# main.tf — dedicated NAT network + 3 cloud-init'd VMs, each with a thin OS disk
# (backed by the cloud image) and a blank thin Longhorn data disk (Phase 1 T-1.1).
#
# Node lifecycle stage 1 ("Create") per docs/02. cloud-init (infra/cloud-init/)
# does stage 2 ("Baseline"); Ansible (infra/ansible/) does stage 3 ("Cluster-join").

locals {
  # 1 GiB in bytes; libvirt volume sizes are bytes.
  gib = 1073741824

  # Per-node identity/addressing, KEYED BY NODE NAME (map, not list).
  # for_each over this map gives every node a stable, name-based state address
  # (libvirt_domain.node["k3s-dev-2"]) instead of a positional one (…node[1]).
  # Positional count indexes are brittle under `-target`/`-replace`: a single-node
  # destroy on a count-indexed resource can cascade to siblings (T-1.5 finding F1).
  # Name keys are individually addressable, so one node can be replaced/destroyed
  # without disturbing the others. See DECISIONS-LOG.md "T-1.5 … Finding F1".
  nodes = {
    for i in range(var.node_count) : "${var.node_name_prefix}${i + 1}" => {
      name     = "${var.node_name_prefix}${i + 1}"
      ip       = var.node_ips[i]
      fqdn     = "${var.node_name_prefix}${i + 1}.${var.node_domain}"
      is_first = i == 0
    }
  }

  # Ordered (node1..nodeN) list + primary view for outputs that need positional
  # access — the resource for_each uses the map above; these preserve ordering
  # for the Ansible inventory (primary = cluster-init server, rest = secondaries).
  node_list = [for i in range(var.node_count) : local.nodes["${var.node_name_prefix}${i + 1}"]]
  primary   = local.nodes["${var.node_name_prefix}1"]
}

# --- dedicated NAT network (10.73.0.0/24, gw .1) ---------------------------
# DHCP is OFF: nodes get static IPs from cloud-init network-config, so the
# reserved VIP range (.240-.250) can never be leased to something else.
resource "libvirt_network" "k3s_dev" {
  name      = var.network_name
  mode      = "nat"
  addresses = [var.network_cidr]
  autostart = true

  dhcp {
    enabled = false
  }

  dns {
    enabled    = true
    local_only = true
  }
}

# --- base OS volume (downloaded/copied once, shared as a backing file) ------
resource "libvirt_volume" "base" {
  name   = "${var.cluster_name}-base.qcow2"
  pool   = var.pool_name
  source = var.image_source
  format = "qcow2"
}

# --- per-node OS disk: thin qcow2 backed by the base image ------------------
resource "libvirt_volume" "os" {
  for_each       = local.nodes
  name           = "${each.value.name}-os.qcow2"
  pool           = var.pool_name
  base_volume_id = libvirt_volume.base.id
  size           = var.os_disk_gib * local.gib
  format         = "qcow2"
}

# --- per-node data disk: blank thin qcow2 for Longhorn ----------------------
resource "libvirt_volume" "data" {
  for_each = local.nodes
  name     = "${each.value.name}-data.qcow2"
  pool     = var.pool_name
  size     = var.data_disk_gib * local.gib
  format   = "qcow2"
}

# --- cloud-init seed (user-data + meta-data + static network-config) --------
# Templates live in the sibling infra/cloud-init/ subtree (T-1.2).
resource "libvirt_cloudinit_disk" "seed" {
  for_each = local.nodes
  name     = "${each.value.name}-seed.iso"
  pool     = var.pool_name

  user_data = templatefile("${path.module}/../cloud-init/user-data.yaml.tftpl", {
    hostname           = each.value.name
    fqdn               = each.value.fqdn
    username           = var.login_user
    ssh_authorized_key = var.ssh_authorized_key
  })

  meta_data = templatefile("${path.module}/../cloud-init/meta-data.yaml.tftpl", {
    hostname = each.value.name
    fqdn     = each.value.fqdn
  })

  network_config = templatefile("${path.module}/../cloud-init/network-config.yaml.tftpl", {
    ip      = each.value.ip
    prefix  = var.network_prefix
    gateway = var.network_gateway
  })
}

# --- the VMs ----------------------------------------------------------------
resource "libvirt_domain" "node" {
  for_each = local.nodes
  name     = each.value.name
  memory   = var.memory_mib
  vcpu     = var.vcpu

  # host-passthrough so nested virt is available for KubeVirt in Phase 5.
  cpu {
    mode = var.cpu_mode
  }

  # qemu-guest-agent is installed by cloud-init; lets tofu read the lease/agent.
  qemu_agent = true

  cloudinit = libvirt_cloudinit_disk.seed[each.key].id

  # IP + hostname come from cloud-init (DHCP is off on this network), so we do NOT
  # set addresses/hostname here — the provider couples those to DHCP reservations.
  network_interface {
    network_id     = libvirt_network.k3s_dev.id
    wait_for_lease = false
  }

  # OS disk first (vda, boot), Longhorn data disk second (vdb).
  disk {
    volume_id = libvirt_volume.os[each.key].id
  }

  disk {
    volume_id = libvirt_volume.data[each.key].id
  }

  console {
    type        = "pty"
    target_port = "0"
    target_type = "serial"
  }

  console {
    type        = "pty"
    target_port = "1"
    target_type = "virtio"
  }

  graphics {
    type        = "spice"
    listen_type = "address"
    autoport    = true
  }
}