import { createHash } from "node:crypto";
import { readFileSync } from "node:fs";
import { createRequire } from "node:module";
import { fileURLToPath } from "node:url";

import { z } from "zod";

import { PACKAGE_METADATA } from "../generatedPackageMetadata.js";

/** A native resource remains opaque until the addon validates its object tag. */
export const windowsHandleSchema = z.custom<object>(
  (value): value is object =>
    typeof value === "object" && value !== null && !Array.isArray(value),
);

/** Observed identity of an opened local NTFS object. */
export const windowsFileIdentitySchema = z.strictObject({
  requestedPath: z.string(),
  finalPath: z.string(),
  filesystem: z.literal("NTFS"),
  volumeSerial: z.string().regex(/^[a-f0-9]{16}$/u),
  fileId: z.string().regex(/^[a-f0-9]{32}$/u),
  size: z.number().int().nonnegative().max(Number.MAX_SAFE_INTEGER),
  directory: z.boolean(),
});

/** Metadata bound to one packaged Windows x64 Node-API artifact. */
export const windowsNativeManifestSchema = z.strictObject({
  packageVersion: z.string(),
  platform: z.literal("win32"),
  architecture: z.literal("x64"),
  abiVersion: z.literal(1),
  nodeApiVersion: z.literal(8),
  artifact: z.literal("rea-windows-x64.node"),
  artifactSha256: z.string().regex(/^[a-f0-9]{64}$/u),
});

const inspectionSchema = z.strictObject({
  abiVersion: z.literal(1),
  nodeApiVersion: z.literal(8),
  architecture: z.literal("x64"),
  filesystem: windowsFileIdentitySchema,
  privateDacl: z.literal(true),
  atomicJobAssignment: z.literal(true),
  killOnOwnerClose: z.literal(true),
  protocolStdin: z.boolean().optional(),
});

type NativeCall = (
  operation: string,
  arguments_: readonly unknown[],
) => unknown;
const bindingSchema = z.strictObject({
  call: z.custom<NativeCall>(
    (value): value is NativeCall => typeof value === "function",
  ),
});

/** Validated native operations and the observations establishing readiness. */
export interface WindowsNativeAuthority {
  readonly call: NativeCall;
  readonly inspection: z.infer<typeof inspectionSchema>;
}

/** Availability of the bundled native implementation, including load failures. */
export type WindowsNativeLoadResult =
  | { readonly available: true; readonly authority: WindowsNativeAuthority }
  | { readonly available: false; readonly reason: string };

/** Trusted package reads and module loading, replaceable in loader tests. */
export interface WindowsNativeLoadHost {
  readonly platform: NodeJS.Platform;
  readonly architecture: string;
  readonly nodeApiVersion: string | undefined;
  readonly packageVersion: string;
  readManifest(): unknown;
  readArtifact(): Buffer;
  loadArtifact(): unknown;
}

/** Validate compatibility and artifact identity before invoking the native addon. */
export const loadWindowsNativeAuthority = (
  host: WindowsNativeLoadHost,
): WindowsNativeLoadResult => {
  if (host.platform !== "win32" || host.architecture !== "x64")
    return {
      available: false,
      reason: "REA Windows native controls require a Windows x64 host.",
    };
  try {
    const manifest = windowsNativeManifestSchema.parse(host.readManifest());
    if (manifest.packageVersion !== host.packageVersion)
      throw new Error("Windows native artifact belongs to another REA version");
    const nodeApiVersion = Number(host.nodeApiVersion);
    if (!Number.isSafeInteger(nodeApiVersion) || nodeApiVersion < 8)
      throw new Error("Windows native artifact requires Node-API 8 or newer");
    const artifact = host.readArtifact();
    if (
      createHash("sha256").update(artifact).digest("hex") !==
      manifest.artifactSha256
    )
      throw new Error(
        "Windows native artifact SHA-256 does not match package metadata",
      );
    assertWindowsX64Artifact(artifact);
    const binding = bindingSchema.parse(host.loadArtifact());
    const inspection = inspectionSchema.parse(binding.call("inspect", []));
    return { available: true, authority: { call: binding.call, inspection } };
  } catch (cause: unknown) {
    return {
      available: false,
      reason: `REA Windows native controls are unavailable: ${cause instanceof Error ? cause.message : String(cause)}`,
    };
  }
};

const assertWindowsX64Artifact = (bytes: Buffer): void => {
  if (bytes.length < 64 || bytes.toString("ascii", 0, 2) !== "MZ")
    throw new Error("Windows native artifact is not a PE image");
  const offset = bytes.readUInt32LE(0x3c);
  if (
    offset > bytes.length - 26 ||
    bytes.toString("ascii", offset, offset + 4) !== "PE\0\0" ||
    bytes.readUInt16LE(offset + 4) !== 0x8664 ||
    bytes.readUInt16LE(offset + 24) !== 0x20b
  )
    throw new Error("Windows native artifact is not a Windows x64 PE32+ image");
};

let cached: WindowsNativeLoadResult | undefined;

/** Load only the package-owned artifact, lazily and once per process. */
export const systemWindowsNativeAuthority = (): WindowsNativeLoadResult => {
  cached ??= loadWindowsNativeAuthority({
    platform: process.platform,
    architecture: process.arch,
    nodeApiVersion: process.versions.napi,
    packageVersion: PACKAGE_METADATA.version,
    readManifest: () => {
      const encoded = readFileSync(
        new URL("../../native/windows/build/manifest.json", import.meta.url),
        "utf8",
      );
      const value: unknown = JSON.parse(encoded);
      return value;
    },
    readArtifact: () =>
      readFileSync(
        new URL(
          "../../native/windows/build/rea-windows-x64.node",
          import.meta.url,
        ),
      ),
    loadArtifact: () => {
      const value: unknown = createRequire(import.meta.url)(
        fileURLToPath(
          new URL(
            "../../native/windows/build/rea-windows-x64.node",
            import.meta.url,
          ),
        ),
      );
      return value;
    },
  });
  return cached;
};

/** Require the verified backend when an operation depends on native authority. */
export const requireWindowsNativeAuthority = (): WindowsNativeAuthority => {
  const loaded = systemWindowsNativeAuthority();
  if (!loaded.available) throw new Error(loaded.reason);
  return loaded.authority;
};