#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "util/versie.h"
#include "util/option.h"

static int max_depth = -1;

static bool show_hidden = false;
static bool dirs_only = false;

static const char *usage_string =
  "Gebruik: %s [OPTIES]... [STARTPUNTEN]...\n"
  "\n"
  "Geef inhoud van mapjes weer in een boom-achtig formaat.\n"
  "\n"
  "  -a          Alle bestanden worden weergegeven, ook al beginnen ze met een puntje\n"
  "  -m          Geef alleen mapjes weer\n"
  "  -d DIEPTE   Maximale diepte\n"
  "  -h          Toon deze hulptekst\n"
  "  -V          Toon versienummer\n";

// Returns pointer to argument array containing the starting points
static char** parse_options(int argc, char **argv) {
  char *max_depth_str;

  const struct option_spec spec[] = {
    {'a', OPTION_SETBOOL(&show_hidden)},
    {'m', OPTION_SETBOOL(&dirs_only)},
    {'d', OPTION_WITHARG(&max_depth_str)},
    {'h', OPTION_HELPUSAGE(usage_string)},
    {'V', OPTION_VERSION()},
    OPTION_SPEC_END
  };

  char **rest = option_parse(argc, argv, spec);

  if (max_depth_str != NULL) {
    errno = 0;
    max_depth = strtol(max_depth_str, NULL, 10);
    if (errno != 0) {
      fprintf(stderr, "boom: maximale diepte moet een getal zijn\n");
      exit(1);
    }
    if (max_depth <= 0) {
      fprintf(stderr, "boom: maximale diepte moet groter zijn dan 0\n");
      exit(1);
    }
  }

  return rest;
}

static int scandir_filterfunc(const struct dirent *ent) {
  if (dirs_only && ent->d_type != DT_DIR) return 0;
  if (!show_hidden && ent->d_name[0] == '.') return 0;
  if (strcmp(ent->d_name, ".") == 0) return 0;
  if (strcmp(ent->d_name, "..") == 0) return 0;
  return 1;
}

static const char *branches[] = {
  "├── ",
  "└── ",
  "│   ",
  "    "
};

// Contains indices into 'branches'
static int8_t prefix[PATH_MAX / 2 + 1];

// Buffer to store the target of a symlink in
static char linknamebuf[PATH_MAX];

static size_t total_dirs = 0;
static size_t total_files = 0;

static bool encountered_error = false;

static void print_prefix(int depth) {
  for (int i = 0; i < depth; i++) {
    printf("%s", branches[prefix[i]]);
  }
}

// Pass -1 as parentdirfd if dirname is to be resolved relative to $PWD or is absolute.
static void boom(int parentdirfd, const char *dirname, unsigned depth) {
  total_dirs++;

  if (depth > (unsigned)max_depth) return;

  struct dirent **list;
  const int nitems =
    parentdirfd == -1
      ? scandir(dirname, &list, scandir_filterfunc, alphasort)
      : scandirat(parentdirfd, dirname, &list, scandir_filterfunc, alphasort);

  if (nitems == -1) {
    printf("%s  [kon mapje niet openen]\n", dirname);
    total_dirs--;  // not a directory after all
    encountered_error = true;
    return;
  }

  const int dirfd = parentdirfd == -1
                      ? open(dirname, O_DIRECTORY)
                      : openat(parentdirfd, dirname, O_DIRECTORY);

  if (dirfd == -1) {
    printf("%s  [kon mapje niet open(2)en]\n", dirname);
    total_dirs--;  // not a directory after all
    encountered_error = true;
    return;
  }

  if (parentdirfd == -1) {
    printf("%s\n", dirname);
  }

  for (int i = 0; i < nitems; i++) {
    if (i < nitems - 1) prefix[depth-1] = 0;
    else prefix[depth-1] = 1;

    print_prefix(depth);
    if (list[i]->d_type == DT_LNK) {
      ssize_t len = readlinkat(dirfd, list[i]->d_name, linknamebuf, PATH_MAX - 1);
      if (len == -1) {
        printf("%s -> [kon niet leeslinken]\n", list[i]->d_name);
      } else {
        linknamebuf[len] = '\0';
        printf("%s -> %s\n", list[i]->d_name, linknamebuf);
      }
    } else printf("%s\n", list[i]->d_name);

    if (list[i]->d_type == DT_DIR) {
      if (i < nitems - 1) prefix[depth-1] = 2;
      else prefix[depth-1] = 3;
      boom(dirfd, list[i]->d_name, depth + 1);
    } else {
      total_files++;
    }

    free(list[i]);
  }

  close(dirfd);

  free(list);
}

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

  if (*args == NULL) {
    boom(-1, ".", 1);
  } else for (int i = 0; args[i]; i++) {
    boom(-1, args[i], 1);
  }

  putchar('\n');
  printf("%zu map%s", total_dirs, total_dirs == 1 ? "" : "jes");
  if (!dirs_only) printf(", %zu bestand%s", total_files, total_files == 1 ? "" : "en");
  putchar('\n');

  return encountered_error;
}