/**
* Tool: set_frontmatter
* Ensures Marp-required frontmatter fields exist with the correct values.
*/
import { promises as fs } from "fs";
import { z } from "zod";
import matter from "gray-matter";
import { getActiveTheme } from "../themes/index.js";
import { getActiveStyle } from "../styles/index.js";
import { validateFilePath } from "../utils/path-validator.js";
import type { ToolResponse } from "../types/common.js";
const MAX_FILE_SIZE = 10 * 1024 * 1024; // 10MB
type TargetKey = "marp" | "theme" | "header" | "paginate" | "style";
export const setFrontmatterSchema = z.object({
filePath: z.string().describe("Absolute path to the Marp markdown file"),
header: z
.string()
.optional()
.describe("Optional header text. If omitted and no header exists, a blank header entry is created."),
paginate: z
.boolean()
.optional()
.describe("Optional paginate flag. If omitted and no value exists, paginate defaults to false."),
});
/**
* Sets or updates Marp frontmatter fields in a markdown file.
*
* @param {object} options - The frontmatter options
* @param {string} options.filePath - Absolute path to the Marp markdown file
* @param {string} [options.header] - Optional header text
* @param {boolean} [options.paginate] - Optional paginate flag
* @returns {Promise<ToolResponse>} Operation result
*/
export async function setFrontmatter({
filePath,
header,
paginate,
}: z.infer<typeof setFrontmatterSchema>): Promise<ToolResponse> {
// Validate file path
const pathError = validateFilePath(filePath);
if (pathError) {
return {
content: [
{
type: "text",
text: `Error: ${pathError}`,
},
],
};
}
let existingContent: string;
try {
existingContent = await fs.readFile(filePath, "utf-8");
} catch (error) {
return {
content: [
{
type: "text",
text: `Error: Could not read file at ${filePath}: ${error instanceof Error ? error.message : String(error)}`,
},
],
};
}
// Check file size
if (existingContent.length > MAX_FILE_SIZE) {
return {
content: [
{
type: "text",
text: `Error: File too large (${existingContent.length} bytes, max ${MAX_FILE_SIZE} bytes)`,
},
],
};
}
// Parse existing frontmatter
let parsed;
try {
parsed = matter(existingContent);
} catch (error) {
return {
content: [
{
type: "text",
text: `Error: Invalid YAML frontmatter: ${error instanceof Error ? error.message : String(error)}`,
},
],
};
}
const data = parsed.data as Record<string, any>;
// Get active theme and style
const activeTheme = getActiveTheme().name;
const activeStyleDef = getActiveStyle();
// Determine header value
const headerValue = header !== undefined
? header
: (data.header !== undefined ? String(data.header) : "");
// Determine paginate value
const paginateValue = paginate !== undefined
? paginate
: (data.paginate !== undefined ? Boolean(data.paginate) : false);
// Update frontmatter data
const newData: Record<string, any> = {
...data,
marp: true,
theme: activeTheme,
header: headerValue,
paginate: paginateValue,
};
// Inject style CSS if active style has CSS
if (activeStyleDef.css) {
newData.style = activeStyleDef.css;
}
// Stringify with gray-matter
const updatedContent = matter.stringify(parsed.content, newData);
// Check if content actually changed
if (updatedContent === existingContent) {
return {
content: [
{
type: "text",
text: JSON.stringify(
{
success: true,
message: "Frontmatter already satisfied requirements",
file: filePath,
style: activeStyleDef.name,
frontmatter: {
marp: true,
theme: activeTheme,
header: headerValue,
paginate: paginateValue,
},
},
null,
2,
),
},
],
};
}
// Write updated content
await fs.writeFile(filePath, updatedContent, "utf-8");
return {
content: [
{
type: "text",
text: JSON.stringify(
{
success: true,
message: "Updated frontmatter successfully",
file: filePath,
style: activeStyleDef.name,
frontmatter: {
marp: true,
theme: activeTheme,
header: headerValue,
paginate: paginateValue,
},
},
null,
2,
),
},
],
};
}
