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

let
  cfg = config.services.gebos.postgres;
in
{
  options.services.gebos.postgres = {
    enable = lib.mkEnableOption "Gebos Postgres 17 + TimescaleDB";
    listenAddresses = lib.mkOption {
      type = lib.types.listOf lib.types.str;
      default = [ "127.0.0.1" ];
    };
  };

  config = lib.mkIf cfg.enable {
    # TimescaleDB ships under the non-OSI "Timescale License" (TSL), which
    # nixpkgs flags as unfree. Allow just this package rather than opening the
    # whole config to unfree.
    nixpkgs.config.allowUnfreePredicate = pkg:
      lib.elem (lib.getName pkg) [ "timescaledb" ];

    services.postgresql = {
      enable = true;
      package = pkgs.postgresql_17;
      # listen_addresses is managed explicitly below. The upstream postgresql
      # module also defines it (via its own default / enableTCPIP), so mkForce
      # makes this module the single source of truth and avoids the collision.
      settings = {
        listen_addresses = lib.mkForce (lib.concatStringsSep "," cfg.listenAddresses);
        shared_preload_libraries = "timescaledb,pg_stat_statements";
      };
      extensions = ps: with ps; [
        timescaledb
        pgjwt
        pg_graphql
        pgsodium
        # supabase_vault — TODO: package or vendor
      ];
      # Init script creates Supabase's `auth`, `storage`, `_analytics`, `_supavisor`
      # schemas and the Supabase admin/API roles. It only runs at first initdb;
      # everything else arrives via manual supabase migrations (see
      # supabase/README.md) and the password oneshot below.
      initialScript = ../supabase/init.sql;

      # The firewall limits 5432 to 10.0.0.0/8, but NixOS's default pg_hba
      # only covers local sockets and loopback — without this line every
      # connection from app-host / mqtt-ingest is rejected before password
      # auth even starts.
      authentication = ''
        host all all 10.0.0.0/8 scram-sha-256
      '';
    };

    # Role passwords are data, not configuration: NixOS has no declarative
    # option for them (anything reachable from the config lands world-readable
    # in /nix/store, and initialScript only runs at first initdb). This
    # oneshot re-applies them from the sops-rendered env file on every boot /
    # deploy, idempotently. It also enforces two attributes the Supabase
    # services expect because the upstream supabase/postgres image ships them:
    # supabase_admin is SUPERUSER (Studio/postgres-meta connect as it) and
    # supabase_auth_admin owns the auth schema (GoTrue runs its own migrations
    # there on startup).
    #
    # After rotating a password in secrets.yaml, re-run with
    # `systemctl restart gebos-postgres-passwords` (deploys re-run it only
    # when the unit definition itself changed).
    systemd.services.gebos-postgres-passwords =
      lib.mkIf config.services.gebos.secrets.postgresAdmin {
        description = "Gebos — sync Postgres role passwords from sops secrets";
        after = [ "postgresql.service" ];
        requires = [ "postgresql.service" ];
        wantedBy = [ "multi-user.target" ];
        path = [ config.services.postgresql.package ];
        serviceConfig = {
          Type = "oneshot";
          User = "postgres";
          # LoadCredential hands the root-owned 0400 env file to the postgres
          # user without widening its permissions.
          LoadCredential = "gebos-env:${config.services.gebos.secrets.envFile}";
        };
        script = ''
          set -euo pipefail
          set -a; . "$CREDENTIALS_DIRECTORY/gebos-env"; set +a

          # All three come from the gebos-env template; the toggles in
          # db-host.nix (postgresAdmin + supabase + ingester) must be on.
          # --output=/dev/null: the set_config() SELECTs would otherwise echo
          # the passwords into the journal.
          psql -v ON_ERROR_STOP=1 --output=/dev/null \
               -v admin_pw="''${POSTGRES_ADMIN_PASSWORD:?}" \
               -v supabase_pw="''${POSTGRES_PASSWORD:?}" \
               -v ingest_pw="''${GEBOS_POSTGRES_PASSWORD:?}" \
               --dbname postgres <<'SQL'
          -- psql :'var' interpolation does not reach inside DO bodies, so
          -- stash the values in session GUCs first.
          SELECT set_config('gebos.supabase_pw', :'supabase_pw', false);
          SELECT set_config('gebos.ingest_pw',   :'ingest_pw',   false);

          ALTER ROLE postgres PASSWORD :'admin_pw';

          DO $do$
          DECLARE r text;
          BEGIN
            -- One shared password for the roles the compose services log in
            -- as, mirroring upstream's POSTGRES_PASSWORD convention.
            FOREACH r IN ARRAY ARRAY['supabase_admin','supabase_auth_admin','authenticator'] LOOP
              IF EXISTS (SELECT FROM pg_roles WHERE rolname = r) THEN
                EXECUTE format('ALTER ROLE %I PASSWORD %L',
                               r, current_setting('gebos.supabase_pw'));
              END IF;
            END LOOP;

            IF EXISTS (SELECT FROM pg_roles WHERE rolname = 'supabase_admin') THEN
              EXECUTE 'ALTER ROLE supabase_admin SUPERUSER';
            END IF;

            IF EXISTS (SELECT FROM pg_roles WHERE rolname = 'supabase_auth_admin')
               AND EXISTS (SELECT FROM pg_namespace WHERE nspname = 'auth') THEN
              EXECUTE 'ALTER SCHEMA auth OWNER TO supabase_auth_admin';
            END IF;

            -- Created by the schema-v1 migration, so tolerate its absence on
            -- a cluster the migration has not reached yet.
            IF EXISTS (SELECT FROM pg_roles WHERE rolname = 'gebos_ingest') THEN
              EXECUTE format('ALTER ROLE gebos_ingest PASSWORD %L',
                             current_setting('gebos.ingest_pw'));
            END IF;
          END
          $do$;
          SQL
        '';
      };
  };
}