diff --git a/src/flag.h b/src/flag.h
new file mode 100644
index 0000000..59e4eeb
--- /dev/null
+++ b/src/flag.h
@@ -0,0 +1,135 @@
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+
+typedef struct {
+  char**    label;
+  char**    desc;
+  void      (**func_ptr)(void);
+  size_t    count;
+  size_t    capacity;
+} fg_flags;
+
+typedef struct {
+  size_t current;
+  size_t total;
+} fg_progressbar;
+
+#define fg_index fg_naive_index
+#define FG_PB_COUNT 33
+
+void   fg_append(fg_flags *flags, char *label, char *desc);
+size_t fg_naive_index(fg_flags *flags, const char* value);
+void   fg_run(fg_flags *flags, int argc, char** argv);
+void   fg_append_ptr(fg_flags *flags, char *label, void (*func)(void));
+
+#ifdef FG_IMPLEMENTATION
+void fg_append(fg_flags *flags, char *label, char *desc){
+  if (flags->capacity == 0){
+    flags->capacity = 128;
+    flags->label   = (char**)malloc(sizeof(char*)*flags->capacity);
+    flags->desc    = (char**)malloc(sizeof(char*)*flags->capacity); 
+  } if (flags->count >= flags->capacity){
+    flags->capacity *=2;
+    flags->label = (char**)realloc(flags->label, sizeof(char*) * flags->capacity);
+    flags->desc  = (char**)realloc(flags->desc, sizeof(char*) * flags->capacity); 
+  }
+  flags->label[flags->count] = strdup(label);
+  flags->desc[flags->count] = strdup(desc);
+  flags->count++;
+}
+
+void fg_append_ptr(fg_flags *flags, char *label, void(*func)(void)){
+  if (flags->capacity == 0){
+    flags->capacity = 128;
+    flags->label   = (char**)malloc(sizeof(char*)*flags->capacity);
+    flags->desc    = (char**)malloc(sizeof(char*)*flags->capacity);
+    flags->func_ptr = (void(**) (void)) malloc(sizeof(void(*)(void))*flags->capacity);
+  } if (flags->count >= flags->capacity){
+    flags->capacity *=2;
+    flags->label    = (char**)realloc(flags->label, sizeof(char*) * flags->capacity);
+    flags->desc     = (char**)realloc(flags->desc, sizeof(char*) * flags->capacity);
+    flags->func_ptr = (void(**) (void)) realloc(flags->func_ptr, sizeof(void(*)(void)) * flags->capacity);
+  }
+  flags->label[flags->count] = strdup(label);
+  flags->desc[flags->count] = "\0";
+  flags->func_ptr[flags->count] = (void(*)(void))func;
+  // TODO: remove desc null terminator and fix in terms on fg_run to not print \n
+  //flags->func_ptr = func;
+  // func();
+  flags->count++;
+}
+
+size_t fg_naive_index(fg_flags *flags, const char* value){
+  bool found;
+  for(size_t i=0; i<flags->count; ++i){
+    if (strcmp(flags->label[i], value) == 0){
+      return i;
+      found = true;
+    }
+  }
+  if (!found){
+    printf("error: unrecognized command-line option ‘%s’.\n", value); // TODO: did you mean %s?
+    return -1;
+  }
+}
+
+void fg_run(fg_flags *flags, int argc, char** argv){
+  bool called = false;
+  if (flags->count > 0){
+    if (argc < 2){
+      printf("All commands:\n");
+      for (size_t i=0; i<flags->count; ++i){
+        if (!flags->desc[i]) flags->desc[i] = "no given desc"; // impossible case
+          printf("    --%s, -%s  %s\n", flags->label[i], flags->label[i], flags->desc[i]); //use strlen comp to align by longest string
+      }
+    } else {
+      // here add logic for parsing flags
+      for (size_t i=0; i<argc; ++i){
+        //printf("%zu\n", i);
+        if (argv[i][0] == '-' && argv[i][1] != '-'){ // && argv[i][1] == '-'          //printf("found {-} in %s\n", argv[i]);
+          memmove(argv[i], argv[i]+1, strlen(argv[i]));
+          if (fg_index(flags, argv[i]) == -1) exit(-1);
+          if (flags->func_ptr[fg_index(flags, argv[i])] != NULL && !called){
+            flags->func_ptr[fg_index(flags, argv[i])]();
+            called = true;
+          } else printf("%s\n", flags->desc[fg_index(flags, argv[i])]);
+          // in python it would be if flags->labels[argv[i]] != null
+       }
+       if (argv[i][0] == '-' && argv[i][1] == '-'){
+         memmove(argv[i], argv[i]+2, strlen(argv[i]));
+         if (fg_index(flags, argv[i]) == -1) exit(-1);
+         if (flags->func_ptr[fg_index(flags, argv[i])] != NULL && !called){
+           flags->func_ptr[fg_index(flags, argv[i])]();
+           called = true;
+           
+         } else printf("%s\n", flags->desc[fg_index(flags, argv[i])]);
+       }
+       // TODO: run from func pointer if not NULL
+      }  
+    }
+  }     
+}
+
+void fg_progress_update(fg_progressbar *pb, size_t total) {
+    pb->total = total;
+    pb->current++;
+
+    if (pb->current > total)
+        pb->current = total;
+
+    float progress = (float)pb->current / total;
+    size_t filled = (size_t)(progress * FG_PB_COUNT);
+
+    char buf[FG_PB_COUNT + 1];
+    for (size_t i = 0; i < FG_PB_COUNT; ++i)
+        buf[i] = (i < filled) ? '#' : ' ';
+    buf[FG_PB_COUNT] = '\0';
+
+    printf("\r[%s] %3.0f%%", buf, progress * 100);
+    fflush(stdout);
+}
+#endif
+
+