Revert "Revert "Revert "Revert "Revert "Revert "temp. This is probabl…

…y the wrong approach so far, but save it just in case this other idea doesn't work""""""

This reverts commit aa3e4c7.

packages/@aws-cdk/cloudformation-diff/lib/format.ts

@@ -81,6 +81,7 @@ const UPDATE = chalk.yellow('[~]');
 const REMOVAL = chalk.red('[-]');
 
 class Formatter {
+  private nestedDiffIndent: string = '    ';
   constructor(
     private readonly stream: FormatStream,
     private readonly logicalToPathMap: { [logicalId: string]: string },
@@ -96,6 +97,10 @@ class Formatter {
     this.stream.write(chalk.white(format(fmt, ...args)) + '\n');
   }
 
+  public write(fmt: string, ...args: any[]) {
+    this.stream.write(chalk.white(format(fmt, ...args)));
+  }
+
   public warning(fmt: string, ...args: any[]) {
     this.stream.write(chalk.yellow(format(fmt, ...args)) + '\n');
   }
@@ -104,17 +109,29 @@ class Formatter {
     title: string,
     entryType: string,
     collection: DifferenceCollection<V, T>,
-    formatter: (type: string, id: string, diff: T) => void = this.formatDifference.bind(this)) {
+    formatter: (type: string, id: string, diff: T, nestedIndent: boolean) => void = this.formatDifference.bind(this)) {
 
     if (collection.differenceCount === 0) {
       return;
     }
 
     this.printSectionHeader(title);
-    collection.forEachDifference((id, diff) => formatter(entryType, id, diff));
+    collection.forEachDifference((id, diff) => formatter(entryType, id, diff, false));
     this.printSectionFooter();
   }
 
+  public formatNestedSection<V, T extends Difference<V>>(
+    entryType: string,
+    collection: DifferenceCollection<V, T>,
+    formatter: (type: string, id: string, diff: T, nestedIndent: boolean) => void = this.formatDifference.bind(this)) {
+
+    if (collection.differenceCount === 0) {
+      return;
+    }
+
+    collection.forEachDifference((id, diff) => formatter(entryType, id, diff, true));
+  }
+
   public printSectionHeader(title: string) {
     this.print(chalk.underline(chalk.bold(title)));
   }
@@ -153,15 +170,14 @@ class Formatter {
    * @param logicalId the logical ID of the resource that changed.
    * @param diff      the change to be rendered.
    */
-  public formatResourceDifference(_type: string, logicalId: string, diff: ResourceDifference) {
+  public formatResourceDifference(_type: string, logicalId: string, diff: ResourceDifference, useNestedIndent: boolean) {
     if (!diff.isDifferent) { return; }
 
     const resourceType = diff.isRemoval ? diff.oldResourceType : diff.newResourceType;
 
-    if (Object.keys(diff.nestedChanges).length > 0) {
-      formatDifferences(this.stream, diff.nestedChanges as TemplateDiff, this.logicalToPathMap, this.context);
+    if (useNestedIndent) {
+      this.write(this.nestedDiffIndent);
     }
-
     // eslint-disable-next-line max-len
     this.print(`${this.formatPrefix(diff)} ${this.formatValue(resourceType, chalk.cyan)} ${this.formatLogicalId(logicalId)} ${this.formatImpact(diff.changeImpact)}`);
 
@@ -170,8 +186,11 @@ class Formatter {
       let processedCount = 0;
       diff.forEachDifference((_, name, values) => {
         processedCount += 1;
-        this.formatTreeDiff(name, values, processedCount === differenceCount);
+        this.formatTreeDiff(name, values, processedCount === differenceCount, useNestedIndent);
       });
+      if (Object.keys(diff.nestedChanges).length > 0) {
+        this.formatNestedDifferences(diff.nestedChanges as TemplateDiff, this.formatPrefix(diff));
+      }
     }
   }
 
@@ -221,7 +240,7 @@ class Formatter {
    * @param diff    the difference on the tree.
    * @param last    whether this is the last node of a parent tree.
    */
-  public formatTreeDiff(name: string, diff: Difference<any>, last: boolean) {
+  public formatTreeDiff(name: string, diff: Difference<any>, last: boolean, useNestedIndent: boolean) {
     let additionalInfo = '';
     if (isPropertyDifference(diff)) {
       if (diff.changeImpact === ResourceImpact.MAY_REPLACE) {
@@ -230,6 +249,9 @@ class Formatter {
         additionalInfo = ' (requires replacement)';
       }
     }
+    if (useNestedIndent) {
+      this.write(this.nestedDiffIndent);
+    }
     this.print(' %s─ %s %s%s', last ? '└' : '├', this.changeTag(diff.oldValue, diff.newValue), name, additionalInfo);
     return this.formatObjectDiff(diff.oldValue, diff.newValue, ` ${last ? ' ' : '│'}`);
   }
@@ -398,6 +420,28 @@ class Formatter {
       return '${' + (this.normalizedLogicalIdPath(logId) || logId) + (suffix || '') + '}';
     });
   }
+
+  private formatNestedDifferences(templateDiff: TemplateDiff, prefix: string) {
+    this.nestedDiffIndent += ' ';
+    this.print(`${this.nestedDiffIndent}${prefix} NestedTemplate`);
+    if (templateDiff.awsTemplateFormatVersion || templateDiff.transform || templateDiff.description) {
+      this.printSectionHeader('Template');
+      this.formatDifference('AWSTemplateFormatVersion', 'AWSTemplateFormatVersion', templateDiff.awsTemplateFormatVersion);
+      this.formatDifference('Transform', 'Transform', templateDiff.transform);
+      this.formatDifference('Description', 'Description', templateDiff.description);
+      this.printSectionFooter();
+    }
+
+    //formatSecurityChangesWithBanner(this, templateDiff);
+
+    this.formatNestedSection('Parameter', templateDiff.parameters);
+    this.formatNestedSection('Metadata', templateDiff.metadata);
+    this.formatNestedSection('Mapping', templateDiff.mappings);
+    this.formatNestedSection('Condition', templateDiff.conditions);
+    this.formatNestedSection('Resource', templateDiff.resources, this.formatResourceDifference.bind(this));
+    this.formatNestedSection('Output', templateDiff.outputs);
+    this.formatNestedSection('Unknown', templateDiff.unknown);
+  }
 }
 
 /**