Support restoring preferences via new prefs param

Fixes #1352
Fixes #553
Fixes #249

src/routes/router_utils.nim

@@ -1,15 +1,15 @@
 # SPDX-License-Identifier: AGPL-3.0-only
-import strutils, sequtils, uri, tables, json
+import strutils, sequtils, uri, tables, json, base64
 from jester import Request, cookies
 
 import ../views/general
 import ".."/[utils, prefs, types]
-export utils, prefs, types, uri
+export utils, prefs, types, uri, base64
 
 template savePref*(pref, value: string; req: Request; expire=false) =
   if not expire or pref in cookies(req):
     setCookie(pref, value, daysForward(when expire: -10 else: 360),
-              httpOnly=true, secure=cfg.useHttps, sameSite=None)
+              httpOnly=true, secure=cfg.useHttps, sameSite=None, path="/")
 
 template cookiePrefs*(): untyped {.dirty.} =
   getPrefs(cookies(request))
@@ -38,5 +38,31 @@ template getCursor*(req: Request): string =
 proc getNames*(name: string): seq[string] =
   name.strip(chars={'/'}).split(",").filterIt(it.len > 0)
 
+template applyUrlPrefs*() {.dirty.} =
+  if @"prefs".len > 0:
+    try:
+      let decoded = decode(@"prefs")
+      var params = initTable[string, string]()
+      for pair in decoded.split('&'):
+        let kv = pair.split('=', maxsplit=1)
+        if kv.len == 2:
+          params[kv[0]] = kv[1]
+        elif kv.len == 1 and kv[0].len > 0:
+          params[kv[0]] = ""
+      genApplyPrefs(params, request)
+    except: discard
+
+    # Rebuild URL without prefs param
+    var params: seq[(string, string)]
+    for k, v in request.params:
+      if k != "prefs":
+        params.add (k, v)
+
+    if params.len > 0:
+      let cleanUrl = request.getNativeReq.url ? params
+      redirect($cleanUrl)
+    else:
+      redirect(request.path)
+
 template respJson*(node: JsonNode) =
   resp $node, "application/json"