{ config, pkgs, lib, ... }:

# mercury — Raspberry Pi 3B+ (aarch64). Network DNS + DHCP (+ adblock).
# Boots from an SD image (see flake: nixosConfigurations.mercury), so there is
# no disko / hardware-configuration here — the sd-image module provides them.
{
  imports = [
    ../../common.nix           # shared base: user / ssh / nix / firewall
    ./secrets.nix              # sops-nix: darman password (age key on boot part.)
    ../../services/network/unbound.nix      # local recursive resolver (127.0.0.1:5335)
    ../../services/network/pihole.nix        # DNS adblock + DHCP (declarative static leases)
    ../../services/vpn/tailscale.nix        # tailnet node (headscale on neptun)
  ];

  networking.hostName = "mercury";

  # ---- Static networking ----
  # A DNS/DHCP server must have a fixed address. Fill in the Pi's real values
  # (from `ip -brief a` / `ip route` on the running Pi). eth0 = the Pi's NIC.
  networking.useDHCP = false;
  networking.usePredictableInterfaceNames = false;   # keep it named eth0
  networking.interfaces.eth0.ipv4.addresses = [
    { address = "10.0.0.10"; prefixLength = 24; }     # the Pi's current IP
  ];
  # Stable IPv6 (FRITZ!Box ULA prefix) so mercury is a fixed IPv6 DNS target.
  # SLAAC still provides the GUA + default route. Announce THIS address as the
  # DNSv6 server in the FRITZ!Box so IPv6 clients resolve .sol via pihole.
  networking.interfaces.eth0.ipv6.addresses = [
    { address = "fd18:df17:9078:0::10"; prefixLength = 64; }
  ];
  # VERIFY with `ip route` on the Pi — assuming the router is .1.
  networking.defaultGateway = { address = "10.0.0.1"; interface = "eth0"; };
  # Resolvers for the Pi's OWN lookups (not the LAN service). Kept public so the
  # host resolves during boot without depending on its own pihole/unbound.
  networking.nameservers = [ "1.1.1.1" "9.9.9.9" ];

  # Never take MagicDNS on THIS host. headscale pushes override_local_dns, so
  # accepting it would repoint mercury's resolv.conf at 100.100.100.100 and
  # make the LAN's DNS server depend on tailscaled to resolve anything — the
  # same boot-time DNS deadlock this host already hit once (see CLAUDE.md),
  # except a failure here takes the whole network's DNS down with it.
  services.tailscale.extraUpFlags = [ "--accept-dns=false" ];

  # ---- pihole web admin password (from sops) ----
  # The pihole container reads FTLCONF_* env vars. Render an env file from the
  # sops secret and feed it to the container — password stays out of repo/store.
  sops.secrets.pihole_webpassword = { };
  sops.templates."pihole.env".content =
    "FTLCONF_webserver_api_password=${config.sops.placeholder.pihole_webpassword}";
  virtualisation.oci-containers.containers.pihole.environmentFiles =
    [ config.sops.templates."pihole.env".path ];

  # Do not modify after first flash.
  system.stateVersion = "26.05";
}