From 67ab91267d3188402e42b94417da76977d957045 Mon Sep 17 00:00:00 2001
From: Elian Doran <contact@eliandoran.me>
Date: Fri, 21 Mar 2025 22:27:33 +0200
Subject: [PATCH] fix(mermaid): bring back rendering

---
 .../abstract_split_type_widget.ts             | 12 ++----
 .../abstract_svg_split_type_widget.ts         | 42 +++++++++++++++++++
 .../app/widgets/type_widgets/mermaid.ts       | 40 +++++++++++++++++-
 3 files changed, 84 insertions(+), 10 deletions(-)
 create mode 100644 src/public/app/widgets/type_widgets/abstract_svg_split_type_widget.ts

diff --git a/src/public/app/widgets/type_widgets/abstract_split_type_widget.ts b/src/public/app/widgets/type_widgets/abstract_split_type_widget.ts
index d5870d924..42f6896cc 100644
--- a/src/public/app/widgets/type_widgets/abstract_split_type_widget.ts
+++ b/src/public/app/widgets/type_widgets/abstract_split_type_widget.ts
@@ -7,12 +7,8 @@ import { DEFAULT_GUTTER_SIZE } from "../../services/resizer.js";
 
 const TPL = `\
 <div class="note-detail-split note-detail-printable split-horizontal">
-    <div class="note-detail-split-preview">
-        Preview goes here.
-    </div>
-
-    <div class="note-detail-split-editor">
-    </div>
+    <div class="note-detail-split-preview"></div>
+    <div class="note-detail-split-editor"></div>
 
     <style>
         .note-detail-split {
@@ -49,11 +45,11 @@ const TPL = `\
  *
  * - The two panes are resizeable via a split, on desktop.
  */
-export default class SplitTypeEditor extends TypeWidget {
+export default abstract class AbstractSplitTypeWidget extends TypeWidget {
 
     private splitInstance?: Split.Instance;
 
-    private $preview!: JQuery<HTMLElement>;
+    protected $preview!: JQuery<HTMLElement>;
     private $editor!: JQuery<HTMLElement>;
     private editorTypeWidget: EditableCodeTypeWidget;
 
diff --git a/src/public/app/widgets/type_widgets/abstract_svg_split_type_widget.ts b/src/public/app/widgets/type_widgets/abstract_svg_split_type_widget.ts
new file mode 100644
index 000000000..da09076e5
--- /dev/null
+++ b/src/public/app/widgets/type_widgets/abstract_svg_split_type_widget.ts
@@ -0,0 +1,42 @@
+import type FNote from "../../entities/fnote.js";
+import AbstractSplitTypeWidget from "./abstract_split_type_widget.js";
+
+/**
+ * A specialization of `SplitTypeWidget` meant for note types that have a SVG preview.
+ *
+ * This adds the following functionality:
+ *
+ */
+export default abstract class AbstractSvgSplitTypeWidget extends AbstractSplitTypeWidget {
+
+    private $renderContainer!: JQuery<HTMLElement>;
+
+    doRender(): void {
+        super.doRender();
+        this.$renderContainer = $(`<div class="render-container"></div>`);
+        this.$preview.append(this.$renderContainer);
+    }
+
+    async doRefresh(note: FNote | null | undefined) {
+        super.doRefresh(note);
+
+        if (note) {
+            const blob = await note.getBlob();
+            const content = blob?.content || "";
+            console.log(content);
+
+            const svg = await this.renderSvg(content);
+            this.$renderContainer.html(svg);
+        }
+    }
+
+    /**
+     * Called upon when the SVG preview needs refreshing, such as when the editor has switched to a new note or the content has switched.
+     *
+     * The method must return a valid SVG string that will be automatically displayed in the preview.
+     *
+     * @param content the content of the note, in plain text.
+     */
+    abstract renderSvg(content: string): Promise<string>;
+
+}
diff --git a/src/public/app/widgets/type_widgets/mermaid.ts b/src/public/app/widgets/type_widgets/mermaid.ts
index 40099f748..1edd184f7 100644
--- a/src/public/app/widgets/type_widgets/mermaid.ts
+++ b/src/public/app/widgets/type_widgets/mermaid.ts
@@ -1,9 +1,45 @@
-import SplitTypeEditor from "./abstract_split_type_widget.js";
+import library_loader from "../../services/library_loader.js";
+import { postprocessMermaidSvg } from "../../services/mermaid.js";
+import AbstractSvgSplitTypeWidget from "./abstract_svg_split_type_widget.js";
 
-export class MermaidTypeWidget extends SplitTypeEditor {
+let idCounter = 1;
+
+export class MermaidTypeWidget extends AbstractSvgSplitTypeWidget {
 
     static getType() {
         return "mermaid";
     }
 
+    async renderSvg(content: string) {
+        await library_loader.requireLibrary(library_loader.MERMAID);
+
+        mermaid.mermaidAPI.initialize({
+            startOnLoad: false,
+            ...(getMermaidConfig() as any)
+        });
+
+        idCounter++;
+        const { svg } = await mermaid.mermaidAPI.render(`mermaid-graph-${idCounter}`, content);
+        return postprocessMermaidSvg(svg);
+    }
+
+}
+
+export function getMermaidConfig(): MermaidConfig {
+    const documentStyle = window.getComputedStyle(document.documentElement);
+    const mermaidTheme = documentStyle.getPropertyValue("--mermaid-theme");
+
+    return {
+        theme: mermaidTheme.trim(),
+        securityLevel: "antiscript",
+        // TODO: Are all these options correct?
+        flow: { useMaxWidth: false },
+        sequence: { useMaxWidth: false },
+        gantt: { useMaxWidth: false },
+        class: { useMaxWidth: false },
+        state: { useMaxWidth: false },
+        pie: { useMaxWidth: true },
+        journey: { useMaxWidth: false },
+        git: { useMaxWidth: false }
+    };
 }