#!/usr/bin/env python
from __future__ import print_function
import sys
import numpy as np
import cv2
import time
import ctypes
import multiprocessing
from astropy.coordinates import EarthLocation
from astropy.time import Time
from astropy.io import fits
import astropy.units as u
from utils import get_sunset_and_sunrise

# Capture images
def capture(buf,z1,t1,z2,t2,device,nx,ny,nz,tend):
    # Array flag
    first=True

    # Loop until reaching end time
    while float(time.time())<tend:
        # Get frames
        for i in range(nz):
            # Get frame
            ret,frame=device.read()
            
            # Skip lost frames
            if ret==True:
                # Store time
                t=float(time.time())
                
                # Convert image to grayscale
                gray=np.asarray(cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)).astype(np.uint8)
                
                # Store buffer        
                z=gray

                # Store results
                if first:
                    z1[i]=z
                    t1[i]=t
                else:
                    z2[i]=z
                    t2[i]=t

        # Assign buffer ready
        if first:
            buf.value=1
        else:
            buf.value=2
        
        # Swap flag
        first=not first

    print("Exiting capture")    
        
def compress(buf,z1,t1,z2,t2,nx,ny,nz,tend):
    # Flag to keep track of processed buffer
    process_buf=1

    # Start processing
    while True:
        # Wait for buffer to become available
        while buf.value!=process_buf:
            time.sleep(1.0)

        # Process first buffer
        if buf.value==1:
            t=t1
            z=z1.astype('float32')
            process_buf=2
        elif buf.value==2:
            t=t2
            z=z2.astype('float32')
            process_buf=1

        # Compute statistics
        zmax=np.max(z,axis=0)
        znum=np.argmax(z,axis=0)
        zs1=np.sum(z,axis=0)-zmax
        zs2=np.sum(z*z,axis=0)-zmax*zmax
        zavg=zs1/float(nz-1)
        zstd=np.sqrt((zs2-zs1*zavg)/float(nz-2))

        # Convert to float and flip
        zmax=np.flipud(zmax.astype('float32'))
        znum=np.flipud(znum.astype('float32'))
        zavg=np.flipud(zavg.astype('float32'))
        zstd=np.flipud(zstd.astype('float32'))

        # Format time
        nfd="%s.%03d"%(time.strftime("%Y-%m-%dT%T", time.gmtime(t[0])),int((t[0]-np.floor(t[0]))*1000))
        t0=Time(nfd,format='isot')
        dt=t-t[0]

        # Generate fits
        fname="%s.fits"%nfd

        # Format header
        hdr=fits.Header()
        hdr['DATE-OBS']="%s"%nfd
        hdr['MJD-OBS']=t0.mjd
        hdr['EXPTIME']=dt[-1]-dt[0]
        hdr['NFRAMES']=nz
        hdr['CRPIX1']=float(nx)/2.0
        hdr['CRPIX2']=float(ny)/2.0
        hdr['CRVAL1']=0.0
        hdr['CRVAL2']=0.0
        hdr['CD1_1']=1.0/3600.0
        hdr['CD1_2']=0.0
        hdr['CD2_1']=0.0
        hdr['CD2_2']=1.0/3600.0
        hdr['CTYPE1']="RA---TAN"
        hdr['CTYPE2']="DEC--TAN"
        hdr['CUNIT1']="deg"
        hdr['CUNIT2']="deg"
        hdr['CRRES1']=0.0
        hdr['CRRES2']=0.0
        hdr['EQUINOX']=2000.0
        hdr['RADECSYS']="ICRS"
        hdr['COSPAR']=4171
        hdr['OBSERVER']="Cees Bassa"
        for i in range(nz):
            hdr['DT%04d'%i]=dt[i]
        for i in range(10):
            hdr['DUMY%03d'%i]=0.0
        
        # Write fits file
        hdu=fits.PrimaryHDU(data=np.array([zavg,zstd,zmax,znum]),header=hdr)
        hdu.writeto(fname)
        print("Compressed",fname)

        # Exit on end of capture
        if t[-1]>tend:
            break

    # Exiting
    print("Exiting compress")
        
 # Main function
if __name__ == '__main__':
    # Current time
    tnow=Time.now()

    # Set location
    loc=EarthLocation(lat=52.8344*u.deg,lon=6.3785*u.deg,height=10*u.m)

    # Reference altitude
    refalt=-6.0*u.deg
    
    # Get sunrise and sunset times
    state,tset,trise=get_sunset_and_sunrise(tnow,loc,refalt)
    
    # Start/end logic
    if state=="sun never rises":
        print("The sun never rises. Exiting program.")
        sys.exit()
    elif state=="sun never sets":
        print("The sun never sets.")
        tend=tnow+24*u.h
    elif (trise<tset):
        print("The sun is below the horizon.")
        tend=trise
    elif (trise>=tset):
        dt=np.floor((tset-tnow).to(u.s).value)
        print("The sun is above the horizon. Sunset at %s.\nWaiting %.0f seconds."%(tset.isot,dt))
        tend=trise
        try:
            time.sleep(dt)
        except KeyboardInterrupt:
            sys.exit()

    print("Starting data acquisition. Acquisition will end at "+tend.isot)

    # Settings
    devid=int(sys.argv[1])
    nx=720
    ny=576
    nz=250

    # Initialize device
    device=cv2.VideoCapture(devid)

    # Set properties
    device.set(3,nx)
    device.set(4,ny)

    # Initialize arrays
    z1base=multiprocessing.Array(ctypes.c_uint8,nx*ny*nz)
    z1=np.ctypeslib.as_array(z1base.get_obj()).reshape(nz,ny,nx)
    t1base=multiprocessing.Array(ctypes.c_double,nz)
    t1=np.ctypeslib.as_array(t1base.get_obj())
    z2base=multiprocessing.Array(ctypes.c_uint8,nx*ny*nz)
    z2=np.ctypeslib.as_array(z2base.get_obj()).reshape(nz,ny,nx)
    t2base=multiprocessing.Array(ctypes.c_double,nz)
    t2=np.ctypeslib.as_array(t2base.get_obj())
    buf=multiprocessing.Value('i',0)

    # Set processes
    pcapture=multiprocessing.Process(target=capture,args=(buf,z1,t1,z2,t2,device,nx,ny,nz,tend.unix))
    pcompress=multiprocessing.Process(target=compress,args=(buf,z1,t1,z2,t2,nx,ny,nz,tend.unix))

    # Start
    pcapture.start()
    pcompress.start()

    # End
    try:
        pcapture.join()
        pcompress.join()
    except KeyboardInterrupt:
        pcapture.terminate()
        pcompress.terminate()
                        
    # Release device
    device.release()