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

# Immich photo/video library. Native nixpkgs module (not the upstream compose
# stack) — it owns its own postgres (with the pgvector + vectorchord extensions
# it needs for search) and a unix-socket redis, so nothing else is required here.
#
# Storage: everything lives under /mnt/data/AppData/immich, which is the media
# store MIGRATED from the old ZimaOS/CasaOS install's UPLOAD_LOCATION
# (/mnt/data/Immich/upload — same layout: library/ upload/ thumbs/
# encoded-video/ profile/ backups/). See scripts/immich-import-legacy-db for the
# matching database 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
  # The PACKAGE comes from nixpkgs-unstable (3.0.3); the MODULE comes from the
  # 26.05 pin (which ships 2.7.5). That combination is safe because the two
  # module files are byte-identical — verified by diffing them at the revisions
  # in flake.lock. RE-CHECK THAT DIFF on any input bump:
  #   diff <(nixpkgs)/nixos/modules/services/web-apps/immich.nix \
  #        <(unstable)/nixos/modules/services/web-apps/immich.nix
  #
  # Why: jupiter's imported database was last written by immich 3.0.0, and
  # immich runs its migrations forward only — 2.7.5 refuses to start against it
  # with "corrupted migrations: previously executed migration
  # 1776217577402-DropAuditTable is missing". Drop this override once nixos-26.11
  # (or whatever the pin becomes) ships >= 3.0.0.
  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, and
    # that is ALL-OR-NOTHING (dist/utils/config.js: the config is
    # `configFile ? loadFromFile(...) : metadataRepo.get(SystemConfig)` — the
    # database copy is IGNORED, not merged). Two consequences:
    #   1. Anything not declared here falls back to immich's DEFAULTS, not to
    #      whatever the admin UI had. The old settings stay in the
    #      system_metadata table, so deleting this block restores them.
    #   2. The admin settings UI goes read-only — saving throws "Cannot update
    #      configuration while IMMICH_CONFIG_FILE is in use". Change settings
    #      HERE and redeploy.
    # An unknown/misspelled key is a HARD startup failure under a config file
    # (the same code path only logs a warning without one), so keys below are
    # taken 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 Authentik application/provider is
      # created BY HAND in its UI — same as headscale's and headplane's, which
      # are also separate apps (hosts/neptun/secrets.nix). Only the client
      # secret is managed here.
      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";
        # Existing accounts (the 2 imported users) keep working: matching is by
        # email, so an Authentik user with the same address adopts that account
        # rather than creating a second one.
        autoRegister = true;
        # Leave the password form reachable — autoLaunch would bounce straight
        # to Authentik, locking everyone out if the OIDC app is misconfigured.
        autoLaunch = false;
        # Land back on immich's own login page after logout. Without this,
        # immich falls back to the IdP's discovered end_session_endpoint
        # (auth.service.js:320-326) and logout dumps you on Authentik's
        # "you've been logged out" page instead. Must be an ABSOLUTE url —
        # the config schema rejects a relative path — and mirrors immich's
        # internal LOGIN_URL, including autoLaunch=0.
        #
        # Note this ends the IMMICH session only; the Authentik SSO session
        # survives, so the next "Login with Authentik" click signs straight
        # back in without a credential prompt. To end both, drop this line and
        # let the IdP endpoint take over again.
        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 would need the iGPU passed in explicitly, e.g.
    # accelerationDevices = [ "/dev/dri/renderD128" ]; the default [ ] means
    # PrivateDevices=yes and CPU-only transcode. The ZimaBlade's Celeron does
    # this slowly but it only runs on upload.
  };

  # /mnt/data/AppData is drwx--x--- darman:users — immich needs group "users"
  # just to TRAVERSE into its own media dir. The dir itself stays 0700
  # immich:immich (the module's tmpfiles rule re-asserts that every rebuild,
  # and UMask=0077 keeps new files private), so this grants nothing else.
  users.users.immich.extraGroups = [ "users" ];

  # mediaLocation is outside /var/lib, so the module won't create it — its own
  # tmpfiles entry only ADJUSTS an existing dir. Harmless no-op after the
  # legacy import, which puts the real store here.
  systemd.tmpfiles.rules = [
    "d /mnt/data/AppData/immich 0700 immich immich -"
  ];

  # The unit's automatic RequiresMountsFor covers /run/immich and /var/lib/immich
  # only — nothing points it at mediaLocation. Without this immich starts with
  # the array missing and writes uploaded photos onto the 29G eMMC, into a
  # directory that becomes invisible the moment /mnt/data mounts over it.
  systemd.services.immich-server.unitConfig.RequiresMountsFor = [ "/mnt/data" ];
}