#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "util/versie.h"
#include "io/read_file.h"

static void usage(FILE *f) {
  fprintf(f,
      "Gebruik: tak [-hV] <bestand...>\n"
      "\n"
      "Schakel bestanden aaneen naar standaard uitvoer omgekeerd.\n"
      "\n"
      "  -h    Toon deze hulptekst\n"
      "  -V    Toon versienummer\n");
}

// Returns pointer to argument array containing the file names
static char** parse_options(int argc, char **argv) {
  int opt;
  while ((opt = getopt(argc, argv, "hV")) != -1) {
    switch (opt) {
      case 'h':
        usage(stdout);
        exit(0);

      case 'V':
        drukkedoos_print_versie(stdout);
        exit(0);

      case '?':
        fprintf(stderr, "tak: Ongeldige optie: -%c\n", optopt);
        usage(stderr);
        exit(1);
    }
  }

  return argv + optind;
}

static void process(struct filebuf *fb) {
  char *lstart, *lend;
  lend = &fb->buf[fb->sz - 1];

  while (lend > fb->buf) {
    if (*lend == '\n') {
      lend--;
    }

    lstart = lend;
    while (*lstart != '\n' && lstart != fb->buf) {
      lstart--;
    }
    if (lstart != fb->buf) {
      lstart++;
    }

    fwrite(lstart, 1, lend - lstart + 2, stdout);

    lend = lstart-1;
  }

  free_filebuf(fb);
}

int entry_tak(int argc, char **argv) {
  char **args = parse_options(argc, argv);

  if (*args == NULL) {
    struct filebuf *fb = stream_to_filebuf(stdin, 0);
    if (fb == NULL) goto err_stdin;

    process(fb);
    return 0;
  }

  while (*args != NULL) {
    struct filebuf *fb = NULL;

    if (!strcmp(*args, "-")) {
      fb = stream_to_filebuf(stdin, 0);
      if (fb == NULL) goto err_stdin;
    }

    if (fb == NULL) fb = file_to_filebuf(*args, 0);

    if (fb == NULL) goto err_file;
    process(fb);

    args++;
  }

  return 0;

err_stdin:
  fprintf(stderr, "tak: fout bij lezen van standaard invoer\n");
  return 1;

err_file:
  fprintf(stderr, "tak: fout bij lezen van bestand\n");
  return 1;
}