;
float rssi_threshold = -45.0;
int max_track_lost=9;
int nof_frames_find=20, nof_frames_track=100, nof_samples_rssi=50000;
int track_len=500;

cf_t *input_buffer, *fft_buffer, *ce[MAX_PORTS];
pbch_t pbch;
lte_fft_t fft;
chest_t chest;
sync_t ssync;
cfo_t cfocorr;

float *cfo_v;
int *idx_v, *idx_valid, *t;
float *p2a_v;
void *uhd;
int nof_bands;
float uhd_gain = 20.0;

#define MAX_EARFCN 1000
lte_earfcn_t channels[MAX_EARFCN];
float rssi[MAX_EARFCN];
float rssi_d[MAX_EARFCN/RSSI_DECIM];
float freqs[MAX_EARFCN];
float cfo[MAX_EARFCN];
float p2a[MAX_EARFCN];

enum sync_state {INIT, FIND, TRACK, MIB, DONE};


void usage(char *prog) {
  printf("Usage: %s [seRrFfTgv] -b band\n", prog);
  printf("\t-s earfcn_start [Default All]\n");
  printf("\t-e earfcn_end [Default All]\n");
  printf("\t-R rssi_nof_samples [Default %d]\n", nof_samples_rssi);
  printf("\t-r rssi_threshold [Default %.2f dBm]\n", rssi_threshold);
  printf("\t-F pss_find_nof_frames [Default %d]\n", nof_frames_find);
  printf("\t-f pss_find_threshold [Default %.2f]\n", find_threshold);
  printf("\t-T pss_track_nof_frames [Default %d]\n", nof_frames_track);
  printf("\t-l pss_track_len [Default %d]\n", track_len);
  printf("\t-g gain [Default %.2f dB]\n", uhd_gain);
  printf("\t-v [set verbose to debug, default none]\n");
}

void parse_args(int argc, char **argv) {
  int opt;
  while ((opt = getopt(argc, argv, "bseRrFfTgv")) != -1) {
    switch(opt) {
    case 'b':
      band = atoi(argv[optind]);
      break;
    case 's':
      earfcn_start = atoi(argv[optind]);
      break;
    case 'e':
      earfcn_end = atoi(argv[optind]);
      break;
    case 'R':
      nof_samples_rssi = atoi(argv[optind]);
      break;
    case 'r':
      rssi_threshold = -atof(argv[optind]);
      break;
    case 'F':
      nof_frames_find = atoi(argv[optind]);
      break;
    case 'f':
      find_threshold = atof(argv[optind]);
      break;
    case 'T':
      nof_frames_track = atoi(argv[optind]);
      break;
    case 'g':
      uhd_gain = atof(argv[optind]);
      break;
    case 'v':
      verbose++;
      break;
    default:
      usage(argv[0]);
      exit(-1);
    }
  }
}

int base_init(int frame_length) {
  int i;

  input_buffer = malloc(2 * frame_length * sizeof(cf_t));
  if (!input_buffer) {
    perror("malloc");
    return -1;
  }

  fft_buffer = malloc(CPNORM_NSYMB * 72 * sizeof(cf_t));
  if (!fft_buffer) {
    perror("malloc");
    return -1;
  }

  for (i=0;i<MAX_PORTS;i++) {
    ce[i] = malloc(CPNORM_NSYMB * 72 * sizeof(cf_t));
    if (!ce[i]) {
      perror("malloc");
      return -1;
    }
  }
  if (sync_init(&ssync, FLEN, 128, 128)) {
    fprintf(stderr, "Error initiating PSS/SSS\n");
    return -1;
  }
  if (chest_init(&chest, CPNORM, 6, MAX_PORTS)) {
    fprintf(stderr, "Error initializing equalizer\n");
    return -1;
  }

  if (lte_fft_init(&fft, CPNORM, 6)) {
    fprintf(stderr, "Error initializing FFT\n");
    return -1;
  }
  if (cfo_init(&cfocorr, FLEN)) {
    fprintf(stderr, "Error initiating CFO\n");
    return -1;
  }

  idx_v = malloc(nof_frames_track * sizeof(int));
  if (!idx_v) {
    perror("malloc");
    return -1;
  }
  idx_valid = malloc(nof_frames_track * sizeof(int));
  if (!idx_valid) {
    perror("malloc");
    return -1;
  }
  t = malloc(nof_frames_track * sizeof(int));
  if (!t) {
    perror("malloc");
    return -1;
  }
  cfo_v = malloc(nof_frames_track * sizeof(float));
  if (!cfo_v) {
    perror("malloc");
    return -1;
  }
  p2a_v = malloc(nof_frames_track * sizeof(float));
  if (!p2a_v) {
    perror("malloc");
    return -1;
  }

  bzero(cfo, sizeof(float) * MAX_EARFCN);
  bzero(p2a, sizeof(float) * MAX_EARFCN);

  /* open UHD device */
#ifndef DISABLE_UHD
  printf("Opening UHD device...\n");
  if (cuhd_open("",&uhd)) {
    fprintf(stderr, "Error opening uhd\n");
    return -1;
  }
#endif
  return 0;
}

void base_free() {
  int i;

#ifndef DISABLE_UHD
  cuhd_close(uhd);
#endif

  sync_free(&ssync);
  lte_fft_free(&fft);
  chest_free(&chest);
  cfo_free(&cfocorr);

  free(input_buffer);
  free(fft_buffer);
  for (i=0;i<MAX_PORTS;i++) {
      free(ce[i]);
  }
  free(idx_v);
  free(idx_valid);
  free(t);
  free(cfo_v);
  free(p2a_v);
}

float mean_valid(int *idx_v, float *x, int nof_frames) {
  int i;
  float mean = 0;
  int n = 0;
  for (i=0;i<nof_frames;i++) {
    if (idx_v[i] != -1) {
      mean += x[i];
      n++;
    }
  }
  if (n > 0) {
    return mean/n;
  } else {
    return 0.0;
  }
}

int preprocess_idx(int *in, int *out, int *period, int len) {
  int i, n;
  n=0;
  for (i=0;i<len;i++) {
    if (in[i] != -1) {
      out[n] = in[i];
      period[n] = i;
      n++;
    }
  }
  return n;
}

int rssi_scan() {
  int n=0;
  int i;

  if (nof_bands > 100) {
    /* scan every Mhz, that is 10 freqs */
    for (i=0;i<nof_bands;i+=RSSI_DECIM) {
      freqs[n] = channels[i].fd * MHZ;
      n++;
    }
#ifndef DISABLE_UHD
    if (cuhd_rssi_scan(uhd, freqs, rssi_d, n, (double) RSSI_FS, nof_samples_rssi)) {
      fprintf(stderr, "Error while doing RSSI scan\n");
      return -1;
    }
#endif
    /* linearly interpolate the rssi vector */
    interp_linear_f(rssi_d, rssi, RSSI_DECIM, n);
  } else {
    for (i=0;i<nof_bands;i++) {
      freqs[i] = channels[i].fd * MHZ;
    }
#ifndef DISABLE_UHD
    if (cuhd_rssi_scan(uhd, freqs, rssi, nof_bands, (double) RSSI_FS, nof_samples_rssi)) {
      fprintf(stderr, "Error while doing RSSI scan\n");
      return -1;
    }
#endif
    n = nof_bands;
  }

  return n;
}


int mib_decoder_init(int cell_id) {

  lte_cell_t cell;
  cell.id = cell_id;
  cell.nof_prb = 6;
  cell.nof_ports = 2;
  cell.cp = CPNORM;
  
  if (chest_ref_LTEDL(&chest, cell)) {
    fprintf(stderr, "Error initializing reference signal\n");
    return -1;
  }

  if (pbch_init(&pbch, cell)) {
    fprintf(stderr, "Error initiating PBCH\n");
    return -1;
  }
  DEBUG("PBCH initiated cell_id=%d\n", cell_id);
  return 0;
}

int mib_decoder_run(cf_t *input, pbch_mib_t *mib) {
  int i;
  lte_fft_run_slot(&fft, input, fft_buffer);

  /* Get channel estimates for each port */
  for (i=0;i<MAX_PORTS;i++) {
    chest_ce_slot_port(&chest, fft_buffer, ce[i], 1, i);
  }

  DEBUG("Decoding PBCH\n", 0);
  return pbch_decode(&pbch, fft_buffer, ce, mib);
}

int main(int argc, char **argv) {
  int frame_cnt, valid_frames;
  int freq;
  int cell_id;
  float max_peak_to_avg;
  float sfo;
  uint32_t track_idx, find_idx; 
  int last_found;
  enum sync_state state;
  int n;
  int mib_attempts;
  int nslot;
  pbch_mib_t mib;
  int ret;
  
  if (argc < 3) {
    usage(argv[0]);
    exit(-1);
  }

  parse_args(argc,argv);

  if (base_init(FLEN)) {
    fprintf(stderr, "Error initializing memory\n");
    exit(-1);
  }

  sync_pss_det_peak_to_avg(&ssync);

  nof_bands = lte_band_get_fd_band(band, channels, earfcn_start, earfcn_end, MAX_EARFCN);
  printf("RSSI scan: %d freqs in band %d, RSSI threshold %.2f dBm\n", nof_bands, band, rssi_threshold);

  n = rssi_scan();
  if (n == -1) {
    exit(-1);
  }

  printf("\nDone. Starting PSS search on %d channels\n", n);
  usleep(500000);
  INFO("Setting sampling frequency %.2f MHz\n", (float) SAMP_FREQ/MHZ);
#ifndef DISABLE_UHD
  cuhd_set_rx_srate(uhd, SAMP_FREQ);

  cuhd_set_rx_gain(uhd, uhd_gain);
#endif

  freq=0;
  state = INIT;
  nslot = 0;
  sfo = 0;
  find_idx = 0;
  frame_cnt = 0;
  max_peak_to_avg = -1;
  last_found = 0;
  cell_id = 0;

  while(freq<nof_bands) {
    /* scan only bands above rssi_threshold */
    if (!IS_SIGNAL(freq)) {
      INFO("[%3d/%d]: Skipping EARFCN %d %.2f MHz RSSI %.2f dB\n", freq, nof_bands,
                channels[freq].id, channels[freq].fd,10*log10f(rssi[freq]) + 30);
      freq++;
    } else {
      if (state != INIT && state != DONE) {
#ifndef DISABLE_UHD
        DEBUG(" -----   RECEIVING %d SAMPLES ---- \n", FLEN);
        cuhd_recv(uhd, &input_buffer[FLEN], FLEN, 1);
#endif
      }
      switch(state) {
      case INIT:
        DEBUG("Stopping receiver...\n",0);
#ifndef DISABLE_UHD
        cuhd_stop_rx_stream(uhd);

        /* set freq */
        cuhd_set_rx_freq(uhd, (double) channels[freq].fd * MHZ);
        cuhd_rx_wait_lo_locked(uhd);
        DEBUG("Set freq to %.3f MHz\n", (double) channels[freq].fd);

        DEBUG("Starting receiver...\n",0);
        cuhd_start_rx_stream(uhd);
#endif
        /* init variables */
        frame_cnt = 0;
        max_peak_to_avg = -1;
        cell_id = -1;

        /* receive first frame */
#ifndef DISABLE_UHD
        cuhd_recv(uhd, input_buffer, FLEN, 1);
#endif
        /* set find_threshold and go to FIND state */
        sync_set_threshold(&ssync, find_threshold, find_threshold/2);
        state = FIND;
        break;
      case FIND:
        /* find peak in all frame */
        ret = sync_find(&ssync, &input_buffer[FLEN], &find_idx);
        DEBUG("[%3d/%d]: PAR=%.2f\n", freq, nof_bands, sync_get_peak_to_avg(&ssync));
        if (ret == 1) {
          /* if found peak, go to track and set lower threshold */
          frame_cnt = -1;
          last_found = 0;
          max_peak_to_avg = -1;
          cell_id = sync_get_cell_id(&ssync);

          state = TRACK;
          INFO("[%3d/%d]: EARFCN %d Freq. %.2f MHz PSS found PAR %.2f dB\n", freq, nof_bands,
                        channels[freq].id, channels[freq].fd,
                        10*log10f(sync_get_peak_to_avg(&ssync)));
        } else {
          if (frame_cnt >= nof_frames_find) {
            state = INIT;
            freq++;
          }
        }
        break;
      case TRACK:
        INFO("Tracking PSS find_idx %d offset %d\n", find_idx, find_idx - track_len);

        ret = sync_track(&ssync, input_buffer, FLEN + find_idx - track_len, &track_idx);
        p2a_v[frame_cnt] = sync_get_peak_to_avg(&ssync);

        /* save cell id for the best peak-to-avg */
        if (p2a_v[frame_cnt] > max_peak_to_avg) {
          max_peak_to_avg = p2a_v[frame_cnt];
          cell_id = sync_get_cell_id(&ssync);
        }
        if (ret == 1) {
          cfo_v[frame_cnt] = sync_get_cfo(&ssync);
          last_found = frame_cnt;
          find_idx += track_idx - track_len;
          idx_v[frame_cnt] = find_idx;
          nslot = sync_get_slot_id(&ssync);
        } else {
          idx_v[frame_cnt] = -1;
          cfo_v[frame_cnt] = 0.0;
        }
        /* if we missed to many PSS it is not a cell, next freq */
        if (frame_cnt - last_found > max_track_lost) {
          INFO("\n[%3d/%d]: EARFCN %d Freq. %.2f MHz %d frames lost\n", freq, nof_bands,
              channels[freq].id, channels[freq].fd, frame_cnt - last_found);

          state = INIT;
          freq++;
        } else if (frame_cnt >= nof_frames_track) {
          mib_decoder_init(cell_id);

          cfo[freq] = mean_valid(idx_v, cfo_v, frame_cnt);
          p2a[freq] = mean_valid(idx_v, p2a_v, frame_cnt);
          valid_frames = preprocess_idx(idx_v, idx_valid, t, frame_cnt);
          sfo = sfo_estimate_period(idx_valid, t, valid_frames, FLEN_PERIOD);

          state = MIB;
          nslot=(nslot+10)%20;
        }
        break;
      case MIB:
        INFO("Finding MIB at freq %.2f Mhz offset=%d, cell_id=%d, slot_idx=%d\n", channels[freq].fd, find_idx, cell_id, nslot);

        // TODO: Correct SFO

        // Correct CFO
        INFO("Correcting CFO=%.4f\n", cfo[freq]);
        cfo_correct(&cfocorr, &input_buffer[FLEN], &input_buffer[FLEN], (-cfo[freq])/128);

        if (nslot == 0) {
          if (mib_decoder_run(&input_buffer[FLEN+find_idx], &mib)) {
            INFO("MIB detected attempt=%d\n", mib_attempts);
            state = DONE;
          } else {
            INFO("MIB not detected attempt=%d\n", mib_attempts);
            if (mib_attempts == 0) {
              freq++;
              state = INIT;
            }
          }
          mib_attempts++;
        }
        nslot = (nslot+10)%20;


        break;
      case DONE:
        printf("\n[%3d/%d]: FOUND EARFCN %d Freq. %.2f MHz. "
            "PAR %2.2f dB, CFO=%+.2f KHz, SFO=%+2.3f KHz, CELL_ID=%3d\n", freq, nof_bands,
                channels[freq].id, channels[freq].fd,
                10*log10f(p2a[freq]), cfo[freq] * 15, sfo / 1000, cell_id);
        pbch_mib_fprint(stdout, &mib);
        state = INIT;
        freq++;
        break;
      }

      /** FIXME: This is not necessary at all */
      if (state == TRACK || state == FIND) {
        memcpy(input_buffer, &input_buffer[FLEN], FLEN * sizeof(cf_t));
      }
      frame_cnt++;
    }
  }

  base_free();

  printf("\n\nDone\n");
  exit(0);
}