# UltraCloud Bootstrap ISO
# Minimal ISO with DHCP + Phone Home to Deployer + Auto-Install
# For VM cluster deployment: boots, phones home, partitions disk, installs NixOS

{
  config,
  lib,
  pkgs,
  modulesPath,
  ultracloudBaremetalFormatMountPaths ? { },
  ultracloudBaremetalSystemPaths ? { },
  ...
}:

{
  imports = [
    "${modulesPath}/installer/cd-dvd/installation-cd-minimal.nix"
  ];

  # ISO metadata
  image.fileName = "ultracloud-bootstrap.iso";
  isoImage = {
    makeEfiBootable = true;
    makeUsbBootable = true;
  };

  # Embed the repository into the ISO for offline flake install
  isoImage.contents = [
    { source = ../../.; target = "/opt/ultracloud-src"; }
  ];

  # Minimal network: DHCP on all interfaces
  networking.useNetworkd = true;
  networking.networkmanager.enable = lib.mkForce false;
  systemd.network.networks."10-dhcp" = {
    matchConfig.Name = "*";
    DHCP = "yes";
  };

  # Phone Home service — fetches secrets from Deployer
  systemd.services.ultracloud-bootstrap = {
    description = "UltraCloud Bootstrap via Phone Home";
    wantedBy = [ "multi-user.target" ];
    after = [ "network-online.target" ];
    wants = [ "network-online.target" ];

    serviceConfig = {
      Type = "oneshot";
      RemainAfterExit = true;
    };

    script = ''
      set -euo pipefail

      cmdline_value() {
        local key="$1"
        local arg
        for arg in $(cat /proc/cmdline); do
          case "$arg" in
            "$key"=*)
              echo "''${arg#*=}"
              return 0
              ;;
          esac
        done
        return 1
      }

      dmi_value() {
        local path="$1"
        if [ -r "$path" ]; then
          tr -d '\n' <"$path" 2>/dev/null || true
        fi
      }

      resolve_deployer_url() {
        local explicit_url="''${DEPLOYER_URL:-}"
        if [ -z "$explicit_url" ]; then
          explicit_url="$(cmdline_value ultracloud.deployer_url || true)"
        fi
        if [ -n "$explicit_url" ]; then
          echo "$explicit_url"
          return 0
        fi
        if ${pkgs.curl}/bin/curl -fsS --connect-timeout 2 --max-time 5 \
          http://10.0.2.2:8088/health >/dev/null 2>&1; then
          echo "http://10.0.2.2:8088"
          return 0
        fi
        echo "http://192.168.100.1:8080"
      }

      mkdir -p /etc/ultracloud

      # Discover Deployer via environment, kernel cmdline, or fallback.
      DEPLOYER_URL="$(resolve_deployer_url)"

      # Get machine identity
      MACHINE_ID=$(cat /etc/machine-id)

      echo "UltraCloud Bootstrap starting..."
      echo "Machine ID: $MACHINE_ID"
      echo "Deployer URL: $DEPLOYER_URL"

      # Optional bootstrap token (from file or environment)
      TOKEN_FILE="/etc/ultracloud/bootstrap-token"
      DEPLOYER_TOKEN=""
      if [ -s "$TOKEN_FILE" ]; then
        DEPLOYER_TOKEN=$(cat "$TOKEN_FILE")
      elif [ -n "''${DEPLOYER_BOOTSTRAP_TOKEN:-}" ]; then
        DEPLOYER_TOKEN="''${DEPLOYER_BOOTSTRAP_TOKEN}"
      else
        DEPLOYER_TOKEN="$(cmdline_value ultracloud.bootstrap_token || true)"
      fi

      DEPLOYER_CA_CERT_PATH="''${DEPLOYER_CA_CERT:-}"
      if [ -z "$DEPLOYER_CA_CERT_PATH" ]; then
        DEPLOYER_CA_CERT_URL="$(cmdline_value ultracloud.ca_cert_url || true)"
        if [ -n "$DEPLOYER_CA_CERT_URL" ]; then
          DEPLOYER_CA_CERT_PATH="/etc/ultracloud/bootstrap-ca.crt"
          ${pkgs.curl}/bin/curl -sfL --connect-timeout 5 --max-time 30 \
            "$DEPLOYER_CA_CERT_URL" \
            -o "$DEPLOYER_CA_CERT_PATH"
        fi
      fi

      CURL_ARGS=(-sf --connect-timeout 5 --max-time 15)
      if [ -n "$DEPLOYER_TOKEN" ]; then
        CURL_ARGS+=(-H "X-Deployer-Token: $DEPLOYER_TOKEN")
      fi
      if [ -n "$DEPLOYER_CA_CERT_PATH" ] && [ -f "$DEPLOYER_CA_CERT_PATH" ]; then
        CURL_ARGS+=(--cacert "$DEPLOYER_CA_CERT_PATH")
      fi

      NODE_IP=$(${pkgs.iproute2}/bin/ip -4 route get 1.1.1.1 2>/dev/null | ${pkgs.gawk}/bin/awk '{for(i=1;i<=NF;i++) if ($i=="src") {print $(i+1); exit}}')
      if [ -z "$NODE_IP" ]; then
        NODE_IP=$(${pkgs.iproute2}/bin/ip -4 addr show scope global 2>/dev/null | ${pkgs.gawk}/bin/awk '/inet / {sub("/.*","",$2); print $2; exit}')
      fi
      if [ -z "$NODE_IP" ]; then
        NODE_IP=$(hostname -I 2>/dev/null | ${pkgs.gawk}/bin/awk '{print $1}')
      fi
      REQUESTED_NODE_ID="''${ULTRACLOUD_NODE_ID:-}"
      if [ -z "$REQUESTED_NODE_ID" ]; then
        REQUESTED_NODE_ID="$(cmdline_value ultracloud.node_id || true)"
      fi
      if [ -z "$REQUESTED_NODE_ID" ]; then
        REQUESTED_NODE_ID="$(dmi_value /sys/class/dmi/id/product_serial)"
      fi
      if [ -z "$REQUESTED_NODE_ID" ]; then
        REQUESTED_NODE_ID="$(hostname)"
      fi
      REQUESTED_HOSTNAME="''${ULTRACLOUD_HOSTNAME:-}"
      if [ -z "$REQUESTED_HOSTNAME" ]; then
        REQUESTED_HOSTNAME="$(cmdline_value ultracloud.hostname || true)"
      fi
      if [ -z "$REQUESTED_HOSTNAME" ]; then
        REQUESTED_HOSTNAME="$REQUESTED_NODE_ID"
      fi
      echo "ULTRACLOUD_MARKER pre-install.boot.$REQUESTED_NODE_ID"
      CPU_MODEL=$(${pkgs.gawk}/bin/awk -F: '/model name/ {gsub(/^[ \t]+/, "", $2); print $2; exit}' /proc/cpuinfo 2>/dev/null || true)
      CPU_CORES=$(${pkgs.gawk}/bin/awk '/^cpu cores/ {print $4; exit}' /proc/cpuinfo 2>/dev/null || true)
      CPU_THREADS=$(${pkgs.coreutils}/bin/nproc --all 2>/dev/null || true)
      MEMORY_KIB=$(${pkgs.gawk}/bin/awk '/MemTotal:/ {print $2; exit}' /proc/meminfo 2>/dev/null || true)
      MEMORY_BYTES=""
      if [ -n "$MEMORY_KIB" ]; then
        MEMORY_BYTES=$((MEMORY_KIB * 1024))
      fi

      DISKS_JSON=$(${pkgs.util-linux}/bin/lsblk -J -b -o NAME,PATH,SIZE,MODEL,SERIAL,ROTA,TYPE 2>/dev/null | ${pkgs.jq}/bin/jq '
        [.blockdevices[] | select(.type == "disk") | {
          name: .name,
          path: (.path // null),
          size_bytes: (.size | tonumber?),
          model: ((.model // "") | if . == "" then null else . end),
          serial: ((.serial // "") | if . == "" then null else . end),
          rotational: (if .rota == null then null else (.rota == 1) end)
        }]
      ')
      NICS_JSON=$(${pkgs.iproute2}/bin/ip -j link 2>/dev/null | ${pkgs.jq}/bin/jq '
        [.[] | select(.ifname != "lo") | {
          name: .ifname,
          mac_address: ((.address // "") | if . == "" or . == "00:00:00:00:00:00" then null else . end),
          oper_state: ((.operstate // "") | ascii_downcase | if . == "" then null else . end)
        }]
      ')
      DMI_VENDOR=$(tr -d '\n' </sys/class/dmi/id/sys_vendor 2>/dev/null || true)
      DMI_PRODUCT=$(tr -d '\n' </sys/class/dmi/id/product_name 2>/dev/null || true)
      DMI_SERIAL=$(tr -d '\n' </sys/class/dmi/id/product_serial 2>/dev/null || true)
      HARDWARE_FACTS=$(${pkgs.jq}/bin/jq -n \
        --arg architecture "$(${pkgs.coreutils}/bin/uname -m)" \
        --arg cpu_model "$CPU_MODEL" \
        --arg cpu_threads "$CPU_THREADS" \
        --arg cpu_cores "$CPU_CORES" \
        --arg memory_bytes "$MEMORY_BYTES" \
        --arg dmi_vendor "$DMI_VENDOR" \
        --arg dmi_product "$DMI_PRODUCT" \
        --arg dmi_serial "$DMI_SERIAL" \
        --argjson disks "$DISKS_JSON" \
        --argjson nics "$NICS_JSON" '
          {
            architecture: (if $architecture == "" then null else $architecture end),
            cpu_model: (if $cpu_model == "" then null else $cpu_model end),
            cpu_threads: (if $cpu_threads == "" then null else ($cpu_threads | tonumber) end),
            cpu_cores: (if $cpu_cores == "" then null else ($cpu_cores | tonumber) end),
            memory_bytes: (if $memory_bytes == "" then null else ($memory_bytes | tonumber) end),
            disks: $disks,
            nics: $nics,
            dmi: ({
              vendor: (if $dmi_vendor == "" then null else $dmi_vendor end),
              product_name: (if $dmi_product == "" then null else $dmi_product end),
              serial_number: (if $dmi_serial == "" then null else $dmi_serial end)
            } | with_entries(select(.value != null)))
          }
          | if (.dmi | length) == 0 then del(.dmi) else . end
        ')
      REQUEST_JSON=$(${pkgs.jq}/bin/jq -n \
        --arg machine_id "$MACHINE_ID" \
        --arg node_id "$REQUESTED_NODE_ID" \
        --arg hostname "$REQUESTED_HOSTNAME" \
        --arg ip "$NODE_IP" \
        --argjson hardware_facts "$HARDWARE_FACTS" '
          {
            machine_id: $machine_id,
            node_id: $node_id,
            hostname: $hostname,
            ip: $ip,
            hardware_facts: $hardware_facts
          }
        ')

      # Phone Home request with retry
      for i in 1 2 3 4 5; do
        echo "Attempt $i/5: Contacting Deployer..."

        if RESPONSE=$(${pkgs.curl}/bin/curl "''${CURL_ARGS[@]}" -X POST \
          -H "Content-Type: application/json" \
          -d "$REQUEST_JSON" \
          "$DEPLOYER_URL/api/v1/phone-home"); then

          echo "✓ Phone Home successful"

          # Create directories
          mkdir -p /etc/ssh /etc/ultracloud /root/.ssh

          # Validate success flag
          SUCCESS=$(echo "$RESPONSE" | ${pkgs.jq}/bin/jq -r '.success // false' || echo "false")
          if [ "$SUCCESS" != "true" ]; then
            MESSAGE=$(echo "$RESPONSE" | ${pkgs.jq}/bin/jq -r '.message // empty' || true)
            echo "✗ Phone Home rejected: $MESSAGE"
            sleep $((2 ** i))
            continue
          fi

          NODE_CONFIG=$(echo "$RESPONSE" | ${pkgs.jq}/bin/jq -c '.node_config // empty' || true)
          if [ -z "$NODE_CONFIG" ] || [ "$NODE_CONFIG" = "null" ]; then
            echo "✗ Phone Home response missing node_config"
            sleep $((2 ** i))
            continue
          fi
          echo "$NODE_CONFIG" > /etc/ultracloud/node-config.json
          echo "$RESPONSE" | ${pkgs.jq}/bin/jq -r '
            .node_config.bootstrap_secrets.ssh_authorized_keys[]?
          ' > /root/.ssh/authorized_keys

          # Apply SSH host key if provided
          SSH_HOST_KEY=$(echo "$RESPONSE" | ${pkgs.jq}/bin/jq -r '.node_config.bootstrap_secrets.ssh_host_key // empty')
          if [ -n "$SSH_HOST_KEY" ]; then
            umask 077
            echo "$SSH_HOST_KEY" > /etc/ssh/ssh_host_ed25519_key
            ${pkgs.openssh}/bin/ssh-keygen -y -f /etc/ssh/ssh_host_ed25519_key > /etc/ssh/ssh_host_ed25519_key.pub
          fi

          # Apply TLS material if provided
          TLS_CERT=$(echo "$RESPONSE" | ${pkgs.jq}/bin/jq -r '.node_config.bootstrap_secrets.tls_cert // empty')
          TLS_KEY=$(echo "$RESPONSE" | ${pkgs.jq}/bin/jq -r '.node_config.bootstrap_secrets.tls_key // empty')
          if [ -n "$TLS_CERT" ] && [ -n "$TLS_KEY" ]; then
            umask 077
            mkdir -p /etc/ultracloud/tls
            echo "$TLS_CERT" > /etc/ultracloud/tls/node.crt
            echo "$TLS_KEY" > /etc/ultracloud/tls/node.key
          fi

          # Generate host keys locally if missing
          if [ ! -s /etc/ssh/ssh_host_ed25519_key ]; then
            ${pkgs.openssh}/bin/ssh-keygen -A
          fi

          # Set permissions
          chmod 644 /etc/ultracloud/node-config.json 2>/dev/null || true
          chmod 700 /root/.ssh 2>/dev/null || true
          chmod 600 /root/.ssh/authorized_keys 2>/dev/null || true
          chmod 600 /etc/ssh/ssh_host_ed25519_key 2>/dev/null || true
          chmod 644 /etc/ssh/ssh_host_ed25519_key.pub 2>/dev/null || true
          chmod 600 /etc/ultracloud/tls/node.key 2>/dev/null || true
          chmod 644 /etc/ultracloud/tls/node.crt 2>/dev/null || true

          # Signal success
          NODE_ID=$(echo "$RESPONSE" | ${pkgs.jq}/bin/jq -r '.node_config.assignment.node_id // "unknown"')
          echo "ULTRACLOUD_MARKER pre-install.phone-home.complete.$NODE_ID"
          echo "✓ Bootstrap complete: $NODE_ID"
          exit 0
        else
          echo "✗ Phone Home failed, attempt $i/5"
          sleep $((2 ** i))
        fi
      done

      echo "✗ Bootstrap failed after 5 attempts"
      exit 1
    '';
  };

  # Auto-install service - partitions disk and runs nixos-install
  systemd.services.ultracloud-install = {
    description = "UltraCloud Auto-Install to Disk";
    wantedBy = [ "multi-user.target" ];
    after = [ "ultracloud-bootstrap.service" ];
    requires = [ "ultracloud-bootstrap.service" ];

    serviceConfig = {
      Type = "oneshot";
      RemainAfterExit = true;
      StandardOutput = "journal+console";
      StandardError = "journal+console";
    };

    script = ''
            set -euo pipefail
            export PATH="${pkgs.nix}/bin:${config.system.build.nixos-install}/bin:$PATH"

            cmdline_value() {
              local key="$1"
              local arg
              for arg in $(cat /proc/cmdline); do
                case "$arg" in
                  "$key"=*)
                    echo "''${arg#*=}"
                    return 0
                    ;;
                esac
              done
              return 1
            }

            resolve_deployer_url() {
              local explicit_url="''${DEPLOYER_URL:-}"
              if [ -z "$explicit_url" ]; then
                explicit_url="$(cmdline_value ultracloud.deployer_url || true)"
              fi
              if [ -n "$explicit_url" ]; then
                echo "$explicit_url"
                return 0
              fi
              if ${pkgs.curl}/bin/curl -fsS --connect-timeout 2 --max-time 5 \
                http://10.0.2.2:8088/health >/dev/null 2>&1; then
                echo "http://10.0.2.2:8088"
                return 0
              fi
              echo "http://192.168.100.1:8080"
            }

            resolve_binary_cache_url() {
              local explicit_url="''${ULTRACLOUD_BINARY_CACHE_URL:-}"
              if [ -z "$explicit_url" ]; then
                explicit_url="$(cmdline_value ultracloud.binary_cache_url || true)"
              fi
              if [ -n "$explicit_url" ]; then
                echo "$explicit_url"
                return 0
              fi
              if ${pkgs.curl}/bin/curl -fsS --connect-timeout 2 --max-time 5 \
                http://10.0.2.2:8090/nix-cache-info >/dev/null 2>&1; then
                echo "http://10.0.2.2:8090"
                return 0
              fi
              return 1
            }

            if [ ! -s /etc/ultracloud/node-config.json ]; then
              echo "ERROR: node-config.json missing (bootstrap not complete?)"
              exit 1
            fi

            NODE_ID=$(${pkgs.jq}/bin/jq -r '.assignment.hostname // .assignment.node_id // empty' /etc/ultracloud/node-config.json)
            NODE_IP=$(${pkgs.jq}/bin/jq -r '.assignment.ip // empty' /etc/ultracloud/node-config.json)
            NIXOS_CONFIGURATION=$(${pkgs.jq}/bin/jq -r '.bootstrap_plan.install_plan.nixos_configuration // .assignment.hostname // empty' /etc/ultracloud/node-config.json)
            INSTALL_PLAN_DISKO_CONFIG_PATH=$(${pkgs.jq}/bin/jq -r '.bootstrap_plan.install_plan.disko_config_path // empty' /etc/ultracloud/node-config.json)
            DISKO_SCRIPT_PATH=$(${pkgs.jq}/bin/jq -r '.bootstrap_plan.install_plan.disko_script_path // empty' /etc/ultracloud/node-config.json)
            if [ -z "$DISKO_SCRIPT_PATH" ] && [ -r /etc/ultracloud/disko-script-paths.json ]; then
              DISKO_SCRIPT_PATH=$(${pkgs.jq}/bin/jq -r --arg cfg "$NIXOS_CONFIGURATION" '.[$cfg] // empty' /etc/ultracloud/disko-script-paths.json)
              if [ -n "$DISKO_SCRIPT_PATH" ]; then
                echo "Resolved pre-built Disko script for install profile $NIXOS_CONFIGURATION from the ISO profile map"
              fi
            fi
            TARGET_SYSTEM_PATH=$(${pkgs.jq}/bin/jq -r '.bootstrap_plan.install_plan.target_system_path // empty' /etc/ultracloud/node-config.json)
            if [ -z "$TARGET_SYSTEM_PATH" ] && [ -r /etc/ultracloud/system-paths.json ]; then
              TARGET_SYSTEM_PATH=$(${pkgs.jq}/bin/jq -r --arg cfg "$NIXOS_CONFIGURATION" '.[$cfg] // empty' /etc/ultracloud/system-paths.json)
              if [ -n "$TARGET_SYSTEM_PATH" ]; then
                echo "Resolved pre-built target system for install profile $NIXOS_CONFIGURATION from the ISO profile map"
              fi
            fi
            TARGET_DISK=$(${pkgs.jq}/bin/jq -r '.bootstrap_plan.install_plan.target_disk // empty' /etc/ultracloud/node-config.json)
            TARGET_DISK_BY_ID=$(${pkgs.jq}/bin/jq -r '.bootstrap_plan.install_plan.target_disk_by_id // empty' /etc/ultracloud/node-config.json)
            DEPLOYER_URL="$(resolve_deployer_url)"
            SRC_ROOT="/opt/ultracloud-src"

            if [ -z "$NODE_ID" ] || [ -z "$NODE_IP" ]; then
              echo "ERROR: node-config.json missing hostname/ip"
              exit 1
            fi

            if [ -z "$NIXOS_CONFIGURATION" ]; then
              echo "ERROR: node-config.json missing install_plan.nixos_configuration"
              exit 1
            fi

            TOKEN_FILE="/etc/ultracloud/bootstrap-token"
            DEPLOYER_TOKEN=""
            if [ -s "$TOKEN_FILE" ]; then
              DEPLOYER_TOKEN=$(cat "$TOKEN_FILE")
            elif [ -n "''${DEPLOYER_BOOTSTRAP_TOKEN:-}" ]; then
              DEPLOYER_TOKEN="''${DEPLOYER_BOOTSTRAP_TOKEN}"
            else
              DEPLOYER_TOKEN="$(cmdline_value ultracloud.bootstrap_token || true)"
            fi

            DEPLOYER_CA_CERT_PATH="''${DEPLOYER_CA_CERT:-}"
            if [ -z "$DEPLOYER_CA_CERT_PATH" ]; then
              DEPLOYER_CA_CERT_URL="$(cmdline_value ultracloud.ca_cert_url || true)"
              if [ -n "$DEPLOYER_CA_CERT_URL" ]; then
                DEPLOYER_CA_CERT_PATH="/etc/ultracloud/bootstrap-ca.crt"
                ${pkgs.curl}/bin/curl -sfL --connect-timeout 5 --max-time 30 \
                  "$DEPLOYER_CA_CERT_URL" \
                  -o "$DEPLOYER_CA_CERT_PATH"
              fi
            fi

            CURL_ARGS=(-sfL --connect-timeout 5 --max-time 120)
            if [ -n "$DEPLOYER_TOKEN" ]; then
              CURL_ARGS+=(-H "X-Deployer-Token: $DEPLOYER_TOKEN")
            fi
            if [ -n "$DEPLOYER_CA_CERT_PATH" ] && [ -f "$DEPLOYER_CA_CERT_PATH" ]; then
              CURL_ARGS+=(--cacert "$DEPLOYER_CA_CERT_PATH")
            fi

            BUNDLE_PATH="/run/ultracloud/flake-bundle.tar.gz"
            mkdir -p /run/ultracloud
            if ${pkgs.curl}/bin/curl "''${CURL_ARGS[@]}" \
              "$DEPLOYER_URL/api/v1/bootstrap/flake-bundle" \
              -o "$BUNDLE_PATH"; then
              echo "Downloaded bootstrap flake bundle from deployer"
              echo "ULTRACLOUD_MARKER install.bundle-downloaded.$NODE_ID"
              rm -rf "$SRC_ROOT"
              mkdir -p "$SRC_ROOT"
              ${pkgs.gzip}/bin/gzip -dc "$BUNDLE_PATH" | ${pkgs.gnutar}/bin/tar -xf - -C "$SRC_ROOT"
            else
              echo "No deployer flake bundle available; using embedded source tree"
            fi

            echo "ULTRACLOUD_MARKER install.start.$NODE_ID"
            DISPLAY_TARGET_DISK="$TARGET_DISK"
            DISK_SELECTOR_SOURCE="auto-discovery"
            if [ -n "$TARGET_DISK_BY_ID" ]; then
              DISPLAY_TARGET_DISK="$TARGET_DISK_BY_ID"
              DISK_SELECTOR_SOURCE="install_plan.target_disk_by_id"
            elif [ -n "$TARGET_DISK" ]; then
              DISK_SELECTOR_SOURCE="install_plan.target_disk"
            fi
            echo "UltraCloud install starting for $NODE_ID (ip=$NODE_IP, nixos_configuration=$NIXOS_CONFIGURATION, target_disk=$DISPLAY_TARGET_DISK)"
            if [ -n "$INSTALL_PLAN_DISKO_CONFIG_PATH" ]; then
              echo "Install contract: disko_config_path=$INSTALL_PLAN_DISKO_CONFIG_PATH, disk_selector_source=$DISK_SELECTOR_SOURCE"
            else
              echo "Install contract: disko_config_path=(embedded profile map for $NIXOS_CONFIGURATION), disk_selector_source=$DISK_SELECTOR_SOURCE"
            fi

            # Resolve installation target disk.
            if [ -n "$TARGET_DISK_BY_ID" ]; then
              if [ ! -b "$TARGET_DISK_BY_ID" ]; then
                echo "ERROR: target_disk_by_id does not exist: $TARGET_DISK_BY_ID"
                exit 1
              fi
              DISK="$TARGET_DISK_BY_ID"
            elif [ -n "$TARGET_DISK" ]; then
              if [ ! -b "$TARGET_DISK" ]; then
                echo "ERROR: target_disk does not exist: $TARGET_DISK"
                exit 1
              fi
              DISK="$TARGET_DISK"
            else
              DISK=$(${pkgs.util-linux}/bin/lsblk -dpno NAME,TYPE | ${pkgs.gawk}/bin/awk '$2=="disk"{print $1; exit}')
            fi
            if [ -z "$DISK" ]; then
              echo "ERROR: No disk found"
              exit 1
            fi

            ROOT_PART=$(${pkgs.util-linux}/bin/lsblk -lnpo NAME,TYPE "$DISK" 2>/dev/null | ${pkgs.gawk}/bin/awk '$2=="part"{print $1}' | sed -n '2p')
            mkdir -p /mnt

            # Skip if already installed
            if [ -n "$ROOT_PART" ] && ${pkgs.util-linux}/bin/lsblk -no FSTYPE "$ROOT_PART" 2>/dev/null | ${pkgs.gnugrep}/bin/grep -q '^ext4$'; then
              mount "$ROOT_PART" /mnt 2>/dev/null || true
              if [ -e /mnt/etc/NIXOS ]; then
                echo "✓ Existing NixOS detected; skipping install"
                umount /mnt || true
                exit 0
              fi
              umount /mnt || true
            fi

            NIX_CONFIG_LINES=(
              "experimental-features = nix-command flakes"
            )
            BINARY_CACHE_URL="$(resolve_binary_cache_url || true)"
            NIXPKGS_PATH="$SRC_ROOT/.bundle-inputs/nixpkgs"
            if [ ! -e "$NIXPKGS_PATH" ]; then
              NIXPKGS_PATH="${pkgs.path}"
            fi
            if [ -n "$BINARY_CACHE_URL" ]; then
              echo "Using bootstrap binary cache: $BINARY_CACHE_URL"
              NIX_CONFIG_LINES+=("substituters = $BINARY_CACHE_URL")
              NIX_CONFIG_LINES+=("trusted-substituters = $BINARY_CACHE_URL")
              NIX_CONFIG_LINES+=("require-sigs = false")
            fi
            export NIX_CONFIG="$(printf '%s\n' "''${NIX_CONFIG_LINES[@]}")"
            export NIX_PATH="nixpkgs=$NIXPKGS_PATH"

            echo "Preparing NixOS installation for configuration $NIXOS_CONFIGURATION"

            echo "Running disko to partition $DISK..."
            if [ -n "$DISKO_SCRIPT_PATH" ]; then
              echo "Realising pre-built Disko script: $DISKO_SCRIPT_PATH"
              ${pkgs.nix}/bin/nix-store --realise "$DISKO_SCRIPT_PATH" >/dev/null
              "$DISKO_SCRIPT_PATH/bin/disko-format-mount"
            else
              ${pkgs.disko}/bin/disko \
                --mode destroy,format,mount \
                --yes-wipe-all-disks \
                --root-mountpoint /mnt \
                --flake "$SRC_ROOT#$NIXOS_CONFIGURATION"
            fi
            echo "ULTRACLOUD_MARKER install.disko.complete.$NODE_ID"

            echo "Running nixos-install..."
            if [ -n "$TARGET_SYSTEM_PATH" ]; then
              echo "Realising pre-built target system: $TARGET_SYSTEM_PATH"
              ${pkgs.nix}/bin/nix-store --realise "$TARGET_SYSTEM_PATH" >/dev/null
              ${config.system.build.nixos-install}/bin/nixos-install \
                --system "$TARGET_SYSTEM_PATH" \
                --no-root-passwd \
                --no-channel-copy
            else
              ${config.system.build.nixos-install}/bin/nixos-install \
                --flake "$SRC_ROOT#$NIXOS_CONFIGURATION" \
                --no-root-passwd \
                --no-channel-copy
            fi
            echo "ULTRACLOUD_MARKER install.nixos-install.complete.$NODE_ID"

            mkdir -p /mnt/etc/ssh /mnt/etc/ultracloud /mnt/root/.ssh /mnt/var/lib
            cp -f /etc/ultracloud/node-config.json /mnt/etc/ultracloud/node-config.json
            cp -f /root/.ssh/authorized_keys /mnt/root/.ssh/authorized_keys
            shopt -s nullglob
            for host_key in /etc/ssh/ssh_host_*; do
              cp -f "$host_key" /mnt/etc/ssh/"$(basename "$host_key")"
            done
            shopt -u nullglob
            chmod 700 /mnt/root/.ssh
            chmod 600 /mnt/root/.ssh/authorized_keys
            chmod 600 /mnt/etc/ssh/ssh_host_*_key 2>/dev/null || true
            chmod 644 /mnt/etc/ssh/ssh_host_*_key.pub 2>/dev/null || true

            rm -rf /mnt/var/lib/photon-src
            cp -a "$SRC_ROOT" /mnt/var/lib/photon-src

            sync
            echo "ULTRACLOUD_MARKER reboot.$NODE_ID"
            echo "Allowing the harness to observe the reboot marker before shutting down..."
            sleep 15
            echo "✓ Install complete; rebooting..."
            ${pkgs.systemd}/bin/systemctl reboot
    '';
  };

  # Packages for bootstrap + install
  environment.etc."ultracloud/disko-script-paths.json".text =
    builtins.toJSON ultracloudBaremetalFormatMountPaths;
  environment.etc."ultracloud/system-paths.json".text =
    builtins.toJSON ultracloudBaremetalSystemPaths;

  environment.systemPackages = with pkgs; [
    curl
    jq
    vim
    htop
    nix
    gawk
    gnugrep
    util-linux
    parted
    dosfstools
    e2fsprogs
    disko
    gnutar
    gzip
  ];

  # SSH with key-based auth for non-interactive access
  services.openssh = {
    enable = true;
    settings.PermitRootLogin = "prohibit-password";
  };

  # SSH access keys are provisioned dynamically via phone-home
  users.users.root.openssh.authorizedKeys.keys = [ ];
}