webkit2-ffi.ts

import { FFIType, ptr } from 'bun:ffi';
import { dlopen } from '../dlopen';
import { existsSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { FFIError } from '../../../common/errors';
import { type ResolveDeps, resolveEngineWith } from '../../engine/resolve';
import { winLibraryAccessor, wstr } from './win32';
import { loadKernel32 } from './win32-ffi';

/**
 * WinCairo WebKit2 C API FFI. Opaque `WK*Ref` handles are plain pointers (`ptr`) and
 * `size_t` is `u64` on x64. Unlike Linux there is NO system-WebKit fallback — Windows
 * ships none — so any `system` resolution outcome means "no engine" here.
 */

const WEBKIT2_SYMBOLS = {
  // ── Context + configuration ──────────────────────────────────────────────
  WKContextConfigurationCreate: { args: [], returns: FFIType.ptr },
  WKContextCreateWithConfiguration: { args: [FFIType.ptr], returns: FFIType.ptr },
  WKPageConfigurationCreate: { args: [], returns: FFIType.ptr },
  WKPageConfigurationSetContext: { args: [FFIType.ptr, FFIType.ptr], returns: FFIType.void },
  WKPageConfigurationSetUserContentController: {
    args: [FFIType.ptr, FFIType.ptr],
    returns: FFIType.void,
  },
  WKPageConfigurationGetPreferences: { args: [FFIType.ptr], returns: FFIType.ptr },
  WKPreferencesSetJavaScriptEnabled: { args: [FFIType.ptr, FFIType.u8], returns: FFIType.void },

  // ── View (hosted in an HWND) ─────────────────────────────────────────────
  // WKViewCreate(RECT rect, WKPageConfigurationRef, HWND parent): RECT is 16
  // bytes -> passed by hidden pointer on the Win64 ABI, so `rect` binds as ptr.
  WKViewCreate: { args: [FFIType.ptr, FFIType.ptr, FFIType.u64], returns: FFIType.ptr },
  WKViewGetPage: { args: [FFIType.ptr], returns: FFIType.ptr },
  WKViewGetWindow: { args: [FFIType.ptr], returns: FFIType.u64 },
  WKViewSetIsInWindow: { args: [FFIType.ptr, FFIType.u8], returns: FFIType.void },
  WKViewSetParentWindow: { args: [FFIType.ptr, FFIType.u64], returns: FFIType.void },

  // ── Navigation + history ─────────────────────────────────────────────────
  WKPageLoadURL: { args: [FFIType.ptr, FFIType.ptr], returns: FFIType.void },
  WKPageLoadHTMLString: { args: [FFIType.ptr, FFIType.ptr, FFIType.ptr], returns: FFIType.void },
  WKPageReload: { args: [FFIType.ptr], returns: FFIType.void },
  WKPageReloadFromOrigin: { args: [FFIType.ptr], returns: FFIType.void },
  WKPageStopLoading: { args: [FFIType.ptr], returns: FFIType.void },
  WKPageGoBack: { args: [FFIType.ptr], returns: FFIType.void },
  WKPageGoForward: { args: [FFIType.ptr], returns: FFIType.void },
  WKPageCanGoBack: { args: [FFIType.ptr], returns: FFIType.bool },
  WKPageCanGoForward: { args: [FFIType.ptr], returns: FFIType.bool },
  WKPageCopyActiveURL: { args: [FFIType.ptr], returns: FFIType.ptr },
  WKPageCopyTitle: { args: [FFIType.ptr], returns: FFIType.ptr },
  // (page, script, void* context, completion) — context+completion passed NULL for
  // fire-and-forget eval; executeJavaScript results return out-of-band (D022).
  WKPageEvaluateJavaScriptInMainFrame: {
    args: [FFIType.ptr, FFIType.ptr, FFIType.ptr, FFIType.ptr],
    returns: FFIType.void,
  },
  WKPageSetPageZoomFactor: { args: [FFIType.ptr, FFIType.f64], returns: FFIType.void },
  WKPageSetCustomUserAgent: { args: [FFIType.ptr, FFIType.ptr], returns: FFIType.void },
  // (page, const WKPageNavigationClientBase*) — register navigation lifecycle callbacks.
  WKPageSetPageNavigationClient: { args: [FFIType.ptr, FFIType.ptr], returns: FFIType.void },

  // ── Errors (for did-fail-load) ───────────────────────────────────────────
  WKErrorGetErrorCode: { args: [FFIType.ptr], returns: FFIType.i32 },
  WKErrorCopyLocalizedDescription: { args: [FFIType.ptr], returns: FFIType.ptr },

  // ── User content: document-start injection + the renderer->main bridge ────
  WKUserContentControllerCreate: { args: [], returns: FFIType.ptr },
  WKUserContentControllerAddUserScript: {
    args: [FFIType.ptr, FFIType.ptr],
    returns: FFIType.void,
  },
  WKUserContentControllerRemoveAllUserScripts: { args: [FFIType.ptr], returns: FFIType.void },
  // (ucc, WKStringRef name, WKScriptMessageHandlerCallback, const void* context)
  WKUserContentControllerAddScriptMessageHandler: {
    args: [FFIType.ptr, FFIType.ptr, FFIType.ptr, FFIType.ptr],
    returns: FFIType.void,
  },
  WKUserContentControllerRemoveAllUserMessageHandlers: {
    args: [FFIType.ptr],
    returns: FFIType.void,
  },
  // (WKStringRef source, _WKUserScriptInjectionTime, bool forMainFrameOnly)
  WKUserScriptCreateWithSource: {
    args: [FFIType.ptr, FFIType.i32, FFIType.u8],
    returns: FFIType.ptr,
  },
  WKScriptMessageGetBody: { args: [FFIType.ptr], returns: FFIType.ptr },

  // ── Strings / URLs ───────────────────────────────────────────────────────
  WKStringCreateWithUTF8CString: { args: [FFIType.cstring], returns: FFIType.ptr },
  WKStringGetMaximumUTF8CStringSize: { args: [FFIType.ptr], returns: FFIType.u64 },
  WKStringGetUTF8CString: { args: [FFIType.ptr, FFIType.ptr, FFIType.u64], returns: FFIType.u64 },
  WKURLCreateWithUTF8CString: { args: [FFIType.cstring], returns: FFIType.ptr },
  WKURLCopyString: { args: [FFIType.ptr], returns: FFIType.ptr },

  // ── Website data (used by the session backend) ───────────────────────────
  // () -> WKWebsiteDataStoreRef — the process-wide default store.
  WKWebsiteDataStoreGetDefaultDataStore: { args: [], returns: FFIType.ptr },
  // (WKWebsiteDataStoreRef) -> WKHTTPCookieStoreRef
  WKWebsiteDataStoreGetHTTPCookieStore: { args: [FFIType.ptr], returns: FFIType.ptr },
  // (WKHTTPCookieStoreRef, void* context, callback(void* context)) -> void — async.
  WKHTTPCookieStoreDeleteAllCookies: {
    args: [FFIType.ptr, FFIType.ptr, FFIType.ptr],
    returns: FFIType.void,
  },
  // (WKWebsiteDataStoreRef, void* context, callback(void* context)) -> void — async.
  WKWebsiteDataStoreRemoveAllFetchCaches: {
    args: [FFIType.ptr, FFIType.ptr, FFIType.ptr],
    returns: FFIType.void,
  },

  // ── Reference counting ───────────────────────────────────────────────────
  WKRetain: { args: [FFIType.ptr], returns: FFIType.ptr },
  WKRelease: { args: [FFIType.ptr], returns: FFIType.void },
} as const;

/** `_WKUserScriptInjectionTime`: inject before the page's own scripts run. */
export const WK_INJECT_AT_DOCUMENT_START = 0;
/** `_WKUserScriptInjectionTime`: inject after the document has parsed. */
export const WK_INJECT_AT_DOCUMENT_END = 1;

/** The subdir an embedded engine is bundled into (must match `build-windows.ts`). */
const BUNDLED_ENGINE_DIRNAME = 'webkit';

/**
 * A WinCairo engine bundled next to the executable — `<exeDir>/webkit/` with a
 * `WebKit2.dll` (what `bunmaska build --embed-engine` produces) — or `undefined`.
 * This is what lets a packaged `.exe` run with no environment variables. Pure;
 * `exists` is a test seam.
 */
export const bundledEngineDir = (
  execPath: string,
  exists: (path: string) => boolean,
): string | undefined => {
  const dir = join(dirname(execPath), BUNDLED_ENGINE_DIRNAME);
  return exists(join(dir, 'WebKit2.dll')) ? dir : undefined;
};

/**
 * The directory of the WinCairo WebKit engine this process loads, or `undefined`
 * when none is available (there is no system WebKit to fall back to on Windows).
 * Precedence: an explicit/store pin via {@link resolveEngineWith} (the engine's
 * `lib/`, or the verbatim `BUNMASKA_WEBKIT_PATH`), then a {@link bundledEngineDir}
 * shipped next to the executable. `deps` is a test seam.
 */
export const resolveWindowsEngineDir = (deps: ResolveDeps = {}): string | undefined => {
  const resolution = resolveEngineWith(deps);
  if (resolution.mode === 'pinned') {
    return resolution.libDir;
  }
  return bundledEngineDir(process.execPath, existsSync);
};

/**
 * Open the engine's `WebKit2.dll` and return its symbol table. Memoised;
 * import-safe (throws on non-Windows via the accessor). Puts the engine dir on
 * the DLL search path first so the bundled closure resolves beside `WebKit2.dll`.
 * A pinned-but-uninstalled engine surfaces the resolver's warning in the error.
 */
export const loadWebKit2 = winLibraryAccessor('WebKit2', () => {
  // Use the full resolution (store/explicit pin AND an engine bundled next to the
  // executable) — NOT resolveEngineWith alone, which misses the bundled fallback.
  const dir = resolveWindowsEngineDir();
  if (dir === undefined) {
    const detail = resolveEngineWith().warnings.join('; ');
    throw new FFIError(
      `no WinCairo WebKit engine configured${detail.length > 0 ? ` (${detail})` : ''}; bundle one ` +
        'with `bunmaska build --embed-engine`, set BUNMASKA_WEBKIT_PATH, or pin an installed engine',
    );
  }
  loadKernel32().symbols.SetDllDirectoryW(ptr(wstr(dir)));
  return dlopen(`${dir}\\WebKit2.dll`, WEBKIT2_SYMBOLS);
});