{ config, pkgs, lib, ... }:
let
  cfg = config.my.services.cgit;
  # there's no need for web crawlers on that site
  robots-deny = pkgs.writeText "robots.txt" ''
    User-agent: *
    Disallow: /
  '';
  cgitrc = ''
    # Global configuration
    virtual-root=/

    # clone will be handled by gerrit
    enable-http-clone=0
    clone-url=https://cl.fcuny.net/$CGIT_REPO_URL

    # I've fewer than 150 repos, all should be able to be listed on
    # the main page
    max-repo-count=150

    # limit to year for the stats
    max-stats=year

    snapshots=tar.gz

    source-filter=${pkgs.cgit}/lib/cgit/filters/syntax-highlighting.py
    about-filter=${pkgs.cgit}/lib/cgit/filters/about-formatting.sh

    enable-git-config=1
    enable-index-owner=0

    remove-suffix=1

    # sort repositories by section and branches by date
    repository-sort=age
    branch-sort=age

    readme=:README.md
    readme=:README.org
    readme=:readme.org

    # print the number of modified files
    enable-log-filecount=1
    # print the number of modified lines
    enable-log-linecount=1
    enable-follow-links=1
    enable-blame=1

    root-title="Franck git repositories"
    root-desc="source code of my various projects"

    # don't index or follow
    robots="noindex, nofollow"

    project-list=/var/lib/cgit/cache/projects.list
    scan-path=/var/lib/gerrit/git
  '';
in
{
  options.my.services.cgit = with lib; {
    enable = mkEnableOption "git web viewer";
  };

  config = lib.mkIf cfg.enable {
    services.fcgiwrap = {
      enable = true;
      user = "git";
      group = "git";
    };

    systemd = {
      timers.sync-cgit-repo = {
        description = "synchronize the list of repositories from gerrit";
        wantedBy = [ "timers.target" ];
        partOf = [ "sync-cgit-repo.service" ];
        timerConfig.OnCalendar = "*:0/10";
      };
      services.sync-cgit-repo = {
        description = "synchronize the list of repositories from gerrit";
        serviceConfig.Type = "oneshot";
        script = ''
          mkdir -p /var/lib/cgit/cache
          tmplist=$(mktemp)

          # as per https://gerrit-review.googlesource.com/Documentation/rest-api.html#output we need to remove `)]}' from the response
          repos=$(${pkgs.curl}/bin/curl -s -H "Content-Type: application/json" "https://cl.fcuny.net/projects/?state=ACTIVE"|sed "s/^)]}'//"|${pkgs.jq}/bin/jq -r 'to_entries | .[] | .value | .id')

          # list of repositories that I still want to be active in gerrit but I don't want to list here
          exclude_repos="password-store|All-Projects|All-Users|homelab"

          for repo in ''${repos}; do
            if [[ ! $exclude_repos =~ $repo ]]; then
              echo "''${repo}.git" >> $tmplist
            fi
          done
          mv $tmplist /var/lib/cgit/cache/projects.list
          # TODO(fcuny): this should run as the git user
          chown git:git /var/lib/cgit/cache/projects.list
        '';
      };
    };

    services.nginx.virtualHosts."git.fcuny.net" = {
      # make cgit the default site: if a request goes through nginx
      # without a host header, this will be the default site we serve
      # for that request.
      default = true;
      forceSSL = true;
      enableACME = true;
      locations = {
        "~* ^.+.(css|png|ico)$" = { root = "${pkgs.cgit}/cgit"; };
        "/robots.txt".alias = robots-deny;
        "/".extraConfig = ''
          include ${pkgs.nginx}/conf/fastcgi_params;
          fastcgi_param CGIT_CONFIG ${pkgs.writeText "cgitrc" cgitrc};
          fastcgi_param SCRIPT_FILENAME ${pkgs.cgit}/cgit/cgit.cgi;
          fastcgi_split_path_info ^(/?)(.+)$;
          fastcgi_param PATH_INFO $fastcgi_path_info;
          fastcgi_param HTTP_HOST $server_name;
          fastcgi_param QUERY_STRING $args;
          fastcgi_pass unix:${config.services.fcgiwrap.socketAddress};
        '';
      };
    };
  };
}