#include <stdint.h>
#include <stddef.h>
#include <stdnoreturn.h>
#include "task.h"
#include <lib/kstdio.h>

struct arch_register_context
{
	uint64_t
		r15,
		r14,
		r13,
		r12,
		r11,
		r10,
		r9,
		r8,
		rsi,
		rdi,
		rdx,
		rcx,
		rbx,
		rax,
		rbp,
		rsp;
};

extern uint64_t *get_tss_rsp0(void);

struct arch_thread_context
{
	struct arch_register_context register_context;
	void *return_address;
};

extern void arch_swap_thread_stack(
		void * volatile *outgoing_stack,
		void *incoming_stack);

extern void arch_begin_thread(
		void *(func)(void *),
		void *params);

void arch_create_thread(
		struct kc_thread *thread,
		void *(*func)(void *),
		void *params)
{
	uintptr_t stack_pointer = (uintptr_t)thread->kernel_stack_pointer;
	struct arch_thread_context *context = (struct arch_thread_context *)
		(stack_pointer -= sizeof(*context));
	thread->kernel_stack_pointer = (void *)stack_pointer;

	context->return_address = (void *)arch_begin_thread;
	context->register_context.rdi = (uint64_t)func;
	context->register_context.rsi = (uint64_t)params;
	context->register_context.rdx = (uint64_t)thread;
	context->register_context.rsp = (uint64_t)&context->return_address;
}

void arch_swap_thread(
		struct kc_thread *outgoing,
		struct kc_thread *incoming)
{
	kprintf("swapping thread...\n");
	kprintf("stack pointer %p\n", incoming->kernel_stack_pointer);
	arch_swap_thread_stack(&outgoing->kernel_stack_pointer, incoming->kernel_stack_pointer);
}

void *arch_idle_loop(void *)
{
	for (;;) __asm__ ("hlt");
	return nullptr;
}

noreturn void arch_terminate_thread(void *result, struct kc_thread *thread)
{
	thread->result = (union kc_thread_result){ .pointer = result };
	thread->status = TERMINATED;
	thread->kernel_stack_pointer = thread->kernel_stack_head;
	task_schedule();
	for (;;) __asm__ ("hlt");
}