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

interface BackupToPathParams {
  destinationPath: string;
  filename: string; // should end in .zip
}

export async function backupDatabaseToPath({
  destinationPath,
  filename,
}: BackupToPathParams): Promise<void> {
  // Verify write access before spawning pg_dump
  try {
    fs.accessSync(destinationPath, fs.constants.W_OK);
  } catch {
    throw new Error(
      `No write permission to "${destinationPath}". Try running: sudo chmod a+w "${destinationPath}"`
    );
  }

  const zipFile = path.join(destinationPath, filename);
  const sqlName = filename.replace(/\.zip$/, ".sql");

  return new Promise((resolve, reject) => {
    const output = fs.createWriteStream(zipFile);
    const archive = archiver("zip", { zlib: { level: 6 } });

    output.on("close", () => resolve());
    archive.on("error", (err) => {
      try { if (fs.existsSync(zipFile)) fs.unlinkSync(zipFile); } catch {}
      reject(err);
    });

    archive.pipe(output);

    const pgDump = spawn(
      "pg_dump",
      [
        "--no-acl",
        "--no-owner",
        "-h", process.env.DB_HOST || "localhost",
        "-U", process.env.DB_USER || "postgres",
        process.env.DB_NAME || "dental_db",
      ],
      {
        env: { ...process.env, PGPASSWORD: process.env.DB_PASSWORD },
      }
    );

    let pgError = "";
    pgDump.stderr.on("data", (d) => (pgError += d.toString()));

    pgDump.on("error", (err) => {
      try { if (fs.existsSync(zipFile)) fs.unlinkSync(zipFile); } catch {}
      reject(new Error(`Failed to start pg_dump: ${err.message}. Make sure postgresql-client is installed.`));
    });

    pgDump.on("close", (code) => {
      if (code !== 0) {
        try { if (fs.existsSync(zipFile)) fs.unlinkSync(zipFile); } catch {}
        reject(new Error(pgError.trim() || `pg_dump exited with code ${code}`));
        return;
      }
      archive.finalize();
    });

    // Stream pg_dump stdout directly into the zip as a .sql entry
    archive.append(pgDump.stdout, { name: sqlName });
  });
}