added command line arguments handler

.gitignore

@@ -2,3 +2,4 @@ bin
 build
 debug
 !.gitignore
+*.out

src/main.c

@@ -1,6 +1,74 @@
-#include <stdio.h>
+#include "utilities.h"
+#include <getopt.h>
 
-int main(void) {
-  printf("Hello World!\n");
+#define NOERROR 0
+#define ARGERROR 1
+
+void help(int exit_code) {
+  puts("Usage:");
+  puts("surfaces-unies -i path [-o path] [-options]\n");
+  puts("The default action is to compress the mandatory input image to a .sf");
+  puts("file saved in the current directory.");
+  puts("The input image MUST be saved in the ppm format.");
+  puts("Options available:");
+  puts("-h --help\n\tdisplay the current message");
+  puts("-i --input\n\tpath to the input file (MANDATORY)");
+  puts("-o --output");
+  puts("\tpath to the output file (if the file already exists, it will be\n");
+  puts("-c --compress\n\tcompress the input file");
+  puts("-u --uncompress\n\tuncompresses the input file to the output file.");
+  exit(exit_code);
+}
+
+struct Argres {
+  char *input;
+  char *output;
+  bool compress;
+};
+typedef struct Argres Argres;
+
+void get_args(Argres *args, int *c) {
+  switch (*c) {
+  case 0:   break;
+  case 'h': help(NOERROR); break;
+  case 'i': (*args).input = optarg;   break;
+  case 'o': (*args).output = optarg;  break;
+  case 'c': (*args).compress = true;  break;
+  case 'u': (*args).compress = false; break;
+  case '?':
+  default: help(ARGERROR);
+  }
+}
+
+Argres process_args(int t_argc, char *t_argv[]) {
+  Argres res;
+  res.input = NULL;
+  res.output = NULL;
+  while (true) {
+    int option_index = 0;
+    static struct option long_options[] = {
+        {"help", no_argument, NULL, 'h'},         {"input", required_argument, NULL, 'i'},
+        {"output", required_argument, NULL, 'o'}, {"compress", no_argument, NULL, 'c'},
+        {"uncompress", no_argument, NULL, 'u'},   {NULL, 0, NULL, 0}};
+    int c = getopt_long(t_argc, t_argv, "hi:o:cu", long_options, &option_index);
+    if (c == -1) break;
+    get_args(&res, &c);
+  }
+  return res;
+}
+
+int main(int argc, char **argv) {
+  Argres argresults = process_args(argc, argv);
+  if (argresults.input) {
+    printf("input: %s\n", argresults.input);
+  } else {
+    fprintf(stderr, "ERROR: no input file.");
+    help(ARGERROR);
+  }
+  if (!argresults.output) {
+    argresults.output = "output.fs";
+  }
+  printf("output: %s\n", argresults.output);
+  printf("Compress? %s\n", (argresults.compress) ? "true" : "false");
   return 0;
 }