home-manager/modules/programs/getmail.nix

{ config, lib, pkgs, ... }:
let
  accounts = lib.filter (a: a.getmail.enable)
    (lib.attrValues config.accounts.email.accounts);

  renderAccountConfig = account:
    let
      inherit (account) getmail imap passwordCommand;
      passCmd = lib.concatMapStringsSep ", " (x: "'${x}'") passwordCommand;
      renderedMailboxes =
        lib.concatMapStrings (x: "'${x}', ") getmail.mailboxes;
      retrieverType = if imap.tls.enable then
        "SimpleIMAPSSLRetriever"
      else
        "SimpleIMAPRetriever";
      destination = if getmail.destinationCommand != null then {
        destinationType = "MDA_external";
        destinationPath = getmail.destinationCommand;
      } else {
        destinationType = "Maildir";
        destinationPath = "${account.maildir.absPath}/";
      };
      renderGetmailBoolean = v: if v then "true" else "false";
    in ''
      # Generated by Home-Manager.
      [retriever]
      type = ${retrieverType}
      server = ${imap.host}
      ${lib.optionalString (imap.port != null) "port = ${toString imap.port}"}
      username = ${account.userName}
      password_command = (${passCmd})
      mailboxes = ( ${renderedMailboxes} )

      [destination]
      type = ${destination.destinationType}
      path = ${destination.destinationPath}

      [options]
      delete = ${renderGetmailBoolean getmail.delete}
      read_all = ${renderGetmailBoolean getmail.readAll}
    '';
  getmailEnabled = lib.length (lib.filter (a: a.getmail.enable) accounts) > 0;
  # Watch out! This is used by the getmail.service too!
  renderConfigFilepath = a:
    ".getmail/getmail${if a.primary then "rc" else a.name}";

in {
  options = {
    accounts.email.accounts = lib.mkOption {
      type = with lib.types;
        attrsOf (submodule (import ./getmail-accounts.nix));
    };
  };

  config = lib.mkIf getmailEnabled {
    assertions = [
      (lib.hm.assertions.assertPlatform "programs.getmail" pkgs
        lib.platforms.linux)
    ];

    home.file = lib.foldl' (a: b: a // b) { }
      (map (a: { "${renderConfigFilepath a}".text = renderAccountConfig a; })
        accounts);
  };
}