#include "kthread.h"
#include "alloc.h"
#include "assert.h"
#include "irq.h"
#include "klibc.h"
#include "list.h"
#include "vga.h"

static struct kthread *currentThread;

void kthreadExit()
{
        uint32_t flags;
        disable_IRQs(flags);
        struct kthread *current = currentThread;
        struct kthread *next    = kthreadSelectNext();
        if (next == current)
                assert("cannot exit thread");
        currentThread = next;
        cpu_context_exit_to(next->cpuState, (cpu_kstate_function_arg1_t *)kthreadDelete,
                            (uint32_t)current);
        restore_IRQs(flags);
        return;
}

int kthreadSetup(vaddr_t mainStack, size_t mainStackSize)
{
        struct kthread *current = (struct kthread *)malloc(sizeof(struct kthread));
        strzcpy(current->name, "[KINIT]", KTHREAD_NAME_MAX_LENGTH);
        current->stackAddr = mainStack;
        current->stackSize = mainStackSize;

        list_singleton(currentThread, current);

        return 0;
}

struct kthread *kthreadCreate(const char *name, cpu_kstate_function_arg1_t func, void *args)
{
        struct kthread *thread = (struct kthread *)malloc(sizeof(struct kthread));
        if (!thread)
                return NULL;

        thread->stackAddr = (vaddr_t)malloc(KTHREAD_DEFAULT_STACK_SIZE);
        printf("Alloc stask at 0x%x strcut at 0x%x\n", thread->stackAddr, thread);
        thread->stackSize = KTHREAD_DEFAULT_STACK_SIZE;

        if (!thread->stackAddr)
                goto free_mem;

        if (name)
                strzcpy(thread->name, name, KTHREAD_NAME_MAX_LENGTH);
        else
                strzcpy(thread->name, "[UNKNOW]", KTHREAD_NAME_MAX_LENGTH);

        if (cpu_kstate_init(&thread->cpuState, (cpu_kstate_function_arg1_t *)func,
                            (vaddr_t)args, thread->stackAddr, thread->stackSize,
                            (cpu_kstate_function_arg1_t *)kthreadExit, 0))
                goto free_mem;

        list_add_tail(currentThread, thread);
        return thread;
free_mem:
        free((void *)thread->stackAddr);
        free((void *)thread);
        return NULL;
}

void kthreadDelete(struct kthread *thread)
{
        list_delete(currentThread, thread);

        free((void *)thread->stackAddr);
        free((void *)thread);
}

struct kthread *kthreadSelectNext()
{
        struct kthread *nextThread = currentThread->next;
        return nextThread;
}

struct cpu_state *switchKthread(struct cpu_state *prevCpu)
{
        uint32_t flags;
        disable_IRQs(flags);
        currentThread->cpuState    = prevCpu;
        struct kthread *nextThread = kthreadSelectNext();
        printStringDetails(nextThread->name, RED, BLACK, 40, VGA_HEIGHT - 1);
        currentThread = nextThread;
        restore_IRQs(flags);
        return nextThread->cpuState;
}

int kthreadYield()
{
        uint32_t flags;
        disable_IRQs(flags);
        struct kthread *next    = kthreadSelectNext();
        struct kthread *current = currentThread;
        currentThread           = next;
        cpu_context_switch(&current->cpuState, next->cpuState);
        restore_IRQs(flags);
        return 0;
}