#include "api/error.h"
#include "api/obj.h"
#include "api/syscall.h"
#include "jove.h"
#include "lib/printf.h"
#include "proc/process.h"
#include "proc/scheduler.h"
#include "sys/objdir.h"
#include "syscall.h"

int
s_syscall_pcb_yield(jove_owned_obj_t *pcb_obj,
        size_t bytes_left,
        void *payload_data)
{
    //Verify message is big enough for payload
    size_t bytes_needed = sizeof(pid_t);
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for payload");

    //Get subject PID from payload.
    pid_t subject_pid = *((pid_t*)payload_data);

    //Yield to target.
    return scheduler_yield(subject_pid);
}

int
s_syscall_pcb_send(jove_owned_obj_t *pcb_obj,
                   lockstack_t *lockstack,
                   jove_obj_t *objdir_obj,
                   size_t bytes_left,
                   void *payload_data)
{
    //Verify message is big enough for payload.
    size_t bytes_needed = sizeof(struct syscall_pcb_send);
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for payload");
    struct syscall_pcb_send *payload = payload_data;

    //Verify message is big enough for payload object path.
    bytes_needed += payload->send_path_length;
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for subject path");

    //Verify subject object path is not the root directory.
    if(payload->send_path_length == 0) {
        kprintf("%s: Unable to send root directory\n", __func__);
        return -EBADPATH;
    }

    //Verify the subject objdir path is valid.
    jove_perm_obj_t subject_objdir = link_traverse_objdir(objdir_obj, payload->send_path_length - 1, payload->send_path);

    if(subject_objdir.obj == NULL) {
        klogf("Unable to get subject %P objdir : %s\n",
              payload->send_path, payload->send_path_length, errstr(errno));
        obj_release(subject_objdir.obj);
        return -errno;
    }

    //Verify the currently running PCB has mutate permissions for this objdir.
    CHECK_OBJPERM(subject_objdir, SYSCALL_PERM_PCB_SEND_OBJDIR, "Subject objdir does not permit send");

    //Verify the subject exists in the subject objdir.
    jove_owned_obj_t *subject = objdir_getlocal(
            obj_release(subject_objdir.obj), payload->send_path[payload->send_path_length-1]);
    lockstack_push(lockstack, subject);

    if(subject == 0) {
        klogf("Unable to get subject %P object : %s\n",
              payload->send_path, payload->send_path_length, errstr(errno));
        return -errno;
    }

    //Send subject to target.
    return pcb_send(obj_deref(pcb_obj), payload->send_target, subject, payload->send_timeout);
}

int
s_syscall_pcb_recv(jove_owned_obj_t *pcb_obj,
                   lockstack_t *lockstack,
                   jove_obj_t *objdir_obj,
                   size_t bytes_left,
                   void *payload_data)
{
    //Verify the message is big enough for the payload.
    size_t bytes_needed = sizeof(struct syscall_pcb_recv);
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for payload");
    struct syscall_pcb_recv *payload = payload_data;

    //Verify the message is big enough for the payload object.
    bytes_needed += payload->recv_path_length * sizeof(objpath_part_t);
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for destination path");

    //Verify the destination object exists.
    jove_perm_obj_t destination = link_traverse_objdir(objdir_obj, payload->recv_path_length, payload->recv_path);
    lockstack_push(lockstack, destination.obj);

    if(errno) {
        klogf("Unable to get destination %P : %s\n",
              payload->recv_path, payload->recv_path_length, errstr(errno));
        return -errno;
    }

    //Verify the destination path is JOVE_OBJ_NONE and that the object has recieve permissions.
    CHECK_OBJTYPE(destination.obj, JOVE_OBJ_NONE, "Destination object is occupied");
    CHECK_OBJPERM(destination, SYSCALL_PERM_PCB_RECV_DST, "Destination object does not permit recv.");

    //Recieve from some PID into destination.
    return pcb_recv(obj_deref(pcb_obj), payload->recv_target, destination.obj, payload->recv_timeout);
}

int
s_syscall_pcb_swap(jove_owned_obj_t *pcb_obj,
                   lockstack_t *lockstack,
                   jove_obj_t *objdir_obj,
                   size_t bytes_left,
                   void *payload_data)
{
    //Verify the message is big enough for payload.
    size_t bytes_needed = sizeof(struct syscall_pcb_recv);
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for payload");
    struct syscall_pcb_swap *payload = payload_data;

    //Verify the message is big enough for the subject path.
    bytes_needed += payload->swap_path_length * sizeof(objpath_part_t);
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for swap path");

    //Verify the subject is not the rootdir.
    if(payload->swap_path_length == 0) {
        kprintf("%s: Unable to swap the root directory\n", __func__);
        return -EBADPATH;
    }

    //Verify the subject objdir exists.
    jove_perm_obj_t subject_objdir = link_traverse_objdir(objdir_obj, payload->swap_path_length - 1, payload->swap_path);

    if(subject_objdir.obj == NULL) {
        klogf("Unable to get subject %P objdir : %s\n",
              payload->swap_path, payload->swap_path_length, errstr(errno));
        obj_release(subject_objdir.obj);
        return -errno;
    }
    //Verify the subject objdir has send permissions.
    CHECK_OBJPERM(subject_objdir, SYSCALL_PERM_PCB_SEND_OBJDIR, "Subject objdir does not permit send");

    //Verify the subject object exists.
    jove_owned_obj_t *subject = objdir_getlocal(
            obj_release(subject_objdir.obj), payload->swap_path[payload->swap_path_length-1]);
    lockstack_push(lockstack, subject);

    if(subject == 0) {
        klogf("Unable to get subject %P object : %s\n",
              payload->swap_path, payload->swap_path_length, errstr(errno));
        return -errno;
    }

    //Verify the target PCB exists.
    if(pcb_frompid(payload->swap_target) == 0) {
        klogf("Swap PCB target %i does not exist\n", payload->swap_target);
        return -EBADPROC;
    }

    //Verify the message was sent before timeout.
    int send_result = pcb_send(
            obj_deref(pcb_obj), payload->swap_target, subject, payload->send_timeout);
    if(send_result < 0) {
        klogf("Send to %i failed with code %s\n", payload->swap_target, errstr(-send_result));
        return send_result;
    }

    //Verify a message was recieved before timeout.
    int recv_result = pcb_recv(
            obj_deref(pcb_obj), payload->swap_target, subject, payload->recv_timeout);
    return recv_result;
}

int
s_syscall_pcb_stack(jove_owned_obj_t *pcb_obj,
        lockstack_t *lockstack,
        jove_obj_t *rootdir,
        size_t bytes_left,
        void *payload_data)
{
    //Verify the message is big enough for the payload struct.
    size_t bytes_needed = sizeof(struct syscall_pcb_stack);
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for payload");

    //Verify the message is big enough for the untyped object path.
    struct syscall_pcb_stack *payload = payload_data;
    bytes_needed += sizeof(objpath_part_t) * payload->stack_path_length;
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for untyped path");

    jove_perm_obj_t untyped = link_traverse_objdir(rootdir, payload->stack_path_length, payload->stack_path);
    lockstack_push(lockstack, untyped.obj);

    //Verify the untyped object exists.
    if(untyped.obj == NULL) {
        klogf("Unable to get untyped %P : %s\n",
              payload->stack_path, payload->stack_path_length, errstr(errno));
        return -errno;
    }

    //Verify the correct type and permissions.
    CHECK_OBJTYPE(untyped.obj, JOVE_OBJ_UNTYPED, "Subject untyped is not an untyped.");
    CHECK_OBJPERM(untyped, SYSCALL_PERM_PCB_STACK_OBJ, "Untyped is missing permissions");

    jove_untyped_t *untyped_data = obj_deref(untyped.obj);
    if((uintptr_t)untyped_data & 0xFFF) {
        klogf("Untyped object %P is not aligned to page boundary.\n",
              payload->stack_path, payload->stack_path_length);
        return -EALIGN;
    }
    if(untyped_data->limit != 0x1000) {
        klogf("Untyped object %P is not page sized.\n",
              payload->stack_path, payload->stack_path_length);
        return -EBADSIZE;
    }

    //Set the stack. Error if bad type or stack already exists.
    pcb_t *pcb = obj_deref(pcb_obj);
    switch(payload->type) {
        case PCB_STACK_SYSTEM:
            if(pcb_get_syscall_stack(pcb) != 0) {
                klogf("PCB %p Already has a system stack!\n", pcb);
                return -EFULL;
            }
            pcb_set_syscall_stack(pcb, obj_getvalue(untyped.obj));
            break;
        case PCB_STACK_INTERRUPT:
            if(pcb_get_interrupt_stack(pcb) != 0) {
                klogf("PCB %p Already has a interrupt stack!\n", pcb);
                return -EFULL;
            }
            pcb_set_interrupt_stack(pcb, obj_getvalue(untyped.obj));
            break;
        default:
            klogf("Unknown stack type %i\n", payload->type);
            return -EBADARG;
    }

    //Destroy untyped object.
    obj_settype(untyped.obj, JOVE_OBJ_NONE);
    obj_setvalue(untyped.obj, 0);
    return 0;
}

int s_syscall_pcb_ready(
    jove_owned_obj_t *target_obj,
    lockstack_t *lockstack,
    jove_obj_t *objdir)
{
    jove_objdir_t *target_objdir = obj_getobjdir(obj_asunowned(target_obj));
    if(!obj_compare(&target_objdir->entries[PCB_ROOTDIR_SELF_I], obj_asunowned(target_obj))) {
        klogf("Target PCB is not in entry %i of it's objdir!\n", PCB_ROOTDIR_SELF_I);
        return -EBADPATH;
    }

    jove_owned_obj_t *pagedir_obj = obj_take(&target_objdir->entries[PCB_ROOTDIR_PAGEDIR_I]);
    if(obj_gettype(pagedir_obj) != JOVE_OBJ_PAGEDIR) {
        klogf("Target PCB rootdir does not have pagedir in entry %i\n", PCB_ROOTDIR_PAGEDIR_I);
        obj_release(pagedir_obj);
        return -EBADPATH;
    }
    
    obj_release(pagedir_obj);
    return 0;
}

int
s_syscall_pcb_stop(jove_owned_obj_t *pcb_obj,
                   size_t bytes_left,
                   void *payload_data)
{
    size_t bytes_needed = sizeof(int);
    CHECK_TOOSMALL(bytes_needed, bytes_left, "Message too small for payload");

    int stop_code = *((int*)payload_data);
    return scheduler_stop(pcb_obj, stop_code);
}

int
_syscall_handle_pcb(syscall_context_t *ctx)
{
    switch(ctx->header->callid) {
        case SYSCALL_PCB_YIELD:
            if(ctx->target.permissions & SYSCALL_PERM_PCB_YIELD)
                return s_syscall_pcb_yield(ctx->target.obj, ctx->bytes_left, ctx->payload);
            return -EPERM;

        case SYSCALL_PCB_SEND:
            if(ctx->target.permissions & SYSCALL_PERM_PCB_SEND)
                return s_syscall_pcb_send(
                    ctx->target.obj, &ctx->lockstack, ctx->objdir, ctx->bytes_left, ctx->payload);
            return -EPERM;

        case SYSCALL_PCB_RECV:
            if(ctx->target.permissions & SYSCALL_PERM_PCB_RECV)
                return s_syscall_pcb_recv(
                    ctx->target.obj, &ctx->lockstack, ctx->objdir, ctx->bytes_left, ctx->payload);
            return -EPERM;

        case SYSCALL_PCB_SWAP:
            if(ctx->target.permissions & SYSCALL_PERM_PCB_SWAP)
                return s_syscall_pcb_swap(
                    ctx->target.obj, &ctx->lockstack, ctx->objdir, ctx->bytes_left, ctx->payload);
            return -EPERM;

        case SYSCALL_PCB_STACK:
            if(ctx->target.permissions & SYSCALL_PERM_PCB_STACK)
                return s_syscall_pcb_stack(
                    ctx->target.obj, &ctx->lockstack, ctx->objdir, ctx->bytes_left, ctx->payload);
            return -EPERM;

        case SYSCALL_PCB_READY:
            if(ctx->target.permissions & SYSCALL_PERM_PCB_READY)
                return s_syscall_pcb_ready(
                    ctx->target.obj, &ctx->lockstack, ctx->objdir);
            return -EPERM;
        case SYSCALL_PCB_STOP:
            if(ctx->target.permissions & SYSCALL_PERM_PCB_STOP)
                return s_syscall_pcb_stop(
                    ctx->target.obj, ctx->bytes_left, ctx->payload);

        default:
            return -EBADCALL;
    }
}