nix-gitlab-ci/flakeModule.nix

{
  flake-parts-lib,
  lib,
  inputs,
  ...
}: {
  options.perSystem = flake-parts-lib.mkPerSystemOption (
    {
      config,
      pkgs,
      system,
      ...
    }: let
      cfg = config.ci.config;

      filterAttrsRec = pred: v:
        if lib.isAttrs v
        then lib.filterAttrs pred (lib.mapAttrs (path: filterAttrsRec pred) v)
        else v;

      subType = options: lib.types.submodule {inherit options;};

      configType = with lib;
        subType {
          default-nix-image = mkOption {
            type = types.str;
            default = "registry.gitlab.com/technofab/nix-gitlab-ci/nix-ci:latest";
            description = "The image to use on nix jobs";
          };
          nix-jobs-per-default = mkOption {
            type = types.bool;
            default = true;
            description = "Handle jobs nix-based by default or via opt-in (in job set nix = true) if false";
          };
        };
      jobType = with lib;
        subType {
          # nix ci opts
          nix = mkOption {
            type = types.bool;
            default = cfg.nix-jobs-per-default;
          };
          deps = mkOption {
            type = types.listOf types.package;
            default = [];
          };
          # gitlab opts
          before_script = mkOption {
            type = types.listOf types.str;
            default = [];
          };
          script = mkOption {
            type = types.listOf types.str;
            default = [];
          };
          after_script = mkOption {
            type = types.listOf types.str;
            default = [];
          };
          stage = mkOption {
            type = types.str;
          };
          image = mkOption {
            type = types.str;
            default = cfg.default-nix-image;
          };
          variables = mkOption {
            type = types.nullOr types.attrs;
            default = null;
          };
          when = mkOption {
            type = types.nullOr types.str;
            default = null;
          };
          start_in = mkOption {
            type = types.nullOr types.str;
            default = null;
          };
          allow_failure = mkOption {
            type = types.nullOr types.bool;
            default = null;
          };
          needs = mkOption {
            type = types.nullOr (types.listOf types.str);
            default = null;
          };
          rules = mkOption {
            type = types.nullOr types.attrs;
            default = null;
          };
        };
    in {
      options = with lib; {
        ci = mkOption {
          type = subType {
            config = mkOption {
              type = configType;
              description = ''
                Configuration options for the nix part itself
              '';
              default = {};
            };
            image = mkOption {
              type = types.nullOr types.str;
              default = null;
            };
            variables = mkOption {
              type = types.nullOr types.attrs;
              default = null;
            };
            default = mkOption {
              type = types.nullOr types.attrs;
              default = null;
            };
            stages = mkOption {
              type = types.nullOr (types.listOf types.str);
              default = null;
            };
            jobs = mkOption {
              type = types.lazyAttrsOf jobType;
              default = {};
            };
          };
          description = ''
            Generate a Gitlab CI configuration which can be used to trigger a child pipeline.
            This will inject code which pre-downloads the nix deps before each job and adds them to PATH.
          '';
          default = {};
        };
      };

      config.packages = let
        toYaml = (pkgs.formats.yaml {}).generate;
        mapAttrs = cb: set: builtins.listToAttrs (builtins.map (key: cb key (builtins.getAttr key set)) (builtins.attrNames set));
        prependToBeforeScript = arr: job:
          job
          // lib.optionalAttrs job.nix {
            before_script =
              arr
              ++ job.before_script;
          };

        jobs = filterAttrsRec (n: v: v != null) config.ci.jobs;
        rest = filterAttrsRec (n: v: v != null) (builtins.removeAttrs config.ci ["jobs" "config"]);
        # this allows us to nix build this to get all the mentioned dependencies from the binary cache
        # pro: we don't have to download everything, just the deps for the current job
        # before, we just allowed pkgs inside the script string directly, but now with the ability to source this file
        # we can support different architectures between runners (eg. the arch of the initial runner does not matter)
        jobsMappedForDeps =
          mapAttrs (key: job: {
            name = "gitlab-ci-job-deps:${key}";
            value = pkgs.writeShellScript "gitlab-ci-jobs:${key}" ''
              export PATH="${lib.makeBinPath job.deps}:$PATH";
            '';
          })
          jobs;
        # allows the user to directly run the script
        jobsMappedForScript =
          mapAttrs (key: job: {
            name = "gitlab-ci-job:${key}";
            value = pkgs.writeShellScriptBin "gitlab-ci-jobs:${key}" (lib.strings.concatLines (job.before_script ++ job.script ++ job.after_script));
          })
          jobs;
        # build the deps specific for this job before anything, this way the deps should be fetched from the cache
        jobsPatched =
          mapAttrs (key: job: {
            name = key;
            value = builtins.removeAttrs (
              (prependToBeforeScript [
                  "echo -e \"\\e[0Ksection_start:`date +%s`:nix_deps[collapsed=true]\\r\\e[0KDownload Nix deps for job\""
                  "nix build .#gitlab-ci-job-deps:${key}"
                  "source $(readlink -f result)"
                  "echo -e \"\\e[0Ksection_end:`date +%s`:nix_deps\\r\\e[0K\""
                ]
                job)
              // lib.optionalAttrs job.nix {
                image = job.image;
              }
            ) ["nix" "deps"];
          })
          jobs;
      in
        {
          gitlab-ci-config = toYaml "generated-gitlab-ci.yml" (rest // jobsPatched);
        }
        // jobsMappedForDeps
        // jobsMappedForScript;
    }
  );
}