/*
Copyright (c) 2014, Ashley Mills
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/

let ReachabilityChangedNotification = "ReachabilityChangedNotification"

class Reachability {
    
    typealias NetworkReachable = (Reachability) -> ()
    typealias NetworkUneachable = (Reachability) -> ()
    typealias StartNotifier = (Reachability) -> (Bool)
    
    enum NetworkStatus {
        // Apple NetworkStatus Compatible Names.
        case NotReachable, ReachableViaWiFi, ReachableViaWWAN
    }
    
    var reachabilityRef: SCNetworkReachability?
    var reachabilitySerialQueue: dispatch_queue_t?
    var reachabilityObject: AnyObject?
    var reachableBlock: NetworkReachable?
    var unreachableBlock: NetworkUneachable?
    var startNotifierBlock: StartNotifier?
    var reachableOnWWAN: Bool
    
    init(reachabilityRef: SCNetworkReachability) {
        reachableOnWWAN = true;
        self.reachabilityRef = reachabilityRef;
    }
    
    convenience init(hostname: String) {
        let ref = SCNetworkReachabilityCreateWithName(nil, (hostname as NSString).UTF8String).takeRetainedValue()
        self.init(reachabilityRef: ref)
    }
    
    class func reachabilityForInternetConnection() -> Reachability {
        
        var zeroAddress = sockaddr_in(sin_len: __uint8_t(0), sin_family: sa_family_t(0), sin_port: in_port_t(0), sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)
        
        let ref = withUnsafePointer(&zeroAddress) {
            SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, UnsafePointer($0)).takeRetainedValue()
        }
        return Reachability(reachabilityRef: ref)
    }
    
    class func reachabilityForLocalWiFi() -> Reachability {
        
        var localWifiAddress: sockaddr_in = sockaddr_in(sin_len: __uint8_t(0), sin_family: sa_family_t(0), sin_port: in_port_t(0), sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        localWifiAddress.sin_len = UInt8(sizeofValue(localWifiAddress))
        localWifiAddress.sin_family = sa_family_t(AF_INET)
        
        // IN_LINKLOCALNETNUM is defined in <netinet/in.h> as 169.254.0.0
        localWifiAddress.sin_addr.s_addr = in_addr_t(Int64(0xA9FE0000).bigEndian)
        
        let ref = withUnsafePointer(&localWifiAddress) {
            SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, UnsafePointer($0)).takeRetainedValue()
        }
        return Reachability(reachabilityRef: ref)
    }
    
    func startNotifier() -> Bool {
        
        reachabilityObject = self
        // First, we need to create a serial queue.
        // We allocate this once for the lifetime of the notifier.
        reachabilitySerialQueue = dispatch_queue_create("com.joylordsystems.reachability", nil)
        if reachabilitySerialQueue == nil {
            return false
        }
        
        // TODO:
        let callback:(SCNetworkReachability!, SCNetworkReachabilityFlags, UnsafeMutablePointer<Void>) -> () = { (target: SCNetworkReachability!, flags: SCNetworkReachabilityFlags, info: UnsafeMutablePointer<Void>) in
            self.reachabilityChanged(flags)
        }
        
        let p = UnsafeMutablePointer<(SCNetworkReachability!, SCNetworkReachabilityFlags, UnsafeMutablePointer<Void>) -> Void>.alloc(1)
        p.initialize(callback)
        
        let cp = COpaquePointer(p) // convert UnsafeMutablePointer to COpaquePointer
        let fp = CFunctionPointer<(SCNetworkReachability!, SCNetworkReachabilityFlags, UnsafeMutablePointer<Void>) -> Void>(cp) // convert COpaquePointer to CFunctionPointer
        
        if SCNetworkReachabilitySetCallback(self.reachabilityRef, fp, nil) != 0 {
            
            println("SCNetworkReachabilitySetCallback() failed: \(SCErrorString(SCError()))")
            
            // Clear out the dispatch queue
            reachabilitySerialQueue = nil;
            reachabilityObject = nil;
            
            return false;
        }
        
        // Set it as our reachability queue, which will retain the queue
        if SCNetworkReachabilitySetDispatchQueue(reachabilityRef, reachabilitySerialQueue) == 0
        {
            println("SCNetworkReachabilitySetDispatchQueue() failed: \(SCErrorString(SCError()))")
            
            // First stop, any callbacks!
            SCNetworkReachabilitySetCallback(reachabilityRef, nil, nil)
            
            // Then clear out the dispatch queue.
            reachabilitySerialQueue = nil
            reachabilityObject = nil
            
            return false
        }
        
        return true;
    }
    
    func stopNotifier() {
        
        // First stop, any callbacks!
        SCNetworkReachabilitySetCallback(reachabilityRef, nil, nil)
        
        // Unregister target from the GCD serial dispatch queue.
        SCNetworkReachabilitySetDispatchQueue(nil, nil);
        
        reachabilitySerialQueue = nil;
        reachabilityObject = nil;
    }
    
    func reachabilityChanged(flags: SCNetworkReachabilityFlags) {
        if isReachableWithFlags(flags) {
            if let block = reachableBlock {
                block(self)
            }
        } else {
            if let block = unreachableBlock {
                block(self)
            }
        }
        
        // this makes sure the change notification happens on the MAIN THREAD
        dispatch_async(dispatch_get_main_queue()) {
            NSNotificationCenter.defaultCenter().postNotificationName(ReachabilityChangedNotification, object:self)
        }
    }
    
    func isReachableWithFlags(flags: SCNetworkReachabilityFlags) -> Bool {
        
        let reachable = isReachable(flags)
        
        if reachable == 0 {
            return false
        }
        
        if isConnectionRequiredOrTransient(flags) {
            return false
        }
        
        #if TARGET_OS_IPHONE
            if isOnWWAN(flags) && !reachableOnWWAN {
            // We don't want to connect when on 3G.
            return false
            }
        #endif
        
        return true
    }
    
    func isReachableWithTest(test: (SCNetworkReachabilityFlags) -> (Bool)) -> Bool {
        var flags: SCNetworkReachabilityFlags = 0
        let gotFlags = SCNetworkReachabilityGetFlags(reachabilityRef, &flags) != 0
        if gotFlags {
            return test(flags)
        }
        
        return false
    }
    
    func isReachable() -> Bool {
        return isReachableWithTest({ (flags: SCNetworkReachabilityFlags) -> (Bool) in
            return self.isReachableWithFlags(flags)
        })
    }
    
    func isReachableViaWWAN() -> Bool {
        #if TARGET_OS_IPHONE
            return isReachableWithTest({ (flags: SCNetworkReachabilityFlags) -> (Bool) in
            // Check we're REACHABLE
            if self.isReachable(flags) {
            
            // Now, check we're on WWAN
            if self.isOnWWAN(flags) {
            return true
            }
            }
            return false
            })
        #endif
        return false
    }
    
    func isReachableViaWiFi() -> Bool {
        
        return isReachableWithTest({ (flags: SCNetworkReachabilityFlags) -> (Bool) in
            
            // Check we're reachable
            if self.isReachable(flags) {
                #if TARGET_OS_IPHONE
                    
                    // Check we're NOT on WWAN
                    if self.isOnWWAN(flags) {
                    return false
                    }
                #endif
                return true
            }
            
            return false
        })
    }
    
    // WWAN may be available, but not active until a connection has been established.
    // WiFi may require a connection for VPN on Demand.
    func isConnectionRequired() -> Bool {
        return connectionRequired()
    }
    
    func connectionRequired() -> Bool {
        return isReachableWithTest({ (flags: SCNetworkReachabilityFlags) -> (Bool) in
            return self.isConnectionRequired(flags)
        })
    }
    
    // Dynamic, on demand connection?
    func isConnectionOnDemand() -> Bool {
        return isReachableWithTest({ (flags: SCNetworkReachabilityFlags) -> (Bool) in
            return self.isConnectionRequired(flags) && self.isConnectionOnTrafficOrDemand(flags)
        })
    }
    
    // Is user intervention required?
    func isInterventionRequired() -> Bool {
        return isReachableWithTest({ (flags: SCNetworkReachabilityFlags) -> (Bool) in
            return self.isConnectionRequired(flags) && self.isInterventionRequired(flags)
        })
    }
    
    func isOnWWAN(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsIsWWAN) != 0
    }
    func isReachable(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsReachable) != 0
    }
    func isConnectionRequired(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsConnectionRequired) != 0
    }
    func isInterventionRequired(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsInterventionRequired) != 0
    }
    func isConnectionOnTraffic(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0
    }
    func isConnectionOnDemand(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsConnectionOnDemand) != 0
    }
    func isConnectionOnTrafficOrDemand(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsConnectionOnTraffic | kSCNetworkReachabilityFlagsConnectionOnDemand) != 0
    }
    func isTransientConnection(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsTransientConnection) != 0
    }
    func isLocalAddress(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsIsLocalAddress) != 0
    }
    func isDirect(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags & SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsIsDirect) != 0
    }
    func isConnectionRequiredOrTransient(flags: SCNetworkReachabilityFlags) -> Bool {
        let testcase = SCNetworkReachabilityFlags(kSCNetworkReachabilityFlagsConnectionRequired | kSCNetworkReachabilityFlagsTransientConnection)
        return flags & testcase == testcase
    }
    
    // MARK: - *** xx methods ***
    
    var currentReachabilityStatus: NetworkStatus {
        if isReachable() {
            if isReachableViaWiFi() {
                return .ReachableViaWiFi
            }
            #if	TARGET_OS_IPHONE
                return .ReachableViaWWAN;a
            #endif
            }
            
            return .NotReachable
    }
    
    var reachabilityFlags: SCNetworkReachabilityFlags {
        var flags: SCNetworkReachabilityFlags = 0
            let gotFlags = SCNetworkReachabilityGetFlags(reachabilityRef, &flags) != 0
            if gotFlags {
                return flags
            }
            
            return 0
    }
    
    var currentReachabilityString: String {
        
        switch currentReachabilityStatus {
        case .ReachableViaWWAN:
            return NSLocalizedString("Cellular", comment: "")
        case .ReachableViaWiFi:
            return NSLocalizedString("WiFi", comment: "")
        case .NotReachable:
            return NSLocalizedString("No Connection", comment: "");
            }
    }
    
    var currentReachabilityFlags: String {
        #if	TARGET_OS_IPHONE
            let W = isOnWWAN(reachabilityFlags) ? "W" : "-"
            #else
            let W = "X"
            #endif
            let R = isReachable(reachabilityFlags) ? "R" : "-"
            let c = isConnectionRequired(reachabilityFlags) ? "c" : "-"
            let t = isTransientConnection(reachabilityFlags) ? "t" : "-"
            let i = isInterventionRequired(reachabilityFlags) ? "i" : "-"
            let C = isConnectionOnTraffic(reachabilityFlags) ? "C" : "-"
            let D = isConnectionOnDemand(reachabilityFlags) ? "D" : "-"
            let l = isLocalAddress(reachabilityFlags) ? "l" : "-"
            let d = isDirect(reachabilityFlags) ? "d" : "-"
            
            return "\(W)\(R) \(c)\(t)\(i)\(C)\(D)\(l)\(d)"
    }
    
    deinit {
        stopNotifier()
        
        reachabilityRef = nil
        reachableBlock = nil
        unreachableBlock = nil
    }
}