data "vkcs_images_image" "ubuntu24" {
  visibility  = "public"
  most_recent = true
  properties = {
    mcs_os_distro  = "ubuntu"
    mcs_os_version = "24.04"
  }
}

data "vkcs_networking_network" "extnet" {
  name = "internet"
  sdn  = "sprut"
}

# Every VK Cloud project auto-creates a "default" security group with a
# UUID unique to that project - resolve it dynamically instead of
# hardcoding one project's UUID. var.default_security_group_id is a
# last-resort manual override (e.g. non-standard name/SDN in a project).
data "vkcs_networking_secgroup" "default" {
  name = "default"
  sdn  = "sprut"
}

locals {
  default_security_group_id = coalesce(
    var.default_security_group_id,
    data.vkcs_networking_secgroup.default.id
  )
}

# Nova keypairs are per-user, not per-project - a keypair uploaded under a
# different account is invisible to whichever account Terraform deploys as.
# Register it here from var.ssh_public_key when supplied; otherwise assume
# var.ssh_key_name already exists under the deploying account.
resource "vkcs_compute_keypair" "router" {
  count      = var.ssh_public_key != null ? 1 : 0
  name       = var.ssh_key_name
  public_key = var.ssh_public_key
}

locals {
  ssh_key_name = var.ssh_public_key != null ? vkcs_compute_keypair.router[0].name : var.ssh_key_name
}

# Security Groups
resource "vkcs_networking_secgroup" "router_sg" {
  name = "router-sg"
  sdn  = "sprut"
}

# Router SG rules
resource "vkcs_networking_secgroup_rule" "router_ssh" {
  direction         = "ingress"
  protocol          = "tcp"
  port_range_min    = 22
  port_range_max    = 22
  remote_ip_prefix  = "0.0.0.0/0"
  security_group_id = vkcs_networking_secgroup.router_sg.id
  sdn               = "sprut"
}

resource "vkcs_networking_secgroup_rule" "router_icmp" {
  direction         = "ingress"
  protocol          = "icmp"
  remote_ip_prefix  = "0.0.0.0/0"
  security_group_id = vkcs_networking_secgroup.router_sg.id
  sdn               = "sprut"
}

resource "vkcs_networking_secgroup_rule" "router_ipsec_ike" {
  direction         = "ingress"
  protocol          = "udp"
  port_range_min    = 500
  port_range_max    = 500
  remote_ip_prefix  = "0.0.0.0/0"
  security_group_id = vkcs_networking_secgroup.router_sg.id
  sdn               = "sprut"
}

resource "vkcs_networking_secgroup_rule" "router_ipsec_nat_t" {
  direction         = "ingress"
  protocol          = "udp"
  port_range_min    = 4500
  port_range_max    = 4500
  remote_ip_prefix  = "0.0.0.0/0"
  security_group_id = vkcs_networking_secgroup.router_sg.id
  sdn               = "sprut"
}

# Per-router private interfaces: one shared private network per admin-supplied
# CIDR in private_network_cidrs (no VRRP), each router getting its own
# port/IP inside every such network.
locals {
  private_network_cidr = {
    for idx, cidr in var.private_network_cidrs :
    "priv${idx + 1}" => cidr
  }
}

# Unify both sources of per-router interfaces into one role -> definition map:
# - roles from private_network_cidr are project-managed (network/subnet created
#   below), address chosen by Neutron IPAM (fixed_ips left null).
# - roles from var.router_networks are pre-existing networks owned elsewhere,
#   referenced by UUID only, with a specific IP per router (fixed_ips set).
locals {
  router_interfaces = merge(
    {
      for role, cidr in local.private_network_cidr : role => {
        network_id = vkcs_networking_network.router_priv_net[role].id
        subnet_id  = vkcs_networking_subnet.router_priv_subnet[role].id
        cidr       = cidr
        fixed_ips  = null
      }
    },
    {
      for role, net in var.router_networks : role => {
        network_id = net.network_id
        subnet_id  = net.subnet_id
        cidr       = net.cidr
        fixed_ips  = net.ip_addresses
      }
    }
  )

  router_interface_roles = keys(local.router_interfaces)
}

resource "vkcs_networking_network" "router_priv_net" {
  for_each       = local.private_network_cidr
  name           = "router-${each.key}-net"
  sdn            = "sprut"
  admin_state_up = true
}

resource "vkcs_networking_subnet" "router_priv_subnet" {
  for_each   = local.private_network_cidr
  network_id = vkcs_networking_network.router_priv_net[each.key].id
  name       = "router-${each.key}-subnet"
  cidr       = each.value
  gateway_ip = cidrhost(each.value, 1)
  sdn        = "sprut"

  # No in-guest DHCP client is needed for these interfaces: with
  # config_drive = true (set on every router instance), cloud-init learns
  # each interface's assigned address from the config-drive metadata and
  # renders it directly, then network-init.sh.tpl re-pins it deterministically
  # to ethN by MAC - no actual DHCP protocol exchange with this subnet ever
  # happens. (Note: this does NOT avoid IP collisions with VKCS's own
  # auto-created service ports on the network, e.g. a "network:dns" port -
  # see router_iface_port below, which leaves ip_address unset for these
  # project-managed roles instead.)
  enable_dhcp = false
}

resource "vkcs_networking_port" "router_iface_port" {
  for_each = {
    for pair in setproduct(range(var.router_count), local.router_interface_roles) :
    "router${pair[0] + 1}-${pair[1]}" => pair
  }
  name                         = "router-${each.key}-port"
  network_id                   = local.router_interfaces[each.value[1]].network_id
  admin_state_up               = true
  port_security_enabled        = false
  full_security_groups_control = true
  security_group_ids           = []
  sdn                          = "sprut"

  # For project-managed roles (private_network_cidr), ip_address is left null
  # so Neutron's IPAM auto-assigns one from the subnet's pool: VKCS
  # auto-creates its own service ports on this network (observed: a
  # "network:dns" port) that can silently consume whichever low address a
  # hand-computed offset would have picked, causing IpAddressAlreadyAllocated
  # - IPAM guarantees no double-booking, our own arithmetic doesn't.
  # network-init.sh.tpl matches interfaces by which declared CIDR their live
  # IP falls into, not by an exact expected IP, so this works either way.
  # For var.router_networks roles, the address is pre-agreed externally
  # (another project's admin already carved it out), so it's set explicitly.
  fixed_ip {
    subnet_id = local.router_interfaces[each.value[1]].subnet_id
    ip_address = (
      local.router_interfaces[each.value[1]].fixed_ips == null
      ? null
      : local.router_interfaces[each.value[1]].fixed_ips[each.value[0]]
    )
  }

  lifecycle {
    precondition {
      condition = (
        local.router_interfaces[each.value[1]].fixed_ips == null ||
        each.value[0] < length(local.router_interfaces[each.value[1]].fixed_ips)
      )
      error_message = "router_networks[\"${each.value[1]}\"].ip_addresses must have at least var.router_count entries."
    }
  }
}

resource "vkcs_compute_instance" "router" {
  count             = var.router_count
  name              = "router${count.index + 1}"
  flavor_name       = "STD3-4-4"
  availability_zone = element(var.router_availability_zones, count.index % length(var.router_availability_zones))
  key_pair          = local.ssh_key_name

  security_group_ids = [
    vkcs_networking_secgroup.router_sg.id,
    local.default_security_group_id
  ]

  config_drive = true

  # Configure persistent networking using script: WAN via heuristic public-IP
  # detection, private interfaces matched by their expected CIDR.
  user_data = templatefile("${path.module}/scripts/network-init.sh.tpl", {
    private_interfaces = [
      for role in local.router_interface_roles : {
        name = "eth${index(local.router_interface_roles, role) + 1}"
        cidr = local.router_interfaces[role].cidr
      }
    ]
  })

  # WAN: dynamically created port
  network {
    uuid = data.vkcs_networking_network.extnet.id
  }

  # Private: one pre-created port per role, into that role's network (either
  # project-managed via private_network_cidrs, or a pre-existing externally
  # owned one via router_networks)
  dynamic "network" {
    for_each = local.router_interface_roles
    content {
      port = vkcs_networking_port.router_iface_port["router${count.index + 1}-${network.value}"].id
    }
  }

  block_device {
    uuid                  = data.vkcs_images_image.ubuntu24.id
    source_type           = "image"
    volume_size           = 20
    boot_index            = 0
    destination_type      = "volume"
    volume_type           = "ceph-ssd"
    delete_on_termination = true
  }
}