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

with lib;
let
  cfg = config.modules.services.akkoma;

  poorObfuscation = y: x: "${x}@${y}";
  federation-blocklist = lib.importTOML ./blocklist.toml;

  inherit (lib.my) wrapFile;
in
{
  options.modules.services.akkoma = {
    enable = mkEnableOption "Akkoma instance";
    domain = mkOption { type = types.str; };
    realHost = mkOption { type = types.str; };
    instanceName = mkOption { type = types.str; default = "Akkoma on ${cfg.domain}"; };

    oauthBaseUrl = mkOption { type = types.str; default = "Base URL of the OAuth provider"; };
    secrets.akkoma-envs = mkOption { type = types.str; default = "Path to the akkoma environment file"; };
  };

  config = mkIf cfg.enable {
    modules.services.postgresql.enable = true;

    services.akkoma = {
      enable = true;
      package = pkgs.akkoma.overrideAttrs (old: {
        # Akkoma doesn't include OAuth2 dependencies by default
        # This can be obtained by running `OAUTH_CONSUMER_STRATEGIES="..." mix deps.get`.
        # The server should also be launched with the same environment variable set.
        nativeBuildInputs = let
          inherit (pkgs.beamPackages) fetchHex buildMix;
          oldMixDeps = old.passthru.mixNixDeps;
        in old.nativeBuildInputs ++ builtins.attrValues rec {
          # TODO: This needs to be bumped from time to time
          oauth2 = buildMix rec {
            name = "oauth2";
            version = "2.1.0";

            src = fetchHex {
              pkg = name;
              inherit version;
              sha256 = "0h9bps7gq7bac5gc3q0cgpsj46qnchpqbv5hzsnd2z9hnf2pzh4a";
            };

            beamDeps = [ oldMixDeps.tesla ];
          };
          ueberauth_keycloak_strategy = buildMix rec {
            name = "ueberauth_keycloak_strategy";
            version = "0.4.0";

            src = fetchHex {
              pkg = name;
              inherit version;
              sha256 = "06r10w0azlpypjgggar1lf7h2yazn2dpyicy97zxkjyxgf9jfc60";
            };

            beamDeps = [ oauth2 oldMixDeps.ueberauth ];
          };
        };
        OAUTH_CONSUMER_STRATEGIES = "keycloak:ueberauth_keycloak_strategy";
      });

      initDb.enable = true;

      extraStatic = {
        "static/terms-of-service.html" = wrapFile "terms-of-service.html" ./terms-of-service.html;
        "static/logo.svg" = wrapFile "logo.svg" ./logo.svg;
        "static/logo.png" = wrapFile "logo.png" ./logo.png;
        "static/logo-512.png" = wrapFile "logo-512.png" ./favicon-withbg.png; # Intentional, for PWA favicon.
        "static/icon.png" = wrapFile "icon.png" ./favicon.png;
        "favicon.png" = wrapFile "favicon.png" ./favicon-withbg.png;
      };
      config =
        let inherit ((pkgs.formats.elixirConf { }).lib) mkRaw mkMap mkTuple;
        in {
          ":pleroma"."Pleroma.Web.Endpoint".url.host = cfg.realHost;
          ":pleroma"."Pleroma.Web.WebFinger".domain = cfg.domain;
          ":pleroma".":media_proxy".enabled = false;
          ":pleroma".":instance" = {
            name = cfg.instanceName;

            description = "Private akkoma instance";
            email = poorObfuscation cfg.domain "postmaster";
            notify_email = poorObfuscation cfg.domain "postmaster";

            registrations_open = false;
            invites_enabled = true;

            limit = 5000;
          };
          ":pleroma".":frontend_configurations" = {
            pleroma_fe = mkMap {
              logo = "/static/logo.png";
              # FIXME: https://akkoma.dev/AkkomaGang/akkoma/pulls/668
              # TODO: enable on next release
              # loginMethod = "token";
            };
          };
          ":pleroma".":mrf" = {
            policies = map mkRaw [ "Pleroma.Web.ActivityPub.MRF.SimplePolicy" ];
          };
          ":pleroma".":mrf_simple" = {
            followers_only = mkMap federation-blocklist.followers_only;
            media_nsfw = mkMap federation-blocklist.media_nsfw;
            reject = mkMap federation-blocklist.reject;
          };
          ":pleroma"."Pleroma.Captcha" = {
            enabled = true;
            method = mkRaw "Pleroma.Captcha.Kocaptcha";
          };
          ":ueberauth" = {
            "Ueberauth.Strategy.Keycloak.OAuth" = {
              client_id = mkRaw ''System.get_env("AUTHENTIK_CLIENT_ID")'';
              client_secret = mkRaw ''System.get_env("AUTHENTIK_CLIENT_SECRET")'';
              site = cfg.oauthBaseUrl;
              authorize_url = "${cfg.oauthBaseUrl}/application/o/authorize/";
              token_url = "${cfg.oauthBaseUrl}/application/o/token/";
              userinfo_url = "${cfg.oauthBaseUrl}/application/o/userinfo/";
              token_method = mkRaw ":post";
            };
            Ueberauth.providers = {
              keycloak = mkTuple [(mkRaw "Ueberauth.Strategy.Keycloak") {
                default_scope = "openid profile email";
                uid_field = mkRaw ":preferred_username";
              }];
            };
          };
        };

      nginx = {
        forceSSL = true;
        useACMEHost = cfg.domain;

        locations."~ \\.(js|css|woff|woff2?|png|jpe?g|svg)$" = {
          extraConfig = ''
            add_header Cache-Control "public, max-age=14400, must-revalidate";
          '';

          proxyPass = "http://unix:${config.services.akkoma.config.":pleroma"."Pleroma.Web.Endpoint".http.ip}";
          proxyWebsockets = true;
          recommendedProxySettings = true;
        };
      };
    };

    systemd.services.akkoma = {
      after = [ "authentik.service" ];
      environment.OAUTH_CONSUMER_STRATEGIES = "keycloak:ueberauth_keycloak_strategy";
      serviceConfig.EnvironmentFile = cfg.secrets.akkoma-envs;
    };

    services.nginx.virtualHosts.${cfg.domain} = {
      forceSSL = true;
      useACMEHost = cfg.domain;

      locations."/.well-known/host-meta" = {
        extraConfig = ''
          return 301 https://${cfg.realHost}$request_uri;
        '';
      };
    };
    modules.persistence.directories = [
      "/var/lib/akkoma"
    ];
  };
}