#!/usr/bin/python
# -*- coding: utf-8 -*-
# \file Differential.py
# \brief TODO
# \author Florent Guiotte <florent.guiotte@gmail.com>
# \version 0.1
# \date 16 avril 2018
#
# TODO details

from ld2dap.core import Filter, Stack
import numpy as np

class Differential(Filter):
    def __init__(self, overflow='auto'):
        super().__init__(self.__class__.__name__)
        self.overflow = overflow

    def _process(self, data, metadata):
        self.logger.info('Run differential on stack of size {}'.format(data.shape))
        raster_list = list()
        metadata_new = list()

        offset = 0
        for stack in metadata:
            self.logger.debug('{}'.format(stack))
            overflow = (data[:, :, stack.begin:stack.end-1] >
                        data[:, :, stack.begin+1:stack.end]).any() and \
                       str(data.dtype).startswith('u')
                       
            dtype = data.dtype
            if overflow:
                self.logger.warn('Overflow detected')
                if self.overflow == 'auto':
                    dtype = np.dtype(str(data.dtype).lstrip('u'))
                    self.logger.info('Changing dtype from {} to {}'.format(
                                      data.dtype, dtype))

            raster_list.append(np.subtract(data[:, :, stack.begin+1:stack.end],
                               data[:, :, stack.begin:stack.end-1], dtype=dtype))

            size_new  = stack.end - stack.begin - 1
            stack_new = Stack(offset, size_new)

            for i in range(len(stack_new.desc)):
                desc = stack.desc[i].copy()
                desc.append(':Differential:')
                desc.extend(stack.desc[i+1])
                stack_new.desc[i] = desc
            metadata_new.append(stack_new)

            for i in range(len(stack_new.symb)):
                symb = list() #['D(']
                symb.extend(stack.symb[i])
                symb.append(' - ')
                symb.extend(stack.symb[i+1])
                #symb.append(')')
                stack_new.symb[i] = symb

            offset += size_new

        data = np.dstack(raster_list)

        return data, metadata_new