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

with lib;

let
  cfg = config.services.jitsi-meet;

  # The configuration files are JS of format "var <<string>> = <<JSON>>;". In order to
  # override only some settings, we need to extract the JSON, use jq to merge it with
  # the config provided by user, and then reconstruct the file.
  overrideJs =
    source: varName: userCfg: appendExtra:
    let
      extractor = pkgs.writeText "extractor.js" ''
        var fs = require("fs");
        eval(fs.readFileSync(process.argv[2], 'utf8'));
        process.stdout.write(JSON.stringify(eval(process.argv[3])));
      '';
      userJson = pkgs.writeText "user.json" (builtins.toJSON userCfg);
    in (pkgs.runCommand "${varName}.js" { } ''
      ${pkgs.nodejs}/bin/node ${extractor} ${source} ${varName} > default.json
      (
        echo "var ${varName} = "
        ${pkgs.jq}/bin/jq -s '.[0] * .[1]' default.json ${userJson}
        echo ";"
        echo ${escapeShellArg appendExtra}
      ) > $out
    '');

  # Essential config - it's probably not good to have these as option default because
  # types.attrs doesn't do merging. Let's merge explicitly, can still be overriden if
  # user desires.
  defaultCfg = {
    hosts = {
      domain = cfg.hostName;
      muc = "conference.${cfg.hostName}";
      focus = "focus.${cfg.hostName}";
    };
    bosh = "//${cfg.hostName}/http-bind";
  };
in
{
  options.services.jitsi-meet = with types; {
    enable = mkEnableOption "Jitsi Meet - Secure, Simple and Scalable Video Conferences";

    hostName = mkOption {
      type = str;
      example = "meet.example.org";
      description = ''
        Hostname of the Jitsi Meet instance.
      '';
    };

    config = mkOption {
      type = attrs;
      default = { };
      example = literalExample ''
        {
          enableWelcomePage = false;
          defaultLang = "fi";
        }
      '';
      description = ''
        Client-side web application settings that override the defaults in <filename>config.js</filename>.

        See <link xlink:href="https://github.com/jitsi/jitsi-meet/blob/master/config.js" /> for default
        configuration with comments.
      '';
    };

    extraConfig = mkOption {
      type = lines;
      default = "";
      description = ''
        Text to append to <filename>config.js</filename> web application config file.

        Can be used to insert JavaScript logic to determine user's region in cascading bridges setup.
      '';
    };

    interfaceConfig = mkOption {
      type = attrs;
      default = { };
      example = literalExample ''
        {
          SHOW_JITSI_WATERMARK = false;
          SHOW_WATERMARK_FOR_GUESTS = false;
        }
      '';
      description = ''
        Client-side web-app interface settings that override the defaults in <filename>interface_config.js</filename>.

        See <link xlink:href="https://github.com/jitsi/jitsi-meet/blob/master/interface_config.js" /> for
        default configuration with comments.
      '';
    };

    videobridge = {
      enable = mkOption {
        type = bool;
        default = true;
        description = ''
          Whether to enable Jitsi Videobridge instance and configure it to connect to Prosody.

          Additional configuration is possible with <option>services.jitsi-videobridge</option>.
        '';
      };

      passwordFile = mkOption {
        type = nullOr str;
        default = null;
        example = "/run/keys/videobridge";
        description = ''
          File containing password to the Prosody account for videobridge.

          If <literal>null</literal>, a file with password will be generated automatically. Setting
          this option is useful if you plan to connect additional videobridges to the XMPP server.
        '';
      };
    };

    jicofo.enable = mkOption {
      type = bool;
      default = true;
      description = ''
        Whether to enable JiCoFo instance and configure it to connect to Prosody.

        Additional configuration is possible with <option>services.jicofo</option>.
      '';
    };

    nginx.enable = mkOption {
      type = bool;
      default = true;
      description = ''
        Whether to enable nginx virtual host that will serve the javascript application and act as
        a proxy for the XMPP server. Further nginx configuration can be done by adapting
        <option>services.nginx.virtualHosts.&lt;hostName&gt;</option>.
        When this is enabled, ACME will be used to retrieve a TLS certificate by default. To disable
        this, set the <option>services.nginx.virtualHosts.&lt;hostName&gt;.enableACME</option> to
        <literal>false</literal> and if appropriate do the same for
        <option>services.nginx.virtualHosts.&lt;hostName&gt;.forceSSL</option>.
      '';
    };

    prosody.enable = mkOption {
      type = bool;
      default = true;
      description = ''
        Whether to configure Prosody to relay XMPP messages between Jitsi Meet components. Turn this
        off if you want to configure it manually.
      '';
    };
  };

  config = mkIf cfg.enable {
    services.prosody = mkIf cfg.prosody.enable {
      enable = mkDefault true;
      xmppComplianceSuite = mkDefault false;
      modules = {
        admin_adhoc = mkDefault false;
        bosh = mkDefault true;
        ping = mkDefault true;
        roster = mkDefault true;
        saslauth = mkDefault true;
        tls = mkDefault true;
      };
      muc = [
        {
          domain = "conference.${cfg.hostName}";
          name = "Jitsi Meet MUC";
          roomLocking = false;
          roomDefaultPublicJids = true;
          extraConfig = ''
            storage = "memory"
          '';
        }
        {
          domain = "internal.${cfg.hostName}";
          name = "Jitsi Meet Videobridge MUC";
          extraConfig = ''
            storage = "memory"
            admins = { "focus@auth.${cfg.hostName}", "jvb@auth.${cfg.hostName}" }
          '';
          #-- muc_room_cache_size = 1000
        }
      ];
      extraModules = [ "pubsub" ];
      extraConfig = mkAfter ''
        Component "focus.${cfg.hostName}"
          component_secret = os.getenv("JICOFO_COMPONENT_SECRET")
      '';
      virtualHosts.${cfg.hostName} = {
        enabled = true;
        domain = cfg.hostName;
        extraConfig = ''
          authentication = "anonymous"
          c2s_require_encryption = false
          admins = { "focus@auth.${cfg.hostName}" }
        '';
        ssl = {
          cert = "/var/lib/jitsi-meet/jitsi-meet.crt";
          key = "/var/lib/jitsi-meet/jitsi-meet.key";
        };
      };
      virtualHosts."auth.${cfg.hostName}" = {
        enabled = true;
        domain = "auth.${cfg.hostName}";
        extraConfig = ''
          authentication = "internal_plain"
        '';
        ssl = {
          cert = "/var/lib/jitsi-meet/jitsi-meet.crt";
          key = "/var/lib/jitsi-meet/jitsi-meet.key";
        };
      };
    };
    systemd.services.prosody.serviceConfig = mkIf cfg.prosody.enable {
      EnvironmentFile = [ "/var/lib/jitsi-meet/secrets-env" ];
      SupplementaryGroups = [ "jitsi-meet" ];
    };

    users.groups.jitsi-meet = {};
    systemd.tmpfiles.rules = [
      "d '/var/lib/jitsi-meet' 0750 root jitsi-meet - -"
    ];

    systemd.services.jitsi-meet-init-secrets = {
      wantedBy = [ "multi-user.target" ];
      before = [ "jicofo.service" "jitsi-videobridge2.service" ] ++ (optional cfg.prosody.enable "prosody.service");
      serviceConfig = {
        Type = "oneshot";
      };

      script = let
        secrets = [ "jicofo-component-secret" "jicofo-user-secret" ] ++ (optional (cfg.videobridge.passwordFile == null) "videobridge-secret");
        videobridgeSecret = if cfg.videobridge.passwordFile != null then cfg.videobridge.passwordFile else "/var/lib/jitsi-meet/videobridge-secret";
      in
      ''
        cd /var/lib/jitsi-meet
        ${concatMapStringsSep "\n" (s: ''
          if [ ! -f ${s} ]; then
            tr -dc a-zA-Z0-9 </dev/urandom | head -c 64 > ${s}
            chown root:jitsi-meet ${s}
            chmod 640 ${s}
          fi
        '') secrets}

        # for easy access in prosody
        echo "JICOFO_COMPONENT_SECRET=$(cat jicofo-component-secret)" > secrets-env
        chown root:jitsi-meet secrets-env
        chmod 640 secrets-env
      ''
      + optionalString cfg.prosody.enable ''
        ${config.services.prosody.package}/bin/prosodyctl register focus auth.${cfg.hostName} "$(cat /var/lib/jitsi-meet/jicofo-user-secret)"
        ${config.services.prosody.package}/bin/prosodyctl register jvb auth.${cfg.hostName} "$(cat ${videobridgeSecret})"

        # generate self-signed certificates
        if [ ! -f /var/lib/jitsi-meet.crt ]; then
          ${getBin pkgs.openssl}/bin/openssl req \
            -x509 \
            -newkey rsa:4096 \
            -keyout /var/lib/jitsi-meet/jitsi-meet.key \
            -out /var/lib/jitsi-meet/jitsi-meet.crt \
            -days 36500 \
            -nodes \
            -subj '/CN=${cfg.hostName}/CN=auth.${cfg.hostName}'
          chmod 640 /var/lib/jitsi-meet/jitsi-meet.{crt,key}
          chown root:jitsi-meet /var/lib/jitsi-meet/jitsi-meet.{crt,key}
        fi
      '';
    };

    services.nginx = mkIf cfg.nginx.enable {
      enable = mkDefault true;
      virtualHosts.${cfg.hostName} = {
        enableACME = mkDefault true;
        forceSSL = mkDefault true;
        root = pkgs.jitsi-meet;
        extraConfig = ''
          ssi on;
        '';
        locations."@root_path".extraConfig = ''
          rewrite ^/(.*)$ / break;
        '';
        locations."~ ^/([^/\\?&:'\"]+)$".tryFiles = "$uri @root_path";
        locations."=/http-bind" = {
          proxyPass = "http://localhost:5280/http-bind";
          extraConfig = ''
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $host;
          '';
        };
        locations."=/external_api.js" = mkDefault {
          alias = "${pkgs.jitsi-meet}/libs/external_api.min.js";
        };
        locations."=/config.js" = mkDefault {
          alias = overrideJs "${pkgs.jitsi-meet}/config.js" "config" (recursiveUpdate defaultCfg cfg.config) cfg.extraConfig;
        };
        locations."=/interface_config.js" = mkDefault {
          alias = overrideJs "${pkgs.jitsi-meet}/interface_config.js" "interfaceConfig" cfg.interfaceConfig "";
        };
      };
    };

    services.jitsi-videobridge = mkIf cfg.videobridge.enable {
      enable = true;
      xmppConfigs."localhost" = {
        userName = "jvb";
        domain = "auth.${cfg.hostName}";
        passwordFile = "/var/lib/jitsi-meet/videobridge-secret";
        mucJids = "jvbbrewery@internal.${cfg.hostName}";
        disableCertificateVerification = true;
      };
    };

    services.jicofo = mkIf cfg.jicofo.enable {
      enable = true;
      xmppHost = "localhost";
      xmppDomain = cfg.hostName;
      userDomain = "auth.${cfg.hostName}";
      userName = "focus";
      userPasswordFile = "/var/lib/jitsi-meet/jicofo-user-secret";
      componentPasswordFile = "/var/lib/jitsi-meet/jicofo-component-secret";
      bridgeMuc = "jvbbrewery@internal.${cfg.hostName}";
      config = {
        "org.jitsi.jicofo.ALWAYS_TRUST_MODE_ENABLED" = "true";
      };
    };
  };

  meta.maintainers = with lib.maintainers; [ ];
}