From f11bd88153ca6ab57d9ebb58807f8771cbd40924 Mon Sep 17 00:00:00 2001
From: Lieuwe Rooijakkers <lieuwerooijakkers@gmail.com>
Date: Sun, 8 Sep 2024 21:57:14 +0200
Subject: hus

---
 src/hus.c | 160 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)
 create mode 100644 src/hus.c

diff --git a/src/hus.c b/src/hus.c
new file mode 100644
index 0000000..9604954
--- /dev/null
+++ b/src/hus.c
@@ -0,0 +1,160 @@
+#include <assert.h>
+#include <errno.h>
+#include <getopt.h>
+#include <pwd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/random.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "util/debug.h"
+#include "util/error.h"
+#include "util/versie.h"
+
+static char *shufrange = NULL;
+
+static char **lines = NULL;
+static size_t nlines = 0;
+
+static void shuf_lines() {
+  size_t *js = calloc(nlines, sizeof(size_t));
+  errno = 0;
+  if (getrandom(js, nlines*sizeof(size_t), 0) == -1) exit(1);
+
+  for (ssize_t i = nlines - 1; i > 0; i--) {
+    size_t j = js[i] % (nlines-1);
+
+    char *x = lines[i];
+    lines[i] = lines[j];
+    lines[j] = x;
+  }
+
+  free(js);
+}
+
+static void usage(FILE *f) {
+  fprintf(f,
+      "Gebruik: hus [-hV] [BESTAND]\n"
+      "         hus -i LA-HO [-hV]\n"
+      "\n"
+      "Hussel de regels van het gegeven bestand.\n"
+      "Als er geen bestand gegeven is, of bestand is -, hussel dan de regels op standaard invoer.\n"
+      "\n"
+      "  -i LA-HO    Genereer regels van laag naar hoog en hussel deze\n"
+      "  -h          Toon deze hulptekst\n"
+      "  -V          Toon versienummer\n");
+}
+
+static char** parse_options(int argc, char **argv) {
+  int opt;
+  while ((opt = getopt(argc, argv, "i:hV")) != -1) {
+    switch (opt) {
+      case 'i':
+        shufrange = optarg;
+        break;
+
+      case 'h':
+        usage(stdout);
+        exit(0);
+
+      case 'V':
+        drukkedoos_print_versie(stdout);
+        exit(0);
+
+      case '?':
+        fprintf(stderr, "hus: Ongeldige optie: -%c\n", optopt);
+        usage(stderr);
+        exit(1);
+    }
+  }
+
+  return argv + optind;
+}
+
+static int exec_shufrange() {
+  assert(shufrange != NULL);
+  char *seploc = NULL;
+
+  if ((seploc = strchr(shufrange, '-')) != NULL) {
+    *seploc = '\0';
+    const long long start = strtoll(shufrange, NULL, 10);
+    const long long end = strtoll(seploc+1, NULL, 10);
+
+    if (start > end) {
+      fprintf(stderr, "hus: HO groter dan LA\n");
+      return 1;
+    }
+
+    nlines = end - start + 1;
+    lines = calloc(nlines, sizeof(char*));
+    for (long long i = 0; i <= start+end; i++) {
+      long long n = i + start;
+      asprintf(lines + i, "%lld", n);
+    }
+  } else {
+    fprintf(stderr, "hus: geen LA en HO waarde opgegeven\n");
+    return 1;
+  }
+
+  return 0;
+}
+
+static int exec_shufstream(FILE *restrict stream) {
+  size_t cap = 1 << 8;
+  lines = malloc(sizeof(char*)*cap);
+
+  char *line = NULL;
+  size_t linen = 0;
+
+  ssize_t nread = 0;
+  while ((errno = 0, nread = getline(&line, &linen, stream)) != -1) {
+    if (nread > 0 && line[nread-1] == '\n') line[--nread] = '\0';
+
+    if (nlines == cap) {
+      cap *= 2;
+      lines = realloc(lines, sizeof(char*)*cap);
+    }
+    lines[nlines] = strdup(line);
+    nlines++;
+  }
+  free(line);
+
+  return 0;
+}
+
+int entry_hus(int argc, char **argv) {
+  int res;
+#define CHECK(f) if ((res = f) != 0) return res;
+
+  char **args = parse_options(argc, argv);
+
+  // count the amount of arguments provided
+  size_t nargs;
+  for (nargs = 0; args[nargs] != NULL; nargs++);
+
+  if (shufrange) {
+    CHECK(exec_shufrange());
+  } else if (nargs == 0 || (nargs == 1 && strcmp(args[0], "-") == 0)) {
+    CHECK(exec_shufstream(stdin));
+  } else if (nargs == 1) {
+    FILE *stream = fopen(args[0], "r");
+    if (stream == NULL) {
+      fprintf(stderr, "hus: %s: kon bestand niet openen\n", args[0]);
+      return 1;
+    }
+
+    CHECK(exec_shufstream(stream));
+    fclose(stream);
+  } else {
+    fprintf(stderr, "hus: teveel argumenten gegeven\n");
+    return 1;
+  }
+
+  shuf_lines();
+  for (size_t i = 0; i < nlines; i++) {
+    printf("%s\n", lines[i]);
+  }
+
+  return 0;
+}
-- 
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