/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* Code for throwing errors into JavaScript. */

#include "xpcprivate.h"
#include "XPCWrapper.h"
#include "js/CharacterEncoding.h"
#include "js/Printf.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/DOMException.h"
#include "mozilla/dom/Exceptions.h"
#include "nsString.h"

using namespace mozilla;
using namespace mozilla::dom;

bool XPCThrower::sVerbose = true;

// static
void XPCThrower::Throw(nsresult rv, JSContext* cx) {
  const char* format;
  if (JS_IsExceptionPending(cx)) {
    return;
  }
  if (!nsXPCException::NameAndFormatForNSResult(rv, nullptr, &format)) {
    format = "";
  }
  dom::Throw(cx, rv, nsDependentCString(format));
}

namespace xpc {

bool Throw(JSContext* cx, nsresult rv) {
  XPCThrower::Throw(rv, cx);
  return false;
}

}  // namespace xpc

/*
 * If there has already been an exception thrown, see if we're throwing the
 * same sort of exception, and if we are, don't clobber the old one. ccx
 * should be the current call context.
 */
// static
bool XPCThrower::CheckForPendingException(nsresult result, JSContext* cx) {
  RefPtr<Exception> e = XPCJSContext::Get()->GetPendingException();
  if (!e) {
    return false;
  }
  XPCJSContext::Get()->SetPendingException(nullptr);

  if (e->GetResult() != result) {
    return false;
  }

  ThrowExceptionObject(cx, e);
  return true;
}

// static
void XPCThrower::Throw(nsresult rv, XPCCallContext& ccx) {
  char* sz;
  const char* format;

  if (CheckForPendingException(rv, ccx)) {
    return;
  }

  if (!nsXPCException::NameAndFormatForNSResult(rv, nullptr, &format)) {
    format = "";
  }

  sz = (char*)format;
  NS_ENSURE_TRUE_VOID(sz);

  if (sz && sVerbose) {
    Verbosify(ccx, &sz, false);
  }

  dom::Throw(ccx, rv, nsDependentCString(sz));

  if (sz && sz != format) {
    js_free(sz);
  }
}

// static
void XPCThrower::ThrowBadResult(nsresult rv, nsresult result,
                                XPCCallContext& ccx) {
  char* sz;
  const char* format;
  const char* name;

  /*
   *  If there is a pending exception when the native call returns and
   *  it has the same error result as returned by the native call, then
   *  the native call may be passing through an error from a previous JS
   *  call. So we'll just throw that exception into our JS.  Note that
   *  we don't need to worry about NS_ERROR_UNCATCHABLE_EXCEPTION,
   *  because presumably there would be no pending exception for that
   *  nsresult!
   */

  if (CheckForPendingException(result, ccx)) {
    return;
  }

  // else...

  if (!nsXPCException::NameAndFormatForNSResult(rv, nullptr, &format) ||
      !format) {
    format = "";
  }

  if (nsXPCException::NameAndFormatForNSResult(result, &name, nullptr) &&
      name) {
    sz = JS_smprintf("%s 0x%x (%s)", format, (unsigned)result, name).release();
  } else {
    sz = JS_smprintf("%s 0x%x", format, (unsigned)result).release();
  }
  NS_ENSURE_TRUE_VOID(sz);

  if (sz && sVerbose) {
    Verbosify(ccx, &sz, true);
  }

  dom::Throw(ccx, result, nsDependentCString(sz));

  if (sz) {
    js_free(sz);
  }
}

// static
void XPCThrower::ThrowBadParam(nsresult rv, unsigned paramNum,
                               XPCCallContext& ccx) {
  char* sz;
  const char* format;

  if (!nsXPCException::NameAndFormatForNSResult(rv, nullptr, &format)) {
    format = "";
  }

  sz = JS_smprintf("%s arg %d", format, paramNum).release();
  NS_ENSURE_TRUE_VOID(sz);

  if (sz && sVerbose) {
    Verbosify(ccx, &sz, true);
  }

  dom::Throw(ccx, rv, nsDependentCString(sz));

  if (sz) {
    js_free(sz);
  }
}

// static
void XPCThrower::Verbosify(XPCCallContext& ccx, char** psz, bool own) {
  char* sz = nullptr;

  if (ccx.HasInterfaceAndMember()) {
    XPCNativeInterface* iface = ccx.GetInterface();
    jsid id = ccx.GetMember()->GetName();
    const char* name;
    JS::UniqueChars bytes;
    if (!id.isVoid()) {
      bytes = JS_EncodeStringToLatin1(ccx, id.toString());
      name = bytes ? bytes.get() : "";
    } else {
      name = "Unknown";
    }
    sz =
        JS_smprintf("%s [%s.%s]", *psz, iface->GetNameString(), name).release();
  }

  if (sz) {
    if (own) {
      js_free(*psz);
    }
    *psz = sz;
  }
}