Implement drop-down menus for extension blocks

Also, add `ANGLE` argument type (like `NUMBER` but adds an angle picker)

src/engine/runtime.js

@@ -33,6 +33,10 @@ const defaultBlockPackages = {
  */
 const ArgumentTypeMap = (() => {
     const map = {};
+    map[ArgumentType.ANGLE] = {
+        shadowType: 'math_angle',
+        fieldType: 'NUM'
+    };
     map[ArgumentType.COLOR] = {
         shadowType: 'colour_picker'
     };
@@ -388,6 +392,18 @@ class Runtime extends EventEmitter {
         }
     }
 
+    /**
+     * Generate an extension-specific menu ID.
+     * @param {string} menuName - the name of the menu.
+     * @param {string} extensionId - the ID of the extension hosting the menu.
+     * @returns {string} - the constructed ID.
+     * @private
+     */
+    _makeExtensionMenuId (menuName, extensionId) {
+        /** @TODO: protect against XML characters in menu name */
+        return `${extensionId}.menu.${menuName}`;
+    }
+
     /**
      * Register the primitives provided by an extension.
      * @param {ExtensionInfo} extensionInfo - information about the extension (id, blocks, etc.)
@@ -400,11 +416,19 @@ class Runtime extends EventEmitter {
             color1: '#FF6680',
             color2: '#FF4D6A',
             color3: '#FF3355',
-            blocks: []
+            blocks: [],
+            menus: []
         };
 
         this._blockInfo.push(categoryInfo);
 
+        for (const menuName in extensionInfo.menus) {
+            if (extensionInfo.menus.hasOwnProperty(menuName)) {
+                const menuItems = extensionInfo.menus[menuName];
+                const convertedMenu = this._buildMenuForScratchBlocks(menuName, menuItems, extensionInfo);
+                categoryInfo.menus.push(convertedMenu);
+            }
+        }
         for (const blockInfo of extensionInfo.blocks) {
             const convertedBlock = this._convertForScratchBlocks(blockInfo, categoryInfo);
             const opcode = convertedBlock.json.type;
@@ -412,7 +436,51 @@ class Runtime extends EventEmitter {
             this._primitives[opcode] = convertedBlock.info.func;
         }
 
-        this.emit(Runtime.EXTENSION_ADDED, categoryInfo.blocks);
+        this.emit(Runtime.EXTENSION_ADDED, categoryInfo.blocks.concat(categoryInfo.menus));
+    }
+
+    /**
+     * Build the scratch-blocks JSON for a menu. Note that scratch-blocks treats menus as a special kind of block.
+     * @param {string} menuName - the name of the menu
+     * @param {array|string} menuItems - the list of menu items, or the name of an extension method to collect them.
+     * @param {CategoryInfo} categoryInfo - the category for this block
+     * @returns {object} - a JSON-esque object ready for scratch-blocks' consumption
+     * @private
+     */
+    _buildMenuForScratchBlocks (menuName, menuItems, categoryInfo) {
+        const menuId = this._makeExtensionMenuId(menuName, categoryInfo.id);
+
+        /** @TODO: support dynamic menus when 'menuItems' is a method name string (see extension spec) */
+        const options = menuItems.map(item => {
+            switch (typeof item) {
+            case 'string':
+                return [item, item];
+            case 'object':
+                return [item.text, item.value];
+            default:
+                throw new Error(`Can't interpret menu item: ${item}`);
+            }
+        });
+
+        return {
+            json: {
+                message0: '%1',
+                type: menuId,
+                inputsInline: true,
+                output: 'String',
+                colour: categoryInfo.color1,
+                colourSecondary: categoryInfo.color2,
+                colourTertiary: categoryInfo.color3,
+                outputShape: ScratchBlocksConstants.OUTPUT_SHAPE_ROUND,
+                args0: [
+                    {
+                        type: 'field_dropdown',
+                        name: menuName,
+                        options: options
+                    }
+                ]
+            }
+        };
     }
 
     /**
@@ -460,14 +528,19 @@ class Runtime extends EventEmitter {
             const argTypeInfo = ArgumentTypeMap[argInfo.type] || {};
             const defaultValue = (typeof argInfo.defaultValue === 'undefined' ? '' : argInfo.defaultValue.toString());
 
+            const shadowType = (argInfo.menu ?
+                this._makeExtensionMenuId(argInfo.menu, categoryInfo.id) :
+                argTypeInfo.shadowType);
+            const fieldType = argInfo.menu || argTypeInfo.fieldType;
+
             // <value> is the ScratchBlocks name for a block input.
             // The <shadow> is a placeholder for a reporter and is visible when there's no reporter in this input.
-            inputList.push(`<value name="${placeholder}"><shadow type="${argTypeInfo.shadowType}">`);
+            inputList.push(`<value name="${placeholder}"><shadow type="${shadowType}">`);
 
             // <field> is a text field that the user can type into. Some shadows, like the color picker, don't allow
             // text input and therefore don't need a field element.
-            if (argTypeInfo.fieldType) {
-                inputList.push(`<field name="${argTypeInfo.fieldType}">${defaultValue}</field>`);
+            if (fieldType) {
+                inputList.push(`<field name="${fieldType}">${defaultValue}</field>`);
             }
 
             inputList.push('</shadow></value>');

src/extension-support/argument-type.js

@@ -1,4 +1,5 @@
 const ArgumentType = {
+    ANGLE: 'angle',
     BOOLEAN: 'Boolean',
     COLOR: 'color',
     NUMBER: 'number',

src/extension-support/extension-manager.js

@@ -151,7 +151,7 @@ class ExtensionManager {
                 result.push(this._prepareBlockInfo(serviceName, blockInfo));
             } catch (e) {
                 // TODO: more meaningful error reporting
-                log.error(`Skipping malformed block: ${JSON.stringify(e)}`);
+                log.error(`Error processing block: ${e.message}, Block:\n${JSON.stringify(blockInfo)}`);
             }
             return result;
         }, []);