syncthing: Declarative

I could split this commit in more but I won't.
The first commit in this repository said it would be the last legible
one, and I haven't followed that, so YOLO.

options.nix

@@ -1,6 +1,17 @@
-{ lib, config, ... }:
+{ pkgs, lib, config, ... }:
+let
+  capitalizeFirstLetter = str: (lib.strings.toUpper (builtins.substring 0 1 str)) + (builtins.substring 1 (builtins.stringLength str) str);
+in
 {
   options.frogeye = {
+    name = lib.mkOption {
+      description = "Name of the system";
+      type = lib.types.str;
+    };
+    toplevel = lib.mkOption {
+      description = "top-level flake";
+      type = lib.types.attrs;
+    };
     extra = lib.mkEnableOption "Big software";
     gaming = lib.mkEnableOption "Games";
     polarity = lib.mkOption {
@@ -40,11 +51,98 @@
       prose = lib.mkEnableOption "Writing stuff";
       python = lib.mkEnableOption "Python dev stuff";
     };
+    storageSize = lib.mkOption {
+      default = "small";
+      type = lib.types.enum [ "small" "big" "phone" ];
+      description = "Type of storage for the device. Used to determine which folder to include.";
+    };
+    folders = lib.mkOption {
+      default = { };
+      description = "Folders used by users";
+      # Top-level so Syncthing can work for all users. Also there's no real home-manager syncthing module.
+      type = lib.types.attrsOf (lib.types.submodule ({ config, name, ... }: {
+        options = {
+          name = lib.mkOption {
+            type = lib.types.str;
+            default = name;
+            readOnly = true;
+            internal = true;
+            description = "Name accessing this entry";
+          };
+          enable = lib.mkOption {
+            type = lib.types.bool;
+            default = true;
+            description = "Whether to use this folder.";
+          };
+          path = lib.mkOption {
+            type = lib.types.str;
+            description = "Path relative to HOME. Prefer French names which has more varied initials, easing navigation.";
+          };
+          label = lib.mkOption {
+            type = lib.types.str;
+            description = "Friendly name";
+            default = capitalizeFirstLetter config.path;
+          };
+          user = lib.mkOption {
+            type = lib.types.str;
+            default = "geoffrey";
+            description = "User using this directory.";
+          };
+          fullPath = lib.mkOption {
+            type = lib.types.str;
+            default = "/home/${config.user}/${config.path}";
+            # Hardcoded due to outside of any user context
+            description = "Absolute path.";
+          };
+          xdgUserDirVariable = lib.mkOption {
+            type = lib.types.nullOr lib.types.str;
+            default = "XDG_${lib.strings.toUpper name}_DIR";
+            description = "Name for the XDG user dir variable. If set, will automatically create the directory.";
+          };
+          syncthing = lib.mkOption {
+            default = { };
+            description = "Syncthing configuration for the folder";
+            type = lib.types.submodule ({ ... }: {
+              freeformType = (pkgs.formats.json { }).type;
+              options = {
+                enable = lib.mkOption {
+                  type = lib.types.bool;
+                  default = config.enable && config.syncthing.id != null;
+                  description = "Whether to sync.";
+                };
+                id = lib.mkOption {
+                  type = lib.types.nullOr lib.types.str;
+                  default = null;
+                  description = "Syncthing folder id";
+                };
+              };
+            });
+          };
+          versionsMaxDays = lib.mkOption {
+            type = lib.types.nullOr lib.types.int;
+            default = 365;
+            description = "For big systems, how many days of staggered versions should be kept";
+          };
+        };
+      }));
+    };
     hooks.lock = lib.mkOption {
       type = lib.types.lines;
       default = "";
       description = "Bash commands to execute on locking the session.";
     };
+    syncthing = {
+      id = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        description = "Full syncthing id";
+      };
+      name = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = "Geoffrey ${capitalizeFirstLetter config.frogeye.name}";
+        description = "Syncthing name";
+      };
+    };
   };
 
   config = {
@@ -53,6 +151,7 @@
         prose = lib.mkDefault true;
         python = lib.mkDefault true;
       };
+      folders.download.path = "Téléchargements";
     };
   };
 }