feat: compute step parameters with prior steps

packages/backend/src/services/processor.ts

@@ -1,13 +1,19 @@
+import get from 'lodash.get';
 import App from '../models/app';
 import Flow from '../models/flow';
 import Step from '../models/step';
 import Execution from '../models/execution';
 import ExecutionStep from '../models/execution-step';
+import { StepType } from '../types/step';
+
+type ExecutionSteps = Record<string, ExecutionStep>;
 
 class Processor {
   flow: Flow;
   untilStep: Step;
 
+  static variableRegExp = /({{step\.\d*\..+?}})/g;
+
   constructor(flow: Flow, untilStep: Step) {
     this.flow = flow;
     this.untilStep = untilStep;
@@ -26,48 +32,71 @@ class Processor {
 
     let previousExecutionStep: ExecutionStep;
     let fetchedData;
+    const priorExecutionSteps: ExecutionSteps = {};
 
     for await (const step of steps) {
       const appData = App.findOneByKey(step.appKey);
+      const {
+        appKey,
+        connection,
+        key,
+        type,
+        parameters: rawParameters = {},
+        id
+      } = step;
+      const isTrigger = type === StepType.Trigger;
+      const AppClass = (await import(`../apps/${appKey}`)).default;
+      const computedParameters = Processor.computeParameters(rawParameters, priorExecutionSteps);
+      const appInstance = new AppClass(appData, connection.data, computedParameters);
+      const commands = isTrigger ? appInstance.triggers : appInstance.actions;
+      const command = commands[key];
+      fetchedData = await command.run();
 
-      if (step.type.toString() === 'trigger') {
-        const appClass = (await import(`../apps/${step.appKey}`)).default;
-        const appInstance = new appClass(appData, step.connection.data);
-        fetchedData = await appInstance.triggers[step.key].run();
+      previousExecutionStep = await execution
+        .$relatedQuery('executionSteps')
+        .insertAndFetch({
+          stepId: id,
+          status: 'success',
+          dataIn: previousExecutionStep?.dataOut,
+          dataOut: fetchedData,
+        });
 
-        previousExecutionStep = await execution
-          .$relatedQuery('executionSteps')
-          .insertAndFetch({
-            stepId: step.id,
-            status: 'success',
-            dataOut: fetchedData,
-          });
-      } else {
-        const appClass = (await import(`../apps/${step.appKey}`)).default;
-        const appInstance = new appClass(
-          appData,
-          step.connection.data,
-          step.parameters
-        );
-        fetchedData = await appInstance.actions[step.key].run();
+      priorExecutionSteps[id] = previousExecutionStep;
 
-        previousExecutionStep = await execution
-          .$relatedQuery('executionSteps')
-          .insertAndFetch({
-            stepId: step.id,
-            status: 'success',
-            dataIn: previousExecutionStep.dataOut,
-            dataOut: fetchedData,
-          });
-      }
-
-      if (step.id === this.untilStep.id) {
+      if (id === this.untilStep.id) {
         return fetchedData;
       }
     }
 
     return fetchedData;
   }
+
+  static computeParameters(parameters: Step["parameters"], executionSteps: ExecutionSteps): Step["parameters"] {
+    const entries = Object.entries(parameters);
+    return entries.reduce((result, [key, value]: [string, string]) => {
+      const parts = value.split(Processor.variableRegExp);
+
+      const computedValue = parts.map((part: string) => {
+        const isVariable = part.match(Processor.variableRegExp);
+        if (isVariable) {
+          const stepIdAndKeyPath = part.replace(/{{step.|}}/g, '') as string;
+          const [stepId, ...keyPaths] = stepIdAndKeyPath.split('.');
+          const keyPath = keyPaths.join('.');
+          const executionStep = executionSteps[stepId.toString() as string];
+          const data = executionStep?.dataOut;
+          const dataValue = get(data, keyPath);
+          return dataValue;
+        }
+
+        return part;
+      }).join('');
+
+      return {
+        ...result,
+        [key]: computedValue,
+      }
+    }, {});
+  }
 }
 
 export default Processor;