Adds 'constructForm' javascript function

- Skeleton only (for now!)

InvenTree/templates/js/forms.js

@@ -16,15 +16,70 @@
  * - min_value / max_value 
  */
 
+/*
+ * Return true if the OPTIONS specify that the user
+ * can perform a GET method at the endpoint.
+ */
+function canView(OPTIONS) {
+    
+    if ('actions' in OPTIONS) {
+        return ('GET' in OPTIONS.actions);
+    } else {
+        return false;
+    }
+}
+
+
+/*
+ * Return true if the OPTIONS specify that the user
+ * can perform a POST method at the endpoint
+ */
+function canCreate(OPTIONS) {
+
+    if ('actions' in OPTIONS) {
+        return ('POST' in OPTIONS.actions);
+    } else {
+        return false;
+    }
+}
+
+
+/*
+ * Return true if the OPTIONS specify that the user
+ * can perform a PUT or PATCH method at the endpoint
+ */
+function canChange(OPTIONS) {
+    
+    if ('actions' in OPTIONS) {
+        return ('PUT' in OPTIONS.actions || 'PATCH' in OPTIONS.actions);
+    } else {
+        return false;
+    }
+}
+
+
+/*
+ * Return true if the OPTIONS specify that the user
+ * can perform a DELETE method at the endpoint
+ */
+function canDelete(OPTIONS) {
+
+    if ('actions' in OPTIONS) {
+        return ('DELETE' in OPTIONS.actions);
+    } else {
+        return false;
+    }
+}
+
 
 /*
  * Get the API endpoint options at the provided URL,
  * using a HTTP options request.
  */
-function getApiEndpointOptions(url, options={}) {
+function getApiEndpointOptions(url, callback, options={}) {
 
     // Return the ajax request object
-    return $.ajax({
+    $.ajax({
         url: url,
         type: 'OPTIONS',
         contentType: 'application/json',
@@ -32,7 +87,76 @@ function getApiEndpointOptions(url, options={}) {
         accepts: {
             json: 'application/json',
         },
+        success: callback,
     });
 }
 
 
+/*
+ * Request API OPTIONS data from the server,
+ * and construct a modal form based on the response.
+ * 
+ * arguments:
+ * - method: The HTTP method e.g. 'PUT', 'POST', 'DELETE',
+ * 
+ * options:
+ * - method:
+ */
+function constructForm(url, method, options={}) {
+
+    method = method.toUpperCase();
+
+    // Request OPTIONS endpoint from the API
+    getApiEndpointOptions(url, function(OPTIONS) {
+
+        /*
+         * Determine what "type" of form we want to construct,
+         * based on the requested action.
+         * 
+         * First we must determine if the user has the correct permissions!
+         */
+
+        switch (method) {
+            case 'POST':
+                if (canCreate(OPTIONS)) {
+                    console.log('create');
+                } else {
+                    // User does not have permission to POST to the endpoint
+                    console.log('cannot POST');
+                    // TODO
+                }
+                break;
+            case 'PUT':
+            case 'PATCH':
+                if (canChange(OPTIONS)) {
+                    console.log("change");
+                } else {
+                    // User does not have permission to PUT/PATCH to the endpoint
+                    // TODO
+                    console.log('cannot edit');
+                }
+                break;
+            case 'DELETE':
+                if (canDelete(OPTIONS)) {
+                    console.log('delete');
+                } else {
+                    // User does not have permission to DELETE to the endpoint
+                    // TODO
+                    console.log('cannot delete');
+                }
+                break;
+            case 'GET':
+                if (canView(OPTIONS)) {
+                    console.log('view');
+                } else {
+                    // User does not have permission to GET to the endpoint
+                    // TODO
+                    console.log('cannot view');
+                }
+                break;
+            default:
+                console.log(`constructForm() called with invalid method '${method}'`);
+                break;
+        }
+    });
+}