webdav: interpret 'dcache-view.endpoints.webdav' as an override

Motivation:

The admin may configure a specific WebDAV endpoint that should be used
for all data transfers, and for the URL returned to the user (via a
context menu).  This is done with the `dcache-view.endpoints.webdav` (in
configuration, which is exposed in dCache as the
`frontend.static!dcache-view.endpoints.webdav` configuration property.

Currently, 'dcache-view.endpoints.webdav' only takes effect if there are
no auto-discovered doors; i.e., it is a fall-back.

This isn't terribly useful -- a more useful behaviour would be as an
override.  Like this the value is used, if supplied by the admin,
otherwise dCacheView will use a WebDAV door that it has discovered.

Modification:

Change the order of precedence: `dcache-view.endpoints.webdav` now has
the highest precedence.  If the admin specifies this, then it overrides
the auto-discovered value.

Result:

The admin has more control over which WebDAV door dCacheView uses.

Target: master
Request: 1.6
Request: 1.5
Closes: #252
Patch: https://rb.dcache.org/r/12976/
Acked-by: Tigran Mkrtchyan

Author: paulmillar

src/elements/dv-elements/utils/mixins/commons.html

@@ -177,10 +177,11 @@
                 } else {
                     throw new TypeError("Invalid path: only absolute path is accepted.");
                 }
-                const arr = window.CONFIG["webdav"][operationType].length > 0 ?
-                    window.CONFIG["webdav"][operationType] : window.CONFIG["dcache-view.endpoints.webdav"] !== "" ?
-                        [window.CONFIG["dcache-view.endpoints.webdav"]] :
-                        [`${window.location.protocol}//${window.location.hostname}:2880`];
+                const arr = window.CONFIG["dcache-view.endpoints.webdav"] !== ""
+                            ? [window.CONFIG["dcache-view.endpoints.webdav"]]
+                            : window.CONFIG["webdav"][operationType].length > 0
+                                    ? window.CONFIG["webdav"][operationType]
+                                    : [`${window.location.protocol}//${window.location.hostname}:2880`];
                 const len = arr.length;
                 const url = [];
                 for (let i=0; i<len; i++) {
@@ -204,4 +205,4 @@
             }
         }
     })
-</script>
+</script>

src/scripts/dv.js

@@ -478,10 +478,11 @@
         } else {
             throw new TypeError("Invalid path: only absolute path is accepted.");
         }
-        const arr = window.CONFIG["webdav"][operationType].length > 0 ?
-            window.CONFIG["webdav"][operationType] : window.CONFIG["dcache-view.endpoints.webdav"] !== "" ?
-                [window.CONFIG["dcache-view.endpoints.webdav"]] :
-                [`${window.location.protocol}//${window.location.hostname}:2880`];
+        const arr = window.CONFIG["dcache-view.endpoints.webdav"] !== ""
+                ? [window.CONFIG["dcache-view.endpoints.webdav"]]
+                : window.CONFIG["webdav"][operationType].length > 0
+                        ? window.CONFIG["webdav"][operationType]
+                        : [`${window.location.protocol}//${window.location.hostname}:2880`];
         const len = arr.length;
         const url = [];
         for (let i=0; i<len; i++) {