Refactor to avoid duplicate handler parsing and improve middleware bu…

…ilders
juanjoDiaz · Mar 7, 2019 · 08fa271 · 08fa271
1 parent b220538
commit 08fa271
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Showing 4 changed files with 141 additions and 179 deletions.
diff --git a/src/index.js b/src/index.js
@@ -92,8 +92,15 @@ class Middleware {
             .concat(fn.handler)
             .concat(this.middlewareOpts.pos)
             .map((handler) => {
-              if (typeof handler === 'string') return { then: handler };
-              if (handler.then || handler.catch) return handler;
+              if (handler.then && handler.catch) {
+                return {
+                  then: parseHandler(handler.then),
+                  catch: parseHandler(handler.catch),
+                };
+              }
+              if (handler.then) return { then: parseHandler(handler.then) };
+              if (handler.catch) return { catch: parseHandler(handler.catch) };
+              if (typeof handler === 'string') return { then: parseHandler(handler) };
 
               throw new Error(`Invalid handler: ${JSON.stringify(handler)}`);
             });
@@ -135,7 +142,7 @@ class Middleware {
     const getNodeType = (handler) => {
       if (handler === undefined) return false;
 
-      const { module } = parseHandler(handler);
+      const { module } = handler;
 
       if (fs.existsSync(`${module}.js`) || fs.existsSync(`${module}.jsx`)) return 'js';
       if (fs.existsSync(`${module}.ts`) || fs.existsSync(`${module}.tsx`)) return 'ts';

diff --git a/src/javascript.js b/src/javascript.js
@@ -3,41 +3,61 @@
  *
  * @param {Array<string>} handlers - handlers to be run as middleware
  *
- * @fulfil {} — Middleware handler created
- * @reject {Error} Middleware error
- *
- * @return {Promise}
+ * @return {string} Javascript middleware handler
  * */
-function createJSMiddlewareHandler(handlers, pathToRoot = '.') {
+function createJSMiddlewareHandler(handlers, pathToRoot) {
+  const handlersInfo = handlers
+    .reduce((modules, handler) => {
+      if (handler.then && handler.catch) {
+        const { name, module } = handler.then;
+        const { name: name2, module: module2 } = handler.catch;
+        return { ...modules, [module]: name, [module2]: name2 };
+      }
+      if (handler.then) {
+        const { name, module } = handler.then;
+        return { ...modules, [module]: name };
+      }
+
+      const { name, module } = handler.catch;
+      return { ...modules, [module]: name };
+    }, {});
+
+  const imports = Object.keys(handlersInfo)
+    .map(handler => `const ${handlersInfo[handler]} = require('${pathToRoot}/${handler}');`).join('\n');
+
+  const promiseChain = handlers.map((handler) => {
+    if (handler.then && handler.catch) {
+      const { name, fn } = handler.then;
+      const { name: name2, fn: fn2 } = handler.catch;
+      return `    .then(wrappedHandler(${name}.${fn}.bind(${name})))
+    .catch(wrappedHandler(${name2}.${fn2}.bind(${name2})))`;
+    }
+
+    if (handler.then) {
+      const { name, fn } = handler.then;
+      return `    .then(wrappedHandler(${name}.${fn}.bind(${name})))`;
+    }
+
+    const { name, fn } = handler.catch;
+    return `    .catch(wrappedHandler(${name}.${fn}.bind(${name})))`;
+  }).join('\n');
+
   return `'use strict';
     
-const handlers = ${JSON.stringify(handlers)};
+${imports}
+
 module.exports.handler = async (event, context) => {
   let end = false;
   context.end = () => end = true;
 
   const wrappedHandler = handler => prev => {
     if (end) return prev;
     context.prev = prev;
-    const [module, fn] = handler.split(/\\.(?=[^\\.]+$)/);
-    return require(\`${pathToRoot}/\${module}\`)[fn](event, context);
+    return handler(event, context);
   };
 
-  return handlers
-    .reduce((promise, handler) => {
-      if (typeof handler === 'object') {
-        if (handler.then && handler.catch) {
-          return promise
-            .then(wrappedHandler(handler.then))
-            .catch(wrappedHandler(handler.catch));
-        }
-        if (handler.then) return promise.then(wrappedHandler(handler.then));
-        if (handler.catch) return promise.catch(wrappedHandler(handler.catch));
-        throw new Error(\`Unkownw handler: \${JSON.stringify(handler)}\`);
-      }
-
-      return promise.then(wrappedHandler(handler));
-    }, Promise.resolve());
+  return Promise.resolve()
+${promiseChain};
 };`;
 }
 

diff --git a/src/typescript.js b/src/typescript.js
@@ -1,52 +1,45 @@
-const { parseHandler } = require('./utils');
-
 /**
  * @description Create TypeScript middleware handler
  *
  * @param {Array<string>} handlers - handlers to be run as middleware
- *
- * @fulfil {} — Middleware handler created
- * @reject {Error} Middleware error
- *
- * @return {Promise}
+ *np
+ * @return {string} TypeScript Middleware handler
  * */
-function createTSMiddlewareHandler(handlers, pathToRoot = '.') {
+function createTSMiddlewareHandler(handlers, pathToRoot) {
   const handlersInfo = handlers
     .reduce((modules, handler) => {
       if (handler.then && handler.catch) {
-        const { name, module } = parseHandler(handler.then);
-        const { name: name2, module: module2 } = parseHandler(handler.catch);
+        const { name, module } = handler.then;
+        const { name: name2, module: module2 } = handler.catch;
         return { ...modules, [module]: name, [module2]: name2 };
       }
       if (handler.then) {
-        const { name, module } = parseHandler(handler.then);
+        const { name, module } = handler.then;
         return { ...modules, [module]: name };
       }
 
-      const { name, module } = parseHandler(handler.catch);
+      const { name, module } = handler.catch;
       return { ...modules, [module]: name };
     }, {});
 
   const imports = Object.keys(handlersInfo)
-    .map(handler => `import * as ${handlersInfo[handler]} from '${pathToRoot}/${handler}'`).join('\n');
-
-  const wrapHandler = (handler) => {
-    const { name, fn } = parseHandler(handler);
-    return `prev => {
-    if (end) return prev;
-    context.prev = prev;
-    return ${name}.${fn}(event, context, () => { throw new Error('Callback can\\'t be used in middlewares.'); });
-  }`;
-  };
+    .map(handler => `import * as ${handlersInfo[handler]} from '${pathToRoot}/${handler}';`).join('\n');
 
   const promiseChain = handlers.map((handler) => {
     if (handler.then && handler.catch) {
-      return `    .then(${wrapHandler(handler.then)})\n    .catch(${wrapHandler(handler.catch)})`;
+      const { name, fn } = handler.then;
+      const { name: name2, fn: fn2 } = handler.catch;
+      return `    .then(wrappedHandler(${name}.${fn}.bind(${name})))
+    .catch(wrappedHandler(${name2}.${fn2}.bind(${name2})))`;
     }
 
-    if (handler.then) return `    .then(${wrapHandler(handler.then)})`;
+    if (handler.then) {
+      const { name, fn } = handler.then;
+      return `    .then(wrappedHandler(${name}.${fn}.bind(${name})))`;
+    }
 
-    return `    .catch(${wrapHandler(handler.catch)})`;
+    const { name, fn } = handler.catch;
+    return `    .catch(wrappedHandler(${name}.${fn}.bind(${name})))`;
   }).join('\n');
 
   return `'use strict';
@@ -57,6 +50,12 @@ export async function handler(event, context) {
   let end = false;
   context.end = () => end = true;
 
+  const wrappedHandler = handler => prev => {
+    if (end) return prev;
+    context.prev = prev;
+    return handler(event, context);
+  };
+
   return Promise.resolve()
 ${promiseChain};
 };`;