#include <mango/handle.h>
#include <mango/task.h>
#include <mango/types.h>
#include <mango/vm.h>
#include <stdint.h>

#define BRK_SIZE 0x400000

static virt_addr_t brk_base = 0, brk_ptr = 0;
static kern_handle_t brk_region = KERN_HANDLE_INVALID;
static kern_handle_t brk_object = KERN_HANDLE_INVALID;

static void *init_brk(size_t size)
{
	kern_status_t status = KERN_OK;
	kern_handle_t self, address_space;
	status = task_self(&self);
	if (status != KERN_OK) {
		return (void *)-1;
	}

	status = task_get_address_space(self, &address_space);
	if (status != KERN_OK) {
		kern_handle_close(self);
		return (void *)-1;
	}

	status = vm_object_create(
		"ulibc-brk",
		10,
		BRK_SIZE,
		VM_PROT_READ | VM_PROT_WRITE | VM_PROT_USER,
		&brk_object);
	if (status != KERN_OK) {
		kern_handle_close(address_space);
		kern_handle_close(self);
		return (void *)-1;
	}

	status = vm_region_create(
		address_space,
		"ulibc-brk",
		10,
		VM_REGION_ANY_OFFSET,
		BRK_SIZE,
		VM_PROT_READ | VM_PROT_WRITE | VM_PROT_USER,
		&brk_region,
		&brk_base);
	if (status != KERN_OK) {
		kern_handle_close(brk_object);
		kern_handle_close(address_space);
		kern_handle_close(self);

		brk_object = KERN_HANDLE_INVALID;
		return (void *)-1;
	}

	status = vm_region_map_relative(
		brk_region,
		0,
		brk_object,
		0,
		BRK_SIZE,
		VM_PROT_READ | VM_PROT_WRITE | VM_PROT_USER,
		NULL);
	if (status != KERN_OK) {
		kern_handle_close(brk_object);
		kern_handle_close(brk_region);
		kern_handle_close(address_space);
		kern_handle_close(self);

		brk_region = KERN_HANDLE_INVALID;
		brk_object = KERN_HANDLE_INVALID;
		return (void *)-1;
	}

	brk_ptr = brk_base;
	return (void *)brk_ptr;
}

void *sbrk(intptr_t increment)
{
	kern_status_t status = KERN_OK;
	if (brk_region == KERN_HANDLE_INVALID
	    || brk_object == KERN_HANDLE_INVALID) {
		init_brk(BRK_SIZE);
	}

	if (brk_ptr == 0 || brk_ptr >= brk_base + BRK_SIZE) {
		return (void *)-1;
	}

	void *result = (void *)brk_ptr;
	brk_ptr += increment;
	return result;
}