export function addSvelteKitEnvModules(aliases: Record<string, string>) {
  aliases["$env/dynamic/private"] = createDataUriModule(createDynamicEnvModule());
  aliases["$env/dynamic/public"] = createDataUriModule(createDynamicEnvModule());
  aliases["$env/static/private"] = createDataUriModule(createStaticEnvModule(filterPrivateEnv("PUBLIC_", "")));
  aliases["$env/static/public"] = createDataUriModule(createStaticEnvModule(filterPublicEnv("PUBLIC_", "")));
}

function createDataUriModule(module: string) {
  return `data:text/javascript;charset=utf-8,${encodeURIComponent(module)}`;
}

function createStaticEnvModule(env: Record<string, string>) {
  const declarations = Object.keys(env)
    .filter((k) => validIdentifier.test(k) && !reserved.has(k))
    .map((k) => `export const ${k} = ${JSON.stringify(env[k])};`);

  return `
  ${declarations.join("\n")}
  // jiti dirty hack: .unknown
  `;
}

function createDynamicEnvModule() {
  return `
  export const env = process.env;
  // jiti dirty hack: .unknown
  `;
}

export function filterPrivateEnv(publicPrefix: string, privatePrefix: string) {
  return Object.fromEntries(
    Object.entries(process.env).filter(
      ([k]) => k.startsWith(privatePrefix) && (publicPrefix === "" || !k.startsWith(publicPrefix)),
    ),
  ) as Record<string, string>;
}

export function filterPublicEnv(publicPrefix: string, privatePrefix: string) {
  return Object.fromEntries(
    Object.entries(process.env).filter(
      ([k]) => k.startsWith(publicPrefix) && (privatePrefix === "" || !k.startsWith(privatePrefix)),
    ),
  ) as Record<string, string>;
}

const validIdentifier = /^[a-zA-Z_$][a-zA-Z0-9_$]*$/;
const reserved = new Set([
  "do",
  "if",
  "in",
  "for",
  "let",
  "new",
  "try",
  "var",
  "case",
  "else",
  "enum",
  "eval",
  "null",
  "this",
  "true",
  "void",
  "with",
  "await",
  "break",
  "catch",
  "class",
  "const",
  "false",
  "super",
  "throw",
  "while",
  "yield",
  "delete",
  "export",
  "import",
  "public",
  "return",
  "static",
  "switch",
  "typeof",
  "default",
  "extends",
  "finally",
  "package",
  "private",
  "continue",
  "debugger",
  "function",
  "arguments",
  "interface",
  "protected",
  "implements",
  "instanceof",
]);