#include "gtest/gtest.h"
#include "ariba/utility/system/SystemQueue.h"

#include <unistd.h>  // usleep
#include <boost/date_time.hpp> // local_time()

#include <ostream>

using namespace ::testing;
using namespace ariba::utility;
using namespace std;

using boost::posix_time::microsec_clock;


/**
 *  Tests if the SystemQueue is initialized empty and not running.
 */
TEST(SystemQueue, Instantiation)
{
    SystemQueue& sysq = SystemQueue::instance();
    
//     cout << &sysq << endl;
    
    EXPECT_FALSE( sysq.isRunning() );
    EXPECT_TRUE( sysq.isEmpty() );
}


/**
 *  Tests whether calling the SystemQueue::instance() always returns the same object.
 * 
 *  NOTE: This is an easy case, since this is the same compile unit..
 *    But can't hurt to test it anyway.
 */
TEST(SystemQueue, Singleton)
{
    SystemQueue& sysq = SystemQueue::instance();
    SystemQueue& sysq2 = SystemQueue::instance();

//     cout << &sysq << endl;
    
    EXPECT_TRUE( &sysq == &sysq2 );
}


/**
 *  Start and stop the SystemQueue
 */
TEST(SystemQueue, StartStop)
{
    SystemQueue& sysq = SystemQueue::instance();

    EXPECT_FALSE( sysq.isRunning() );
    
    // start
    sysq.run();
    
    EXPECT_TRUE( sysq.isRunning() );
    
    // stop
    sysq.cancel();
    
    EXPECT_FALSE( sysq.isRunning() );
}


/**
 *  Test fixture
 * 
 *  class that can be called by the SystemQueue
 */
// To use a test fixture, derive a class from testing::Test.
class SystemQueueTest : 
        public testing::Test
{
public:

// sleep time when waiting for the system queue (max total / each step)
#define MAX_WAIT 100  // microseconds
#define SLEEP_TIME 10  // microseconds

    SystemQueueTest() :
        checkmark(false),
        last_ordered_call(0)
    {
    }
        
    void Check()
    {
        checkmark = true;
    }
    
    void LongRunner()
    {
        usleep( MAX_WAIT / 2 );
        
        checkmark = true;
    }
    
    
    /// wait for the checkmark to be set by a SystemQueue call, (but not too long!)
    void wait_for_checkmark(int max_wait = MAX_WAIT)
    {
        for ( int i = 0; i < max_wait / SLEEP_TIME; i++)
        {
            if ( checkmark )
                break;
            
            cout << "/// sleeping for " << SLEEP_TIME << " microseconds ..." << endl;
            usleep(SLEEP_TIME);
        }
    }

    /// call that checks wheather it was performed in order
    void OrderedCall(int num)
    {
        // XXX
        cout << "### OrderedCall num: " << num << endl;
        
        // check ordering
        EXPECT_EQ( num, last_ordered_call + 1);
        
        last_ordered_call = num;
    }
    
    /// like OrderedCall, but calls itself to test nested calls
    void NestedOrderedCall(int from, int to)
    {
        // check ordering
        OrderedCall(from);
        
        // nested call
        if ( from < to )
        {
            SystemQueue::instance().scheduleCall( 
                boost::bind(&SystemQueueTest::NestedOrderedCall,
                            this,
                            from+1,
                            to)
            );
        }
        else
        {
            /// XXX because the current/old SystemQueue does not pass the Threading test,
            /// we have to signal, that when all nested calls are finished,
            /// so we need to set the checkmark here..
            
            checkmark = true;
        }
    }

    bool checkmark;
    int last_ordered_call;
};


/**
 *  schedule a call and test whether it is actually performed by the SystemQueue
 */
TEST_F(SystemQueueTest, ScheduleCall)
{
    SystemQueue& sysq = SystemQueue::instance();
    checkmark = false;  // just to be sure..
    
    // start
    sysq.run();
    
    // scheduleCall
    sysq.scheduleCall(
        boost::bind(&SystemQueueTest::Check, this)
    );

    // wait for the event to happen
    wait_for_checkmark(MAX_WAIT);
    
    // stop
    sysq.cancel();
    
    EXPECT_TRUE( checkmark ) << "Function was not called within " << MAX_WAIT << " microseconds.";
}


/**
 *  This test actually tests two things [sorry, but it's hard to test them separately!]
 * 
 *  - first: the SystemQueue should not consider itself empty, while an event is processed
 *  - second: SystemQueue events should be processed in parallel to the main thread
 * 
 *  NOTE: The timings here are not obvious, maybe they have to be adjusted on very slow machines
 * 
 *  NOTE: !! The current/old SystemQueue does NOT pass this test!!
 * 
 *    That's also why we need the unhandy wait_for_checkmark function,
 *    instead a wait_until_empty function.
 */
TEST_F(SystemQueueTest, DISABLED_Threading)
{
    SystemQueue& sysq = SystemQueue::instance();
    checkmark = false;  // just to be sure..
    
    // start
    sysq.run();
    
    // scheduleCall
    sysq.scheduleCall(
        boost::bind(&SystemQueueTest::LongRunner, this)
    );
    
    // SystemQueue must not be empty as long as the event is not finished
    if ( sysq.isEmpty() )
    {
        // assert that this test is actually meaningful
        ASSERT_FALSE( checkmark )
            << "NOTE: This is not necessarily a bug, maybe the timing just have to adjusted. Try to increase MAX_WAIT.";

        EXPECT_TRUE( ! sysq.isEmpty() || checkmark );
    }

    // wait for the event to finish
    wait_for_checkmark(MAX_WAIT);

    // stop
    sysq.cancel();

    // even the long-runner should finally finish
    EXPECT_TRUE( checkmark ) << "Function has not finished within " << MAX_WAIT << " microseconds.";
}

/**
 *  schedule multiple calls
 * 
 *  each call must be performed, in the correct order
 * 
 *  NOTE: The nested calls are not necessarily in order with calls scheduled from the main thread,
 *  that's fine, therefore we make sure the nested calls are done, before scheduling new ones.
 */
TEST_F(SystemQueueTest, MultipleCalls)
{
    SystemQueue& sysq = SystemQueue::instance();
    
    // start
    sysq.run();

    sysq.scheduleCall( boost::bind(&SystemQueueTest::OrderedCall, this, 1) );
    sysq.scheduleCall( boost::bind(&SystemQueueTest::OrderedCall, this, 2) );
    sysq.scheduleCall( boost::bind(&SystemQueueTest::NestedOrderedCall, this, 3, 5) );
    
    // make sure all nested calls are done
    wait_for_checkmark(MAX_WAIT);  // XXX should be "wait_until_empty() ...."

    checkmark = false;
    sysq.scheduleCall( boost::bind(&SystemQueueTest::OrderedCall, this, 6) );
    
    // XXX same here...  [ wait_until_empty() ]
    sysq.scheduleCall( boost::bind(&SystemQueueTest::Check, this) );
    wait_for_checkmark(MAX_WAIT);
    
    // evaluation
    EXPECT_EQ( 6, last_ordered_call);
    
    // stop
    sysq.cancel();
}



/**
 *  This subclass has some special member functions suitable for timing tests
 * 
 *  NOTE: Timing tests are not always reproducable.. sorry. :-/
 */
class SystemQueueTimingTest : 
        public SystemQueueTest
{
public:

/**
 *  typical delay time
 * 
 *  should be long enough for meaningful tests,
 *  but should not lengthen the test excessivly
 */
#define DELAY_TIME 20  // ms
#define DELAY_MARGIN 2000  // microseconds (1/1000 ms)   // TODO maybe this is too much..


    /// constructor
    SystemQueueTimingTest() :
        SystemQueueTest()  /* super constructor */,
        sysq( SystemQueue::instance() ),
        calls(0)
    {
    }
    
    virtual void SetUp()
    {
        // start SystemQueue
        sysq.run();
    }
    

    virtual void TearDown()
    {
        // stop SystemQueue
        sysq.cancel();
    }
    
    
    /**
     * @param placed_in_queue The time (as ptime) when this event is put into the delay queue
     * @param intended_sleep_time The time (in microseconds) the event is supposed to sleep in the queue
     * @param margin The acceptable margin (in microseconds)
     */
    void TimeCheckingCall(ptime placed_in_queue, uint64_t intended_sleep_time, uint64_t margin)
    {
        ptime called_at = microsec_clock::local_time();
        
        // calculate actual sleep time and difference to intended sleep time
        boost::posix_time::time_duration actual_sleep_time = called_at - placed_in_queue;
        uint64_t diff = actual_sleep_time.total_microseconds() - intended_sleep_time;
        
        // info
        cout << "### Timing difference: " << diff << " microseconds" << endl;
        
        EXPECT_LT( abs(diff), margin );
        
        calls++;
        checkmark = true;
    }

    SystemQueue& sysq;
    int calls;
};


/**
 *  schedules a delayed call and tests whether it is called (more or less timely..)
 */
TEST_F(SystemQueueTimingTest, DelayedCall)
{
    // scheduleCall
    sysq.scheduleCall(
        boost::bind(&SystemQueueTimingTest::Check, this), DELAY_TIME
    );

    // noting to do until the delay is up..
    usleep(DELAY_TIME*1000 + DELAY_MARGIN*10);  // XXX margin too high (TODO lower when SysQ is reimplemented)
    
    // wait for the event to happen
    wait_for_checkmark(MAX_WAIT);
    
    EXPECT_TRUE( checkmark ) << "Delayed function was not called within delaytime (" 
        << DELAY_TIME << " ms) + " << (MAX_WAIT + DELAY_MARGIN) << " microseconds.";
}


/**
 *  tests whether the SystemQueue is considered non-empty, while an event is delayed-waiting
 */
TEST_F(SystemQueueTimingTest, NotEmptyWhileWaiting)
{
    // scheduleCall
    sysq.scheduleCall(
        boost::bind(&SystemQueueTimingTest::Check, this), DELAY_TIME
    );

    // SystemQueue must not be empty as long as the event is not finished (and especially while stille queued)
    if ( sysq.isEmpty() )
    {
        // assert that this test is actually meaningful
        ASSERT_FALSE( checkmark )
            << "NOTE: This is not necessarily a bug, maybe the timing just have to adjusted. Try to increase MAX_WAIT.";

        EXPECT_TRUE( ! sysq.isEmpty() || checkmark );
    }
}



/**
 *  schedules a delayed call and tests whether it is called (more or less timely..)
 */
TEST_F(SystemQueueTimingTest, MultipleCalls)
{
    // schedule 4th call 
    sysq.scheduleCall(
        boost::bind(&SystemQueueTest::OrderedCall, this, 4),
                    DELAY_TIME*3
    );
    
    // schedule 2nd call 
    sysq.scheduleCall(
        boost::bind(&SystemQueueTest::OrderedCall, this, 2),
                    DELAY_TIME*1
    );
    
    // schedule 3rd call 
    sysq.scheduleCall(
        boost::bind(&SystemQueueTest::OrderedCall, this, 3),
                    DELAY_TIME*2
    );

    // schedule 1st call (without delay)
    sysq.scheduleCall(
        boost::bind(&SystemQueueTest::OrderedCall, this, 1)
    );
    
    
    // XXX the usual bug..
    sysq.scheduleCall(
        boost::bind(&SystemQueueTimingTest::Check, this),
                    DELAY_TIME*4
    );

    // noting to do until the delay is up..
    usleep(DELAY_TIME * 4000 + DELAY_MARGIN*100);  // XXX margin too high
    
    // wait for the event to happen
    wait_for_checkmark(MAX_WAIT);
    
    // evaluation
    EXPECT_EQ( 4, last_ordered_call);
}


/**
 *  Schedules a delayed call and test whether the sleep time is acurate
 */
TEST_F(SystemQueueTimingTest, TimingSingleCall)
{
    ptime now = microsec_clock::local_time();
    
    sysq.scheduleCall(
        boost::bind(&SystemQueueTimingTest::TimeCheckingCall, this, 
                    now, DELAY_TIME*1000, DELAY_MARGIN),
        DELAY_TIME
    );

    // main thread is going to sleep..
    usleep(DELAY_TIME * 1000 + DELAY_MARGIN * 2);
    wait_for_checkmark(MAX_WAIT);
    
    // make sure the measurement function was called at all
    EXPECT_TRUE(checkmark) << "Measurement function was NOT RUN AT ALL!";
}


/**
 *  Like TimingSingleCall but tests whether the timings change when multiple events are scheduled.
 */
TEST_F(SystemQueueTimingTest, TimingMultipleCalls)
{
    ptime now = microsec_clock::local_time();
    
    sysq.scheduleCall(
        boost::bind(&SystemQueueTimingTest::TimeCheckingCall, this, 
                    now, DELAY_TIME*1000 * 2, DELAY_MARGIN),
        DELAY_TIME * 2
    );

    sysq.scheduleCall(
        boost::bind(&SystemQueueTimingTest::TimeCheckingCall, this, 
                    now, DELAY_TIME*1000 * 3, DELAY_MARGIN),
        DELAY_TIME * 3
    );

    sysq.scheduleCall(
        boost::bind(&SystemQueueTimingTest::TimeCheckingCall, this, 
                    now, DELAY_TIME*1000, DELAY_MARGIN),
        DELAY_TIME
    );

    // main thread is going to sleep..
    usleep(DELAY_TIME * 3000 + DELAY_MARGIN * 2);
    wait_for_checkmark(MAX_WAIT);  // XXX wait_until_empty
    
    // make sure the measurement function was called at all
    EXPECT_EQ(3, calls) << "Not every event was performed..";
}


/*
 * TODO
 * 
 * maybe one more complicated testcall with timing and directly scheduled events
 * 
 * but this probably only makes sense after a working SysQ implementation exists..
 */