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

enum stringType {
    stringTypeFixed,
    stringTypeHeap
};

typedef struct _string {
    char *buffer;
    int length;
    int bufSize;
    enum stringType type;
} *string;

int LowestPow2(int min) {
    int result = 1;
    while(result < min) {
        result *= 2;
    }
    return result;
}

void string_CheckSize(string str, int minSize) {
    if(str->bufSize >= minSize) {
        return;
    }
    if(str->type == stringTypeFixed) {
        printf("size limit exceeded for fixed string");
        exit(1);
    }
    str->bufSize = LowestPow2(minSize);
    str->buffer = realloc(str->buffer, str->bufSize);
}

void string_copy(string dest, string source) {
    string_CheckSize(dest, source->length);
    memcpy(dest->buffer, source->buffer, source->length);
    dest->length = source->length;
}

void string_print(string str) {
    for(int i = 0; i < str->length; i++) {
        fputc(str->buffer[i], stdout);
    }
}


#define STACK_STRING(size) &(struct _string) { \
    .type = stringTypeFixed, .buffer = (char[size]) {}, .length = 0, .bufSize = size \
}

#define HEAP_STRING(size) &(struct _string) { \
    .type = stringTypeHeap, .buffer = malloc(size), .length = 0, .bufSize = size \
}

#define STRING_LITERAL(literal) &(struct _string) { \
    .type = stringTypeFixed, .buffer = literal, .length = strlen(literal), .bufSize = strlen(literal) + 1 \
}

int main() {
    string stackString = STACK_STRING(32);
    string_copy(stackString, STRING_LITERAL("hello pls\n"));

    string heapString = HEAP_STRING(2);
    string_copy(heapString, STRING_LITERAL("This string is too long and will trigger a realloc.\n"));

    string_print(stackString);
    string_print(heapString);
    return 0;
}