#include "arena.h"
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

bool ArenaInit(Arena *arena, size_t capacity) {
    arena->mem = malloc(capacity);
    if (!arena->mem) {
        return false;
    }
    arena->head = 0;
    arena->capacity = capacity;
    return true;
}

void *ArenaAlloc(Arena *arena, size_t size) {
    uintptr_t current_ptr = (uintptr_t)arena->mem + arena->head;
    // Alignment
    uintptr_t aligned_ptr = (current_ptr + 7) & ~7;

    size_t alignment_padding = aligned_ptr - current_ptr;
    size_t total_needed = size + alignment_padding;
    if (arena->head + total_needed > arena->capacity) {
        return NULL;
    }

    arena->head += total_needed;
    return (void *)aligned_ptr;
}

char *ArenaStrdup(Arena *arena, const char *str) {
    size_t len = strlen(str) + 1; // adding a \0
    char *ptr = ArenaAlloc(arena, len);
    if (ptr == NULL) return NULL;
    memcpy(ptr, str, len);
    return ptr;
}