import { spawn } from "child_process";
import path from "path";
import fs from "fs";

/**
 * Executes the Python watermark processor on an image file on disk.
 * Applies:
 * 1. School logo without background in top-left corner
 * 2. Scannable official WeChat QR code in bottom-right corner
 * 3. Bottom text: '上海健志空手道馆 · Shanghai Karate Club · Est. 2008'
 */
export async function applyWatermarkToFile(filePath: string): Promise<void> {
  return new Promise((resolve, reject) => {
    if (!fs.existsSync(filePath)) {
      return resolve();
    }

    const scriptPath = path.join(process.cwd(), "watermark_processor.py");
    const py = spawn("python", [scriptPath, filePath, filePath]);

    py.on("close", (code) => {
      if (code === 0) {
        resolve();
      } else {
        console.warn(`[Watermark] Python watermark process exited with code ${code}`);
        resolve(); // Graceful fallback
      }
    });

    py.on("error", (err) => {
      console.warn("[Watermark] Failed to spawn watermark process:", err);
      resolve(); // Graceful fallback
    });
  });
}