chore(nx/server): move source code

apps/server/src/services/export/markdown.spec.ts

@@ -0,0 +1,345 @@
+import { describe, it, expect } from "vitest";
+import markdownExportService from "./markdown.js";
+import { trimIndentation } from "@triliumnext/commons";
+
+describe("Markdown export", () => {
+
+    it("exports correct language tag for known languages", () => {
+        const conversionTable = {
+            "language-text-x-nginx-conf": "nginx",
+            "language-text-x-diff": "diff",
+            "language-application-javascript-env-frontend": "javascript",
+            "language-application-javascript-env-backend": "javascript",
+            "language-text-x-asm-mips": "mips"
+        };
+
+        for (const [ input, output ] of Object.entries(conversionTable)) {
+            const html = trimIndentation`\
+                <p>A diff:</p>
+                <pre><code class="${input}">Hello
+                -world
+                +worldy
+                </code></pre>`;
+            const expected = trimIndentation`\
+                A diff:
+
+                \`\`\`${output}
+                Hello
+                -world
+                +worldy
+
+                \`\`\``;
+
+            expect(markdownExportService.toMarkdown(html)).toBe(expected);
+        }
+    });
+
+    it("removes auto tag for code blocks", () => {
+        const html = trimIndentation`\
+            <pre><code class="language-text-x-trilium-auto">Hello
+            -world
+            +worldy
+            </code></pre>`;
+        const expected = trimIndentation`\
+            \`\`\`
+            Hello
+            -world
+            +worldy
+
+            \`\`\``;
+
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("supports code block with no language tag", () => {
+        const html = trimIndentation`\
+            <pre><code>Hello</code></pre>`;
+        const expected = trimIndentation`\
+            \`\`\`
+            Hello
+            \`\`\``;
+
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("exports strikethrough text correctly", () => {
+        const html = "<s>hello</s>Hello <s>world</s>";
+        const expected = "~~hello~~Hello ~~world~~";
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("exports headings properly", () => {
+        const html = trimIndentation`\
+            <h1>Heading 1</h1>
+            <h2>Heading 2</h2>
+            <h3>Heading 3</h3>
+            <h4>Heading 4</h4>
+            <h5>Heading 5</h5>
+            <h6>Heading 6</h6>
+        `;
+        const expected = trimIndentation`\
+            # Heading 1
+
+            ## Heading 2
+
+            ### Heading 3
+
+            #### Heading 4
+
+            ##### Heading 5
+
+            ###### Heading 6`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("rewrites image URL with spaces", () => {
+        const html = `<img src="Hello world  .png"/>`;
+        const expected = `![](Hello%20world%20%20.png)`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("supports keyboard shortcuts", () => {
+        const html = "<kbd>Ctrl</kbd> + <kbd>Alt</kbd> + <kbd>Delete</kbd>";
+        expect(markdownExportService.toMarkdown(html)).toBe(html);
+    });
+
+    it("exports admonitions properly", () => {
+        const html = trimIndentation`\
+            <p>
+                Before
+            </p>
+            <aside class="admonition note">
+                <p>
+                    This is a note.
+                </p>
+            </aside>
+            <aside class="admonition tip">
+                <p>
+                    This is a tip.
+                </p>
+            </aside>
+            <aside class="admonition important">
+                <p>
+                    This is a very important information.
+                </p>
+                <figure class="table">
+                    <table>
+                        <tbody>
+                            <tr>
+                                <td>
+                                    1
+                                </td>
+                                <td>
+                                    2
+                                </td>
+                            </tr>
+                            <tr>
+                                <td>
+                                    3
+                                </td>
+                                <td>
+                                    4
+                                </td>
+                            </tr>
+                        </tbody>
+                    </table>
+                </figure>
+            </aside>
+            <aside class="admonition caution">
+                <p>
+                    This is a caution.
+                </p>
+            </aside>
+            <aside class="admonition warning">
+                <h2>
+                    Title goes here
+                </h2>
+                <p>
+                    This is a warning.
+                </p>
+            </aside>
+            <p>
+                After
+            </p>
+        `;
+
+        const space = " ";  // editor config trimming space.
+        const expected = trimIndentation`\
+            Before
+
+            > [!NOTE]
+            > This is a note.
+
+            > [!TIP]
+            > This is a tip.
+
+            > [!IMPORTANT]
+            > This is a very important information.
+            >${space}
+            > <figure class="table"><table><tbody><tr><td>1</td><td>2</td></tr><tr><td>3</td><td>4</td></tr></tbody></table></figure>
+
+            > [!CAUTION]
+            > This is a caution.
+
+            > [!WARNING]
+            > ## Title goes here
+            >${space}
+            > This is a warning.
+
+            After`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("exports code in tables properly", () => {
+        const html = trimIndentation`\
+        <table>
+            <tr>
+                <td>
+                    Row 1
+                </td>
+                <td>
+                    <p>Allows displaying the value of one or more attributes in the calendar
+                        like this:&nbsp;</p>
+                    <p>
+                        <img src="13_Calendar View_image.png" alt="">
+                    </p>
+
+                    <pre><code class="language-text-x-trilium-auto">#weight="70"
+                    #Mood="Good"
+                    #calendar:displayedAttributes="weight,Mood"</code></pre>
+                    <p>It can also be used with relations, case in which it will display the
+                        title of the target note:</p><pre><code class="language-text-x-trilium-auto">~assignee=@My assignee
+                    #calendar:displayedAttributes="assignee"</code></pre>
+                </td>
+            </tr>
+        </table>
+        `;
+
+        const expected = trimIndentation`\
+            <table><tbody><tr><td>Row 1</td><td><p>Allows displaying the value of one or more attributes in the calendar like this:&nbsp;</p><p><img src="13_Calendar View_image.png" alt=""></p><pre><code class="language-text-x-trilium-auto">#weight="70"
+                        #Mood="Good"
+                        #calendar:displayedAttributes="weight,Mood"</code></pre><p>It can also be used with relations, case in which it will display the title of the target note:</p><pre><code class="language-text-x-trilium-auto">~assignee=@My assignee
+                        #calendar:displayedAttributes="assignee"</code></pre></td></tr></tbody></table>`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("converts &nbsp; to character", () => {
+        const html = /*html*/`<p>Hello&nbsp;world.</p>`;
+        const expected = `Hello\u00a0world.`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("preserves non-breaking space character", () => {
+        const html = /*html*/`<p>Hello\u00adworld.</p>`;
+        const expected = `Hello\u00adworld.`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("exports normal links verbatim", () => {
+        const html = /*html*/`<p><a href="https://www.google.com">Google</a></p>`;
+        const expected = `[Google](https://www.google.com)`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("exports reference links verbatim", () => {
+        const html = /*html*/`<p><a class="reference-link" href="../../Canvas.html">Canvas</a></p>`;
+        const expected = `<a class="reference-link" href="../../Canvas.html">Canvas</a>`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("converts image if it has no custom properties", () => {
+        const html = /*html*/`<p><img src="Include Note_image.png"></p>`;
+        const expected = `![](Include%20Note_image.png)`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("preserves image verbatim if it has a width or height attribute", () => {
+        const scenarios = [
+            /*html*/`<img src="Include Note_image.png" width="16" height="16">`,
+            /*html*/`<img src="Include Note_image.png" width="16">`,
+            /*html*/`<img src="Include Note_image.png" height="16">`,
+            /*html*/`<img class="image_resized" style="aspect-ratio:853/315;width:50%;" src="6_File_image.png" width="853" height="315">`
+        ];
+        for (const expected of scenarios) {
+            const html = /*html*/`<p>${expected}</p>`;
+            expect(markdownExportService.toMarkdown(html)).toBe(expected);
+        }
+    });
+
+    it("preserves figures", () => {
+        const html = /*html*/trimIndentation`\
+              <figure class="image" style="width:53.44%;">
+                <img style="aspect-ratio:991/403;" src="Jump to Note_image.png" width="991"
+                height="403">
+              </figure>
+        `;
+        const expected = `<figure class="image" style="width:53.44%;"><img style="aspect-ratio:991/403;" src="Jump to Note_image.png" width="991" height="403"></figure>`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("converts inline math expressions into proper Markdown syntax", () => {
+        const html = /*html*/String.raw`<span class="math-tex">\(H(X, Y) = \sum_{i=1}^{M} \sum_{j=1}^{L} p(x_i, y_j) \log_2 \frac{1}{p(x_i, y_j)} = - \sum_{i=1}^{M} \sum_{j=1}^{L} p(x_i, y_j) \log_2 p(x_i, y_j) \frac{\text{bits}}{\text{symbol}}\)</span></span>`;
+        const expected = String.raw`$H(X, Y) = \sum_{i=1}^{M} \sum_{j=1}^{L} p(x_i, y_j) \log_2 \frac{1}{p(x_i, y_j)} = - \sum_{i=1}^{M} \sum_{j=1}^{L} p(x_i, y_j) \log_2 p(x_i, y_j) \frac{\text{bits}}{\text{symbol}}$`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("converts display math expressions into proper Markdown syntax", () => {
+        const html = /*html*/String.raw`<span class="math-tex">\[H(X, Y) = \sum_{i=1}^{M} \sum_{j=1}^{L} p(x_i, y_j) \log_2 \frac{1}{p(x_i, y_j)} = - \sum_{i=1}^{M} \sum_{j=1}^{L} p(x_i, y_j) \log_2 p(x_i, y_j) \frac{\text{bits}}{\text{symbol}}\]</span></span>`;
+        const expected = String.raw`$$H(X, Y) = \sum_{i=1}^{M} \sum_{j=1}^{L} p(x_i, y_j) \log_2 \frac{1}{p(x_i, y_j)} = - \sum_{i=1}^{M} \sum_{j=1}^{L} p(x_i, y_j) \log_2 p(x_i, y_j) \frac{\text{bits}}{\text{symbol}}$$`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("does not generate additional spacing when exporting lists with paragraph", () => {
+        const html = trimIndentation`\
+            <ul>
+                <li><a href="https://github.com/JYC333">@JYC333</a> made their first contribution
+                            in <a href="https://github.com/TriliumNext/Notes/pull/294">#294</a>
+
+                </li>
+                <li>
+                <p><a href="https://github.com/TriliumNext/Notes/issues/375">Note Tooltip isn't removed when clicking on internal trilium link in read-only mode</a>
+
+                </p>
+                </li>
+                <li>
+                <p><a href="https://github.com/TriliumNext/Notes/issues/384">Calendar dropdown won't close if click/right-click other button that open notes from launcher bar</a>
+
+                </p>
+                </li>
+            </ul>
+        `;
+        const expected = trimIndentation`\
+            *   [@JYC333](https://github.com/JYC333) made their first contribution in [#294](https://github.com/TriliumNext/Notes/pull/294)
+            *   [Note Tooltip isn't removed when clicking on internal trilium link in read-only mode](https://github.com/TriliumNext/Notes/issues/375)
+            *   [Calendar dropdown won't close if click/right-click other button that open notes from launcher bar](https://github.com/TriliumNext/Notes/issues/384)`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("preserves include note", () => {
+        const html = /*html*/`<section class="include-note" data-note-id="i4A5g9iOg9I0" data-box-size="full"> </section>`;
+        const expected = /*markdown*/`<section class="include-note" data-note-id="i4A5g9iOg9I0" data-box-size="full">&nbsp;</section>`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+    it("exports todo lists properly", () => {
+        const html = trimIndentation/*html*/`\
+            <ul class="todo-list">
+                <li>
+                    <label class="todo-list__label">
+                        <input type="checkbox" checked="checked" disabled="disabled"><span class="todo-list__label__description">Hello</span>
+                    </label>
+                </li>
+                <li>
+                    <label class="todo-list__label">
+                        <input type="checkbox" disabled="disabled"><span class="todo-list__label__description">World</span>
+                    </label>
+                </li>
+            </ul>
+        `;
+        const expected = trimIndentation`\
+            - [x] Hello
+            - [ ] World`;
+        expect(markdownExportService.toMarkdown(html)).toBe(expected);
+    });
+
+});

apps/server/src/services/export/markdown.ts

@@ -0,0 +1,283 @@
+"use strict";
+
+import TurndownService, { type Rule } from "turndown";
+import { gfm } from "@triliumnext/turndown-plugin-gfm";
+
+let instance: TurndownService | null = null;
+
+// TODO: Move this to a dedicated file someday.
+export const ADMONITION_TYPE_MAPPINGS: Record<string, string> = {
+    note: "NOTE",
+    tip: "TIP",
+    important: "IMPORTANT",
+    caution: "CAUTION",
+    warning: "WARNING"
+};
+
+export const DEFAULT_ADMONITION_TYPE = ADMONITION_TYPE_MAPPINGS.note;
+
+const fencedCodeBlockFilter: TurndownService.Rule = {
+    filter: function (node, options) {
+        return options.codeBlockStyle === "fenced" && node.nodeName === "PRE" && node.firstChild !== null && node.firstChild.nodeName === "CODE";
+    },
+
+    replacement: function (content, node, options) {
+        if (!node.firstChild || !("getAttribute" in node.firstChild) || typeof node.firstChild.getAttribute !== "function") {
+            return content;
+        }
+
+        const className = node.firstChild.getAttribute("class") || "";
+        const language = rewriteLanguageTag((className.match(/language-(\S+)/) || [null, ""])[1]);
+
+        return "\n\n" + options.fence + language + "\n" + node.firstChild.textContent + "\n" + options.fence + "\n\n";
+    }
+};
+
+function toMarkdown(content: string) {
+    if (instance === null) {
+        instance = new TurndownService({
+            headingStyle: "atx",
+            codeBlockStyle: "fenced",
+            blankReplacement(content, node, options) {
+                if (node.nodeName === "SECTION" && (node as HTMLElement).classList.contains("include-note")) {
+                    return (node as HTMLElement).outerHTML;
+                }
+
+                // Original implementation as per https://github.com/mixmark-io/turndown/blob/master/src/turndown.js.
+                return ("isBlock" in node && node.isBlock) ? '\n\n' : ''
+            }
+        });
+        // Filter is heavily based on: https://github.com/mixmark-io/turndown/issues/274#issuecomment-458730974
+        instance.addRule("fencedCodeBlock", fencedCodeBlockFilter);
+        instance.addRule("img", buildImageFilter());
+        instance.addRule("admonition", buildAdmonitionFilter());
+        instance.addRule("inlineLink", buildInlineLinkFilter());
+        instance.addRule("figure", buildFigureFilter());
+        instance.addRule("math", buildMathFilter());
+        instance.addRule("li", buildListItemFilter());
+        instance.use(gfm);
+        instance.keep([ "kbd" ]);
+    }
+
+    return instance.turndown(content);
+}
+
+function rewriteLanguageTag(source: string) {
+    if (!source) {
+        return source;
+    }
+
+    switch (source) {
+        case "text-x-trilium-auto":
+            return "";
+        case "application-javascript-env-frontend":
+        case "application-javascript-env-backend":
+            return "javascript";
+        case "text-x-nginx-conf":
+            return "nginx";
+        default:
+            return source.split("-").at(-1);
+    }
+}
+
+// TODO: Remove once upstream delivers a fix for https://github.com/mixmark-io/turndown/issues/467.
+function buildImageFilter() {
+    const ESCAPE_PATTERNS = {
+        before: /([\\*`[\]_]|(?:^[-+>])|(?:^~~~)|(?:^#{1-6}))/g,
+        after: /((?:^\d+(?=\.)))/
+    }
+
+    const escapePattern = new RegExp('(?:' + ESCAPE_PATTERNS.before.source + '|' + ESCAPE_PATTERNS.after.source + ')', 'g');
+
+    function escapeMarkdown (content: string) {
+        return content.replace(escapePattern, function (match, before, after) {
+            return before ? '\\' + before : after + '\\'
+        })
+    }
+
+    function escapeLinkDestination(destination: string) {
+        return destination
+            .replace(/([()])/g, '\\$1')
+            .replace(/ /g, "%20");
+    }
+
+    function escapeLinkTitle (title: string) {
+        return title.replace(/"/g, '\\"')
+    }
+
+    const imageFilter: TurndownService.Rule = {
+        filter: "img",
+        replacement(content, _node) {
+            const node = _node as HTMLElement;
+
+            // Preserve image verbatim if it has a width or height attribute.
+            if (node.hasAttribute("width") || node.hasAttribute("height")) {
+                return node.outerHTML;
+            }
+
+            // TODO: Deduplicate with upstream.
+            const untypedNode = (node as any);
+            const alt = escapeMarkdown(cleanAttribute(untypedNode.getAttribute('alt')))
+            const src = escapeLinkDestination(untypedNode.getAttribute('src') || '')
+            const title = cleanAttribute(untypedNode.getAttribute('title'))
+            const titlePart = title ? ' "' + escapeLinkTitle(title) + '"' : ''
+
+            return src ? '![' + alt + ']' + '(' + src + titlePart + ')' : ''
+        }
+    };
+    return imageFilter;
+}
+
+function buildAdmonitionFilter() {
+    function parseAdmonitionType(_node: Node) {
+        if (!("getAttribute" in _node)) {
+            return DEFAULT_ADMONITION_TYPE;
+        }
+
+        const node = _node as Element;
+        const classList = node.getAttribute("class")?.split(" ") ?? [];
+
+        for (const className of classList) {
+            if (className === "admonition") {
+                continue;
+            }
+
+            const mappedType = ADMONITION_TYPE_MAPPINGS[className];
+            if (mappedType) {
+                return mappedType;
+            }
+        }
+
+        return DEFAULT_ADMONITION_TYPE;
+    }
+
+    const admonitionFilter: TurndownService.Rule = {
+        filter(node, options) {
+            return node.nodeName === "ASIDE" && node.classList.contains("admonition");
+        },
+        replacement(content, node) {
+            // Parse the admonition type.
+            const admonitionType = parseAdmonitionType(node);
+
+            content = content.replace(/^\n+|\n+$/g, '');
+            content = content.replace(/^/gm, '> ');
+            content = `> [!${admonitionType}]\n` + content;
+
+            return "\n\n" + content + "\n\n";
+        }
+    }
+    return admonitionFilter;
+}
+
+/**
+ * Variation of the original ruleset: https://github.com/mixmark-io/turndown/blob/master/src/commonmark-rules.js.
+ *
+ * Detects if the URL is a Trilium reference link and returns it verbatim if that's the case.
+ *
+ * @returns
+ */
+function buildInlineLinkFilter(): Rule {
+    return {
+        filter: function (node, options) {
+            return (
+                options.linkStyle === 'inlined' &&
+                node.nodeName === 'A' &&
+                !!node.getAttribute('href')
+            )
+        },
+
+        replacement: function (content, _node) {
+            const node = _node as HTMLElement;
+
+            // Return reference links verbatim.
+            if (node.classList.contains("reference-link")) {
+                return node.outerHTML;
+            }
+
+            // Otherwise treat as normal.
+            // TODO: Call super() somehow instead of duplicating the implementation.
+            let href = node.getAttribute('href')
+            if (href) href = href.replace(/([()])/g, '\\$1')
+            let title = cleanAttribute(node.getAttribute('title'))
+            if (title) title = ' "' + title.replace(/"/g, '\\"') + '"'
+            return '[' + content + '](' + href + title + ')'
+        }
+    }
+}
+
+function buildFigureFilter(): Rule {
+    return {
+        filter(node, options) {
+            return node.nodeName === 'FIGURE'
+        },
+        replacement(content, node) {
+            return (node as HTMLElement).outerHTML;
+        }
+    }
+}
+
+// Keep in line with https://github.com/mixmark-io/turndown/blob/master/src/commonmark-rules.js.
+function buildListItemFilter(): Rule {
+    return {
+        filter: "li",
+        replacement(content, node, options) {
+            content = content
+                .trim()
+                .replace(/\n/gm, '\n    ') // indent
+            let prefix = options.bulletListMarker + '   '
+            const parent = node.parentNode as HTMLElement;
+            if (parent.nodeName === 'OL') {
+                var start = parent.getAttribute('start')
+                var index = Array.prototype.indexOf.call(parent.children, node)
+                prefix = (start ? Number(start) + index : index + 1) + '.  '
+            } else if (parent.classList.contains("todo-list")) {
+                const isChecked = node.querySelector("input[type=checkbox]:checked");
+                prefix = (isChecked ? "- [x] " : "- [ ] ");
+            }
+
+            const result = prefix + content + (node.nextSibling && !/\n$/.test(content) ? '\n' : '');
+            return result;
+        }
+    }
+}
+
+function buildMathFilter(): Rule {
+    const MATH_INLINE_PREFIX = "\\(";
+    const MATH_INLINE_SUFFIX = "\\)";
+
+    const MATH_DISPLAY_PREFIX = "\\[";
+    const MATH_DISPLAY_SUFFIX = "\\]";
+
+    return {
+        filter(node) {
+            return node.nodeName === "SPAN" && node.classList.contains("math-tex");
+        },
+        replacement(_, node) {
+            // We have to use the raw HTML text, otherwise the content is escaped too much.
+            const content = (node as HTMLElement).innerText;
+
+            // Inline math
+            if (content.startsWith(MATH_INLINE_PREFIX) && content.endsWith(MATH_INLINE_SUFFIX)) {
+                return `$${content.substring(MATH_INLINE_PREFIX.length, content.length - MATH_INLINE_SUFFIX.length)}$`;
+            }
+
+            // Display math
+            if (content.startsWith(MATH_DISPLAY_PREFIX) && content.endsWith(MATH_DISPLAY_SUFFIX)) {
+                return `$$${content.substring(MATH_DISPLAY_PREFIX.length, content.length - MATH_DISPLAY_SUFFIX.length)}$$`;
+            }
+
+            // Unknown.
+            return content;
+        }
+    }
+}
+
+// Taken from upstream since it's not exposed.
+// https://github.com/mixmark-io/turndown/blob/master/src/commonmark-rules.js
+function cleanAttribute(attribute: string | null | undefined) {
+    return attribute ? attribute.replace(/(\n+\s*)+/g, '\n') : ''
+}
+
+export default {
+    toMarkdown
+};

apps/server/src/services/export/opml.ts

@@ -0,0 +1,99 @@
+"use strict";
+
+import { getContentDisposition, stripTags } from "../utils.js";
+import becca from "../../becca/becca.js";
+import type TaskContext from "../task_context.js";
+import type BBranch from "../../becca/entities/bbranch.js";
+import type { Response } from "express";
+
+function exportToOpml(taskContext: TaskContext, branch: BBranch, version: string, res: Response) {
+    if (!["1.0", "2.0"].includes(version)) {
+        throw new Error(`Unrecognized OPML version ${version}`);
+    }
+
+    const opmlVersion = parseInt(version);
+
+    const note = branch.getNote();
+
+    function exportNoteInner(branchId: string) {
+        const branch = becca.getBranch(branchId);
+        if (!branch) {
+            throw new Error("Unable to find branch.");
+        }
+
+        const note = branch.getNote();
+        if (!note) {
+            throw new Error("Unable to find note.");
+        }
+
+        if (note.hasOwnedLabel("excludeFromExport")) {
+            return;
+        }
+
+        const title = `${branch.prefix ? `${branch.prefix} - ` : ""}${note.title}`;
+
+        if (opmlVersion === 1) {
+            const preparedTitle = escapeXmlAttribute(title);
+            const preparedContent = note.hasStringContent() ? prepareText(note.getContent() as string) : "";
+
+            res.write(`<outline title="${preparedTitle}" text="${preparedContent}">\n`);
+        } else if (opmlVersion === 2) {
+            const preparedTitle = escapeXmlAttribute(title);
+            const preparedContent = note.hasStringContent() ? escapeXmlAttribute(note.getContent() as string) : "";
+
+            res.write(`<outline text="${preparedTitle}" _note="${preparedContent}">\n`);
+        } else {
+            throw new Error(`Unrecognized OPML version ${opmlVersion}`);
+        }
+
+        taskContext.increaseProgressCount();
+
+        for (const child of note.getChildBranches()) {
+            if (child?.branchId) {
+                exportNoteInner(child.branchId);
+            }
+        }
+
+        res.write("</outline>");
+    }
+
+    const filename = `${branch.prefix ? `${branch.prefix} - ` : ""}${note.title}.opml`;
+
+    res.setHeader("Content-Disposition", getContentDisposition(filename));
+    res.setHeader("Content-Type", "text/x-opml");
+
+    res.write(`<?xml version="1.0" encoding="UTF-8"?>
+<opml version="${version}">
+<head>
+<title>Trilium export</title>
+</head>
+<body>`);
+
+    if (branch.branchId) {
+        exportNoteInner(branch.branchId);
+    }
+
+    res.write(`</body>
+</opml>`);
+    res.end();
+
+    taskContext.taskSucceeded();
+}
+
+function prepareText(text: string) {
+    const newLines = text.replace(/(<p[^>]*>|<br\s*\/?>)/g, "\n").replace(/&nbsp;/g, " "); // nbsp isn't in XML standard (only HTML)
+
+    const stripped = stripTags(newLines);
+
+    const escaped = escapeXmlAttribute(stripped);
+
+    return escaped.replace(/\n/g, "&#10;");
+}
+
+function escapeXmlAttribute(text: string) {
+    return text.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;").replace(/'/g, "&apos;");
+}
+
+export default {
+    exportToOpml
+};

apps/server/src/services/export/single.spec.ts

@@ -0,0 +1,17 @@
+import { describe, expect, it } from "vitest";
+import BNote from "../../becca/entities/bnote.js";
+import { mapByNoteType } from "./single.js";
+
+describe("Note type mappings", () => {
+    it("supports mermaid note", () => {
+        const note = new BNote({
+            type: "mermaid",
+            title: "New note"
+        });
+
+        expect(mapByNoteType(note, "", "html")).toMatchObject({
+            extension: "mermaid",
+            mime: "text/vnd.mermaid"
+        });
+    });
+});

apps/server/src/services/export/single.ts

@@ -0,0 +1,138 @@
+"use strict";
+
+import mimeTypes from "mime-types";
+import html from "html";
+import { getContentDisposition, escapeHtml } from "../utils.js";
+import mdService from "./markdown.js";
+import becca from "../../becca/becca.js";
+import type TaskContext from "../task_context.js";
+import type BBranch from "../../becca/entities/bbranch.js";
+import type { Response } from "express";
+import type BNote from "../../becca/entities/bnote.js";
+
+function exportSingleNote(taskContext: TaskContext, branch: BBranch, format: "html" | "markdown", res: Response) {
+    const note = branch.getNote();
+
+    if (note.type === "image" || note.type === "file") {
+        return [400, `Note type '${note.type}' cannot be exported as single file.`];
+    }
+
+    if (format !== "html" && format !== "markdown") {
+        return [400, `Unrecognized format '${format}'`];
+    }
+
+    const { payload, extension, mime } = mapByNoteType(note, note.getContent(), format);
+    const fileName = `${note.title}.${extension}`;
+
+    res.setHeader("Content-Disposition", getContentDisposition(fileName));
+    res.setHeader("Content-Type", `${mime}; charset=UTF-8`);
+
+    res.send(payload);
+
+    taskContext.increaseProgressCount();
+    taskContext.taskSucceeded();
+}
+
+export function mapByNoteType(note: BNote, content: string | Buffer<ArrayBufferLike>, format: "html" | "markdown") {
+    let payload, extension, mime;
+
+    if (typeof content !== "string") {
+        throw new Error("Unsupported content type for export.");
+    }
+
+    if (note.type === "text") {
+        if (format === "html") {
+            content = inlineAttachments(content);
+
+            if (!content.toLowerCase().includes("<html")) {
+                content = `<html><head><meta charset="utf-8"></head><body>${content}</body></html>`;
+            }
+
+            payload = content.length < 100_000 ? html.prettyPrint(content, { indent_size: 2 }) : content;
+
+            extension = "html";
+            mime = "text/html";
+        } else if (format === "markdown") {
+            payload = mdService.toMarkdown(content);
+            extension = "md";
+            mime = "text/x-markdown";
+        }
+    } else if (note.type === "code") {
+        payload = content;
+        extension = mimeTypes.extension(note.mime) || "code";
+        mime = note.mime;
+    } else if (note.type === "canvas") {
+        payload = content;
+        extension = "excalidraw";
+        mime = "application/json";
+    } else if (note.type === "mermaid") {
+        payload = content;
+        extension = "mermaid";
+        mime = "text/vnd.mermaid";
+    } else if (note.type === "relationMap" || note.type === "search") {
+        payload = content;
+        extension = "json";
+        mime = "application/json";
+    }
+
+    return { payload, extension, mime };
+}
+
+function inlineAttachments(content: string) {
+    content = content.replace(/src="[^"]*api\/images\/([a-zA-Z0-9_]+)\/?[^"]+"/g, (match, noteId) => {
+        const note = becca.getNote(noteId);
+        if (!note || !note.mime.startsWith("image/")) {
+            return match;
+        }
+
+        const imageContent = note.getContent();
+        if (!Buffer.isBuffer(imageContent)) {
+            return match;
+        }
+
+        const base64Content = imageContent.toString("base64");
+        const srcValue = `data:${note.mime};base64,${base64Content}`;
+
+        return `src="${srcValue}"`;
+    });
+
+    content = content.replace(/src="[^"]*api\/attachments\/([a-zA-Z0-9_]+)\/image\/?[^"]+"/g, (match, attachmentId) => {
+        const attachment = becca.getAttachment(attachmentId);
+        if (!attachment || !attachment.mime.startsWith("image/")) {
+            return match;
+        }
+
+        const attachmentContent = attachment.getContent();
+        if (!Buffer.isBuffer(attachmentContent)) {
+            return match;
+        }
+
+        const base64Content = attachmentContent.toString("base64");
+        const srcValue = `data:${attachment.mime};base64,${base64Content}`;
+
+        return `src="${srcValue}"`;
+    });
+
+    content = content.replace(/href="[^"]*#root[^"]*attachmentId=([a-zA-Z0-9_]+)\/?"/g, (match, attachmentId) => {
+        const attachment = becca.getAttachment(attachmentId);
+        if (!attachment) {
+            return match;
+        }
+
+        const attachmentContent = attachment.getContent();
+        if (!Buffer.isBuffer(attachmentContent)) {
+            return match;
+        }
+
+        const base64Content = attachmentContent.toString("base64");
+        const hrefValue = `data:${attachment.mime};base64,${base64Content}`;
+
+        return `href="${hrefValue}" download="${escapeHtml(attachment.title)}"`;
+    });
+
+    return content;
+}
+
+export default {
+    exportSingleNote
+};

apps/server/src/services/export/zip.ts

@@ -0,0 +1,631 @@
+"use strict";
+
+import html from "html";
+import dateUtils from "../date_utils.js";
+import path from "path";
+import mimeTypes from "mime-types";
+import mdService from "./markdown.js";
+import packageInfo from "../../../package.json" with { type: "json" };
+import { getContentDisposition, escapeHtml } from "../utils.js";
+import protectedSessionService from "../protected_session.js";
+import sanitize from "sanitize-filename";
+import fs from "fs";
+import becca from "../../becca/becca.js";
+import archiver from "archiver";
+import log from "../log.js";
+import TaskContext from "../task_context.js";
+import ValidationError from "../../errors/validation_error.js";
+import type NoteMeta from "../meta/note_meta.js";
+import type AttachmentMeta from "../meta/attachment_meta.js";
+import type AttributeMeta from "../meta/attribute_meta.js";
+import type BBranch from "../../becca/entities/bbranch.js";
+import type { Response } from "express";
+import { RESOURCE_DIR } from "../resource_dir.js";
+import type { NoteMetaFile } from "../meta/note_meta.js";
+
+type RewriteLinksFn = (content: string, noteMeta: NoteMeta) => string;
+
+export interface AdvancedExportOptions {
+    /**
+     * If `true`, then only the note's content will be kept. If `false` (default), then each page will have its own <html> template.
+     */
+    skipHtmlTemplate?: boolean;
+
+    /**
+     * Provides a custom function to rewrite the links found in HTML or Markdown notes. This method is called for every note imported, if it's of the right type.
+     *
+     * @param originalRewriteLinks the original rewrite links function. Can be used to access the default behaviour without having to reimplement it.
+     * @param getNoteTargetUrl the method to obtain a note's target URL, used internally by `originalRewriteLinks` but can be used here as well.
+     * @returns a function to rewrite the links in HTML or Markdown notes.
+     */
+    customRewriteLinks?: (originalRewriteLinks: RewriteLinksFn, getNoteTargetUrl: (targetNoteId: string, sourceMeta: NoteMeta) => string | null) => RewriteLinksFn;
+}
+
+async function exportToZip(taskContext: TaskContext, branch: BBranch, format: "html" | "markdown", res: Response | fs.WriteStream, setHeaders = true, zipExportOptions?: AdvancedExportOptions) {
+    if (!["html", "markdown"].includes(format)) {
+        throw new ValidationError(`Only 'html' and 'markdown' allowed as export format, '${format}' given`);
+    }
+
+    const archive = archiver("zip", {
+        zlib: { level: 9 } // Sets the compression level.
+    });
+
+    const noteIdToMeta: Record<string, NoteMeta> = {};
+
+    function getUniqueFilename(existingFileNames: Record<string, number>, fileName: string) {
+        const lcFileName = fileName.toLowerCase();
+
+        if (lcFileName in existingFileNames) {
+            let index;
+            let newName;
+
+            do {
+                index = existingFileNames[lcFileName]++;
+
+                newName = `${index}_${lcFileName}`;
+            } while (newName in existingFileNames);
+
+            return `${index}_${fileName}`;
+        } else {
+            existingFileNames[lcFileName] = 1;
+
+            return fileName;
+        }
+    }
+
+    function getDataFileName(type: string | null, mime: string, baseFileName: string, existingFileNames: Record<string, number>): string {
+        let fileName = baseFileName.trim();
+
+        // Crop fileName to avoid its length exceeding 30 and prevent cutting into the extension.
+        if (fileName.length > 30) {
+            // We use regex to match the extension to preserve multiple dots in extensions (e.g. .tar.gz).
+            let match = fileName.match(/(\.[a-zA-Z0-9_.!#-]+)$/);
+            let ext = match ? match[0] : "";
+            // Crop the extension if extension length exceeds 30
+            const croppedExt = ext.slice(-30);
+            // Crop the file name section and append the cropped extension
+            fileName = fileName.slice(0, 30 - croppedExt.length) + croppedExt;
+        }
+
+        let existingExtension = path.extname(fileName).toLowerCase();
+        let newExtension;
+
+        // the following two are handled specifically since we always want to have these extensions no matter the automatic detection
+        // and/or existing detected extensions in the note name
+        if (type === "text" && format === "markdown") {
+            newExtension = "md";
+        } else if (type === "text" && format === "html") {
+            newExtension = "html";
+        } else if (mime === "application/x-javascript" || mime === "text/javascript") {
+            newExtension = "js";
+        } else if (type === "canvas" || mime === "application/json") {
+            newExtension = "json";
+        } else if (existingExtension.length > 0) {
+            // if the page already has an extension, then we'll just keep it
+            newExtension = null;
+        } else {
+            if (mime?.toLowerCase()?.trim() === "image/jpg") {
+                newExtension = "jpg";
+            } else if (mime?.toLowerCase()?.trim() === "text/mermaid") {
+                newExtension = "txt";
+            } else {
+                newExtension = mimeTypes.extension(mime) || "dat";
+            }
+        }
+
+        // if the note is already named with the extension (e.g. "image.jpg"), then it's silly to append the exact same extension again
+        if (newExtension && existingExtension !== `.${newExtension.toLowerCase()}`) {
+            fileName += `.${newExtension}`;
+        }
+
+        return getUniqueFilename(existingFileNames, fileName);
+    }
+
+    function createNoteMeta(branch: BBranch, parentMeta: Partial<NoteMeta>, existingFileNames: Record<string, number>): NoteMeta | null {
+        const note = branch.getNote();
+
+        if (note.hasOwnedLabel("excludeFromExport")) {
+            return null;
+        }
+
+        const title = note.getTitleOrProtected();
+        const completeTitle = branch.prefix ? `${branch.prefix} - ${title}` : title;
+        let baseFileName = sanitize(completeTitle);
+
+        if (baseFileName.length > 200) {
+            // the actual limit is 256 bytes(!) but let's be conservative
+            baseFileName = baseFileName.substr(0, 200);
+        }
+
+        if (!parentMeta.notePath) {
+            throw new Error("Missing parent note path.");
+        }
+        const notePath = parentMeta.notePath.concat([note.noteId]);
+
+        if (note.noteId in noteIdToMeta) {
+            const fileName = getUniqueFilename(existingFileNames, `${baseFileName}.clone.${format === "html" ? "html" : "md"}`);
+
+            const meta: NoteMeta = {
+                isClone: true,
+                noteId: note.noteId,
+                notePath: notePath,
+                title: note.getTitleOrProtected(),
+                prefix: branch.prefix,
+                dataFileName: fileName,
+                type: "text", // export will have text description
+                format: format
+            };
+            return meta;
+        }
+
+        const meta: Partial<NoteMeta> = {};
+        meta.isClone = false;
+        meta.noteId = note.noteId;
+        meta.notePath = notePath;
+        meta.title = note.getTitleOrProtected();
+        meta.notePosition = branch.notePosition;
+        meta.prefix = branch.prefix;
+        meta.isExpanded = branch.isExpanded;
+        meta.type = note.type;
+        meta.mime = note.mime;
+        meta.attributes = note.getOwnedAttributes().map((attribute) => {
+            const attrMeta: AttributeMeta = {
+                type: attribute.type,
+                name: attribute.name,
+                value: attribute.value,
+                isInheritable: attribute.isInheritable,
+                position: attribute.position
+            };
+
+            return attrMeta;
+        });
+
+        taskContext.increaseProgressCount();
+
+        if (note.type === "text") {
+            meta.format = format;
+        }
+
+        noteIdToMeta[note.noteId] = meta as NoteMeta;
+
+        // sort children for having a stable / reproducible export format
+        note.sortChildren();
+        const childBranches = note.getChildBranches().filter((branch) => branch?.noteId !== "_hidden");
+
+        const available = !note.isProtected || protectedSessionService.isProtectedSessionAvailable();
+
+        // if it's a leaf, then we'll export it even if it's empty
+        if (available && (note.getContent().length > 0 || childBranches.length === 0)) {
+            meta.dataFileName = getDataFileName(note.type, note.mime, baseFileName, existingFileNames);
+        }
+
+        const attachments = note.getAttachments();
+        meta.attachments = attachments
+            .toSorted((a, b) => ((a.attachmentId ?? "").localeCompare(b.attachmentId ?? "", "en") ?? 1))
+            .map((attachment) => {
+            const attMeta: AttachmentMeta = {
+                attachmentId: attachment.attachmentId,
+                title: attachment.title,
+                role: attachment.role,
+                mime: attachment.mime,
+                position: attachment.position,
+                dataFileName: getDataFileName(null, attachment.mime, baseFileName + "_" + attachment.title, existingFileNames)
+            };
+            return attMeta;
+        });
+
+        if (childBranches.length > 0) {
+            meta.dirFileName = getUniqueFilename(existingFileNames, baseFileName);
+            meta.children = [];
+
+            // namespace is shared by children in the same note
+            const childExistingNames = {};
+
+            for (const childBranch of childBranches) {
+                if (!childBranch) {
+                    continue;
+                }
+
+                const note = createNoteMeta(childBranch, meta as NoteMeta, childExistingNames);
+
+                // can be undefined if export is disabled for this note
+                if (note) {
+                    meta.children.push(note);
+                }
+            }
+        }
+
+        return meta as NoteMeta;
+    }
+
+    function getNoteTargetUrl(targetNoteId: string, sourceMeta: NoteMeta): string | null {
+        const targetMeta = noteIdToMeta[targetNoteId];
+
+        if (!targetMeta || !targetMeta.notePath || !sourceMeta.notePath) {
+            return null;
+        }
+
+        const targetPath = targetMeta.notePath.slice();
+        const sourcePath = sourceMeta.notePath.slice();
+
+        // > 1 for the edge case that targetPath and sourcePath are exact same (a link to itself)
+        while (targetPath.length > 1 && sourcePath.length > 1 && targetPath[0] === sourcePath[0]) {
+            targetPath.shift();
+            sourcePath.shift();
+        }
+
+        let url = "../".repeat(sourcePath.length - 1);
+
+        for (let i = 0; i < targetPath.length - 1; i++) {
+            const meta = noteIdToMeta[targetPath[i]];
+            if (meta.dirFileName) {
+                url += `${encodeURIComponent(meta.dirFileName)}/`;
+            }
+        }
+
+        const meta = noteIdToMeta[targetPath[targetPath.length - 1]];
+
+        // link can target note which is only "folder-note" and as such, will not have a file in an export
+        url += encodeURIComponent(meta.dataFileName || meta.dirFileName || "");
+
+        return url;
+    }
+
+    const rewriteFn = (zipExportOptions?.customRewriteLinks ? zipExportOptions?.customRewriteLinks(rewriteLinks, getNoteTargetUrl) : rewriteLinks);
+
+    function rewriteLinks(content: string, noteMeta: NoteMeta): string {
+        content = content.replace(/src="[^"]*api\/images\/([a-zA-Z0-9_]+)\/[^"]*"/g, (match, targetNoteId) => {
+            const url = getNoteTargetUrl(targetNoteId, noteMeta);
+
+            return url ? `src="${url}"` : match;
+        });
+
+        content = content.replace(/src="[^"]*api\/attachments\/([a-zA-Z0-9_]+)\/image\/[^"]*"/g, (match, targetAttachmentId) => {
+            const url = findAttachment(targetAttachmentId);
+
+            return url ? `src="${url}"` : match;
+        });
+
+        content = content.replace(/href="[^"]*#root[^"]*attachmentId=([a-zA-Z0-9_]+)\/?"/g, (match, targetAttachmentId) => {
+            const url = findAttachment(targetAttachmentId);
+
+            return url ? `href="${url}"` : match;
+        });
+
+        content = content.replace(/href="[^"]*#root[a-zA-Z0-9_\/]*\/([a-zA-Z0-9_]+)[^"]*"/g, (match, targetNoteId) => {
+            const url = getNoteTargetUrl(targetNoteId, noteMeta);
+
+            return url ? `href="${url}"` : match;
+        });
+
+        return content;
+
+        function findAttachment(targetAttachmentId: string) {
+            let url;
+
+            const attachmentMeta = (noteMeta.attachments || []).find((attMeta) => attMeta.attachmentId === targetAttachmentId);
+            if (attachmentMeta) {
+                // easy job here, because attachment will be in the same directory as the note's data file.
+                url = attachmentMeta.dataFileName;
+            } else {
+                log.info(`Could not find attachment meta object for attachmentId '${targetAttachmentId}'`);
+            }
+            return url;
+        }
+    }
+
+    function prepareContent(title: string, content: string | Buffer, noteMeta: NoteMeta): string | Buffer {
+        if (["html", "markdown"].includes(noteMeta?.format || "")) {
+            content = content.toString();
+            content = rewriteFn(content, noteMeta);
+        }
+
+        if (noteMeta.format === "html" && typeof content === "string") {
+            if (!content.substr(0, 100).toLowerCase().includes("<html") && !zipExportOptions?.skipHtmlTemplate) {
+                if (!noteMeta?.notePath?.length) {
+                    throw new Error("Missing note path.");
+                }
+
+                const cssUrl = `${"../".repeat(noteMeta.notePath.length - 1)}style.css`;
+                const htmlTitle = escapeHtml(title);
+
+                // <base> element will make sure external links are openable - https://github.com/zadam/trilium/issues/1289#issuecomment-704066809
+                content = `<html>
+<head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <link rel="stylesheet" href="${cssUrl}">
+    <base target="_parent">
+    <title data-trilium-title>${htmlTitle}</title>
+</head>
+<body>
+  <div class="content">
+    <h1 data-trilium-h1>${htmlTitle}</h1>
+
+    <div class="ck-content">${content}</div>
+  </div>
+</body>
+</html>`;
+            }
+
+            return content.length < 100_000 ? html.prettyPrint(content, { indent_size: 2 }) : content;
+        } else if (noteMeta.format === "markdown" && typeof content === "string") {
+            let markdownContent = mdService.toMarkdown(content);
+
+            if (markdownContent.trim().length > 0 && !markdownContent.startsWith("# ")) {
+                markdownContent = `# ${title}\r
+${markdownContent}`;
+            }
+
+            return markdownContent;
+        } else {
+            return content;
+        }
+    }
+
+    function saveNote(noteMeta: NoteMeta, filePathPrefix: string) {
+        log.info(`Exporting note '${noteMeta.noteId}'`);
+
+        if (!noteMeta.noteId || !noteMeta.title) {
+            throw new Error("Missing note meta.");
+        }
+
+        if (noteMeta.isClone) {
+            const targetUrl = getNoteTargetUrl(noteMeta.noteId, noteMeta);
+
+            let content: string | Buffer = `<p>This is a clone of a note. Go to its <a href="${targetUrl}">primary location</a>.</p>`;
+
+            content = prepareContent(noteMeta.title, content, noteMeta);
+
+            archive.append(content, { name: filePathPrefix + noteMeta.dataFileName });
+
+            return;
+        }
+
+        const note = becca.getNote(noteMeta.noteId);
+        if (!note) {
+            throw new Error("Unable to find note.");
+        }
+        if (!note.utcDateModified) {
+            throw new Error("Unable to find modification date.");
+        }
+
+        if (noteMeta.dataFileName) {
+            const content = prepareContent(noteMeta.title, note.getContent(), noteMeta);
+
+            archive.append(content, {
+                name: filePathPrefix + noteMeta.dataFileName,
+                date: dateUtils.parseDateTime(note.utcDateModified)
+            });
+        }
+
+        taskContext.increaseProgressCount();
+
+        for (const attachmentMeta of noteMeta.attachments || []) {
+            if (!attachmentMeta.attachmentId) {
+                continue;
+            }
+
+            const attachment = note.getAttachmentById(attachmentMeta.attachmentId);
+            const content = attachment.getContent();
+
+            archive.append(content, {
+                name: filePathPrefix + attachmentMeta.dataFileName,
+                date: dateUtils.parseDateTime(note.utcDateModified)
+            });
+        }
+
+        if (noteMeta.children?.length || 0 > 0) {
+            const directoryPath = filePathPrefix + noteMeta.dirFileName;
+
+            // create directory
+            archive.append("", { name: `${directoryPath}/`, date: dateUtils.parseDateTime(note.utcDateModified) });
+
+            for (const childMeta of noteMeta.children || []) {
+                saveNote(childMeta, `${directoryPath}/`);
+            }
+        }
+    }
+
+    function saveNavigation(rootMeta: NoteMeta, navigationMeta: NoteMeta) {
+        if (!navigationMeta.dataFileName) {
+            return;
+        }
+
+        function saveNavigationInner(meta: NoteMeta) {
+            let html = "<li>";
+
+            const escapedTitle = escapeHtml(`${meta.prefix ? `${meta.prefix} - ` : ""}${meta.title}`);
+
+            if (meta.dataFileName && meta.noteId) {
+                const targetUrl = getNoteTargetUrl(meta.noteId, rootMeta);
+
+                html += `<a href="${targetUrl}" target="detail">${escapedTitle}</a>`;
+            } else {
+                html += escapedTitle;
+            }
+
+            if (meta.children && meta.children.length > 0) {
+                html += "<ul>";
+
+                for (const child of meta.children) {
+                    html += saveNavigationInner(child);
+                }
+
+                html += "</ul>";
+            }
+
+            return `${html}</li>`;
+        }
+
+        const fullHtml = `<html>
+<head>
+    <meta charset="utf-8">
+    <link rel="stylesheet" href="style.css">
+</head>
+<body>
+    <ul>${saveNavigationInner(rootMeta)}</ul>
+</body>
+</html>`;
+        const prettyHtml = fullHtml.length < 100_000 ? html.prettyPrint(fullHtml, { indent_size: 2 }) : fullHtml;
+
+        archive.append(prettyHtml, { name: navigationMeta.dataFileName });
+    }
+
+    function saveIndex(rootMeta: NoteMeta, indexMeta: NoteMeta) {
+        let firstNonEmptyNote;
+        let curMeta = rootMeta;
+
+        if (!indexMeta.dataFileName) {
+            return;
+        }
+
+        while (!firstNonEmptyNote) {
+            if (curMeta.dataFileName && curMeta.noteId) {
+                firstNonEmptyNote = getNoteTargetUrl(curMeta.noteId, rootMeta);
+            }
+
+            if (curMeta.children && curMeta.children.length > 0) {
+                curMeta = curMeta.children[0];
+            } else {
+                break;
+            }
+        }
+
+        const fullHtml = `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html>
+<head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+</head>
+<frameset cols="25%,75%">
+    <frame name="navigation" src="navigation.html">
+    <frame name="detail" src="${firstNonEmptyNote}">
+</frameset>
+</html>`;
+
+        archive.append(fullHtml, { name: indexMeta.dataFileName });
+    }
+
+    function saveCss(rootMeta: NoteMeta, cssMeta: NoteMeta) {
+        if (!cssMeta.dataFileName) {
+            return;
+        }
+
+        const cssContent = fs.readFileSync(`${RESOURCE_DIR}/libraries/ckeditor/ckeditor-content.css`);
+
+        archive.append(cssContent, { name: cssMeta.dataFileName });
+    }
+
+    const existingFileNames: Record<string, number> = format === "html" ? { navigation: 0, index: 1 } : {};
+    const rootMeta = createNoteMeta(branch, { notePath: [] }, existingFileNames);
+    if (!rootMeta) {
+        throw new Error("Unable to create root meta.");
+    }
+
+    const metaFile: NoteMetaFile = {
+        formatVersion: 2,
+        appVersion: packageInfo.version,
+        files: [rootMeta]
+    };
+
+    let navigationMeta: NoteMeta | null = null;
+    let indexMeta: NoteMeta | null = null;
+    let cssMeta: NoteMeta | null = null;
+
+    if (format === "html") {
+        navigationMeta = {
+            noImport: true,
+            dataFileName: "navigation.html"
+        };
+
+        metaFile.files.push(navigationMeta);
+
+        indexMeta = {
+            noImport: true,
+            dataFileName: "index.html"
+        };
+
+        metaFile.files.push(indexMeta);
+
+        cssMeta = {
+            noImport: true,
+            dataFileName: "style.css"
+        };
+
+        metaFile.files.push(cssMeta);
+    }
+
+    for (const noteMeta of Object.values(noteIdToMeta)) {
+        // filter out relations which are not inside this export
+        noteMeta.attributes = (noteMeta.attributes || []).filter((attr) => {
+            if (attr.type !== "relation") {
+                return true;
+            } else if (attr.value in noteIdToMeta) {
+                return true;
+            } else if (attr.value === "root" || attr.value?.startsWith("_")) {
+                // relations to "named" noteIds can be preserved
+                return true;
+            } else {
+                return false;
+            }
+        });
+    }
+
+    if (!rootMeta) {
+        // corner case of disabled export for exported note
+        if ("sendStatus" in res) {
+            res.sendStatus(400);
+        }
+        return;
+    }
+
+    const metaFileJson = JSON.stringify(metaFile, null, "\t");
+
+    archive.append(metaFileJson, { name: "!!!meta.json" });
+
+    saveNote(rootMeta, "");
+
+    if (format === "html") {
+        if (!navigationMeta || !indexMeta || !cssMeta) {
+            throw new Error("Missing meta.");
+        }
+
+        saveNavigation(rootMeta, navigationMeta);
+        saveIndex(rootMeta, indexMeta);
+        saveCss(rootMeta, cssMeta);
+    }
+
+    const note = branch.getNote();
+    const zipFileName = `${branch.prefix ? `${branch.prefix} - ` : ""}${note.getTitleOrProtected()}.zip`;
+
+    if (setHeaders && "setHeader" in res) {
+        res.setHeader("Content-Disposition", getContentDisposition(zipFileName));
+        res.setHeader("Content-Type", "application/zip");
+    }
+
+    archive.pipe(res);
+    await archive.finalize();
+
+    taskContext.taskSucceeded();
+}
+
+async function exportToZipFile(noteId: string, format: "markdown" | "html", zipFilePath: string, zipExportOptions?: AdvancedExportOptions) {
+    const fileOutputStream = fs.createWriteStream(zipFilePath);
+    const taskContext = new TaskContext("no-progress-reporting");
+
+    const note = becca.getNote(noteId);
+
+    if (!note) {
+        throw new ValidationError(`Note ${noteId} not found.`);
+    }
+
+    await exportToZip(taskContext, note.getParentBranches()[0], format, fileOutputStream, false, zipExportOptions);
+
+    log.info(`Exported '${noteId}' with format '${format}' to '${zipFilePath}'`);
+}
+
+export default {
+    exportToZip,
+    exportToZipFile
+};