import { X509Certificate } from "npm:@peculiar/x509";
import { AsnParser } from "npm:@peculiar/asn1-schema";
import { SubjectAlternativeName } from "npm:@peculiar/asn1-x509";

// Deno binding for the spire_ffi Rust crate

if (Deno.build.arch !== "x86_64" && Deno.build.arch !== "aarch64") {
  throw new Error("Unsupported architecture");
}

const libPath = (() => {
  if (Deno.build.os === "windows") return "./spire_ffi.dll";
  if (Deno.build.os === "darwin") return "./libspire_ffi.dylib";
  return "./libspire_ffi.so";
})();

let dylib: Deno.DynamicLibrary<any> | null = null;

try {
  dylib = Deno.dlopen(libPath, {
    fetch_svid: {
      parameters: ["pointer"],
      result: "pointer",
      nonblocking: true,
    },
    free_svid: {
      parameters: ["pointer"],
      result: "void",
    },
  });
} catch (_e) {
  console.warn(
    `Failed to load ${libPath}. Workload API fetching will be mocked/disabled if used.`,
  );
}

export interface SvidResponse {
  spiffe_id: string;
  x509_svid: Uint8Array;
  x509_svid_key: Uint8Array;
  bundle: Uint8Array;
}

export async function fetchSpiffeIdentity(
  socketPath: string = "/var/run/spire/agent.sock",
): Promise<SvidResponse> {
  if (!dylib) {
    console.warn(
      `[SPIRE FFI] Dynamic library (${libPath}) is not loaded. Mocking SVID response for local development.`,
    );
    return {
      spiffe_id: "spiffe://local.dev/mock",
      x509_svid: new Uint8Array(),
      x509_svid_key: new Uint8Array(),
      bundle: new Uint8Array(),
    };
  }

  const encoder = new TextEncoder();
  const encodedPath = encoder.encode(socketPath + "\0");
  const pathPtr = Deno.UnsafePointer.of(encodedPath);

  const fetch_svid = dylib.symbols
    .fetch_svid as unknown as ((
      ptr: Deno.PointerValue,
    ) => Promise<Deno.PointerValue>);
  const free_svid = dylib.symbols
    .free_svid as unknown as ((ptr: Deno.PointerValue) => void);

  const resPtr = await fetch_svid(pathPtr);

  if (resPtr === null) {
    throw new Error("fetch_svid returned a null pointer");
  }

  const resView = new Deno.UnsafePointerView(resPtr);
  let errorMsg: string | null = null;
  let spiffe_id: string | null = null;

  let offset = 0;
  const ptrSize = 8; // 64-bit pointers

  const spiffe_id_ptr = resView.getPointer(offset);
  offset += ptrSize;
  const x509_svid_ptr = resView.getPointer(offset);
  offset += ptrSize;
  const x509_svid_len = Number(resView.getBigUint64(offset));
  offset += ptrSize;
  const x509_svid_key_ptr = resView.getPointer(offset);
  offset += ptrSize;
  const x509_svid_key_len = Number(resView.getBigUint64(offset));
  offset += ptrSize;
  const bundle_ptr = resView.getPointer(offset);
  offset += ptrSize;
  const bundle_len = Number(resView.getBigUint64(offset));
  offset += ptrSize;
  const error_ptr = resView.getPointer(offset);

  if (error_ptr !== null) {
    errorMsg = new Deno.UnsafePointerView(error_ptr).getCString();
  }

  if (errorMsg !== null) {
    free_svid(resPtr);
    throw new Error(errorMsg);
  }

  if (spiffe_id_ptr !== null) {
    spiffe_id = new Deno.UnsafePointerView(spiffe_id_ptr).getCString();
  }

  if (!spiffe_id) {
    free_svid(resPtr);
    throw new Error("spiffe_id is null");
  }

  const x509_svid = x509_svid_ptr !== null && x509_svid_len > 0
    ? new Uint8Array(
      new Deno.UnsafePointerView(x509_svid_ptr).getArrayBuffer(x509_svid_len),
    )
    : new Uint8Array();

  const x509_svid_key = x509_svid_key_ptr !== null && x509_svid_key_len > 0
    ? new Uint8Array(
      new Deno.UnsafePointerView(x509_svid_key_ptr).getArrayBuffer(
        x509_svid_key_len,
      ),
    )
    : new Uint8Array();

  const bundle = bundle_ptr !== null && bundle_len > 0
    ? new Uint8Array(
      new Deno.UnsafePointerView(bundle_ptr).getArrayBuffer(bundle_len),
    )
    : new Uint8Array();

  // Create copies of the typed arrays before freeing the memory
  const svidData = {
    spiffe_id,
    x509_svid: new Uint8Array(x509_svid),
    x509_svid_key: new Uint8Array(x509_svid_key),
    bundle: new Uint8Array(bundle),
  };

  // Free the memory on the Rust side
  free_svid(resPtr);

  return svidData;
}

/**
 * Extracts the SPIFFE ID from an incoming client TLS connection.
 */
export function extractSpiffeIdFromCert(certBundle: string): string | null {
  try {
    const cert = new X509Certificate(certBundle);
    const sanExtension = cert.extensions.find((ext) =>
      ext.type === "2.5.29.17"
    ); // Subject Alternative Name

    if (!sanExtension) {
      return null;
    }

    const san = AsnParser.parse(sanExtension.value, SubjectAlternativeName);
    for (const name of san) {
      if (
        name.uniformResourceIdentifier &&
        name.uniformResourceIdentifier.startsWith("spiffe://")
      ) {
        return name.uniformResourceIdentifier;
      }
    }
  } catch (e) {
    console.error("Failed to parse certificate:", e);
    return null;
  }

  return null;
}