introduce StringWriter and generate properly indented Flowchart

src/main/java/net/hostsharing/hsadminng/rbac/rbacdef/RbacViewMermaidFlowchart.java

@@ -1,7 +1,5 @@
 package net.hostsharing.hsadminng.rbac.rbacdef;
 
-import net.hostsharing.hsadminng.hs.office.bankaccount.HsOfficeBankAccountEntity;
-import net.hostsharing.hsadminng.hs.office.debitor.HsOfficeDebitorEntity;
 import net.hostsharing.hsadminng.hs.office.relationship.HsOfficeRelationshipEntity;
 import org.apache.commons.lang3.StringUtils;
 
@@ -16,11 +14,11 @@ public class RbacViewMermaidFlowchart {
     public static final String HOSTSHARING_ORANGE = "#dd4901";
     public static final String HOSTSHARING_LIGHTBLUE = "#99bcdb";
     private final RbacView rbacDef;
-    private final StringBuilder flowchart = new StringBuilder();
+    private final StringWriter flowchart = new StringWriter();
 
     public RbacViewMermaidFlowchart(final RbacView rbacDef) {
         this.rbacDef = rbacDef;
-        flowchart.append("""
+        flowchart.writeLn("""
                 %%{init:{'flowchart':{'htmlLabels':false}}}%%
                 flowchart TB
                 """);
@@ -36,16 +34,16 @@ public class RbacViewMermaidFlowchart {
 
     private void renderEntitySubgraph(final RbacView.EntityAlias entity) {
         final var color = rbacDef.isMainEntityAlias(entity) ? HOSTSHARING_ORANGE : HOSTSHARING_LIGHTBLUE;
-        flowchart.append("""
+        flowchart.writeLn("""
             
             subgraph %{aliasName}["`**%{aliasName}**`"]
                 direction TB
                 style %{aliasName} fill:%{color},stroke:darkblue,stroke-width:8px
-                
             """
             .replace("%{aliasName}", entity.aliasName())
             .replace("%{color}", color ));
 
+        flowchart.indented( () -> {
             rbacDef.getEntityAliases().values().stream()
                     .filter(e -> e.aliasName().startsWith(entity.aliasName() + "."))
                     .forEach(this::renderEntitySubgraph);
@@ -66,24 +64,33 @@ public class RbacViewMermaidFlowchart {
                 renderEntitySubgraph(rbacDef.getEntityAliasProxy());
             }
 
-        flowchart.append("end\n\n");
+        });
+        flowchart.chopEmptyLines();
+        flowchart.writeLn("end");
+        flowchart.writeLn();
     }
 
     private void wrapOutputInSubgraph(final String name, final String color, final String content) {
         if (!StringUtils.isEmpty(content)) {
-            flowchart.append("subgraph " + name + "[ ]\n");
-            flowchart.append("style %{aliasName} fill: %{color}\n\n"
+            flowchart.emptyLine();
+            flowchart.writeLn("subgraph " + name + "[ ]\n");
+            flowchart.indented(() -> {
+                flowchart.writeLn("style %{aliasName} fill: %{color}"
                             .replace("%{aliasName}", name)
                             .replace("%{color}", color));
-            flowchart.append(content);
-            flowchart.append("\nend\n\n");
+                flowchart.writeLn();
+                flowchart.writeLn(content);
+            });
+            flowchart.chopEmptyLines();
+            flowchart.writeLn("end");
+            flowchart.writeLn();
         }
     }
 
     private void renderGrants() {
         rbacDef.getGrantDefs()
                 .forEach(g -> {
-                    flowchart.append(grantDef(g) + "\n" );
+                    flowchart.writeLn(grantDef(g) + "\n");
                 });
     }
 
@@ -141,8 +148,8 @@ public class RbacViewMermaidFlowchart {
     }
 
     public static void main(String[] args) throws IOException {
-        new RbacViewMermaidFlowchart(HsOfficeBankAccountEntity.rbac()).generateToMarkdownFile();
+//        new RbacViewMermaidFlowchart(HsOfficeBankAccountEntity.rbac()).generateToMarkdownFile();
         new RbacViewMermaidFlowchart(HsOfficeRelationshipEntity.rbac()).generateToMarkdownFile();
-        new RbacViewMermaidFlowchart(HsOfficeDebitorEntity.rbac()).generateToMarkdownFile();
+//        new RbacViewMermaidFlowchart(HsOfficeDebitorEntity.rbac()).generateToMarkdownFile();
     }
 }

src/main/java/net/hostsharing/hsadminng/rbac/rbacdef/StringWriter.java

@@ -0,0 +1,71 @@
+package net.hostsharing.hsadminng.rbac.rbacdef;
+
+import org.apache.commons.lang3.StringUtils;
+
+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.joining;
+
+public class StringWriter {
+
+    private final StringBuilder string = new StringBuilder();
+    private int indentLevel = 0;
+
+    void writeLn(final String text) {
+        string.append( indented(text));
+        writeLn();
+    }
+
+    void writeLn() {
+        string.append( "\n");
+    }
+
+    private String indented(final String text) {
+        if ( indentLevel == 0) {
+            return text.trim();
+        }
+        final var indentation = StringUtils.repeat("    ", indentLevel);
+        final var indented = stream(text.split("\n"))
+                .map(line -> line.trim().isBlank() ? "" : indentation + line.trim())
+                .collect(joining("\n"));
+        return indented;
+    }
+
+    void indent() {
+        ++indentLevel;
+    }
+
+    void unindent() {
+        --indentLevel;
+    }
+
+    void indented(final Runnable indented) {
+        indent();
+        indented.run();
+        unindent();
+    }
+
+    boolean chopTail(final String tail) {
+        if (string.toString().endsWith(tail)) {
+            string.setLength(string.length() - tail.length());
+            return true;
+        }
+        return false;
+    }
+
+    void chopEmptyLines() {
+        while (string.toString().endsWith("\n\n")) {
+            string.setLength(string.length() - 1);
+        };
+    }
+
+    void emptyLine() {
+        if (!string.toString().endsWith("\n\n")) {
+            writeLn();
+        }
+    }
+
+    @Override
+    public String toString() {
+        return string.toString();
+    }
+}