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

with lib;
let
  cfg = config.services.tahoe;
in
  {
    options.services.tahoe = {
      introducers = mkOption {
        default = {};
        type = types.loaOf types.optionSet;
        description = ''
          The Tahoe introducers.
        '';
        options = {
          nickname = mkOption {
            type = types.str;
            description = ''
              The nickname of this Tahoe introducer.
            '';
          };
          tub.port = mkOption {
            default = 3458;
            type = types.int;
            description = ''
              The port on which the introducer will listen.
            '';
          };
          package = mkOption {
            default = pkgs.tahoelafs;
            defaultText = "pkgs.tahoelafs";
            type = types.package;
            example = literalExample "pkgs.tahoelafs";
            description = ''
              The package to use for the Tahoe LAFS daemon.
            '';
          };
        };
      };
      nodes = mkOption {
        default = {};
        type = types.loaOf types.optionSet;
        description = ''
          The Tahoe nodes.
        '';
        options = {
          nickname = mkOption {
            type = types.str;
            description = ''
              The nickname of this Tahoe node.
            '';
          };
          tub.port = mkOption {
            default = 3457;
            type = types.int;
            description = ''
              The port on which the tub will listen.

              This is the correct setting to tweak if you want Tahoe's storage
              system to listen on a different port.
            '';
          };
          web.port = mkOption {
            default = 3456;
            type = types.int;
            description = ''
              The port on which the Web server will listen.

              This is the correct setting to tweak if you want Tahoe's WUI to
              listen on a different port.
            '';
          };
          client.introducer = mkOption {
            default = null;
            type = types.nullOr types.str;
            description = ''
              The furl for a Tahoe introducer node.

              Like all furls, keep this safe and don't share it.
            '';
          };
          client.helper = mkOption {
            default = null;
            type = types.nullOr types.str;
            description = ''
              The furl for a Tahoe helper node.

              Like all furls, keep this safe and don't share it.
            '';
          };
          client.shares.needed = mkOption {
            default = 3;
            type = types.int;
            description = ''
              The number of shares required to reconstitute a file.
            '';
          };
          client.shares.happy = mkOption {
            default = 7;
            type = types.int;
            description = ''
              The number of distinct storage nodes required to store
              a file.
            '';
          };
          client.shares.total = mkOption {
            default = 10;
            type = types.int;
            description = ''
              The number of shares required to store a file.
            '';
          };
          storage.enable = mkEnableOption "storage service";
          storage.reservedSpace = mkOption {
            default = "1G";
            type = types.str;
            description = ''
              The amount of filesystem space to not use for storage.
            '';
          };
          helper.enable = mkEnableOption "helper service";
          package = mkOption {
            default = pkgs.tahoelafs;
            defaultText = "pkgs.tahoelafs";
            type = types.package;
            example = literalExample "pkgs.tahoelafs";
            description = ''
              The package to use for the Tahoe LAFS daemon.
            '';
          };
        };
      };
    };
    config = mkMerge [
      (mkIf (cfg.introducers != {}) {
        environment = {
          etc = flip mapAttrs' cfg.introducers (node: settings:
            nameValuePair "tahoe-lafs/introducer-${node}.cfg" {
              mode = "0444";
              text = ''
                # This configuration is generated by Nix. Edit at your own
                # peril; here be dragons.

                [node]
                nickname = ${settings.nickname}
                tub.port = ${toString settings.tub.port}
              '';
            });
          # Actually require Tahoe, so that we will have it installed.
          systemPackages = flip mapAttrsToList cfg.introducers (node: settings:
            settings.package
          );
        };
        # Open up the firewall.
        # networking.firewall.allowedTCPPorts = flip mapAttrsToList cfg.introducers
        #   (node: settings: settings.tub.port);
        systemd.services = flip mapAttrs' cfg.introducers (node: settings:
          let
            pidfile = "/run/tahoe.introducer-${node}.pid";
            # This is a directory, but it has no trailing slash. Tahoe commands
            # get antsy when there's a trailing slash.
            nodedir = "/var/db/tahoe-lafs/introducer-${node}";
          in nameValuePair "tahoe.introducer-${node}" {
            description = "Tahoe LAFS node ${node}";
            wantedBy = [ "multi-user.target" ];
            path = [ settings.package ];
            restartTriggers = [
              config.environment.etc."tahoe-lafs/introducer-${node}.cfg".source ];
            serviceConfig = {
              Type = "simple";
              PIDFile = pidfile;
            };
            preStart = ''
              if [ \! -d ${nodedir} ]; then
                mkdir -p /var/db/tahoe-lafs
                tahoe create-introducer ${nodedir}
              fi

              # Tahoe has created a predefined tahoe.cfg which we must now
              # scribble over.
              # XXX I thought that a symlink would work here, but it doesn't, so
              # we must do this on every prestart. Fixes welcome.
              # rm ${nodedir}/tahoe.cfg
              # ln -s /etc/tahoe-lafs/introducer-${node}.cfg ${nodedir}/tahoe.cfg
              cp /etc/tahoe-lafs/introducer-${node}.cfg ${nodedir}/tahoe.cfg
            '';
            # Believe it or not, Tahoe is very brittle about the order of
            # arguments to $(tahoe start). The node directory must come first,
            # and arguments which alter Twisted's behavior come afterwards.
            script = ''
              tahoe start ${nodedir} -n -l- --pidfile=${pidfile}
            '';
          });
        users.extraUsers = flip mapAttrs' cfg.introducers (node: _:
          nameValuePair "tahoe.introducer-${node}" {
            description = "Tahoe node user for introducer ${node}";
            isSystemUser = true;
          });
      })
      (mkIf (cfg.nodes != {}) {
        environment = {
          etc = flip mapAttrs' cfg.nodes (node: settings:
            nameValuePair "tahoe-lafs/${node}.cfg" {
              mode = "0444";
              text = ''
                # This configuration is generated by Nix. Edit at your own
                # peril; here be dragons.

                [node]
                nickname = ${settings.nickname}
                tub.port = ${toString settings.tub.port}
                # This is a Twisted endpoint. Twisted Web doesn't work on
                # non-TCP. ~ C.
                web.port = tcp:${toString settings.web.port}

                [client]
                ${optionalString (settings.client.introducer != null)
                  "introducer.furl = ${settings.client.introducer}"}
                ${optionalString (settings.client.helper != null)
                  "helper.furl = ${settings.client.helper}"}

                shares.needed = ${toString settings.client.shares.needed}
                shares.happy = ${toString settings.client.shares.happy}
                shares.total = ${toString settings.client.shares.total}

                [storage]
                enabled = ${if settings.storage.enable then "true" else "false"}
                reserved_space = ${settings.storage.reservedSpace}

                [helper]
                enabled = ${if settings.helper.enable then "true" else "false"}
              '';
            });
          # Actually require Tahoe, so that we will have it installed.
          systemPackages = flip mapAttrsToList cfg.nodes (node: settings:
            settings.package
          );
        };
        # Open up the firewall.
        # networking.firewall.allowedTCPPorts = flip mapAttrsToList cfg.nodes
        #   (node: settings: settings.tub.port);
        systemd.services = flip mapAttrs' cfg.nodes (node: settings:
          let
            pidfile = "/run/tahoe.${node}.pid";
            # This is a directory, but it has no trailing slash. Tahoe commands
            # get antsy when there's a trailing slash.
            nodedir = "/var/db/tahoe-lafs/${node}";
          in nameValuePair "tahoe.${node}" {
            description = "Tahoe LAFS node ${node}";
            wantedBy = [ "multi-user.target" ];
            path = [ settings.package ];
            restartTriggers = [
              config.environment.etc."tahoe-lafs/${node}.cfg".source ];
            serviceConfig = {
              Type = "simple";
              PIDFile = pidfile;
            };
            preStart = ''
              if [ \! -d ${nodedir} ]; then
                mkdir -p /var/db/tahoe-lafs
                tahoe create-node ${nodedir}
              fi

              # Tahoe has created a predefined tahoe.cfg which we must now
              # scribble over.
              # XXX I thought that a symlink would work here, but it doesn't, so
              # we must do this on every prestart. Fixes welcome.
              # rm ${nodedir}/tahoe.cfg
              # ln -s /etc/tahoe-lafs/${node}.cfg ${nodedir}/tahoe.cfg
              cp /etc/tahoe-lafs/${node}.cfg ${nodedir}/tahoe.cfg
            '';
            # Believe it or not, Tahoe is very brittle about the order of
            # arguments to $(tahoe start). The node directory must come first,
            # and arguments which alter Twisted's behavior come afterwards.
            script = ''
              tahoe start ${nodedir} -n -l- --pidfile=${pidfile}
            '';
          });
        users.extraUsers = flip mapAttrs' cfg.nodes (node: _:
          nameValuePair "tahoe.${node}" {
            description = "Tahoe node user for node ${node}";
            isSystemUser = true;
          });
      })
    ];
  }