add mermaid stack diagrams

docs/book.toml

@@ -6,10 +6,16 @@ src = "src"
 title = "Shotover"
 
 [output.html]
+additional-js = ["mermaid.min.js", "mermaid-init.js"]
 
 [output.linkcheck]
 # Should we check links on the internet? Enabling this option adds a
 # non-negligible performance impact
 follow-web-links = false
 
 warning-policy = "error"
+
+[preprocessor]
+
+[preprocessor.mermaid]
+command = "mdbook-mermaid"

docs/mermaid-init.js

@@ -0,0 +1,35 @@
+(() => {
+    const darkThemes = ['ayu', 'navy', 'coal'];
+    const lightThemes = ['light', 'rust'];
+
+    const classList = document.getElementsByTagName('html')[0].classList;
+
+    let lastThemeWasLight = true;
+    for (const cssClass of classList) {
+        if (darkThemes.includes(cssClass)) {
+            lastThemeWasLight = false;
+            break;
+        }
+    }
+
+    const theme = lastThemeWasLight ? 'default' : 'dark';
+    mermaid.initialize({ startOnLoad: true, theme });
+
+    // Simplest way to make mermaid re-render the diagrams in the new theme is via refreshing the page
+
+    for (const darkTheme of darkThemes) {
+        document.getElementById(darkTheme).addEventListener('click', () => {
+            if (lastThemeWasLight) {
+                window.location.reload();
+            }
+        });
+    }
+
+    for (const lightTheme of lightThemes) {
+        document.getElementById(lightTheme).addEventListener('click', () => {
+            if (!lastThemeWasLight) {
+                window.location.reload();
+            }
+        });
+    }
+})();