"""A minimal OVF 1.0 descriptor for importing one converted cloud image.

vSphere builds the VM from this (``OvfManager.CreateImportSpec``) and then
takes the disk contents over NFC. The descriptor only has to describe what
the image does not: CPU, memory, one disk and the NICs.

Devices are the ones VMware recommends for a 64-bit Linux guest -- PVSCSI and
VMXNET3. Both drivers are in the mainline kernel; whether every distribution's
*cloud* kernel carries them is one of the things #305 checks on real hardware.
"""

from __future__ import annotations

from xml.sax.saxutils import escape, quoteattr

_HW_VERSION = "vmx-13"  # ESXi 6.5 and later
_GUEST_OS = "otherLinux64Guest"
_STREAM_OPTIMIZED = "http://www.vmware.com/interfaces/specifications/vmdk.html#streamOptimized"


def _item(**elements: str) -> str:
    # CIM requires the rasd elements in alphabetical order.
    body = "".join(f"<rasd:{k}>{escape(v)}</rasd:{k}>" for k, v in sorted(elements.items()))
    return f"<Item>{body}</Item>"


def _nic_items(nic_count: int, first_instance: int) -> str:
    return "".join(
        _item(
            AutomaticAllocation="true",
            Connection=f"net{i}",
            ElementName=f"Network adapter {i + 1}",
            InstanceID=str(first_instance + i),
            ResourceSubType="VmxNet3",
            ResourceType="10",
        )
        for i in range(nic_count)
    )


def ovf_descriptor(
    name: str,
    *,
    cpu: int,
    memory_mb: int,
    capacity_bytes: int,
    nic_count: int,
    firmware: str = "bios",
) -> str:
    networks = "".join(
        f'<Network ovf:name="net{i}"><Description>net{i}</Description></Network>'
        for i in range(nic_count)
    )
    hardware = "".join(
        [
            _item(
                AllocationUnits="hertz * 10^6",
                ElementName=f"{cpu} virtual CPU(s)",
                InstanceID="1",
                ResourceType="3",
                VirtualQuantity=str(cpu),
            ),
            _item(
                AllocationUnits="byte * 2^20",
                ElementName=f"{memory_mb} MB of memory",
                InstanceID="2",
                ResourceType="4",
                VirtualQuantity=str(memory_mb),
            ),
            _item(
                Address="0",
                ElementName="SCSI controller 0",
                InstanceID="3",
                ResourceSubType="VirtualSCSI",
                ResourceType="6",
            ),
            _item(
                AddressOnParent="0",
                ElementName="Hard disk 1",
                HostResource="ovf:/disk/vmdisk1",
                InstanceID="4",
                Parent="3",
                ResourceType="17",
            ),
            _nic_items(nic_count, first_instance=5),
        ]
    )
    firmware_config = (
        '<vmw:Config ovf:required="false" vmw:key="firmware" vmw:value="efi"/>'
        if firmware == "efi"
        else ""
    )
    return (
        '<?xml version="1.0" encoding="UTF-8"?>'
        '<Envelope xmlns="http://schemas.dmtf.org/ovf/envelope/1"'
        ' xmlns:ovf="http://schemas.dmtf.org/ovf/envelope/1"'
        ' xmlns:rasd="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_ResourceAllocationSettingData"'
        ' xmlns:vssd="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_VirtualSystemSettingData"'
        ' xmlns:vmw="http://www.vmware.com/schema/ovf">'
        '<References><File ovf:href="disk.vmdk" ovf:id="file1"/></References>'
        "<DiskSection><Info>Virtual disks</Info>"
        f'<Disk ovf:capacity="{capacity_bytes}" ovf:capacityAllocationUnits="byte"'
        f' ovf:diskId="vmdisk1" ovf:fileRef="file1" ovf:format="{_STREAM_OPTIMIZED}"/>'
        "</DiskSection>"
        f"<NetworkSection><Info>Networks</Info>{networks}</NetworkSection>"
        f"<VirtualSystem ovf:id={quoteattr(name)}>"
        "<Info>A virtual machine</Info>"
        f"<Name>{escape(name)}</Name>"
        f'<OperatingSystemSection ovf:id="101" vmw:osType="{_GUEST_OS}"><Info>Guest OS</Info>'
        "</OperatingSystemSection>"
        "<VirtualHardwareSection><Info>Virtual hardware</Info>"
        "<System><vssd:ElementName>Virtual Hardware Family</vssd:ElementName>"
        "<vssd:InstanceID>0</vssd:InstanceID>"
        f"<vssd:VirtualSystemIdentifier>{escape(name)}</vssd:VirtualSystemIdentifier>"
        f"<vssd:VirtualSystemType>{_HW_VERSION}</vssd:VirtualSystemType></System>"
        f"{hardware}{firmware_config}"
        "</VirtualHardwareSection>"
        "</VirtualSystem>"
        "</Envelope>"
    )