src/ui/inputHandler.ts


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export enum Key {
  CTRL_C = "ctrl_c",
  LEFT_ARROW = "left_arrow",
  RIGHT_ARROW = "right_arrow",
}

const keyToBuffer: Record<Key, Buffer> = {
  [Key.CTRL_C]: Buffer.from("\u0003"),
  [Key.LEFT_ARROW]: Buffer.from("\u001b[D"),
  [Key.RIGHT_ARROW]: Buffer.from("\u001b[C"),
};

export const createAndBindHandler = (
  onInput: (key: Key) => any,
  onExit: () => any
) => {
  process.stdin.setRawMode(true);

  let seq = Buffer.alloc(0);

  process.stdin.on("data", (inputBuffer) => {
    seq = Buffer.concat([seq, inputBuffer]);

    for (const [key, buffer] of Object.entries(keyToBuffer) as [
      Key,
      Buffer
    ][]) {
      if (
        !(
          seq.length >= buffer.length &&
          seq.slice(-buffer.length).equals(buffer)
        )
      ) {
        continue;
      }
      {
        if (key === Key.CTRL_C) {
          onExit();
        } else {
          onInput(key);
        }
        seq = Buffer.alloc(0);
        return;
      }
    }

    if (seq.length > 6) {
      seq = Buffer.alloc(0);
    }
  });

  process.stdin.resume();
};