/*
 * 
 */


#include "cdf.h"

/*
 * Global configuration variables. These are set based on command-line
 * arguments, and read-only beyond that point.
 */
static bool ARG_REVERSE_CDF = false;
static bool ARG_FP_INPUT = false;
static bool ARG_UINT_INPUT = false;
static bool ARG_HELP = false;

static int parse_options(int argc, char*const* argv) {
  int arg_index = 0;
  int arg;
  bool error = false;

  while ((arg = getopt(argc, argv, "frhu")) != -1) {
    switch (arg) {
      case 'f':
        ARG_FP_INPUT = true;
        break;
      case 'r':
        ARG_REVERSE_CDF = true;
        break;
      case 'u':
        ARG_UINT_INPUT = true;
      case 'h':
        ARG_HELP = true;
        break;
      case '?':
        if (isprint(optopt)) {
          fprintf(stderr, "Unknown option `-%c`.\n", optopt);
        } else {
          fprintf(stderr, "Unknown option character `\\x%x`.\n", optopt);
        }
        error = true;
        break;
      default:
        error = true;
        break;
    }
  }

  if (ARG_UINT_INPUT && ARG_FP_INPUT) {
    fprintf(stderr, "Error: the -u and -f flags are mutually exclusive.\n");
    error = true;
  }

  if (!error) {
    arg_index = optind;
  }

  return arg_index;
}

static void help() {
  fprintf(stderr, "Usage:\ncdf [-f|-u] [-r] [filename]\n");
}

static DistRecord *expand_array(DistRecord *records, size_t *capacity) {
  (*capacity) *= 2;
  DistRecord *new = realloc(records, (*capacity*sizeof(DistRecord)));
  if (!new) {
    fprintf(stderr, "ERROR: Memory allocation failed\n");
    return nullptr;
  }

  return new;
}

static int read_data_int(DistRecord **records, size_t capacity, FILE *file) {
  size_t reccnt = 0;
  while (fscanf(file, "%ld %ld\n", &(*records + reccnt)->count,
                &(*records + reccnt)->data.i) != EOF) {

    reccnt++;
    if (reccnt == capacity) {
      if (!(*records = expand_array(*records, &capacity))) {
        return -1;
      }
    }
  }

  return reccnt;
}

static int read_data_fp(DistRecord **records, size_t capacity, FILE *file) {
  size_t reccnt = 0;
  while (fscanf(file, "%ld %lf\n", &(*records + reccnt)->count,
                &(*records + reccnt)->data.d) != EOF) {

    reccnt++;
    if (reccnt == capacity) {
      if (!(*records = expand_array(*records, &capacity))) {
        return -1;
      }
    }
  }

  return reccnt;
}

static int read_data_uint(DistRecord **records, size_t capacity, FILE *file) {
  size_t reccnt = 0;
  while (fscanf(file, "%ld %ld\n", &(*records + reccnt)->count,
                &(*records + reccnt)->data.u) != EOF) {

    reccnt++;
    if (reccnt == capacity) {
      if (!(*records = expand_array(*records, &capacity))) {
        return -1;
      }
    }
  }

  return reccnt;
}

static int print_data_fp(DistRecord *records, long double *freqs, size_t cnt) {
  if (ARG_REVERSE_CDF) {
    long double total_freq = 1.0;
    for (size_t i=0; i<cnt; i++) {
      fprintf(stdout, "%.15Lf\t%lf\n", total_freq, records[i].data.d);
      total_freq -= freqs[i];
    }
    
  } else {
    for (size_t i=0; i<cnt; i++) {
      fprintf(stdout, "%.15Lf\t%lf\n", freqs[i], records[i].data.d);
    }  
  }

  return 1;
}

static int print_data_int(DistRecord *records, long double *freqs, size_t cnt) {
  if (ARG_REVERSE_CDF) {
    long double total_freq = 1.0;
    for (size_t i=0; i<cnt; i++) {
      fprintf(stdout, "%.15Lf\t%ld\n", total_freq, records[i].data.i);
      total_freq -= freqs[i];
    }
  } else {
    for (size_t i=0; i<cnt; i++) {
      fprintf(stdout, "%.15Lf\t%ld\n", freqs[i], records[i].data.i);
    }  
  }

  return 1;
}

static int print_data_uint(DistRecord *records, long double *freqs, size_t cnt) {
  if (ARG_REVERSE_CDF) {
    long double total_freq = 1.0;
    for (size_t i=0; i<cnt; i++) {
      fprintf(stdout, "%.15Lf\t%ld\n", total_freq, records[i].data.u);
      total_freq -= freqs[i];
    }
  } else {
    for (size_t i=0; i<cnt; i++) {
      fprintf(stdout, "%.15Lf\t%ld\n", freqs[i], records[i].data.u);
    }  
  }

  return 1;
}

static int process_data(FILE *file) {
  int rc = 1;
  
  size_t reccap = 100;
  DistRecord *records = malloc(reccap*sizeof(DistRecord));

  ssize_t cnt;
  /* FIXME: this could probably use a type-based macro to collapse the 
            if statements into a single macro call
   */
  if (ARG_FP_INPUT) {
    cnt = read_data_fp(&records, reccap, file);
  } else if (ARG_UINT_INPUT) {
    cnt = read_data_uint(&records, reccap, file);
  } else {
    cnt = read_data_int(&records, reccap, file);
  }

  /* propogate the error */
  if (cnt == -1) {
    rc = 0;
    goto free_records;
  }

  /* calculate total sum of counts */
  uint64_t total_count = 0;
  for (size_t i=0; i<cnt; i++) {
    total_count += records[i].count;
  }

  /* calculate relative frequency for each item */
  long double *freqs = malloc(sizeof(long double) * cnt);
  if (!freqs) {
    fprintf(stderr, "ERROR: memory allocation failure.\n");
    goto free_freqs;
  }

  for (size_t i=0; i<cnt; i++) {
    freqs[i] = (long double) (records[i].count) / (long double) (total_count);
  }

  if (ARG_FP_INPUT) {
    rc = print_data_fp(records, freqs, cnt);
  } else if (ARG_UINT_INPUT) {
    rc = print_data_uint(records, freqs, cnt);
  } else {
    rc = print_data_int(records, freqs, cnt);
  }
  
free_freqs:
  free(freqs);

free_records:
  free(records);

process_data_end:
  return rc;
}


int main(int argc, char **argv) {
  int rc = EXIT_SUCCESS;
  int file_index = 0;
  if (!(file_index = parse_options(argc, argv))) {
    help();
    rc = EXIT_FAILURE;
    goto program_exit;
  }

  /* if the -h argument is supplied, print usage and exit successfully */
  if (ARG_HELP) {
    help();
    goto program_exit;
  }

  /* open the input file, if one is specified, otherwise default to stdin */
  FILE *input_file;
  if (file_index < argc && strcmp(argv[file_index], "-") != 0) {
    if (!(input_file = fopen(argv[file_index], "r"))) {
      fprintf(stderr, "Error: Unable to open input file %s\n", argv[file_index]);
      rc = EXIT_FAILURE;
      goto program_exit;
    }
  } else {
    input_file = stdin;
  }

  if (!process_data(input_file)) {
    rc = EXIT_FAILURE;
  }

close_file:
  fclose(input_file);

program_exit:
  exit(rc);
}