/* This software is licensed by the MIT License, see LICENSE file */
/*                                Copyright © 2022 Gregory Lirent */

#include <stdarg.h>
#include <stdlib.h>
#include "__internal/include.h"
#undef malloc
#undef free

void libcdsb_stack_init(stack_t* x) {
    memset(x, 0, sizeof(*x));
}


void libcdsb_stack_push(stack_t* x, void* value) {
    stack_t* n;

    if (x->value) {
        if (!(n = malloc(sizeof(*n))))
            abort();

        n->prev  = x->prev;
        n->value = x->value;
        x->prev  = n;
    }

    x->value = value;
}


void libcdsb_stack_push_many(stack_t* x, size_t c, ...) {

    va_list args;
    stack_t* n;
    va_start(args, c);

    if (c) {
        if (!x->value) {
            x->value = va_arg(args, void*);
            --c;
        }

        while (c--) {
            if (!(n = malloc(sizeof(*n))))
                abort();

            n->prev  = x->prev;
            n->value = x->value;
            x->prev  = n;
            x->value = va_arg(args, void*);
        }
    }

    va_end(args);
}


void* libcdsb_stack_pop(stack_t* x) {

    stack_t* n;
    void*    v;

    v = x->value;

    if (x->prev) {
        n = x->prev;
        x->prev = n->prev;
        x->value = n->value;
        free(n);
    } else x->value = 0;

    return v;
}


void libcdsb_stack_reverse(stack_t* x) {

    stack_t z, *iter, *n, copy;


    if (x->prev) {
        z.prev  = 0;
        z.value = x->value;
        iter    = x->prev;

        while (iter->prev) {
            n = iter;
            iter = n->prev;

            copy.prev  = z.prev;
            copy.value = z.value;

            z.prev  = n;
            z.value = n->value;

            n->prev  = copy.prev;
            n->value = copy.value;
        }

        copy.prev  = z.prev;
        copy.value = z.value;

        x->prev  = iter;
        x->value = iter->value;

        iter->prev  = copy.prev;
        iter->value = copy.value;
    }
}


void libcdsb_stack_flush(stack_t* x) {
    stack_t* c;

    while (x->prev) {
        c = x->prev;
        x->prev = c->prev;
        free(c);
    }

    x->value = 0;
}