/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* 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/. */

#include "nsNetworkLinkService.h"
#include "nsCOMPtr.h"
#include "nsIObserverService.h"
#include "nsServiceManagerUtils.h"
#include "nsString.h"
#include "nsCRT.h"
#include "mozilla/Preferences.h"

#import <Cocoa/Cocoa.h>
#import <netinet/in.h>

#define NETWORK_NOTIFY_CHANGED_PREF "network.notify.changed"

using namespace mozilla;

// If non-successful, extract the error code and return it.  This
// error code dance is inspired by
// http://developer.apple.com/technotes/tn/tn1145.html
static OSStatus getErrorCodeBool(Boolean success)
{
    OSStatus err = noErr;
    if (!success) {
        int scErr = ::SCError();
        if (scErr == kSCStatusOK) {
            scErr = kSCStatusFailed;
        }
        err = scErr;
    }
    return err;
}

// If given a NULL pointer, return the error code.
static OSStatus getErrorCodePtr(const void *value)
{
    return getErrorCodeBool(value != NULL);
}

// Convenience function to allow NULL input.
static void CFReleaseSafe(CFTypeRef cf)
{
    if (cf) {
        // "If cf is NULL, this will cause a runtime error and your
        // application will crash." / Apple docs
        ::CFRelease(cf);
    }
}

NS_IMPL_ISUPPORTS(nsNetworkLinkService,
                  nsINetworkLinkService,
                  nsIObserver)

nsNetworkLinkService::nsNetworkLinkService()
    : mLinkUp(true)
    , mStatusKnown(false)
    , mAllowChangedEvent(true)
    , mReachability(nullptr)
    , mCFRunLoop(nullptr)
    , mRunLoopSource(nullptr)
    , mStoreRef(nullptr)
{
}

nsNetworkLinkService::~nsNetworkLinkService()
{
}

NS_IMETHODIMP
nsNetworkLinkService::GetIsLinkUp(bool *aIsUp)
{
    *aIsUp = mLinkUp;
    return NS_OK;
}

NS_IMETHODIMP
nsNetworkLinkService::GetLinkStatusKnown(bool *aIsUp)
{
    *aIsUp = mStatusKnown;
    return NS_OK;
}

NS_IMETHODIMP
nsNetworkLinkService::GetLinkType(uint32_t *aLinkType)
{
  NS_ENSURE_ARG_POINTER(aLinkType);

  // XXX This function has not yet been implemented for this platform
  *aLinkType = nsINetworkLinkService::LINK_TYPE_UNKNOWN;
  return NS_OK;
}

NS_IMETHODIMP
nsNetworkLinkService::Observe(nsISupports *subject,
                              const char *topic,
                              const char16_t *data)
{
    if (!strcmp(topic, "xpcom-shutdown")) {
        Shutdown();
    }

    return NS_OK;
}

/* static */
void
nsNetworkLinkService::IPConfigChanged(SCDynamicStoreRef aStoreREf,
                                      CFArrayRef aChangedKeys,
                                      void *aInfo)
{
    nsNetworkLinkService *service =
        static_cast<nsNetworkLinkService*>(aInfo);
    service->SendEvent(true);
}

nsresult
nsNetworkLinkService::Init(void)
{
    nsresult rv;

    nsCOMPtr<nsIObserverService> observerService =
        do_GetService("@mozilla.org/observer-service;1", &rv);
    NS_ENSURE_SUCCESS(rv, rv);

    rv = observerService->AddObserver(this, "xpcom-shutdown", false);
    NS_ENSURE_SUCCESS(rv, rv);

    Preferences::AddBoolVarCache(&mAllowChangedEvent,
                                 NETWORK_NOTIFY_CHANGED_PREF, true);

    // If the network reachability API can reach 0.0.0.0 without
    // requiring a connection, there is a network interface available.
    struct sockaddr_in addr;
    bzero(&addr, sizeof(addr));
    addr.sin_len = sizeof(addr);
    addr.sin_family = AF_INET;
    mReachability =
        ::SCNetworkReachabilityCreateWithAddress(NULL,
                                                 (struct sockaddr *)&addr);
    if (!mReachability) {
        return NS_ERROR_NOT_AVAILABLE;
    }

    SCNetworkReachabilityContext context = {0, this, NULL, NULL, NULL};
    if (!::SCNetworkReachabilitySetCallback(mReachability,
                                            ReachabilityChanged,
                                            &context)) {
        NS_WARNING("SCNetworkReachabilitySetCallback failed.");
        ::CFRelease(mReachability);
        mReachability = NULL;
        return NS_ERROR_NOT_AVAILABLE;
    }

    SCDynamicStoreContext storeContext = {0, this, NULL, NULL, NULL};
    mStoreRef =
        ::SCDynamicStoreCreate(NULL,
                               CFSTR("AddIPAddressListChangeCallbackSCF"),
                               IPConfigChanged, &storeContext);

    CFStringRef patterns[2] = {NULL, NULL};
    OSStatus err = getErrorCodePtr(mStoreRef);
    if (err == noErr) {
        // This pattern is "State:/Network/Service/[^/]+/IPv4".
        patterns[0] =
            ::SCDynamicStoreKeyCreateNetworkServiceEntity(NULL,
                                                          kSCDynamicStoreDomainState,
                                                          kSCCompAnyRegex,
                                                          kSCEntNetIPv4);
        err = getErrorCodePtr(patterns[0]);
        if (err == noErr) {
            // This pattern is "State:/Network/Service/[^/]+/IPv6".
            patterns[1] =
                ::SCDynamicStoreKeyCreateNetworkServiceEntity(NULL,
                                                              kSCDynamicStoreDomainState,
                                                              kSCCompAnyRegex,
                                                              kSCEntNetIPv6);
            err = getErrorCodePtr(patterns[1]);
        }
    }

    CFArrayRef patternList = NULL;
    // Create a pattern list containing just one pattern,
    // then tell SCF that we want to watch changes in keys
    // that match that pattern list, then create our run loop
    // source.
    if (err == noErr) {
        patternList = ::CFArrayCreate(NULL, (const void **) patterns,
                                      2, &kCFTypeArrayCallBacks);
        if (!patternList) {
            err = -1;
        }
    }
    if (err == noErr) {
        err =
            getErrorCodeBool(::SCDynamicStoreSetNotificationKeys(mStoreRef,
                                                                 NULL,
                                                                 patternList));
    }

    if (err == noErr) {
        mRunLoopSource =
            ::SCDynamicStoreCreateRunLoopSource(NULL, mStoreRef, 0);
        err = getErrorCodePtr(mRunLoopSource);
    }

    CFReleaseSafe(patterns[0]);
    CFReleaseSafe(patterns[1]);
    CFReleaseSafe(patternList);

    if (err != noErr) {
        CFReleaseSafe(mStoreRef);
        return NS_ERROR_NOT_AVAILABLE;
    }

    // Get the current run loop.  This service is initialized at startup,
    // so we shouldn't run in to any problems with modal dialog run loops.
    mCFRunLoop = [[NSRunLoop currentRunLoop] getCFRunLoop];
    if (!mCFRunLoop) {
        NS_WARNING("Could not get current run loop.");
        ::CFRelease(mReachability);
        mReachability = NULL;
        return NS_ERROR_NOT_AVAILABLE;
    }
    ::CFRetain(mCFRunLoop);

    ::CFRunLoopAddSource(mCFRunLoop, mRunLoopSource, kCFRunLoopDefaultMode);

    if (!::SCNetworkReachabilityScheduleWithRunLoop(mReachability, mCFRunLoop,
                                                    kCFRunLoopDefaultMode)) {
        NS_WARNING("SCNetworkReachabilityScheduleWIthRunLoop failed.");
        ::CFRelease(mReachability);
        mReachability = NULL;
        ::CFRelease(mCFRunLoop);
        mCFRunLoop = NULL;
        return NS_ERROR_NOT_AVAILABLE;
    }

    UpdateReachability();

    return NS_OK;
}

nsresult
nsNetworkLinkService::Shutdown()
{
    if (!::SCNetworkReachabilityUnscheduleFromRunLoop(mReachability,
                                                      mCFRunLoop,
                                                      kCFRunLoopDefaultMode)) {
        NS_WARNING("SCNetworkReachabilityUnscheduleFromRunLoop failed.");
    }

    CFRunLoopRemoveSource(mCFRunLoop, mRunLoopSource, kCFRunLoopDefaultMode);

    ::CFRelease(mReachability);
    mReachability = nullptr;

    ::CFRelease(mCFRunLoop);
    mCFRunLoop = nullptr;

    ::CFRelease(mStoreRef);
    mStoreRef = nullptr;

    ::CFRelease(mRunLoopSource);
    mRunLoopSource = nullptr;

    return NS_OK;
}

void
nsNetworkLinkService::UpdateReachability()
{
    if (!mReachability) {
        return;
    }

    SCNetworkConnectionFlags flags;
    if (!::SCNetworkReachabilityGetFlags(mReachability, &flags)) {
        mStatusKnown = false;
        return;
    }

    bool reachable = (flags & kSCNetworkFlagsReachable) != 0;
    bool needsConnection = (flags & kSCNetworkFlagsConnectionRequired) != 0;

    mLinkUp = (reachable && !needsConnection);
    mStatusKnown = true;
}

void
nsNetworkLinkService::SendEvent(bool aNetworkChanged)
{
    nsCOMPtr<nsIObserverService> observerService =
        do_GetService("@mozilla.org/observer-service;1");
    if (!observerService)
        return;

    const char *event;
    if (aNetworkChanged) {
        if (!mAllowChangedEvent) {
            return;
        }
        event = NS_NETWORK_LINK_DATA_CHANGED;
    } else if (!mStatusKnown) {
        event = NS_NETWORK_LINK_DATA_UNKNOWN;
    } else {
        event = mLinkUp ? NS_NETWORK_LINK_DATA_UP
            : NS_NETWORK_LINK_DATA_DOWN;
    }

    observerService->NotifyObservers(static_cast<nsINetworkLinkService*>(this),
                                     NS_NETWORK_LINK_TOPIC,
                                     NS_ConvertASCIItoUTF16(event).get());
}

/* static */
void
nsNetworkLinkService::ReachabilityChanged(SCNetworkReachabilityRef target,
                                          SCNetworkConnectionFlags flags,
                                          void *info)
{
    nsNetworkLinkService *service =
        static_cast<nsNetworkLinkService*>(info);

    service->UpdateReachability();
    service->SendEvent(false);
}