//
// Created by nano on 4/30/25.
//


#include <stdlib.h>
#include <string.h>
#include "stack.h"

#include <limits.h>
#include <math.h>

void stack_init(stack *stack) {
	stack -> length = 0;
	stack -> size = 1;
	stack -> data = calloc(stack->size,sizeof(cell));
}

void stack_free(stack *stack) {
	free(stack -> data);
	stack->size = 0;
	stack->length = 0;
}

void stack_reinit(stack *stack) {
	stack_free(stack);
	stack_init(stack);
}

void stack_expand(stack *stack) {
	stack -> size = stack -> size *2;
	cell *new_data = calloc(stack -> size ,sizeof(cell));
	memcpy(new_data, stack -> data, stack -> size/2 * sizeof(cell));
	free(stack -> data);
	stack -> data = new_data;
}

void stack_push(stack *stack, cell c) {
	if (stack -> length + 1 == stack -> size) {
		stack_expand(stack);
	}
	stack -> data[stack -> length++] = c;
}

void stack_shrink(stack *stack) {
	stack -> size = stack -> size / 2;
	cell *new_data = calloc(stack -> size , sizeof(cell));
	memcpy(new_data, stack -> data, stack -> size * sizeof(cell));
	free(stack -> data);
	stack -> data = new_data;
}

cell stack_pop(stack *stack) {
	if (stack -> length > 0) {
		const cell c = stack -> data[stack -> length - 1];
		if ((stack->length - 1) == (stack->size / 2) && stack -> size/2 !=0) {
			stack_shrink(stack);
		}
		stack -> length--;
		return c;
	}
	return (cell) {INT_MAX,INT_MAX};
}

void stack_invert(stack *stack) {
	cell *inv_data = calloc(stack -> size , sizeof(cell));
	for (int i=0;i<stack->length;i++)
		inv_data[stack->length -1 - i] = stack->data[i];
	free(stack -> data);
	stack -> data = inv_data;
}

void stack_append(const stack *from, stack *to) {
	const int size = (int) pow(2, ceil(log2(to->length + from->length)));
	// power of 2 which has enough space to hold all the contents of both stacks.
	cell *new_data = calloc(size,sizeof(cell));
	memcpy(new_data, to->data, to->length * sizeof(cell));
	memcpy(new_data+to->length, from -> data, from -> length * sizeof(cell));
	free(to->data);
	to->data = new_data;
	to->length = to->length + from -> length;
	to->size = size;
}