From 6b5269e64e0f037f2c534e2aea4bf4a041025b43 Mon Sep 17 00:00:00 2001
From: Dilip Kola <kdilipkola@gmail.com>
Date: Sat, 1 Jun 2024 17:54:12 +0530
Subject: [PATCH] refactor: add error handling in flat mapping convertor

---
 src/engine.ts                                 |  5 +++--
 src/reverse_translator.ts                     |  4 ++--
 src/types.ts                                  |  6 +++---
 src/utils/converter.ts                        | 11 +++++++----
 test/scenarios/mappings/data.ts               |  9 ++++++++-
 test/scenarios/mappings/invalid_mappings.json | 10 ++++++++++
 6 files changed, 33 insertions(+), 12 deletions(-)
 create mode 100644 test/scenarios/mappings/invalid_mappings.json

diff --git a/src/engine.ts b/src/engine.ts
index 2036c5f..2a6fe9c 100644
--- a/src/engine.ts
+++ b/src/engine.ts
@@ -42,8 +42,9 @@ export class JsonTemplateEngine {
     options?: EngineOptions,
   ): Expression {
     const flatMappingAST = mappings.map((mapping) => ({
-      input: JsonTemplateEngine.parse(mapping.input, options).statements[0],
-      output: JsonTemplateEngine.parse(mapping.output, options).statements[0],
+      ...mapping,
+      inputExpr: JsonTemplateEngine.parse(mapping.input, options).statements[0],
+      outputExpr: JsonTemplateEngine.parse(mapping.output, options).statements[0],
     }));
     return convertToObjectMapping(flatMappingAST);
   }
diff --git a/src/reverse_translator.ts b/src/reverse_translator.ts
index 97a8e6a..f53d7d2 100644
--- a/src/reverse_translator.ts
+++ b/src/reverse_translator.ts
@@ -429,8 +429,8 @@ export class JsonTemplateReverseTranslator {
 
   translateObjectExpression(expr: ObjectExpression): string {
     const code: string[] = [];
-    code.push('{\n');
-    code.push(this.translateExpressions(expr.props, ',\n'));
+    code.push('{\n\t');
+    code.push(this.translateExpressions(expr.props, ',\n\t'));
     code.push('\n}');
     return code.join('');
   }
diff --git a/src/types.ts b/src/types.ts
index e76f38a..53c283f 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -279,7 +279,7 @@ export type FlatMappingPaths = {
   output: string;
 };
 
-export type FlatMappingAST = {
-  input: PathExpression;
-  output: PathExpression;
+export type FlatMappingAST = FlatMappingPaths & {
+  inputExpr: PathExpression;
+  outputExpr: PathExpression;
 };
diff --git a/src/utils/converter.ts b/src/utils/converter.ts
index 65a9874..bb14974 100644
--- a/src/utils/converter.ts
+++ b/src/utils/converter.ts
@@ -85,11 +85,14 @@ function processAllFilter(
 
 function processFlatMapping(flatMapping: FlatMappingAST, outputAST: ObjectExpression) {
   let currentOutputPropsAST = outputAST.props;
-  const currentInputAST = flatMapping.input;
+  const currentInputAST = flatMapping.inputExpr;
 
-  const numOutputParts = flatMapping.output.parts.length;
+  const numOutputParts = flatMapping.outputExpr.parts.length;
   for (let i = 0; i < numOutputParts; i++) {
-    const outputPart = flatMapping.output.parts[i];
+    if (!currentOutputPropsAST) {
+      throw new Error(`Failed to process output mapping: ${flatMapping.output}`);
+    }
+    const outputPart = flatMapping.outputExpr.parts[i];
 
     if (outputPart.type === SyntaxType.SELECTOR && outputPart.prop?.value) {
       const key = outputPart.prop.value;
@@ -105,7 +108,7 @@ function processFlatMapping(flatMapping: FlatMappingAST, outputAST: ObjectExpres
 
       const currentOutputPropAST = findOrCreateObjectPropExpression(currentOutputPropsAST, key);
       let objectExpr: ObjectExpression = currentOutputPropAST.value as ObjectExpression;
-      const nextOutputPart = flatMapping.output.parts[i + 1] as ArrayFilterExpression;
+      const nextOutputPart = flatMapping.outputExpr.parts[i + 1] as ArrayFilterExpression;
       if (nextOutputPart.filter?.type === SyntaxType.ALL_FILTER_EXPR) {
         objectExpr = processAllFilter(currentInputAST, currentOutputPropAST);
       } else if (nextOutputPart.filter?.type === SyntaxType.ARRAY_INDEX_FILTER_EXPR) {
diff --git a/test/scenarios/mappings/data.ts b/test/scenarios/mappings/data.ts
index d125031..a2f27e1 100644
--- a/test/scenarios/mappings/data.ts
+++ b/test/scenarios/mappings/data.ts
@@ -143,7 +143,14 @@ export const data: Scenario[] = [
       ],
     },
   },
-
+  {
+    containsMappings: true,
+    templatePath: 'invalid_mappings.json',
+    options: {
+      defaultPathType: PathType.JSON,
+    },
+    error: 'Failed to process output mapping',
+  },
   {
     containsMappings: true,
     templatePath: 'mappings_with_root_fields.json',
diff --git a/test/scenarios/mappings/invalid_mappings.json b/test/scenarios/mappings/invalid_mappings.json
new file mode 100644
index 0000000..266a1ec
--- /dev/null
+++ b/test/scenarios/mappings/invalid_mappings.json
@@ -0,0 +1,10 @@
+[
+  {
+    "input": "$.events[0]",
+    "output": "$.events[0].name"
+  },
+  {
+    "input": "$.discount",
+    "output": "$.events[0].name[*].discount"
+  }
+]