// Copyright 2020 Jeisson Hidalgo ECCI-UCR

#include <stdio.h>
#include <stdlib.h>

int process_file(FILE* input, const char* input_filename);
int convert(FILE* input, const char* input_filename, FILE* output
  , const char* output_filename);

// main:
int main(int argc, char* argv[]) {
  int error = EXIT_SUCCESS;
  if (argc >= 2) {
    for (int index = 1; index < argc; ++index) {
      // printf("%d = [%s]\n", index, argv[index]);
      if (*argv[index] != '-') {
        FILE* input = fopen(argv[index], "r");
        if (input) {
          process_file(input, argv[index]);
          fclose(input);
        } else {
          fprintf(stderr, "could not open %s\n", argv[index]);
          error = EXIT_FAILURE;
        }
      }
    }
  } else {
    error = process_file(stdin, "stdin");
  }
  return error;
}

size_t length_idx(const char* text) {
  size_t index = 0;
  while (text[index]) { /* != '\0' */
    ++index;
  }
  return index;
}

size_t length_ptr(const char* text) {
  size_t length = 0;
  while (*text++) { /* != '\0' */
    ++length;
  }
  return length;
}

int process_file(FILE* input, const char* input_filename) {
  int error = EXIT_SUCCESS;
  // const char* output_filename = input_filename + ".bin";
  const char* const extension =  ".bin";
  const size_t len_output_filename = length_ptr(input_filename)
    + length_idx(extension);
  char output_filename[len_output_filename + 1];
  // *output_filename = '\0'; output_filename[0] = '\0';
  snprintf(output_filename, len_output_filename + 1, "%s%s", input_filename
    , extension);
  FILE* output = fopen(output_filename, "wb");
  if (output) {
    error = convert(input, input_filename, output, output_filename);
    fclose(output);
  } else {
    fprintf(stderr, "could not open %s\n", output_filename);
    error = EXIT_FAILURE;
  }
  return error;
}

int convert(FILE* input, const char* input_filename, FILE* output
  , const char* output_filename) {
  (void)input_filename;
  int error = EXIT_SUCCESS;
  // printf("converting from %s to %s\n", input_filename, output_filename);
  double value = 0;
  while (fscanf(input, "%lg", &value) == 1) {
    // fprintf(output, "%lg\n", value);  // text output file
    // size_t fwrite(const void * ptr, size_t size, size_t count, FILE * stream);
    size_t written_count = fwrite(&value, sizeof(value), 1, output);
    if (written_count < 1) {
      fprintf(stderr, "could not write to %s\n", output_filename);
      error = EXIT_FAILURE;
      break;
    }
  }
  return error;
}

#if 0
  for (size_t index = 0; index < length_idx(input); ++index) {
    // O(n^2)
  }

  const size_t len = length_idx(input);
  for (size_t index = 0; index < len; ++index) {
    // O(n^2)
  }
#endif