把 YouTube 影片變成一篇可發佈的文章

const BASE = "https://openapi.felo.ai";
const headers = {
  Authorization: `Bearer ${process.env.FELO_API_KEY}`,
  "Content-Type": "application/json",
};

async function felo<T>(path: string, body?: unknown): Promise<T> {
  const res = await fetch(`${BASE}${path}`, {
    method: body ? "POST" : "GET",
    headers,
    body: body ? JSON.stringify(body) : undefined,
  });
  if (!res.ok) throw new Error(`${res.status}: ${await res.text()}`);
  return res.json() as Promise<T>;
}

type Transcript = {
  data: {
    title: string;
    contents: { text: string; start: number; duration: number }[];
  };
};

export async function fetchTranscript(videoId: string, language = "en") {
  const query = new URLSearchParams({
    video_code: videoId,
    language,
    with_time: "true",
  });
  const { data } = await felo<Transcript>(`/v2/youtube/subtitling?${query}`);
  if (data.contents.length === 0) throw new Error("This video has no subtitles");
  return data;
}

const toClock = (seconds: number) => {
  const minutes = Math.floor(seconds / 60);
  const rest = Math.floor(seconds % 60);
  return `${String(minutes).padStart(2, "0")}:${String(rest).padStart(2, "0")}`;
};

export function toBlocks(
  contents: Transcript["data"]["contents"],
  window = 60,
) {
  const grouped = new Map<number, string[]>();
  for (const line of contents) {
    const bucket = Math.floor(line.start / window) * window;
    grouped.set(bucket, [...(grouped.get(bucket) ?? []), line.text.trim()]);
  }
  return [...grouped]
    .map(([start, lines]) => `[${toClock(start)}] ${lines.join(" ")}`)
    .join("\n\n");
}

type ExtractData = { data: { content: string } };

export async function fetchSources(urls: string[]) {
  return Promise.all(
    urls.slice(0, 5).map(async (url) => {
      const page = await felo<ExtractData>("/v2/web/extract", {
        url,
        output_format: "markdown",
        with_readability: true,
      });
      return { url, content: page.data.content };
    }),
  );
}

const MODEL_API = "https://openapi.felo.ai/api/v1";

type Completion = {
  choices: { message: { content: string } }[];
  usage: { prompt_tokens: number; completion_tokens: number; total_tokens: number };
};

async function complete(model: string, prompt: string): Promise<Completion> {
  const res = await fetch(`${MODEL_API}/chat/completions`, {
    method: "POST",
    headers,
    body: JSON.stringify({ model, messages: [{ role: "user", content: prompt }] }),
  });
  if (!res.ok) throw new Error(`${res.status}: ${await res.text()}`);
  return res.json() as Promise<Completion>;
}

export async function draftArticle(title: string, transcript: string) {
  const outline = await complete(
    "claude-haiku-5-5",
    "Outline a short article from this transcript. Return only headings.\n\n" + transcript,
  );
  const article = await complete(
    "claude-sonnet-5-5",
    `Write the article "${title}" from the transcript. Follow the outline and keep [mm:ss] on direct quotes.\n\nOutline:\n${outline.choices[0].message.content}\n\nTranscript:\n${transcript}`,
  );
  return {
    outline: outline.choices[0].message.content,
    article: article.choices[0].message.content,
    usage: article.usage,
  };
}

type LiveDocData = { data: { short_id: string } };
type ResourceData = { data: { id: string } };

export async function saveDraft(
  title: string,
  result: { outline: string; article: string },
) {
  const doc = await felo<LiveDocData>("/v2/livedocs", {
    name: `Article draft: ${title}`,
    description: "Draft generated from a video transcript",
  });

  await felo<ResourceData>(`/v2/livedocs/${doc.data.short_id}/resources/doc`, {
    title: "Draft",
    content: result.article,
  });

  await felo<ResourceData>(`/v2/livedocs/${doc.data.short_id}/resources/doc`, {
    title: "Outline",
    content: result.outline,
  });

  return doc.data.short_id;
}