tpmjs/packages/tools/createBlogPost/src/index.ts

/**
 * Blog Post Creation Tool for TPMJS
 * Creates structured blog posts with frontmatter and metadata
 *
 * This is a proper AI SDK v6 tool that can be used with streamText()
 * Uses jsonSchema() to avoid Zod 4 JSON Schema conversion issues with OpenAI
 */

import { jsonSchema, tool } from 'ai';

export interface BlogPost {
  frontmatter: {
    title: string;
    author: string;
    date: string;
    tags: string[];
    excerpt?: string;
    slug: string;
    wordCount: number;
    readingTime: number;
  };
  content: string;
  formattedOutput: string;
}

/**
 * Input type for Create Blog Post Tool
 */
type CreateBlogPostInput = {
  title: string;
  author: string;
  content: string;
  tags?: string[];
  format?: 'markdown' | 'mdx';
  excerpt?: string;
};

/**
 * Creates a slug from a title
 */
function createSlug(title: string): string {
  return title
    .toLowerCase()
    .trim()
    .replace(/[^\w\s-]/g, '')
    .replace(/[\s_-]+/g, '-')
    .replace(/^-+|-+$/g, '');
}

/**
 * Calculates reading time based on word count
 * Assumes average reading speed of 200 words per minute
 */
function calculateReadingTime(wordCount: number): number {
  return Math.ceil(wordCount / 200);
}

/**
 * Counts words in content
 */
function countWords(content: string): number {
  return content.trim().split(/\s+/).length;
}

/**
 * Formats frontmatter as YAML
 */
function formatFrontmatter(
  frontmatter: BlogPost['frontmatter'],
  format: 'markdown' | 'mdx'
): string {
  const delimiter = format === 'mdx' ? '---' : '---';
  const lines = [
    delimiter,
    `title: "${frontmatter.title}"`,
    `author: ${frontmatter.author}`,
    `date: ${frontmatter.date}`,
    `slug: ${frontmatter.slug}`,
    `tags: [${frontmatter.tags.map((tag) => `"${tag}"`).join(', ')}]`,
  ];

  if (frontmatter.excerpt) {
    lines.push(`excerpt: "${frontmatter.excerpt}"`);
  }

  lines.push(`wordCount: ${frontmatter.wordCount}`);
  lines.push(`readingTime: ${frontmatter.readingTime}`);
  lines.push(delimiter);

  return lines.join('\n');
}

/**
 * Create Blog Post Tool
 * Creates a structured blog post with frontmatter and metadata
 *
 * This is a proper AI SDK v6 tool that can be used with streamText()
 */
export const createBlogPostTool = tool({
  description:
    'Creates a structured blog post with frontmatter, metadata, slug, word count, and reading time. Outputs in Markdown or MDX format.',
  inputSchema: jsonSchema<CreateBlogPostInput>({
    type: 'object',
    properties: {
      title: {
        type: 'string',
        description: 'The title of the blog post',
      },
      author: {
        type: 'string',
        description: 'The author of the blog post',
      },
      content: {
        type: 'string',
        description: 'The main content of the blog post',
      },
      tags: {
        type: 'array',
        items: { type: 'string' },
        description: 'Array of tags for categorization',
      },
      format: {
        type: 'string',
        enum: ['markdown', 'mdx'],
        description: 'Output format for the blog post (default: markdown)',
      },
      excerpt: {
        type: 'string',
        description: 'Short excerpt or summary of the post',
      },
    },
    required: ['title', 'author', 'content'],
    additionalProperties: false,
  }),
  async execute({ title, author, content, tags = [], format = 'markdown', excerpt }) {
    // Validate required fields
    if (!title || title.trim().length === 0) {
      throw new Error('Title is required');
    }

    if (!author || author.trim().length === 0) {
      throw new Error('Author is required');
    }

    if (!content || content.trim().length === 0) {
      throw new Error('Content is required');
    }

    // Calculate metadata
    const slug = createSlug(title);
    const wordCount = countWords(content);
    const readingTime = calculateReadingTime(wordCount);
    const publishDate = new Date();

    // Build frontmatter
    const frontmatter: BlogPost['frontmatter'] = {
      title,
      author,
      date: publishDate.toISOString().split('T')[0] || '',
      tags,
      slug,
      wordCount,
      readingTime,
    };

    if (excerpt) {
      frontmatter.excerpt = excerpt;
    }

    // Format the complete blog post
    const formattedFrontmatter = formatFrontmatter(frontmatter, format);
    const formattedOutput = `${formattedFrontmatter}\n\n${content}`;

    return {
      frontmatter,
      content,
      formattedOutput,
    };
  },
});

/**
 * Export default for convenience
 */
export default createBlogPostTool;