Add support for underline style headings

main.ts

@@ -12,9 +12,16 @@ import { isExcluded } from './exclusions';
 
 const stockIllegalSymbols = /[\\/:|#^[\]]/g;
 
+// Must be Strings unless settings dialog is updated.
+const enum HeadingStyle {
+  Prefix = 'Prefix',
+  Underline = 'Underline',
+}
+
 interface LinePointer {
   lineNumber: number;
   text: string;
+  style: HeadingStyle;
 }
 
 interface FilenameHeadingSyncPluginSettings {
@@ -23,6 +30,9 @@ interface FilenameHeadingSyncPluginSettings {
   ignoredFiles: { [key: string]: null };
   useFileOpenHook: boolean;
   useFileSaveHook: boolean;
+  newHeadingStyle: HeadingStyle;
+  replaceStyle: boolean;
+  underlineString: string;
 }
 
 const DEFAULT_SETTINGS: FilenameHeadingSyncPluginSettings = {
@@ -31,6 +41,9 @@ const DEFAULT_SETTINGS: FilenameHeadingSyncPluginSettings = {
   ignoreRegex: '',
   useFileOpenHook: true,
   useFileSaveHook: true,
+  newHeadingStyle: HeadingStyle.Prefix,
+  replaceStyle: false,
+  underlineString: '===',
 };
 
 export default class FilenameHeadingSyncPlugin extends Plugin {
@@ -222,14 +235,15 @@ export default class FilenameHeadingSyncPlugin extends Plugin {
 
       if (heading !== null) {
         if (this.sanitizeHeading(heading.text) !== sanitizedHeading) {
-          this.replaceLineInFile(
+          this.replaceHeading(
             file,
             lines,
             heading.lineNumber,
-            `# ${sanitizedHeading}`,
+            heading.style,
+            sanitizedHeading,
           );
         }
-      } else this.insertLineInFile(file, lines, start, `# ${sanitizedHeading}`);
+      } else this.insertHeading(file, lines, start, sanitizedHeading);
     });
   }
 
@@ -267,7 +281,19 @@ export default class FilenameHeadingSyncPlugin extends Plugin {
         return {
           lineNumber: i,
           text: fileLines[i].substring(2),
+          style: HeadingStyle.Prefix,
         };
+      } else {
+        if (
+          fileLines[i + 1] !== undefined &&
+          fileLines[i + 1].match(/^=+$/) !== null
+        ) {
+          return {
+            lineNumber: i,
+            text: fileLines[i],
+            style: HeadingStyle.Underline,
+          };
+        }
       }
     }
     return null; // no heading found
@@ -292,6 +318,84 @@ export default class FilenameHeadingSyncPlugin extends Plugin {
     return text.trim();
   }
 
+  /**
+   * Insert the `heading` at `lineNumber` in `file`.
+   *
+   * @param {TFile} file the file to modify
+   * @param {string[]} fileLines array of the file's contents, line by line
+   * @param {number} lineNumber zero-based index of the line to replace
+   * @param {string} text the new text
+   */
+  insertHeading(
+    file: TFile,
+    fileLines: string[],
+    lineNumber: number,
+    heading: string,
+  ) {
+    const newStyle = this.settings.newHeadingStyle;
+    if (newStyle === HeadingStyle.Underline) {
+      this.insertLineInFile(file, fileLines, lineNumber, `${heading}`);
+
+      this.insertLineInFile(
+        file,
+        fileLines,
+        lineNumber + 1,
+        this.settings.underlineString,
+      );
+    } else {
+      this.insertLineInFile(file, fileLines, lineNumber, `# ${heading}`);
+    }
+  }
+
+  /**
+   * Modified `file` by replacing the heading at `lineNumber` with `newHeading`,
+   * updating the heading style according the user settings.
+   *
+   * @param {TFile} file the file to modify
+   * @param {string[]} fileLines array of the file's contents, line by line
+   * @param {number} lineNumber zero-based index of the line to replace
+   * @param {HeadingStyle} oldStyle the style of the original heading
+   * @param {string} text the new text
+   */
+  replaceHeading(
+    file: TFile,
+    fileLines: string[],
+    lineNumber: number,
+    oldStyle: HeadingStyle,
+    newHeading: string,
+  ) {
+    const newStyle = this.settings.newHeadingStyle;
+    const replaceStyle = this.settings.replaceStyle;
+    // If we replace the style
+    if (replaceStyle) {
+      // For underline style, replace heading line, then add underline if not
+      // already there.
+      if (newStyle === HeadingStyle.Underline) {
+        this.replaceLineInFile(file, fileLines, lineNumber, `${newHeading}`);
+        if (oldStyle === HeadingStyle.Prefix) {
+          this.insertLineInFile(
+            file,
+            fileLines,
+            lineNumber + 1,
+            this.settings.underlineString,
+          );
+        }
+      } else {
+        // If not replacing style, match
+        if (oldStyle === HeadingStyle.Underline) {
+          this.replaceLineInFile(file, fileLines, lineNumber, `${newHeading}`);
+        } else {
+          this.replaceLineInFile(
+            file,
+            fileLines,
+            lineNumber,
+            `# ${newHeading}`,
+          );
+        }
+      }
+    }
+  }
+
   /**
    * Modifies the file by replacing a particular line with new text.
    *
@@ -395,12 +499,10 @@ class FilenameHeadingSyncSettingTab extends PluginSettingTab {
 
     containerEl.createEl('h2', { text: 'Filename Heading Sync' });
     containerEl.createEl('p', {
-      text:
-        'This plugin will overwrite the first heading found in a file with the filename.',
+      text: 'This plugin will overwrite the first heading found in a file with the filename.',
     });
     containerEl.createEl('p', {
-      text:
-        'If no header is found, will insert a new one at the first line (after frontmatter).',
+      text: 'If no header is found, will insert a new one at the first line (after frontmatter).',
     });
 
     new Setting(containerEl)
@@ -468,6 +570,56 @@ class FilenameHeadingSyncSettingTab extends PluginSettingTab {
           }),
       );
 
+    new Setting(containerEl)
+      .setName('New Heading Style')
+      .setDesc(
+        'Which Markdown heading style to use when creating new headings: Prefix ("# Heading") or Underline ("Heading\\n===").',
+      )
+      .addDropdown((cb) =>
+        cb
+          .addOption(HeadingStyle.Prefix, 'Prefix')
+          .addOption(HeadingStyle.Underline, 'Underline')
+          .setValue(this.plugin.settings.newHeadingStyle)
+          .onChange(async (value) => {
+            if (value === 'Prefix') {
+              this.plugin.settings.newHeadingStyle = HeadingStyle.Prefix;
+            }
+            if (value === 'Underline') {
+              this.plugin.settings.newHeadingStyle = HeadingStyle.Underline;
+            }
+            await this.plugin.saveSettings();
+          }),
+      );
+
+    new Setting(containerEl)
+      .setName('Replace Heading Style')
+      .setDesc(
+        'Whether this plugin should replace existing heading styles when updating headings.',
+      )
+      .addToggle((toggle) =>
+        toggle
+          .setValue(this.plugin.settings.replaceStyle)
+          .onChange(async (value) => {
+            this.plugin.settings.replaceStyle = value;
+            await this.plugin.saveSettings();
+          }),
+      );
+
+    new Setting(containerEl)
+      .setName('Underline String')
+      .setDesc(
+        'The string to use when insert Underline-style headings; should be some number of "="s.',
+      )
+      .addText((text) =>
+        text
+          .setPlaceholder('===')
+          .setValue(this.plugin.settings.underlineString)
+          .onChange(async (value) => {
+            this.plugin.settings.underlineString = value;
+            await this.plugin.saveSettings();
+          }),
+      );
+
     containerEl.createEl('h2', { text: 'Ignored Files By Regex' });
     containerEl.createEl('p', {
       text: 'All files matching the above RegEx will get listed here',
@@ -478,8 +630,7 @@ class FilenameHeadingSyncSettingTab extends PluginSettingTab {
 
     containerEl.createEl('h2', { text: 'Manually Ignored Files' });
     containerEl.createEl('p', {
-      text:
-        'You can ignore files from this plugin by using the "ignore this file" command',
+      text: 'You can ignore files from this plugin by using the "ignore this file" command',
     });
 
     // go over all ignored files and add them