// A scheduled Mastra workflow: every morning, fetch the top Hacker News
// stories, have a model write a short digest, and save it to the agent's
// workspace, where the agent can read it later.
// From https://exe.dev/deploy/mastra/hn-digest.ts
import { mkdir, writeFile } from 'node:fs/promises';
import { Agent } from '@mastra/core/agent';
import { createStep, createWorkflow } from '@mastra/core/workflows';
import { z } from 'zod';

const story = z.object({ title: z.string(), url: z.string(), points: z.number() });

const fetchStories = createStep({
  id: 'fetch-stories',
  inputSchema: z.object({ count: z.number().int().min(1).max(30) }),
  outputSchema: z.object({ stories: z.array(story) }),
  execute: async ({ inputData }) => {
    const hn = 'https://hacker-news.firebaseio.com/v0';
    const ids: number[] = await (await fetch(`${hn}/topstories.json`)).json();
    const stories = await Promise.all(
      ids.slice(0, inputData.count).map(async (id) => {
        const item = await (await fetch(`${hn}/item/${id}.json`)).json();
        return {
          title: item.title,
          url: item.url ?? `https://news.ycombinator.com/item?id=${id}`,
          points: item.score ?? 0,
        };
      }),
    );
    return { stories };
  },
});

const writer = new Agent({
  id: 'digest-writer',
  name: 'Digest writer',
  instructions:
    'Write a short Markdown digest of the stories you are given: a one-line theme, then one bullet per story with its link and why it matters, in under 15 words.',
  model: 'openai/gpt-6-luna',
});

const writeDigest = createStep({
  id: 'write-digest',
  inputSchema: z.object({ stories: z.array(story) }),
  outputSchema: z.object({ file: z.string(), digest: z.string() }),
  execute: async ({ inputData }) => {
    const { text } = await writer.generate(JSON.stringify(inputData.stories));
    const file = `workspace/digests/${new Date().toISOString().slice(0, 10)}.md`;
    await mkdir('workspace/digests', { recursive: true });
    await writeFile(file, text + '\n');
    return { file, digest: text };
  },
});

export const hnDigest = createWorkflow({
  id: 'hn-digest',
  inputSchema: z.object({ count: z.number().int().min(1).max(30) }),
  outputSchema: z.object({ file: z.string(), digest: z.string() }),
  schedule: { cron: '0 7 * * *', timezone: 'UTC', inputData: { count: 10 } },
})
  .then(fetchStories)
  .then(writeDigest)
  .commit();