memorium/lib/helpers.ts

export function json(content: unknown) {
  const headers = new Headers();
  headers.append("Content-Type", "application/json");
  return new Response(JSON.stringify(content), {
    headers,
  });
}

export const isValidUrl = (urlString: string) => {
  try {
    return Boolean(new URL(urlString));
  } catch (_e) {
    return false;
  }
};

export const fixRenderedMarkdown = (content: string) => {
  return content.replace("***\n", "---")
    .replace("----------------", "---")
    .replace("\n---", "---")
    .replace(/^(date:[^'\n]*)'|'/gm, (match, p1, p2) => {
      if (p1) {
        // This is a line starting with date: followed by single quotes
        return p1.replace(/'/gm, "");
      } else if (p2) {
        return "";
      } else {
        // This is a line with single quotes, but not starting with date:
        return match;
      }
    });
};

type StreamMessage = {
  type: "info";
  message: string;
} | {
  type: "error";
  message: string;
} | {
  type: "warning";
  message: string;
} | {
  type: "finished";
  url: string;
};

export async function fetchStream(
  url: string,
  cb: (chunk: StreamMessage) => void,
  init?: RequestInit,
) {
  const res = await fetch(url, init);
  if (!res.body) return;

  let buffer = "";
  const reader = res.body
    .pipeThrough(new TextDecoderStream())
    .pipeThrough(
      new TransformStream<string, string>({
        transform(chunk, controller) {
          buffer += chunk;
          let idx;
          while ((idx = buffer.indexOf("\n")) >= 0) {
            const line = buffer.slice(0, idx).trim();
            buffer = buffer.slice(idx + 1);
            if (line) controller.enqueue(line);
          }
        },
        flush(controller) {
          const line = buffer.trim();
          if (line) controller.enqueue(line);
        },
      }),
    )
    .getReader();

  while (true) {
    const { done, value } = await reader.read();
    if (done) break;
    cb(JSON.parse(value));
  }
}

export function hashString(message: string) {
  let hash = 0;
  for (let i = 0; i < message.length; i++) {
    const char = message.charCodeAt(i);
    hash = ((hash << 5) - hash) + char;
    hash = hash & hash; // Convert to 32bit integer
  }
  return hash;
}

export const createStreamResponse = () => {
  const encoder = new TextEncoder();
  let controller: ReadableStreamDefaultController<Uint8Array>;

  const body = new ReadableStream<Uint8Array>({
    start(c) {
      controller = c;
    },
  });

  const response = new Response(body, {
    headers: {
      // newline-delimited JSON
      "content-type": "application/x-ndjson; charset=utf-8",
      // prevent intermediaries from buffering/transforming
      "cache-control": "no-cache, no-transform",
      "x-content-type-options": "nosniff",
      // nginx hint to disable proxy buffering
      "x-accel-buffering": "no",
      // if you control compression, keep it off for streams
      // "content-encoding": "identity",
    },
  });

  const send = (obj: unknown) => {
    controller.enqueue(encoder.encode(JSON.stringify(obj) + "\n")); // ← delimiter
  };
  const cancel = () => controller.close();

  function info(message: string) {
    return send({ type: "info", message });
  }

  function error(message: string) {
    return send({ type: "error", message });
  }

  function warning(message: string) {
    return send({ type: "warning", message });
  }

  return {
    response,
    cancel,
    send,
    info,
    error,
    warning,
  };
};

export type StreamResponse = ReturnType<typeof createStreamResponse>;

export function debounce<T extends (...args: Parameters<T>) => void>(
  this: ThisParameterType<T>,
  fn: T,
  delay = 300,
) {
  let timer: ReturnType<typeof setTimeout> | undefined;
  return (...args: Parameters<T>) => {
    clearTimeout(timer);
    timer = setTimeout(() => fn.apply(this, args), delay);
  };
}

export function parseRating(rating: string | number) {
  if (typeof rating == "number") return rating;
  try {
    const res = parseInt(rating);
    if (!Number.isNaN(res)) return res;
  } catch (_e) {
    // This is okay
  }
  return rating.length / 2;
}

export async function convertOggToMp3(
  oggData: ArrayBuffer,
): Promise<Uint8Array> {
  const ffmpeg = new Deno.Command("ffmpeg", {
    args: ["-f", "ogg", "-i", "pipe:0", "-f", "mp3", "pipe:1"],
    stdin: "piped",
    stdout: "piped",
    stderr: "null",
  });

  const process = ffmpeg.spawn();
  const writer = process.stdin.getWriter();
  await writer.write(new Uint8Array(oggData));
  await writer.close();

  const output = await process.output();
  const { code } = await process.status;
  if (code !== 0) throw new Error(`FFmpeg exited with code ${code}`);
  return output.stdout;
}