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

let
  #federationSenders = lib.range 0 31;
  #federationReceivers = lib.range 10000 10000;
  #initialSyncWorkers = lib.range 10100 10100;
  #syncWorkers = lib.range 10150 10150;
  #streamWriters = lib.range 10200 10200;
in
{

  # Worker plumbing examples: https://github.com/element-hq/synapse/blob/master/docker/configure_workers_and_start.py
  # Documentation: https://github.com/element-hq/synapse/blob/develop/docs/workers.md
  imports = [
    ./workers/module.nix
  ];

  services.matrix-synapse = {
    enable = true;
    withJemalloc = true;

    federationSenders = 8;
    pushers = 2;
    enableStreamWriters = false;
    enableAppserviceWorker = true;
    #eventStreamWriters = 8;

    # https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html
    settings = {
      server_name = "rory.gay";

      enable_registration = true;
      registration_requires_token = true;

      require_membership_for_aliases = false;
      redaction_retention_period = null;
      user_ips_max_age = null;
      allow_device_name_lookup_over_federation = true;

      federation = {
        client_timeout = "60s";
        max_short_retries = 12;
        max_short_retry_delay = "5s";
        max_long_retries = 5;
        max_long_retry_delay = "30s";
      };

      # Alicia - figure this out later...
      #registration_shared_secret = builtins.exec ["cat" "/dev/urandom" "|" "tr" "-dc" "a-zA-Z0-9" "|" "fold" "-w" "256" "|" "head" "-n" "1"];
      registration_shared_secret_path = "/var/lib/matrix-synapse/registration_shared_secret.txt";
      
      listeners = [
        { 
          port = 8008;
          bind_addresses = [ "192.168.1.2" "127.0.0.1" ];
          type = "http";
          tls = false;
          x_forwarded = true;
          resources = [ {
            names = [ "client" "federation" ];
            compress = false;
          } ];
        }
        { 
          type = "http";
          path = "/run/matrix-synapse/replication-listener.sock";
          resources = [ {
            names = [ "replication" ];
            compress = false;
          } ];
        }
      ];
      dynamic_thumbnails = true;
      presence = {
        enable = true;
        update_interval = 60;
      };
      url_preview_enabled = true;
      database = (import ./db.nix { workerName = "main"; dbGroup = "medium"; });
      #database = {
      #  name = "psycopg2";
      #  args = {
      #    user = "matrix-synapse-rory-gay";
      #    #passwordFile = "/run/secrets/matrix-synapse-password";
      #    password = "somepassword";
      #    database = "matrix-synapse-rory-gay";
      #    #host = "127.0.0.1";
      #    host = "/run/postgresql";
      #    application_name = "matrix-synapse (rory.gay)";
      #    cp_min = 5;
      #    cp_max = 10;
      #    #cp_reconnect_interval = "True";
      #  };
      #};
      app_service_config_files = [
        #"/etc/matrix-synapse/appservice-registration.yaml"
        "/var/lib/matrix-synapse/modas-registration.yaml"
      ];

      max_image_pixels = "100M";

      ui_auth = {
        session_timeout = "1m";
      };

      login_via_existing_session = {
        enabled = true;
        require_ui_auth = true;
        token_timeout = "1y";
      };

      report_stats = false;

      user_directory = {
        enabled = true;
        search_all_users = true;
        prefer_local_users = true;
      };

      experimental_features = {
        # These apparently arent valid...
        #"org.matrix.msc3026.busy_presence" = true;
        #"fi.mau.msc2815" = true;
        #"org.matrix.msc3881" = true;
        #"org.matrix.msc3874" = true;
        #"org.matrix.msc3912" = true;

        # These should be, looking at synapse's experimental.py
        "msc2815_enabled" = true; # Redacted event content
        "msc3026_enabled" = true; # Busy presence
        "msc3266_enabled" = true; # Room summary API
        "msc3916_authenticated_media_enabled" = true; # Authenticated media
      };


      redis = {
        enabled = true;
        path = "/run/redis-matrix-synapse/redis.sock";
      };


      instance_map = {
        main = { # replication listener
          #host = "127.0.0.1";
          #port = 8009;
          path = "/run/matrix-synapse/replication-listener.sock";
        };
      } ;
      ### // builtins.listToAttrs (map (port: {
      ###   name = "federation_sender-${toString port}";
      ###   value = {
      ###     path = "/run/matrix-synapse/federation_sender-${toString port}.sock";
      ###   };
      ### }) federationSenders);

      #} // builtins.listToAttrs (map (port: {
      #  name = "federation_receiver-${toString port}";
      #  value = {
      #    path = "/run/matrix-synapse/federation_receiver-${toString port}.sock";
      #  };
      #}) federationReceivers);

      # by type:
      
      #federation_sender_instances = map (port: "federation_sender-${toString port}") federationSenders;
    }
    // import ./ratelimits.nix
    // import ./caches.nix;

    ## TODO: INVESTIGATE
    # worker_listeners:
    # - type: metrics
    #   bind_address: ''
    #   port: 9101

    #workers = 
    #builtins.listToAttrs (map (port: {
    #  name = "federation_receiver-${toString port}";
    #  value = {
    #    worker_app = "synapse.app.generic_worker";
    #    worker_listeners = [
    #      { 
    #        port = port;
    #        type = "http";
    #        resources = [ {
    #          names = [ "federation" ];
    #          compress = false;
    #        } ];
    #      }
    #    ];
    #  };
    #}) federationReceivers)
    ### builtins.listToAttrs (map (port: {
    ###   name = "federation_sender-${toString port}";
    ###   value = {
    ###     worker_app = "synapse.app.generic_worker";
    ###     worker_listeners = [ ];
    ###     database = (import ./db.nix { workerName = "federation sender ${toString port}"; dbGroup = "small"; });
    ###   };
    ### }) federationSenders);
  };

  systemd.services.matrix-synapse-reg-token = {
    description = "Random registration token for Synapse.";
    before = ["matrix-synapse.service"]; # So the registration can be used by Synapse
    wantedBy = ["multi-user.target"];
    after = ["network.target"];

    script = ''

      if [ ! -f "registration_shared_secret.txt" ]
      then
        cat /dev/urandom | tr -dc a-zA-Z0-9 | fold -w 256 | head -n 1 > registration_shared_secret.txt
      else
        echo Not generating key, key exists;
      fi'';
    serviceConfig = {
      User = "matrix-synapse";
      Group = "matrix-synapse";
      WorkingDirectory = "/var/lib/matrix-synapse";
    };
  };

  services.redis = {
    package = pkgs.keydb;
    servers.matrix-synapse = {
      enable = true;
      user = "matrix-synapse";
    };
  };
  
  systemd.tmpfiles.rules = [
    "D /run/redis-matrix-synapse 0755 matrix-synapse matrix-synapse"
  ];
}