import json

from admin.decorators import superuser_only
from django.core import signing
from django.http import HttpResponse
from django.shortcuts import get_object_or_404, redirect, render
from django.urls import reverse
from django.utils import timezone
from instances.models import Instance
from libvirt import libvirtError
from operations import claims
from vrtManager.connection import wvmConnect
from vrtManager.hostdetails import wvmHostDetails

from computes.forms import (
    SocketComputeForm,
    SshComputeForm,
    TcpComputeForm,
    TlsComputeForm,
)
from computes.models import Compute

from . import utils

# The host CPU graph sends back the CPU sample of its previous answer; usage
# is taken since then when it is this recent, otherwise over one second.
CPU_SAMPLE_MAX_AGE = 15
CPU_SAMPLE_SIGNER = signing.TimestampSigner(salt="computes.cpu-sample")


@superuser_only
def computes(request):
    """
    :param request:
    :return:
    """

    computes = Compute.objects.filter().order_by("name")

    return render(request, "computes/list.html", {"computes": computes})


@superuser_only
def overview(request, compute_id):
    compute = get_object_or_404(Compute, pk=compute_id)
    # the connection itself, not a TCP probe: ssh aliases and ProxyJump hosts
    # are not reachable by name and port from here
    status = "true" if compute.status else "false"

    conn = wvmHostDetails(
        compute.hostname,
        compute.login,
        compute.password,
        compute.type,
    )
    (
        hostname,
        host_arch,
        host_memory,
        logical_cpu,
        model_cpu,
        uri_conn,
    ) = conn.get_node_info()
    hypervisor = conn.get_hypervisors_domain_types()
    mem_usage = conn.get_memory_usage()
    emulator = conn.get_emulator(host_arch)
    version = conn.get_version()
    lib_version = conn.get_lib_version()
    conn.close()

    return render(request, "overview.html", locals())


@superuser_only
def instances(request, compute_id):
    compute = get_object_or_404(Compute, pk=compute_id)

    utils.refresh_instance_database(compute)
    instances = Instance.objects.filter(compute=compute).prefetch_related(
        "userinstance_set"
    )

    return render(
        request, "computes/instances.html",
        {"compute": compute, "instances": instances, "job_resource": claims.compute_key(compute.id)},
    )


@superuser_only
def compute_create(request, FormClass):
    form = FormClass(request.POST or None)
    if form.is_valid():
        form.save()
        return redirect(reverse("computes"))

    return render(request, "computes/form.html", {"form": form})


@superuser_only
def compute_update(request, compute_id):
    compute = get_object_or_404(Compute, pk=compute_id)

    if compute.type == 1:
        FormClass = TcpComputeForm
    elif compute.type == 2:
        FormClass = SshComputeForm
    elif compute.type == 3:
        FormClass = TlsComputeForm
    elif compute.type == 4:
        FormClass = SocketComputeForm

    form = FormClass(request.POST or None, instance=compute)
    if form.is_valid():
        form.save()
        return redirect(reverse("computes"))

    return render(request, "computes/form.html", {"form": form})


@superuser_only
def compute_delete(request, compute_id):
    compute = get_object_or_404(Compute, pk=compute_id)
    if request.method == "POST":
        compute.delete()
        return redirect("computes")

    return render(
        request,
        "common/confirm_delete.html",
        {"object": compute},
    )


def compute_graph(request, compute_id):
    """
    :param request:
    :param compute_id:
    :return:
    """
    comp_mgr = ComputeManager(compute_id)
    data = comp_mgr.compute_graph(request.GET.get("cpu_sample"))

    return HttpResponse(data, content_type="application/json")


def get_compute_disk_buses(request, compute_id, arch, machine, disk):
    """
    :param request:
    :param compute_id:
    :param arch:
    :param machine:
    :param disk:
    :return:
    """
    comp_mgr = ComputeManager(compute_id)
    return HttpResponse(comp_mgr.get_disk_buses(arch, machine, disk), content_type="application/json")


def get_compute_machine_types(request, compute_id, arch):
    """
    :param request:
    :param compute_id:
    :param arch:
    :return:
    """
    comp_mgr = ComputeManager(compute_id)
    return HttpResponse(comp_mgr.get_machine_types(arch), content_type="application/json")


def get_dom_capabilities(request, compute_id, arch, machine):
    """
    :param request:
    :param compute_id:
    :param arch:
    :param machine:
    :return:
    """
    comp_mgr = ComputeManager(compute_id)
    return HttpResponse(comp_mgr.get_dom_capabilities(arch, machine), content_type="application/json")


class ComputeManager:
    def __init__(self, compute_id):
        self.compute = get_object_or_404(Compute, pk=compute_id)
        self.conn = wvmConnect(
            self.compute.hostname,
            self.compute.login,
            self.compute.password,
            self.compute.type,
        )

    def get_dom_capabilities(self, arch, machine):
        data = dict()
        try:
            data["videos"] = self.conn.get_disk_device_types(arch, machine)
            data["bus"] = self.conn.get_disk_device_types(arch, machine)
        except libvirtError:
            pass

        return json.dumps(data)

    def get_machine_types(self, arch):
        data = dict()
        try:
            data["machines"] = self.conn.get_machine_types(arch)
        except libvirtError:
            pass

        return json.dumps(data)

    def get_disk_buses(self, arch, machine, disk):
        data = dict()
        try:
            disk_device_types = self.conn.get_disk_device_types(arch, machine)

            if disk in disk_device_types:
                if disk == "disk":
                    data["bus"] = sorted(disk_device_types)
                elif disk == "cdrom":
                    data["bus"] = ["ide", "sata", "scsi"]
                elif disk == "floppy":
                    data["bus"] = ["fdc"]
                elif disk == "lun":
                    data["bus"] = ["scsi"]
        except libvirtError:
            pass

        return json.dumps(data)

    def _cpu_sample(self, token):
        """The (idle, total, time) sample in a token of this compute's graph,
        or None when there is none, it is altered or too old."""
        if not token:
            return None
        try:
            data = CPU_SAMPLE_SIGNER.unsign_object(token, max_age=CPU_SAMPLE_MAX_AGE)
        except signing.BadSignature:
            return None
        if data.get("compute") != self.compute.id:
            return None
        return data["idle"], data["total"], data["time"]

    def compute_graph(self, cpu_sample=None):
        result = {"cpudata": None, "memdata": {"total": None, "usage": None}, "timeline": timezone.now().strftime("%H:%M:%S")}
        try:
            conn = wvmHostDetails(
                self.compute.hostname,
                self.compute.login,
                self.compute.password,
                self.compute.type,
            )
            cpu = conn.get_cpu_usage(previous=self._cpu_sample(cpu_sample))
            idle, total, taken = cpu["sample"]
            result = {
                "cpudata": cpu["usage"],
                "memdata": conn.get_memory_usage(),
                "timeline": timezone.now().strftime("%H:%M:%S"),
                "window": round(cpu["window"], 1),
                "cpu_sample": CPU_SAMPLE_SIGNER.sign_object(
                    {"compute": self.compute.id, "idle": idle, "total": total, "time": taken}
                ),
            }
            conn.close()
        except libvirtError:
            pass

        return json.dumps(result)