{ config, pkgs, inputs, ... }:

# Immich photo/video library. Native nixpkgs module, not the upstream compose
# stack — it owns its own postgres (pgvector + vectorchord) and a unix-socket redis.
#
# Storage lives under /mnt/data/AppData/immich, migrated from the old ZimaOS/CasaOS
# UPLOAD_LOCATION (same subfolder layout); see scripts/immich-import-legacy-db for
# the matching DB import. The postgres cluster itself stays on the OS disk.
#
# ⚠️ The immich DB is the only copy of albums/faces/dates — the files alone
# can't rebuild it. It joins the other unbacked databases on this network.
let
  # Package pinned to nixpkgs-unstable (3.0.3) while the module stays on the 26.05
  # pin (2.7.5) — safe only because the two module files are byte-identical
  # (verified by diff; re-check on any input bump). Needed because immich's
  # migrations are forward-only and jupiter's imported DB was last written by
  # 3.0.0, which 2.7.5 refuses to start against; drop once the pin ships >= 3.0.0.
  #   diff <(nixpkgs)/nixos/modules/services/web-apps/immich.nix \
  #        <(unstable)/nixos/modules/services/web-apps/immich.nix
  unstable = import inputs.nixpkgs-unstable {
    inherit (pkgs.stdenv.hostPlatform) system;
  };
in
{
  services.immich = {
    enable = true;
    # Both the server and immich-machine-learning follow this: the module takes
    # the ML service from cfg.package.machine-learning (passthru).
    package = unstable.immich;
    # Listens on all interfaces: :2283 stays closed on the LAN (no
    # openFirewall), reachable over tailscale0 and via localhost (caddy).
    host = "0.0.0.0";
    port = 2283;
    mediaLocation = "/mnt/data/AppData/immich";
    machine-learning.enable = true;

    # ⚠️ Setting `settings` at all switches immich to IMMICH_CONFIG_FILE mode,
    # which is all-or-nothing: undeclared keys fall back to immich's defaults, not
    # the admin UI's saved values (which stay in system_metadata and return if
    # this block is deleted), and the admin settings UI goes read-only. An
    # unknown/misspelled key is a hard startup failure here (just a warning
    # without a config file), so keys are copied verbatim from `defaults` in
    # immich's dist/config.js.
    settings = {
      server.externalDomain = "https://immich.mgaction.town";
      newVersionCheck.enabled = false;   # nixpkgs pins the version, not immich

      # OIDC via Authentik on neptun; the application/provider is created by hand
      # in its UI (like headscale's and headplane's, separate apps) — only the
      # client secret is managed here (hosts/neptun/secrets.nix).
      oauth = {
        enabled = true;
        # Authentik's per-application issuer. Trailing slash matters: immich
        # appends /.well-known/openid-configuration to it.
        issuerUrl = "https://auth.mgaction.town/application/o/immich/";
        # Authentik generates this; not a secret (it is sent in the browser
        # redirect), so it lives here rather than in sops.
        clientId = "FxrkWFe8keBrN83tu03UbAshSck52he2GphJDYSQ";
        # Read at runtime via systemd LoadCredential — never lands in the
        # world-readable /nix/store copy of the rendered config.
        clientSecret._secret = config.sops.secrets.immich_oauth_client_secret.path;
        scope = "openid email profile";
        buttonText = "Login with Authentik";
        # Matches by email, so the 2 imported users adopt their Authentik account
        # instead of getting a duplicate.
        autoRegister = true;
        # Leave the password form reachable — autoLaunch would bounce straight
        # to Authentik, locking everyone out if the OIDC app is misconfigured.
        autoLaunch = false;
        # Without this, immich falls back to the IdP's discovered
        # end_session_endpoint and logout dumps you on Authentik's own page
        # instead of back here — must be an absolute url, mirroring immich's
        # internal LOGIN_URL. This ends the immich session only; the Authentik
        # SSO session survives, so the next login skips the credential prompt —
        # drop this line to end both.
        endSessionEndpoint = "https://auth.mgaction.town/application/o/immich/end-session?post_logout_redirect_url=https://immich.mgaction.town";
        # The mobile app can't follow a browser redirect back to a custom
        # scheme through Authentik, so immich bounces it via this endpoint.
        mobileOverrideEnabled = true;
        mobileRedirectUri = "https://immich.mgaction.town/api/oauth/mobile-redirect";
      };
    };
    # Hardware transcoding needs accelerationDevices set explicitly (e.g.
    # "/dev/dri/renderD128"); default CPU-only transcode is slow on the
    # ZimaBlade's Celeron but only runs on upload.
  };

  # /mnt/data/AppData is drwx--x--- darman:users; immich only needs group "users"
  # to traverse into it — the dir itself stays 0700 immich:immich (tmpfiles +
  # UMask=0077 reassert that), so this grants nothing else.
  users.users.immich.extraGroups = [ "users" ];

  # mediaLocation is outside /var/lib, so the module won't create it — this rule
  # only adjusts perms on the dir the legacy import already created.
  systemd.tmpfiles.rules = [
    "d /mnt/data/AppData/immich 0700 immich immich -"
  ];

  # The unit's automatic RequiresMountsFor doesn't cover mediaLocation — without
  # this, immich starts before /mnt/data mounts and writes uploads onto the 29G
  # eMMC, invisibly, under the future mountpoint.
  systemd.services.immich-server.unitConfig.RequiresMountsFor = [ "/mnt/data" ];
}