selfhostblocks/modules/contracts/backup.nix

{ pkgs, lib, ... }:
let
  inherit (lib) concatStringsSep literalMD mkOption optionalAttrs optionalString;
  inherit (lib.types) listOf nonEmptyListOf submodule str;

  shblib = pkgs.callPackage ../../lib {};
  inherit (shblib) anyNotNull;
in
{
  mkRequest =
    { user ? "",
      userText ? null,
      sourceDirectories ? [ "/var/lib/example" ],
      sourceDirectoriesText ? null,
      excludePatterns ? [],
      excludePatternsText ? null,
      beforeBackup ? [],
      beforeBackupText ? null,
      afterBackup ? [],
      afterBackupText ? null,
    }: mkOption {
      description = ''
        Request part of the backup contract.

        Options set by the requester module
        enforcing how to backup files.
      '';

      default = {
        inherit user sourceDirectories excludePatterns;
        hooks = {
          inherit beforeBackup afterBackup;
        };
      };

      defaultText = optionalString (anyNotNull [
        userText
        sourceDirectoriesText
        excludePatternsText
        beforeBackupText
        afterBackupText
      ]) (literalMD ''
      {
        user = ${if userText != null then userText else user};
        sourceDirectories = ${if sourceDirectoriesText != null then sourceDirectoriesText else "[ " + concatStringsSep " " sourceDirectories + " ]"};
        excludePatterns = ${if excludePatternsText != null then excludePatternsText else "[ " + concatStringsSep " " excludePatterns + " ]"};
        hooks.beforeBackup = ${if beforeBackupText != null then beforeBackupText else "[ " + concatStringsSep " " beforeBackup + " ]"};
        hooks.afterBackup = ${if afterBackupText != null then afterBackupText else "[ " + concatStringsSep " " afterBackup + " ]"};
      };
      '');

      type = submodule {
        options = {
          user = mkOption {
            description = ''
              Unix user doing the backups.
            '';
            type = str;
            example = "vaultwarden";
            default = user;
          } // optionalAttrs (userText != null) {
            defaultText = literalMD userText;
          };

          sourceDirectories = mkOption {
            description = "Directories to backup.";
            type = nonEmptyListOf str;
            example = "/var/lib/vaultwarden";
            default = sourceDirectories;
          } // optionalAttrs (sourceDirectoriesText != null) {
            defaultText = literalMD sourceDirectoriesText;
          };

          excludePatterns = mkOption {
            description = "File patterns to exclude.";
            type = listOf str;
            default = excludePatterns;
          } // optionalAttrs (excludePatternsText != null) {
            defaultText = literalMD excludePatternsText;
          };

          hooks = mkOption {
            description = "Hooks to run around the backup.";
            default = {};
            type = submodule {
              options = {
                beforeBackup = mkOption {
                  description = "Hooks to run before backup.";
                  type = listOf str;
                  default = beforeBackup;
                } // optionalAttrs (beforeBackupText != null) {
                  defaultText = literalMD beforeBackupText;
                };

                afterBackup = mkOption {
                  description = "Hooks to run after backup.";
                  type = listOf str;
                  default = afterBackup;
                } // optionalAttrs (afterBackupText != null) {
                  defaultText = literalMD afterBackupText;
                };
              };
            };
          };
        };
      };
    };

  mkResult = {
    restoreScript ? "restore",
    restoreScriptText ? null,
    backupService ? "backup.service",
    backupServiceText ? null,
  }: mkOption {
    description = ''
      Result part of the backup contract.

      Options set by the provider module that indicates the name of the backup and restor scripts.
    '';
    default = {
      inherit restoreScript backupService;
    };

    defaultText = optionalString (anyNotNull [
      restoreScriptText
      backupServiceText
    ]) (literalMD ''
    {
      restoreScript = ${if restoreScriptText != null then restoreScriptText else restoreScript};
      backupService = ${if backupServiceText != null then backupServiceText else backupService};
    }
    '');

    type = submodule {
      options = {
        restoreScript = mkOption {
          description = ''
            Name of script that can restore the database.
            One can then list snapshots with:

            ```bash
            $ ${if restoreScriptText != null then restoreScriptText else restoreScript} snapshots
            ```

            And restore the database with:

            ```bash
            $ ${if restoreScriptText != null then restoreScriptText else restoreScript} restore latest
            ```
          '';
          type = str;
          default = restoreScript;
        } // optionalAttrs (restoreScriptText != null) {
          defaultText = literalMD restoreScriptText;
        };

        backupService = mkOption {
          description = ''
            Name of service backing up the database.

            This script can be ran manually to backup the database:

            ```bash
            $ systemctl start ${if backupServiceText != null then backupServiceText else backupService}
            ```
          '';
          type = str;
          default = backupService;
        } // optionalAttrs (backupServiceText != null) {
          defaultText = literalMD backupServiceText;
        };
      };
    };
  };
}