//
//  JSDNuVServer.m
//  JSDNuVFramework
//
//  Copyright © 2018-2019 by Jim Derry. All rights reserved.
//

#import "JSDNuVServer.h"
#import "xcode-version.h"


@interface JSDNuVServer ()

/* Redefine for readwrite. */
@property (atomic, strong, readwrite) NSTask *serverTask;

/* Tracks when server has startedup or not. */
@property (atomic, assign, readwrite) JSDNuVServerStatus internalStatus;

/* We want to ensure the NSTask is restarted properly. */
@property (atomic, strong, readwrite) dispatch_queue_t serial_queue;

/* And we need a watchdog in case the application crashes. */
@property (atomic, strong, readwrite) NSTask *watchdog;

@end


@implementation JSDNuVServer

@synthesize port = _port;


#pragma mark - Singleton


/*–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––*
 * + sharedNuVServer
 *    Implement this class as a singleton.
 *–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––*/
+ (instancetype)sharedNuVServer
{
    static JSDNuVServer *sharedServer = nil;
    
    static dispatch_once_t onceToken;
    
    dispatch_once(&onceToken, ^{ sharedServer = [[self alloc] init]; });
    
    return sharedServer;
}


#pragma mark - Initialization


/*———————————————————————————————————————————————————————————————————*
 * - init
 *———————————————————————————————————————————————————————————————————*/
- (instancetype)init
{
    if ( (self = [super init]) )
    {
        self.serial_queue = dispatch_queue_create("com.balthisar.ser_q", DISPATCH_QUEUE_SERIAL);
    }
    
    return self;
}


/*———————————————————————————————————————————————————————————————————*
 * - dealloc
 *———————————————————————————————————————————————————————————————————*/
- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}


#pragma mark - Properties


/*———————————————————————————————————————————————————————————————————*
 * + serverVersion
 *———————————————————————————————————————————————————————————————————*/
+ (NSString *)serverVersion
{
    return JAR_VERSION;
}


/*———————————————————————————————————————————————————————————————————*
 * + JREVersion
 *———————————————————————————————————————————————————————————————————*/
+ (NSString *)JREVersion
{
    return JRE_VERSION;
}


/*———————————————————————————————————————————————————————————————————*
 * @property port
 *———————————————————————————————————————————————————————————————————*/
- (NSString *)port
{
    return _port;
}
- (void)setPort:(NSString *)port
{
    if ( [port isEqualToString:_port] ) return;
    
    _port = [port copy];
    
    if ( !self.serverTask.running) return;
    
    /* We've accepted the port change. If the server is running, we will
     attempt to restart the server, but this may fail if the newly
     assigned port is already in use. */
    dispatch_async(self.serial_queue, ^{
        [self.serverTask terminate];
        [self.serverTask waitUntilExit];
        dispatch_async(dispatch_get_main_queue(), ^{
            [self serverLaunch];
        });
    });
}


/*———————————————————————————————————————————————————————————————————*
 * @serverStatus
 *   This is a composite property reflecting the status of the
 *   server.
 *———————————————————————————————————————————————————————————————————*/
+ (NSSet *)keyPathsForValuesAffectingServerStatus
{
    return [NSSet setWithArray:@[
        @"port",
        @"serverTask",
        @"serverTask.running",
        @"internalStatus"
    ]];
}
- (JSDNuVServerStatus)serverStatus
{
    /* If there's no server running, then report either:
     - JSDNuVServerStopped
     - JSDNuVServerPortUnavailable
     */
    if ( !self.serverTask || !self.serverTask.running )
    {
        NSSocketPort *check = [[NSSocketPort alloc] initWithTCPPort:[self.port intValue]];
        BOOL available = check != nil;
        [check invalidate];
        check = nil;
        
        if ( available )
        {
            return JSDNuVServerStopped;
        }
        else
        {
            return JSDNuVServerPortUnavailable;
        }
    }
    
    return self.internalStatus;
}


#pragma mark - Private Methods


/*———————————————————————————————————————————————————————————————————*
 * - serverLaunch
 *———————————————————————————————————————————————————————————————————*/
- (JSDNuVServerStatus)serverLaunch
{
    if ( self.serverTask.running || self.serverStatus == JSDNuVServerPortUnavailable)
    {
        return self.serverStatus;
    }
    
    [self configureTask];
    [self.serverTask launch];
    self.internalStatus = JSDNuVServerStarting;
    
    /* Configure our watchdog. */
    self.watchdog = [[NSTask alloc] init];
    self.watchdog.launchPath = @"/bin/sh";
    
    NSString *command = [NSString stringWithFormat:@"while kill -0 %d; do sleep 5; done; kill -9 %d # NuV Watchdog",
                         [[NSProcessInfo processInfo] processIdentifier],
                         self.serverTask.processIdentifier];
    
    self.watchdog.arguments = @[ @"-c", command];
    [self.watchdog launch];
    
    return self.serverStatus;
}


/*———————————————————————————————————————————————————————————————————*
 * - serverStop
 *     This simply provides consistency in the API.
 *———————————————————————————————————————————————————————————————————*/
- (void)serverStop
{
    if (self.serverTask.running)
    {
        dispatch_async(self.serial_queue, ^{
            [self.serverTask terminate];
            [self.serverTask waitUntilExit];
        });
    }
}


#pragma mark - Private Methods


/*———————————————————————————————————————————————————————————————————*
 * - configureTask
 *———————————————————————————————————————————————————————————————————*/
- (void)configureTask
{
    NSBundle *bundle = [NSBundle bundleForClass:[self class]];
    
#if defined(__aarch64__)
    NSString *jre = [bundle pathForResource:@"java_arm"
                                     ofType:@""
                                inDirectory:@"PlugIns/Java-fat64.bundle/Contents/Home/bin"];
#else
    NSString *jre = [bundle pathForResource:@"java"
                                     ofType:@""
                                inDirectory:@"PlugIns/Java-fat64.bundle/Contents/Home/bin"];
#endif
    
    NSString *jar = [bundle pathForResource:@"vnu"
                                     ofType:@"jar"
                                inDirectory:@"Java"];
    
    
    self.serverTask = [[NSTask alloc] init];
    self.serverTask.launchPath = jre;
    self.serverTask.arguments = @[ @"-cp", jar, @"-Dnu.validator.servlet.bind-address=127.0.0.1", @"nu.validator.servlet.Main", self.port ];
    
    /* Capture output in order to scrape STDERR for startup status. */
    
    NSPipe *outPipe = [NSPipe pipe];
    NSFileHandle *outHandle = outPipe.fileHandleForReading;
    
    _serverTask.standardOutput = outPipe;
    
    [outHandle waitForDataInBackgroundAndNotify];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(receivedData:)
                                                 name:NSFileHandleDataAvailableNotification
                                               object:outHandle];
    
    /* Termination Block */
    
    __weak typeof(self) weakSelf = self;
    self.serverTask.terminationHandler = ^(NSTask *aTask)
    {
        __strong typeof(self) strongSelf = weakSelf;
        dispatch_async(dispatch_get_main_queue(), ^{
            
            [strongSelf.watchdog terminate];
            
            if ( strongSelf.serverTask.terminationStatus != NSTaskTerminationReasonExit)
            {
                strongSelf.internalStatus = JSDNuVServerExternalStop;
            }
            else
            {
                strongSelf.internalStatus = JSDNuVServerStopped;
            }
        });
    };
}


/*———————————————————————————————————————————————————————————————————*
 * - receivedData:
 *    Essentially, wait until we see that the server is completely
 *    running so that we can update the status.
 *———————————————————————————————————————————————————————————————————*/
- (void)receivedData:(NSNotification *)notification
{
    NSFileHandle *outHandle = [notification object];
    NSData *data = [outHandle availableData];
    if (data.length > 0)
    {
        [outHandle waitForDataInBackgroundAndNotify];
        NSString *have = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
        NSString *want = @"Checker service started at";
        if ( [have containsString:want] )
        {
            self.internalStatus = JSDNuVServerRunning;
        }
    }}

@end