✨ Add extension management service

frontend/src/views/editor/extensions/fold/foldExtension.ts

@@ -0,0 +1,37 @@
+import {foldService} from '@codemirror/language';
+
+export const foldingOnIndent = foldService.of((state, from, to) => {
+    const line = state.doc.lineAt(from) // First line
+    const lines = state.doc.lines // Number of lines in the document
+    const indent = line.text.search(/\S|$/) // Indent level of the first line
+    let foldStart = from // Start of the fold
+    let foldEnd = to // End of the fold
+
+    // Check the next line if it is on a deeper indent level
+    // If it is, check the next line and so on
+    // If it is not, go on with the foldEnd
+    let nextLine = line
+    while (nextLine.number < lines) {
+        nextLine = state.doc.line(nextLine.number + 1) // Next line
+        const nextIndent = nextLine.text.search(/\S|$/) // Indent level of the next line
+
+        // If the next line is on a deeper indent level, add it to the fold
+        if (nextIndent > indent) {
+            foldEnd = nextLine.to // Set the fold end to the end of the next line
+        } else {
+            break // If the next line is not on a deeper indent level, stop
+        }
+    }
+
+    // If the fold is only one line, don't fold it
+    if (state.doc.lineAt(foldStart).number === state.doc.lineAt(foldEnd).number) {
+        return null
+    }
+
+    // Set the fold start to the end of the first line
+    // With this, the fold will not include the first line
+    foldStart = line.to
+
+    // Return a fold that covers the entire indent level
+    return {from: foldStart, to: foldEnd}
+});