#!/usr/bin/env python
import sys
import optparse
import time
import os
import numpy as np

import detectors
import optics
import generator
from generator import constant
import gpu
from fileio import root
from tools import profile_if_possible, enable_debug_on_crash

def pick_seed():
    '''Returns a seed for a random number generator selected using
    a mixture of the current time and the current process ID.'''
    return int(time.time()) ^ (os.getpid() << 16)

@profile_if_possible
def main():
    parser = optparse.OptionParser('%prog')
    parser.add_option('-b', type='int', dest='nbits', default=10)
    parser.add_option('-j', type='int', dest='device', default=None)
    parser.add_option('-n', type='int', dest='nblocks', default=64)
    parser.add_option('-s', type='int', dest='seed', default=None,
                      help='Set random number generator seed')
    parser.add_option('-g', type='int', dest='ngenerators', default=4,
                      help='Number of GEANT4 generator processes')
    parser.add_option('--detector', type='string', dest='detector', default='microlbne')
    parser.add_option('--nevents', type='int', dest='nevents', default=100)    
    parser.add_option('--particle', type='string', dest='particle', default='e-')
    parser.add_option('--energy', type='float', dest='energy', default=100.0)
    parser.add_option('--pos', type='string', dest='pos', default='(0,0,0)')
    parser.add_option('--dir', type='string', dest='dir', default='(1,0,0)')
    parser.add_option('--save-photon-start', action='store_true', 
                      dest='save_photon_start', default=False,
                      help='Save initial photon vertices to disk')
    parser.add_option('--save-photon-stop', action='store_true', 
                      dest='save_photon_stop', default=False,
                      help='Save final photon vertices to disk')

    options, args = parser.parse_args()
    if len(args) != 1:
        print 'Must specify output filename!'
        sys.exit(1)
    else:
        output_filename = args[0]

    if options.nevents <= 0:
        print '--nevents must be greater than 0!'
        sys.exit(1)

    position = np.array(eval(options.pos), dtype=float)
    direction = np.array(eval(options.dir), dtype=float)
    detector = detectors.find(options.detector)
    if options.seed is None:
        options.seed = pick_seed()

    print >>sys.stderr, 'RNG seed:', options.seed
    # We have three generators to seed: numpy.random, GEANT4, and CURAND.
    # The latter two are done below
    np.random.seed(options.seed)

    print >>sys.stderr, 'Creating generator...'
    if options.particle == 'pi0':
        vertex_generator = generator.vertex.pi0_gun(pi0_position=constant(position),
                                                    pi0_direction=constant(direction),
                                                    pi0_total_energy=constant(options.energy))
    else:
        vertex_generator = generator.vertex.particle_gun(particle_name=constant(options.particle),
                                                         position=constant(position),
                                                         direction=constant(direction),
                                                         total_energy=constant(options.energy))
    detector_material = optics.water_wcsim
    photon_generator = generator.photon.G4ParallelGenerator(options.ngenerators, detector_material,
                                                           base_seed=options.seed)
    print >>sys.stderr, 'WARNING: ASSUMING DETECTOR IS WCSIM WATER!!'

    # Do this now so we can get ahead of the photon propagation
    print >>sys.stderr, 'Starting GEANT4 generators...'
    event_iterator = photon_generator.generate_events(options.nevents, vertex_generator)

    print >>sys.stderr, 'Creating BVH for detector "%s" with %d bits...' % (options.detector, options.nbits)
    detector.build(bits=options.nbits)

    print >>sys.stderr, 'Initializing GPU...'
    gpu_worker = gpu.GPU(options.device)
    
    print >>sys.stderr, 'Loading detector onto GPU...'
    gpu_worker.load_geometry(detector)
    
    print >>sys.stderr, 'Initializing random numbers generators...'
    gpu_worker.setup_propagate(seed=options.seed)
    gpu_worker.setup_daq(max(detector.pmtids))

    # Create output file
    writer = root.RootWriter(output_filename)

    print >>sys.stderr, 'Starting simulation...'
    start_sim = time.time()
    nphotons = 0

    for i, ev in enumerate(event_iterator):
        photons = ev.photon_start
        assert len(photons.positions) > 0, 'GEANT4 generated event with no photons!'

        nphotons += len(photons.positions)

        gpu_worker.load_photons(photons)

        gpu_worker.propagate()
        gpu_worker.run_daq()

        ev.hits = gpu_worker.get_hits()        
        if not options.save_photon_start:
            ev.photon_start = None
        if options.save_photon_stop:
            ev.photon_stop = gpu_worker.get_photons()
        writer.write_event(ev)

        if i % 10 == 0:
            print >>sys.stderr, "\rEvent:", i,

    end_sim = time.time()
    print >>sys.stderr, "\rEvent:", options.nevents - 1

    writer.close()

    print >>sys.stderr, 'Done. %1.1f events/sec, %1.0f photons/sec.' % (options.nevents/(end_sim - start_sim), nphotons/(end_sim - start_sim))

if __name__ == '__main__':
    enable_debug_on_crash()
    main()