# adapted from https://nixos.org/manual/nixos/stable/index.html#module-services-matrix
{ modulesPath, config, lib, pkgs, ... }:
let 
  storage-device = "/dev/disk/by-id/scsi-0DO_Volume_matrix-storage";
  storage-dir = "/opt/matrix-data";
  matrix-reg-key = (builtins.readFile ./matrix_reg_key);
  fqdn = 
    let
      join = hostName: domain: hostName + lib.optionalString (domain != null) ".${domain}";
    in join config.networking.hostName config.networking.domain;
in {
  imports = [
     "${toString modulesPath}/virtualisation/digital-ocean-image.nix"
  ];

  environment.systemPackages = [ pkgs.jq ];
  services.openssh.enable = true;
  networking.firewall.allowedTCPPorts = [ 22 80 443 ];

  users.users.root.openssh.authorizedKeys.keys = [
    (builtins.readFile "/home/mike/.ssh/id_mops.pub")
  ];

  ### app specific config 

  # mount DigitalOcean volume for use by postgres
  fileSystems."${storage-dir}" = {
    device = storage-device;
  };

  networking = {
    hostName = "matrix";
    domain = "waffle.farm";
  };

  services.postgresql = { 
    enable = true;
    dataDir = "${storage-dir}/db";

    initialScript = pkgs.writeText "synapse-init.sql" ''
      CREATE ROLE "matrix-synapse" WITH LOGIN PASSWORD 'synapse';
      CREATE DATABASE "matrix-synapse" WITH OWNER "matrix-synapse"
      TEMPLATE template0
      LC_COLLATE = "C"
      LC_CTYPE = "C";
    '';
  };

  services.nginx = {
    enable = true;
    recommendedTlsSettings = true;
    recommendedOptimisation = true;
    recommendedGzipSettings = true;
    recommendedProxySettings = true;

    virtualHosts = {
      "${config.networking.domain}" = {
        enableACME = true;
        forceSSL = true;

        locations."= /.well-known/matrix/server".extraConfig =
          let
            # use 443 instead of the default 8448 port to unite
            # the client-server and server-server port for simplicity
            server = { "m.server" = "${fqdn}:443"; };
          in ''
            add_header Content-Type application/json;
            return 200 '${builtins.toJSON server}';
          '';
        locations."= /.well-known/matrix/client".extraConfig =
        let
          client = {
            "m.homeserver" =  { "base_url" = "https://${fqdn}"; };
            "m.identity_server" =  { "base_url" = "https://vector.im"; };
          };
        # ACAO required to allow element-web on any URL to request this json file
        in ''
          add_header Content-Type application/json;
          add_header Access-Control-Allow-Origin *;
          return 200 '${builtins.toJSON client}';
        '';
        locations."/".extraConfig = ''
          return 301 https://chat.waffle.farm;
        '';

      };
      # Reverse proxy for Matrix client-server and server-server communication
      ${fqdn} = {
        enableACME = true;
        forceSSL = true;

        # Or do a redirect instead of the 404, or whatever is appropriate for you.
        # But do not put a Matrix Web client here! See the Element web section below.
        locations."/".extraConfig = ''
          return 301 https://chat.waffle.farm;
        '';

        # forward all Matrix API calls to the synapse Matrix homeserver
        locations."/_matrix" = {
          proxyPass = "http://[::1]:8008"; # without a trailing /
        };
      };

      "chat.${config.networking.domain}" = {
        enableACME = true;
        forceSSL = true;
        serverAliases = [
          "chat.${config.networking.domain}"
        ];
        root = pkgs.element-web.override {
          conf = {
            default_server_config."m.homeserver" = {
              "base_url" = "https://${fqdn}";
              "server_name" = "${config.networking.domain}";
            };
          };
        };
      };
    };
  };
  services.matrix-synapse = {
    enable = true;
    server_name = config.networking.domain;
    registration_shared_secret = matrix-reg-key;

    listeners = [
      {
        port = 8008;
        bind_address = "::1";
        type = "http";
        tls = false;
        x_forwarded = true;
        resources = [
          {
            names = [ "client" "federation" ];
            compress = false;
          }
        ];
      }
    ];
  };
  security.acme.acceptTerms = true;
  security.acme.certs = {
    "${fqdn}".email = "mike@betamike.com";
    "${config.networking.domain}".email = "mike@betamike.com";
    "chat.${config.networking.domain}".email = "mike@betamike.com";
  };
}