/*
  target is in current directory:
    entries_single/<PLZ> entries_multi/<PLZ>
    <PLZ> is either [0-9_]{5} or _____ or brken
  opens files in source directory:
    01_Flags 02_Nachname 03_Vorname 04_Zusaetze 07_Strasse 08_Hausnummer 09_Verweise 10_Postleitzahl
    11_Ort 12_Vorwahl 13_Rufnummer 16_Koordinaten
  appends to all of the above dirs plus
    00_Jahr
*/

#include <sys/stat.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <err.h>

enum { F_00, F_01, F_10, F_02, F_03, F_04, F_07, F_08, F_09, F_11, F_12, F_13, F_16, F_COUNT };

static char *g_filenames[] = {
 "00_Jahr", "01_Flags", "10_Postleitzahl", "02_Nachname", "03_Vorname", "04_Zusaetze", "07_Strasse", "08_Hausnummer", "09_Verweise", "11_Ort", "12_Vorwahl", "13_Rufnummer", "16_Koordinaten" };

FILE * fopen_prefix(char *prefix, int file_id, int readonly) {
  char filename[1024];
  snprintf( filename, sizeof(filename), "%s/%s", prefix, g_filenames[file_id]);
  return fopen(filename, readonly ? "r" : "a");
}

int main(int argc, char **args) {
  FILE * in_handles[F_COUNT] = { NULL };
  FILE * out_handles[F_COUNT] = { NULL };
  char flags[4];
  int i, in_multi = 0;
  char *input = malloc(1024);
  size_t input_size = 1024;

  /* First open all input files */
  for (i=F_01; i<F_COUNT; ++i) {
    in_handles[i] = fopen_prefix(args[1], i, 1);
    if (!in_handles[i])
      errx( 1, "Couldn't open file %s\n", g_filenames[i]);
  }

  mkdir( "multi", 0755);
  mkdir( "single", 0755);

  /* Get Flags to check if we're processing a continuation */
  while (fgets(flags, 4, in_handles[F_01])) {
    char out_dir[32];
    ssize_t linelen;
    char flag = strtoul(flags, 0, 16);
    char *type = flag & 1 ? "multi/" : "single/";

    /* If we're in multiline mode, we just copy lines as long as we see continuations */
    if (in_multi) {
      if (flag & 0x2) {
        fputs(args[1], out_handles[F_00]);      // write Jahr
        fputc(10, out_handles[F_00]);
        fwrite(flags, 3, 1, out_handles[F_01]); // copy Flags verbatim
        for (i=F_10; i<F_COUNT; ++i) {          // process the rest of entries
          ssize_t linelen = getline(&input, &input_size, in_handles[i]);
          fwrite(input, linelen, 1, out_handles[i]);
        }
        continue;
      }
      /* If the entry is not a continuation, close all output files and switch off multi mode */
      for (i=0; i<F_COUNT; ++i) {
        fclose(out_handles[i]);
        out_handles[i] = NULL;
      }
      in_multi = 0;
    }

    if (flag & 0x1)
      in_multi = 1;

    /* Read Postleitzahl to get destination */
    linelen = getline(&input, &input_size, in_handles[F_10]);
    if (linelen && input[linelen - 1] == 10) { // chomp
      input[linelen - 1] = 0;
      --linelen;
    }

    if (linelen == 0) // empty PLZ
      strcpy(out_dir, in_multi ? "multi/_____" : "single/_____");
    else if (linelen == 5) { // potentially normal
      int broken = 0;
      char * dest = out_dir + sprintf(out_dir, in_multi ? "multi/" : "single/");
      for (i=0; i<5; ++i) {
        if ( (input[i] < '0' || input[i] > '9') && input[i] != '.') {
          broken = 1;
          break;
        }
        dest[i] = input[i];
        if (dest[i] == '.') dest[i] = '_';
      }
      dest[5] = 0;
      if (broken)
        strcpy(out_dir, in_multi ? "multi/broken" : "single/broken");
    } else
      strcpy(out_dir, in_multi ? "multi/broken" : "single/broken");

    if (mkdir(out_dir, 0755) == -1 && errno != EEXIST)
      errx( 1, "Couldn't create directory %s %d\n", out_dir, errno);

    for (i=F_00; i<F_COUNT; ++i) {
      out_handles[i] = fopen_prefix(out_dir, i, 0);
      if (!out_handles[i])
        errx( 1, "Couldn't open file %s\n", g_filenames[i]);
    }

    fputs(args[1], out_handles[F_00]);            // write Jahr
    fputc(10, out_handles[F_00]);
    fwrite(flags, 3, 1, out_handles[F_01]);       // copy Flags verbatim
    fputs(input, out_handles[F_10]); // copy Postleitzahl verbatim
    fputc(10, out_handles[F_10]);

    for (i=F_02; i<F_COUNT; ++i) {                // process the rest of entries
      ssize_t linelen = getline(&input, &input_size, in_handles[i]);
      fwrite(input, linelen, 1, out_handles[i]);
    }

    if (!in_multi)
      for (i=0; i<F_COUNT; ++i) {
        fclose(out_handles[i]);
        out_handles[i] = NULL;
      }
  }

  return 0;
}