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

with lib;

let
  cfg = config.services.nextcloud;
  fpm = config.services.phpfpm.pools.nextcloud;

  phpPackage =
    let
      base = pkgs.php74;
    in
      base.buildEnv {
        extensions = { enabled, all }: with all;
          enabled ++ [
            apcu redis memcached imagick
          ];
        extraConfig = phpOptionsStr;
      };

  toKeyValue = generators.toKeyValue {
    mkKeyValue = generators.mkKeyValueDefault {} " = ";
  };

  phpOptions = {
    upload_max_filesize = cfg.maxUploadSize;
    post_max_size = cfg.maxUploadSize;
    memory_limit = cfg.maxUploadSize;
  } // cfg.phpOptions;
  phpOptionsStr = toKeyValue phpOptions;

  occ = pkgs.writeScriptBin "nextcloud-occ" ''
    #! ${pkgs.runtimeShell}
    cd ${cfg.package}
    sudo=exec
    if [[ "$USER" != nextcloud ]]; then
      sudo='exec /run/wrappers/bin/sudo -u nextcloud --preserve-env=NEXTCLOUD_CONFIG_DIR --preserve-env=OC_PASS'
    fi
    export NEXTCLOUD_CONFIG_DIR="${cfg.home}/config"
    $sudo \
      ${phpPackage}/bin/php \
      occ "$@"
  '';

  inherit (config.system) stateVersion;

in {

  imports = [
    (mkRemovedOptionModule [ "services" "nextcloud" "nginx" "enable" ] ''
      The nextcloud module supports `nginx` as reverse-proxy by default and doesn't
      support other reverse-proxies officially.

      However it's possible to use an alternative reverse-proxy by

        * disabling nginx
        * setting `listen.owner` & `listen.group` in the phpfpm-pool to a different value

      Further details about this can be found in the `Nextcloud`-section of the NixOS-manual
      (which can be openend e.g. by running `nixos-help`).
    '')
  ];

  options.services.nextcloud = {
    enable = mkEnableOption "nextcloud";
    hostName = mkOption {
      type = types.str;
      description = "FQDN for the nextcloud instance.";
    };
    home = mkOption {
      type = types.str;
      default = "/var/lib/nextcloud";
      description = "Storage path of nextcloud.";
    };
    logLevel = mkOption {
      type = types.ints.between 0 4;
      default = 2;
      description = "Log level value between 0 (DEBUG) and 4 (FATAL).";
    };
    https = mkOption {
      type = types.bool;
      default = false;
      description = "Use https for generated links.";
    };
    package = mkOption {
      type = types.package;
      description = "Which package to use for the Nextcloud instance.";
      relatedPackages = [ "nextcloud18" "nextcloud19" "nextcloud20" ];
    };

    maxUploadSize = mkOption {
      default = "512M";
      type = types.str;
      description = ''
        Defines the upload limit for files. This changes the relevant options
        in php.ini and nginx if enabled.
      '';
    };

    skeletonDirectory = mkOption {
      default = "";
      type = types.str;
      description = ''
        The directory where the skeleton files are located. These files will be
        copied to the data directory of new users. Leave empty to not copy any
        skeleton files.
      '';
    };

    webfinger = mkOption {
      type = types.bool;
      default = false;
      description = ''
        Enable this option if you plan on using the webfinger plugin.
        The appropriate nginx rewrite rules will be added to your configuration.
      '';
    };

    phpOptions = mkOption {
      type = types.attrsOf types.str;
      default = {
        short_open_tag = "Off";
        expose_php = "Off";
        error_reporting = "E_ALL & ~E_DEPRECATED & ~E_STRICT";
        display_errors = "stderr";
        "opcache.enable_cli" = "1";
        "opcache.interned_strings_buffer" = "8";
        "opcache.max_accelerated_files" = "10000";
        "opcache.memory_consumption" = "128";
        "opcache.revalidate_freq" = "1";
        "opcache.fast_shutdown" = "1";
        "openssl.cafile" = "/etc/ssl/certs/ca-certificates.crt";
        catch_workers_output = "yes";
      };
      description = ''
        Options for PHP's php.ini file for nextcloud.
      '';
    };

    poolSettings = mkOption {
      type = with types; attrsOf (oneOf [ str int bool ]);
      default = {
        "pm" = "dynamic";
        "pm.max_children" = "32";
        "pm.start_servers" = "2";
        "pm.min_spare_servers" = "2";
        "pm.max_spare_servers" = "4";
        "pm.max_requests" = "500";
      };
      description = ''
        Options for nextcloud's PHP pool. See the documentation on <literal>php-fpm.conf</literal> for details on configuration directives.
      '';
    };

    poolConfig = mkOption {
      type = types.nullOr types.lines;
      default = null;
      description = ''
        Options for nextcloud's PHP pool. See the documentation on <literal>php-fpm.conf</literal> for details on configuration directives.
      '';
    };

    config = {
      dbtype = mkOption {
        type = types.enum [ "sqlite" "pgsql" "mysql" ];
        default = "sqlite";
        description = "Database type.";
      };
      dbname = mkOption {
        type = types.nullOr types.str;
        default = "nextcloud";
        description = "Database name.";
      };
      dbuser = mkOption {
        type = types.nullOr types.str;
        default = "nextcloud";
        description = "Database user.";
      };
      dbpass = mkOption {
        type = types.nullOr types.str;
        default = null;
        description = ''
          Database password.  Use <literal>dbpassFile</literal> to avoid this
          being world-readable in the <literal>/nix/store</literal>.
        '';
      };
      dbpassFile = mkOption {
        type = types.nullOr types.str;
        default = null;
        description = ''
          The full path to a file that contains the database password.
        '';
      };
      dbhost = mkOption {
        type = types.nullOr types.str;
        default = "localhost";
        description = ''
          Database host.

          Note: for using Unix authentication with PostgreSQL, this should be
          set to <literal>/run/postgresql</literal>.
        '';
      };
      dbport = mkOption {
        type = with types; nullOr (either int str);
        default = null;
        description = "Database port.";
      };
      dbtableprefix = mkOption {
        type = types.nullOr types.str;
        default = null;
        description = "Table prefix in Nextcloud database.";
      };
      adminuser = mkOption {
        type = types.str;
        default = "root";
        description = "Admin username.";
      };
      adminpass = mkOption {
        type = types.nullOr types.str;
        default = null;
        description = ''
          Admin password.  Use <literal>adminpassFile</literal> to avoid this
          being world-readable in the <literal>/nix/store</literal>.
        '';
      };
      adminpassFile = mkOption {
        type = types.nullOr types.str;
        default = null;
        description = ''
          The full path to a file that contains the admin's password.
        '';
      };

      extraTrustedDomains = mkOption {
        type = types.listOf types.str;
        default = [];
        description = ''
          Trusted domains, from which the nextcloud installation will be
          acessible.  You don't need to add
          <literal>services.nextcloud.hostname</literal> here.
        '';
      };

      trustedProxies = mkOption {
        type = types.listOf types.str;
        default = [];
        description = ''
          Trusted proxies, to provide if the nextcloud installation is being
          proxied to secure against e.g. spoofing.
        '';
      };

      overwriteProtocol = mkOption {
        type = types.nullOr (types.enum [ "http" "https" ]);
        default = null;
        example = "https";

        description = ''
          Force Nextcloud to always use HTTPS i.e. for link generation. Nextcloud
          uses the currently used protocol by default, but when behind a reverse-proxy,
          it may use <literal>http</literal> for everything although Nextcloud
          may be served via HTTPS.
        '';
      };
    };

    caching = {
      apcu = mkOption {
        type = types.bool;
        default = true;
        description = ''
          Whether to load the APCu module into PHP.
        '';
      };
      redis = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Whether to load the Redis module into PHP.
          You still need to enable Redis in your config.php.
          See https://docs.nextcloud.com/server/14/admin_manual/configuration_server/caching_configuration.html
        '';
      };
      memcached = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Whether to load the Memcached module into PHP.
          You still need to enable Memcached in your config.php.
          See https://docs.nextcloud.com/server/14/admin_manual/configuration_server/caching_configuration.html
        '';
      };
    };
    autoUpdateApps = {
      enable = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Run regular auto update of all apps installed from the nextcloud app store.
        '';
      };
      startAt = mkOption {
        type = with types; either str (listOf str);
        default = "05:00:00";
        example = "Sun 14:00:00";
        description = ''
          When to run the update. See `systemd.services.&lt;name&gt;.startAt`.
        '';
      };
    };
    occ = mkOption {
      type = types.package;
      default = occ;
      internal = true;
      description = ''
        The nextcloud-occ program preconfigured to target this Nextcloud instance.
      '';
    };
  };

  config = mkIf cfg.enable (mkMerge [
    { assertions = let acfg = cfg.config; in [
        { assertion = !(acfg.dbpass != null && acfg.dbpassFile != null);
          message = "Please specify no more than one of dbpass or dbpassFile";
        }
        { assertion = ((acfg.adminpass != null || acfg.adminpassFile != null)
            && !(acfg.adminpass != null && acfg.adminpassFile != null));
          message = "Please specify exactly one of adminpass or adminpassFile";
        }
      ];

      warnings = let
        latest = 20;
        upgradeWarning = major: nixos:
          ''
            A legacy Nextcloud install (from before NixOS ${nixos}) may be installed.

            After nextcloud${toString major} is installed successfully, you can safely upgrade
            to ${toString (major + 1)}. The latest version available is nextcloud${toString latest}.

            Please note that Nextcloud doesn't support upgrades across multiple major versions
            (i.e. an upgrade from 16 is possible to 17, but not 16 to 18).

            The package can be upgraded by explicitly declaring the service-option
            `services.nextcloud.package`.
          '';
      in (optional (cfg.poolConfig != null) ''
          Using config.services.nextcloud.poolConfig is deprecated and will become unsupported in a future release.
          Please migrate your configuration to config.services.nextcloud.poolSettings.
        '')
        ++ (optional (versionOlder cfg.package.version "18") (upgradeWarning 17 "20.03"))
        ++ (optional (versionOlder cfg.package.version "19") (upgradeWarning 18 "20.09"))
        ++ (optional (versionOlder cfg.package.version "20") (upgradeWarning 19 "21.03"));

      services.nextcloud.package = with pkgs;
        mkDefault (
          if pkgs ? nextcloud
            then throw ''
              The `pkgs.nextcloud`-attribute has been removed. If it's supposed to be the default
              nextcloud defined in an overlay, please set `services.nextcloud.package` to
              `pkgs.nextcloud`.
            ''
          else if versionOlder stateVersion "20.03" then nextcloud17
          else if versionOlder stateVersion "20.09" then nextcloud18
          else if versionOlder stateVersion "21.03" then nextcloud19
          else nextcloud20
        );
    }

    { systemd.timers.nextcloud-cron = {
        wantedBy = [ "timers.target" ];
        timerConfig.OnBootSec = "5m";
        timerConfig.OnUnitActiveSec = "15m";
        timerConfig.Unit = "nextcloud-cron.service";
      };

      systemd.services = {
        # When upgrading the Nextcloud package, Nextcloud can report errors such as
        # "The files of the app [all apps in /var/lib/nextcloud/apps] were not replaced correctly"
        # Restarting phpfpm on Nextcloud package update fixes these issues (but this is a workaround).
        phpfpm-nextcloud.restartTriggers = [ cfg.package ];

        nextcloud-setup = let
          c = cfg.config;
          writePhpArrary = a: "[${concatMapStringsSep "," (val: ''"${toString val}"'') a}]";
          overrideConfig = pkgs.writeText "nextcloud-config.php" ''
            <?php
            ${optionalString (c.dbpassFile != null) ''
              function nix_read_pwd() {
                $file = "${c.dbpassFile}";
                if (!file_exists($file)) {
                  throw new \RuntimeException(sprintf(
                    "Cannot start Nextcloud, dbpass file %s set by NixOS doesn't seem to "
                    . "exist! Please make sure that the file exists and has appropriate "
                    . "permissions for user & group 'nextcloud'!",
                    $file
                  ));
                }

                return trim(file_get_contents($file));
              }
            ''}
            $CONFIG = [
              'apps_paths' => [
                [ 'path' => '${cfg.home}/apps', 'url' => '/apps', 'writable' => false ],
                [ 'path' => '${cfg.home}/store-apps', 'url' => '/store-apps', 'writable' => true ],
              ],
              'datadirectory' => '${cfg.home}/data',
              'skeletondirectory' => '${cfg.skeletonDirectory}',
              ${optionalString cfg.caching.apcu "'memcache.local' => '\\OC\\Memcache\\APCu',"}
              'log_type' => 'syslog',
              'log_level' => '${builtins.toString cfg.logLevel}',
              ${optionalString (c.overwriteProtocol != null) "'overwriteprotocol' => '${c.overwriteProtocol}',"}
              ${optionalString (c.dbname != null) "'dbname' => '${c.dbname}',"}
              ${optionalString (c.dbhost != null) "'dbhost' => '${c.dbhost}',"}
              ${optionalString (c.dbport != null) "'dbport' => '${toString c.dbport}',"}
              ${optionalString (c.dbuser != null) "'dbuser' => '${c.dbuser}',"}
              ${optionalString (c.dbtableprefix != null) "'dbtableprefix' => '${toString c.dbtableprefix}',"}
              ${optionalString (c.dbpass != null) "'dbpassword' => '${c.dbpass}',"}
              ${optionalString (c.dbpassFile != null) "'dbpassword' => nix_read_pwd(),"}
              'dbtype' => '${c.dbtype}',
              'trusted_domains' => ${writePhpArrary ([ cfg.hostName ] ++ c.extraTrustedDomains)},
              'trusted_proxies' => ${writePhpArrary (c.trustedProxies)},
            ];
          '';
          occInstallCmd = let
            dbpass = if c.dbpassFile != null
              then ''"$(<"${toString c.dbpassFile}")"''
              else if c.dbpass != null
              then ''"${toString c.dbpass}"''
              else ''""'';
            adminpass = if c.adminpassFile != null
              then ''"$(<"${toString c.adminpassFile}")"''
              else ''"${toString c.adminpass}"'';
            installFlags = concatStringsSep " \\\n    "
              (mapAttrsToList (k: v: "${k} ${toString v}") {
              "--database" = ''"${c.dbtype}"'';
              # The following attributes are optional depending on the type of
              # database.  Those that evaluate to null on the left hand side
              # will be omitted.
              ${if c.dbname != null then "--database-name" else null} = ''"${c.dbname}"'';
              ${if c.dbhost != null then "--database-host" else null} = ''"${c.dbhost}"'';
              ${if c.dbport != null then "--database-port" else null} = ''"${toString c.dbport}"'';
              ${if c.dbuser != null then "--database-user" else null} = ''"${c.dbuser}"'';
              "--database-pass" = dbpass;
              ${if c.dbtableprefix != null
                then "--database-table-prefix" else null} = ''"${toString c.dbtableprefix}"'';
              "--admin-user" = ''"${c.adminuser}"'';
              "--admin-pass" = adminpass;
              "--data-dir" = ''"${cfg.home}/data"'';
            });
          in ''
            ${occ}/bin/nextcloud-occ maintenance:install \
                ${installFlags}
          '';
          occSetTrustedDomainsCmd = concatStringsSep "\n" (imap0
            (i: v: ''
              ${occ}/bin/nextcloud-occ config:system:set trusted_domains \
                ${toString i} --value="${toString v}"
            '') ([ cfg.hostName ] ++ cfg.config.extraTrustedDomains));

        in {
          wantedBy = [ "multi-user.target" ];
          before = [ "phpfpm-nextcloud.service" ];
          path = [ occ ];
          script = ''
            chmod og+x ${cfg.home}
            ln -sf ${cfg.package}/apps ${cfg.home}/

            # create nextcloud directories.
            # if the directories exist already with wrong permissions, we fix that
            for dir in ${cfg.home}/config ${cfg.home}/data ${cfg.home}/store-apps; do
              if [ ! -e $dir ]; then
                install -o nextcloud -g nextcloud -d $dir
              elif [ $(stat -c "%G" $dir) != "nextcloud" ]; then
                chgrp -R nextcloud $dir
              fi
            done

            ln -sf ${overrideConfig} ${cfg.home}/config/override.config.php

            # Do not install if already installed
            if [[ ! -e ${cfg.home}/config/config.php ]]; then
              ${occInstallCmd}
            fi

            ${occ}/bin/nextcloud-occ upgrade

            ${occ}/bin/nextcloud-occ config:system:delete trusted_domains
            ${occSetTrustedDomainsCmd}
          '';
          serviceConfig.Type = "oneshot";
          serviceConfig.User = "nextcloud";
        };
        nextcloud-cron = {
          environment.NEXTCLOUD_CONFIG_DIR = "${cfg.home}/config";
          serviceConfig.Type = "oneshot";
          serviceConfig.User = "nextcloud";
          serviceConfig.ExecStart = "${phpPackage}/bin/php -f ${cfg.package}/cron.php";
        };
        nextcloud-update-plugins = mkIf cfg.autoUpdateApps.enable {
          serviceConfig.Type = "oneshot";
          serviceConfig.ExecStart = "${occ}/bin/nextcloud-occ app:update --all";
          serviceConfig.User = "nextcloud";
          startAt = cfg.autoUpdateApps.startAt;
        };
      };

      services.phpfpm = {
        pools.nextcloud = {
          user = "nextcloud";
          group = "nextcloud";
          phpOptions = phpOptionsStr;
          phpPackage = phpPackage;
          phpEnv = {
            NEXTCLOUD_CONFIG_DIR = "${cfg.home}/config";
            PATH = "/run/wrappers/bin:/nix/var/nix/profiles/default/bin:/run/current-system/sw/bin:/usr/bin:/bin";
          };
          settings = mapAttrs (name: mkDefault) {
            "listen.owner" = config.services.nginx.user;
            "listen.group" = config.services.nginx.group;
          } // cfg.poolSettings;
          extraConfig = cfg.poolConfig;
        };
      };

      users.users.nextcloud = {
        home = "${cfg.home}";
        group = "nextcloud";
        createHome = true;
      };
      users.groups.nextcloud.members = [ "nextcloud" config.services.nginx.user ];

      environment.systemPackages = [ occ ];

      services.nginx.enable = mkDefault true;

      services.nginx.virtualHosts.${cfg.hostName} = let
        major = toInt (versions.major cfg.package.version);
      in {
        root = cfg.package;
        locations = {
          "= /robots.txt" = {
            priority = 100;
            extraConfig = ''
              allow all;
              log_not_found off;
              access_log off;
            '';
          };
          "/" = {
            priority = 900;
            extraConfig = "rewrite ^ /index.php;";
          };
          "~ ^/store-apps" = {
            priority = 201;
            extraConfig = "root ${cfg.home};";
          };
          "^~ /.well-known" = {
            priority = 210;
            extraConfig = ''
              location = /.well-known/carddav {
                return 301 $scheme://$host/remote.php/dav;
              }
              location = /.well-known/caldav {
                return 301 $scheme://$host/remote.php/dav;
              }
              try_files $uri $uri/ =404;
            '';
          };
          "~ ^/(?:build|tests|config|lib|3rdparty|templates|data)(?:$|/)".extraConfig = ''
            return 404;
          '';
          "~ ^/(?:\\.|autotest|occ|issue|indie|db_|console)".extraConfig = ''
            return 404;
          '';
          "~ ^\\/(?:index|remote|public|cron|core\\/ajax\\/update|status|ocs\\/v[12]|updater\\/.+|oc[ms]-provider\\/.+|.+\\/richdocumentscode\\/proxy)\\.php(?:$|\\/)" = {
            priority = 500;
            extraConfig = ''
              include ${config.services.nginx.package}/conf/fastcgi.conf;
              fastcgi_split_path_info ^(.+?\.php)(\\/.*)$;
              set $path_info $fastcgi_path_info;
              try_files $fastcgi_script_name =404;
              fastcgi_param PATH_INFO $path_info;
              fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
              fastcgi_param HTTPS ${if cfg.https then "on" else "off"};
              fastcgi_param modHeadersAvailable true;
              fastcgi_param front_controller_active true;
              fastcgi_pass unix:${fpm.socket};
              fastcgi_intercept_errors on;
              fastcgi_request_buffering off;
              fastcgi_read_timeout 120s;
            '';
          };
          "~ \\.(?:css|js|woff2?|svg|gif|map)$".extraConfig = ''
            try_files $uri /index.php$request_uri;
            expires 6M;
            access_log off;
          '';
          "~ ^\\/(?:updater|ocs-provider|ocm-provider)(?:$|\\/)".extraConfig = ''
            try_files $uri/ =404;
            index index.php;
          '';
          "~ \\.(?:png|html|ttf|ico|jpg|jpeg|bcmap|mp4|webm)$".extraConfig = ''
            try_files $uri /index.php$request_uri;
            access_log off;
          '';
        };
        extraConfig = ''
          index index.php index.html /index.php$request_uri;
          expires 1m;
          add_header X-Content-Type-Options nosniff;
          add_header X-XSS-Protection "1; mode=block";
          add_header X-Robots-Tag none;
          add_header X-Download-Options noopen;
          add_header X-Permitted-Cross-Domain-Policies none;
          add_header X-Frame-Options sameorigin;
          add_header Referrer-Policy no-referrer;
          add_header Strict-Transport-Security "max-age=15552000; includeSubDomains" always;
          client_max_body_size ${cfg.maxUploadSize};
          fastcgi_buffers 64 4K;
          fastcgi_hide_header X-Powered-By;
          gzip on;
          gzip_vary on;
          gzip_comp_level 4;
          gzip_min_length 256;
          gzip_proxied expired no-cache no-store private no_last_modified no_etag auth;
          gzip_types application/atom+xml application/javascript application/json application/ld+json application/manifest+json application/rss+xml application/vnd.geo+json application/vnd.ms-fontobject application/x-font-ttf application/x-web-app-manifest+json application/xhtml+xml application/xml font/opentype image/bmp image/svg+xml image/x-icon text/cache-manifest text/css text/plain text/vcard text/vnd.rim.location.xloc text/vtt text/x-component text/x-cross-domain-policy;

          ${optionalString cfg.webfinger ''
            rewrite ^/.well-known/host-meta /public.php?service=host-meta last;
            rewrite ^/.well-known/host-meta.json /public.php?service=host-meta-json last;
          ''}
        '';
      };
    }
  ]);

  meta.doc = ./nextcloud.xml;
}