#include "thread.h"
#include "alloc.h"
#include "assert.h"
#include "interrupts.h"
#include "list.h"
#include "memory.h"
#include "process.h"
#include "string.h"
#include "thread.h"

struct tcb *create_thread(struct pcb *process, void (*entry)(void))
{
	struct tcb *new_tcb = vmalloc(sizeof(struct tcb));
	if (!new_tcb)
		return NULL;
	new_tcb->tid = process->tid++;

	new_tcb->esp0 = alloc_pages(STACK_SIZE, NULL);
	if (!new_tcb->esp0) {
		vfree(new_tcb);
		return NULL;
	}
	uint32_t *stack = (uint32_t *)((uint8_t *)new_tcb->esp0 + STACK_SIZE);
	uint32_t *esp = stack;

	// testing out some stuff
	*(--stack) = 0x202; // EFLAGS
	*(--stack) = 0x08;  // CS = kernel code segment
	*(--stack) = (uint32_t)entry;
	// Error code and interrupt number (skipped by add $8, %esp)
	*(--stack) = 0; // err_code
	*(--stack) = 0; // int_no

	// General purpose registers (for popa)
	*(--stack) = 0;             // EAX
	*(--stack) = 0;             // ECX
	*(--stack) = 0;             // EDX
	*(--stack) = 0;             // EBX
	*(--stack) = (uint32_t)esp; // ESP (original - points to exit_process)
	*(--stack) = 0;             // EBP
	*(--stack) = 0;             // ESI
	*(--stack) = 0;             // EDI
	*(--stack) = 0x10;          // kernel DS

	new_tcb->esp = stack;
	new_tcb->process = process;
	new_tcb->state = NEW;

	struct list *new_node = vmalloc(sizeof(struct list));
	if (!new_node) {
		free_pages(new_tcb->esp0, STACK_SIZE);
		vfree(new_tcb);
		return NULL;
	}
	new_node->content = new_tcb;
	new_node->next = NULL;
	if (process->thread_list == NULL) {
		process->thread_list = new_node;
	} else {
		struct list *it = process->thread_list;
		while (it->next)
			it = it->next;
		it->next = new_node;
	}

	return new_tcb;
}

void delete_thread(struct tcb *thread)
{
	vfree(thread->esp0);
	struct list *it = thread->process->thread_list;
	assert(it);
	while (it->next && it->next->content != thread)
		it = it->next;
	struct list *to_free = it;
	it->next = it->next->next;
	vfree(to_free);
	vfree(thread);
}