import { readFileSync } from "node:fs";
import path from "node:path";

export function loadEnvFiles({
  cwd = process.cwd(),
  files = [".env", ".env.local"],
  override = false,
} = {}) {
  const originalKeys = new Set(Object.keys(process.env));

  for (const fileName of files) {
    const filePath = path.join(cwd, fileName);

    try {
      const source = readFileSync(filePath, "utf8");
      applyEnvSource(source, { override, originalKeys });
    } catch {
      continue;
    }
  }
}

function applyEnvSource(source, { override, originalKeys }) {
  for (const line of source.split(/\r?\n/)) {
    const trimmedLine = line.trim();

    if (!trimmedLine || trimmedLine.startsWith("#")) {
      continue;
    }

    const separatorIndex = trimmedLine.indexOf("=");

    if (separatorIndex === -1) {
      continue;
    }

    const key = trimmedLine.slice(0, separatorIndex).trim();
    const rawValue = trimmedLine.slice(separatorIndex + 1).trim();
    const value = rawValue.replace(/^['"]|['"]$/g, "");

    if (!key) {
      continue;
    }

    if (!override && originalKeys.has(key)) {
      continue;
    }

    process.env[key] = value;
  }
}