#
# Author: Heresh Fattahi
# Copyright 2017
#
# Modified by V. Brancato (10.12.2019)
# Including offset filtering with no SNR masking
#

import isce
import isceobj
from osgeo import gdal
import numpy as np
import os

def mask_filterNoSNR(denseOffsetFile,filterSize,outName):
    # Masking the offsets with a data-based approach

    from scipy import ndimage

    # Open the offsets
    ds = gdal.Open(denseOffsetFile+'.vrt',gdal.GA_ReadOnly)
    off_az = ds.GetRasterBand(1).ReadAsArray()
    off_rg = ds.GetRasterBand(2).ReadAsArray()
    ds = None
    
    # Remove values reported as missing data (no value data from ampcor)
    off_rg[np.where(off_rg < -9999)]=0
    off_az[np.where(off_az < -9999)]=0
 
    # Store the offsets in a complex variable
    off = off_rg + 1j*off_az

    # Mask the offset based on MAD
    mask = off_masking(off,filterSize,thre=3) 
    
    xoff_masked = np.ma.array(off.real,mask=mask)
    yoff_masked = np.ma.array(off.imag,mask=mask)
    
    # Delete not used variables
    mask = None
    off = None
    
    # Remove residual noisy spots with a median filter on the range offmap
    xoff_masked.mask =  xoff_masked.mask | \
            (ndimage.median_filter(xoff_masked.filled(fill_value=0),3) == 0) | \
            (ndimage.median_filter(yoff_masked.filled(fill_value=0),3) == 0)
    
    # Fill the range offset map iteratively with smoothed values
    
    data = xoff_masked.data
    data[xoff_masked.mask]=np.nan
    
    off_rg_filled = fill_with_smoothed(data,filterSize)
    
    # Apply the median filter on the offset
    off_rg_filled = ndimage.median_filter(off_rg_filled,filterSize)
    
    # Save the filtered offsets
    length, width = off_rg_filled.shape

    # writing the masked and filtered offsets to a file
    print ('writing masked and filtered offsets to: ', outName)

    ##Write array to offsetfile
    off_rg_filled.tofile(outName)

    # write the xml file
    img = isceobj.createImage()
    img.setFilename(outName)
    img.setWidth(width)
    img.setAccessMode('READ')
    img.bands = 1
    img.dataType = 'FLOAT'
    img.scheme = 'BIP'
    img.renderHdr()
    
    return 

def off_masking(off,filterSize,thre=2):

    from scipy import ndimage

    vram = ndimage.median_filter(off.real, filterSize)
    vazm = ndimage.median_filter(off.imag, filterSize)

    mask =  (np.abs(off.real-vram) > thre) | (np.abs(off.imag-vazm) > thre) | (off.imag == 0) | (off.real == 0)

    return mask


def fill(data, invalid=None):
    """
    Replace the value of invalid 'data' cells (indicated by 'invalid')
    by the value of the nearest valid data cell
    
    Input:
        data:    numpy array of any dimension
        invalid: a binary array of same shape as 'data'.
                 data value are replaced where invalid is True
                 If None (default), use: invalid  = np.isnan(data)
       
    Output:
        Return a filled array.
    """
    from scipy import ndimage

    if invalid is None: invalid = np.isnan(data)

    ind = ndimage.distance_transform_edt(invalid,
                                    return_distances=False,
                                    return_indices=True)
    return data[tuple(ind)]

def fill_with_smoothed(off,filterSize):

    from astropy.convolution import convolve

    off_2filt=np.copy(off)
    kernel = np.ones((filterSize,filterSize),np.float32)/(filterSize*filterSize)
    loop = 0
    cnt2=1
    
    while (cnt2 !=0 & loop<100):
       loop += 1
       idx2= np.isnan(off_2filt)
       cnt2 = np.sum(np.count_nonzero(np.isnan(off_2filt)))
       print(cnt2)
       if cnt2 != 0:
          off_filt= convolve(off_2filt,kernel,boundary='extend',nan_treatment='interpolate')
          off_2filt[idx2]=off_filt[idx2]
          idx3 = np.where(off_filt == 0)
          off_2filt[idx3]=np.nan
          off_filt=None
    
    return off_2filt
    
def mask_filter(denseOffsetFile, snrFile, band, snrThreshold, filterSize, outName):
    #masking and Filtering

    from scipy import ndimage

    ##Read in the offset file
    ds = gdal.Open(denseOffsetFile + '.vrt', gdal.GA_ReadOnly)
    Offset = ds.GetRasterBand(band).ReadAsArray()
    ds = None

    ##Read in the SNR file
    ds = gdal.Open(snrFile + '.vrt', gdal.GA_ReadOnly)
    snr = ds.GetRasterBand(1).ReadAsArray()
    ds = None

    # Masking the dense offsets based on SNR
    print ('masking the dense offsets with SNR threshold: ', snrThreshold)
    Offset[snr<snrThreshold]=np.nan

    # Fill the masked region using valid neighboring pixels
    Offset = fill(Offset)
    ############

    # Median filtering the masked offsets
    print ('Filtering with median filter with size : ', filterSize)
    Offset = ndimage.median_filter(Offset, size=filterSize)
    length, width = Offset.shape

    # writing the masked and filtered offsets to a file
    print ('writing masked and filtered offsets to: ', outName)

    ##Write array to offsetfile
    Offset.tofile(outName)

    # write the xml file
    img = isceobj.createImage()
    img.setFilename(outName)
    img.setWidth(width)
    img.setAccessMode('READ')
    img.bands = 1
    img.dataType = 'FLOAT'
    img.scheme = 'BIP'
    img.renderHdr()

    return None

def resampleOffset(maskedFiltOffset, geometryOffset, outName):
    '''
    Oversample offset and add.
    '''
    from imageMath import IML
    import logging

    resampledOffset = maskedFiltOffset + ".resampled"

    inimg = isceobj.createImage()
    inimg.load(geometryOffset + '.xml')
    length = inimg.getLength()
    width = inimg.getWidth()

    ###Currently making the assumption that top left of dense offsets and interfeorgrams are the same.
    ###This is not true for now. We need to update DenseOffsets to have the ability to have same top left
    ###As the input images. Once that is implemente, the math here should all be consistent.
    ###However, this is not too far off since the skip for doing dense offsets is generally large. 
    ###The offset is not too large to worry about right now. If the skip is decreased, this could be an issue.

    print('oversampling the filtered and masked offsets to the width and length:', width, ' ', length )
    cmd = 'gdal_translate -of ENVI -ot Float64  -outsize  ' + str(width) + ' ' + str(length) + ' ' + maskedFiltOffset + '.vrt ' + resampledOffset
    print(cmd)
    os.system(cmd)

    img = isceobj.createImage()
    img.setFilename(resampledOffset)
    img.setWidth(width)
    img.setLength(length)
    img.setAccessMode('READ')
    img.bands = 1
    img.dataType = 'DOUBLE'
    img.scheme = 'BIP'
    img.renderHdr()


    ###Adding the geometry offset and oversampled offset
    geomoff = IML.mmapFromISCE(geometryOffset, logging)
    osoff = IML.mmapFromISCE(resampledOffset, logging)

    fid = open(outName, 'w')

    for ll in range(length):
        val = geomoff.bands[0][ll,:] + osoff.bands[0][ll,:]
        val.tofile(fid)
    
    fid.close()

    img = isceobj.createImage()
    img.setFilename(outName)
    img.setWidth(width)
    img.setLength(length)
    img.setAccessMode('READ')
    img.bands = 1
    img.dataType = 'DOUBLE'
    img.scheme = 'BIP'
    img.renderHdr()

    

    return None

def runRubbersheetRange(self):

    from scipy import ndimage

    if not self.doRubbersheetingRange:
        print('Rubber sheeting in azimuth not requested ... skipping')
        return

    # denseOffset file name computeed from cross-correlation
    denseOffsetFile = os.path.join(self.insar.denseOffsetsDirname , self.insar.denseOffsetFilename)
    snrFile = denseOffsetFile + "_snr.bil"
    denseOffsetFile = denseOffsetFile + ".bil"

    # we want the range offsets only which are the first band
    band = [2]
    snrThreshold = self.rubberSheetSNRThreshold
    filterSize = self.rubberSheetFilterSize
    filtRgOffsetFile = os.path.join(self.insar.denseOffsetsDirname, self._insar.filtRangeOffsetFilename)

    # masking and median filtering the dense offsets
    if not self.doRubbersheetingRange:
       print('Rubber sheeting in range is off, applying SNR-masking for the offsets maps')
       mask_filter(denseOffsetFile, snrFile, band[0], snrThreshold, filterSize, filtRgOffsetFile)
    else:
       print('Rubber sheeting in range is on, applying a data-based offsets-masking')
       mask_filterNoSNR(denseOffsetFile,filterSize,filtRgOffsetFile)

    # range offsets computed from geometry
    offsetsDir = self.insar.offsetsDirname
    geometryRangeOffset = os.path.join(offsetsDir, self.insar.rangeOffsetFilename)
    RgsheetOffset = os.path.join(offsetsDir, self.insar.rangeRubbersheetFilename)

    # oversampling the filtRgOffsetFile to the same size of geometryRangeOffset
    # and then update the geometryRangeOffset by adding the oversampled 
    # filtRgOffsetFile to it.
    resampleOffset(filtRgOffsetFile, geometryRangeOffset, RgsheetOffset)

    return None