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

with lib;
let
  site = "forum.test.selby.ca";
  hostname = config.instance.hostname;
  host-secrets = config.fudo.secrets.host-secrets.${hostname};

  discourse-user = config.systemd.services.discourse.serviceConfig.User;

  database-name = "forum_selby_ca";
  database-user = "forum_selby_ca";

  state-directory = "/state/selby/forum";

  password-injector-sql = csv-file: pkgs.stdenv.mkDerivation {
    name = "${site}-password-injector-sql";
    phases = [ "installPhase" ];
    buildInputs = [ pkgs.ruby ];
    installPhase = ''
      ${password-convert-script csv-file}
    '';
  };

  password-convert-script = csv-file: pkgs.writeScript "vanilla-forum-password-convert.rb" ''
    #!${pkgs.ruby}/bin/ruby

    require 'csv'

    data = CSV::readlines("${csv-file}")
    File::open(ENV["out"], "w") { |sql|
      data.each { |row|
        sql.puts("UPDATE users SET import_pass='#{row[2]}' FROM user_emails WHERE users.id = user_emails.user_id AND user_emails.email = '#{row[1]}';")
      }
    }
  '';

in {
  config = {
    services.discourse = {
      enable = true;
      hostname = site;
      enableACME = true;
      plugins = with config.services.discourse.package.plugins; [
        discourse-migratepassword
      ];

      admin = {
        username = "admin";
        fullName = "Admin";
        email = "admin@selby.ca";
        passwordFile = host-secrets.selby-discourse-admin.target-file;
      };

      database = {
        name = database-name;
        host = "localhost";
        username = database-user;
        passwordFile =
          host-secrets.selby-discourse-database-passwd.target-file;
      };
    };

    fudo = {
      secrets.host-secrets.${hostname} = let
        selby-discourse-db-password =
          pkgs.lib.passwd.stablerandom-passwd-file
            "selby-discourse-database-password"
            "selby-discourse-database-password-${config.instance.build-seed}";

        files = config.fudo.secrets.files;
      in {
        selby-discourse-database-passwd = {
          source-file = selby-discourse-db-password;
          target-file = "/run/selby/forum/database.passwd";
          user = discourse-user;
        };

        postgresql-selby-discourse-password = {
          source-file = selby-discourse-db-password;
          target-file = "/run/postgres/selby-discourse.passwd";
          user = config.services.postgresql.superUser;
        };

        selby-discourse-admin = {
          source-file = pkgs.lib.passwd.stablerandom-passwd-file
            "selby-discourse-admin"
            "selby-discourse-admin-${config.instance.build-seed}";
          target-file = "/run/selby/forum/admin.passwd";
          user = discourse-user;
        };

        selby-forum-data = {
          source-file = files.blobs."selby-forum-2021-12-14.clean";
          target-file = "/run/selby/forum/forum-data.txt";
          user = discourse-user;
        };

        selby-forum-passwords-sql = {
          source-file = "${password-injector-sql files.blobs."forum_selby_ca-passwd.csv"}";
          target-file = "/run/postgres/selby/forum-passwords.sql";
          user = config.services.postgresql.superUser;
        };
      };

      postgresql = {
        databases.${database-name}.users = [ "niten" ];
        users.${database-user} = {
          password-file = host-secrets.postgresql-selby-discourse-password.target-file;
          databases.${database-name} = {
            access = "CONNECT,CREATE";
            entity-access = {
              "ALL TABLES IN SCHEMA public" = "SELECT,INSERT,UPDATE,DELETE";
              "ALL SEQUENCES IN SCHEMA public" = "SELECT,UPDATE";
            };
          };
        };
      };
    };

    security.acme.certs.${site}.email = "admin@selby.ca";

    systemd = {
      tmpfiles.rules = [
        "d ${state-directory} 750 ${discourse-user} - - -"
        "L /var/lib/discourse - - - - ${state-directory}"
      ];

      services = {
        discourse = {
          bindsTo = [ "postgresql.service" ];
          after = [
            config.fudo.postgresql.systemd-target
            "postgresql.service"
          ];
        };

        discourse-prepare = {
          description = "Do discourse's superuser-requiring database work for it.";
          wantedBy = [ "discourse.service" ];
          before = [ "discourse.service" ];
          requires = [ config.fudo.postgresql.systemd-target ];
          after = [ config.fudo.postgresql.systemd-target ];
          path = with pkgs; [ postgresql ];
          serviceConfig = {
            User = config.services.postgresql.superUser;
            ExecStart = pkgs.writeShellScript "discourse-prepare.sh" ''
              psql -d ${database-name} -c "CREATE EXTENSION IF NOT EXISTS hstore;"
              psql -d ${database-name} -c "CREATE EXTENSION IF NOT EXISTS pg_trgm;"
            '';
          };
        };

        discourse-import-vanilla = let
          env-without-path =
            filterAttrs (attr: _: attr != "PATH")
              config.systemd.services.discourse.environment;
          selby-forum-data = host-secrets.selby-forum-data.target-file;
        in {
          description = "One-off job to import Vanilla forum.";
          path = config.systemd.services.discourse.path;
          environment = env-without-path;
          serviceConfig = {
            User = config.systemd.services.discourse.serviceConfig.User;
            Group = config.systemd.services.discourse.serviceConfig.Group;
            Type = "oneshot";
            WorkingDirectory = config.systemd.services.discourse.serviceConfig.WorkingDirectory;
            ExecStart = pkgs.writeShellScript "import-vanilla-forum.sh" ''
              ruby script/import_scripts/vanilla.rb ${selby-forum-data}
            '';
          };
        };

        discourse-add-password-hash = let
          alter-user-script = pkgs.writeText "create-password-column.sql" ''
            ALTER TABLE users ADD COLUMN IF NOT EXISTS import_pass VARCHAR (64);
          '';
        in {
          description = "One-off job to add user password hashes from Vanilla forum.";
          path = with pkgs; [ postgresql ];
          wantedBy = [ "discourse.service" ];
          serviceConfig = {
            User = config.services.postgresql.superUser;
            Type = "oneshot";
            ExecStart = pkgs.writeShellScript "import-vanilla-passwords.sh" ''
              psql -d ${database-name} -f ${alter-user-script}
              psql -d ${database-name} -f ${host-secrets.selby-forum-passwords-sql.target-file}
            '';
          };
        };
      };
    };
  };
}