from qgis.core import QgsProcessing
from qgis.core import QgsProcessingAlgorithm
from qgis.core import QgsProcessingMultiStepFeedback
from qgis.core import QgsProcessingParameterBand
from qgis.core import QgsProcessingParameterRasterLayer
from qgis.core import QgsProcessingParameterNumber
from qgis.core import QgsProcessingParameterRasterDestination
import processing


class RasterCalculator(QgsProcessingAlgorithm):

def initAlgorithm(self, config=None):
    self.addParameter(QgsProcessingParameterBand('band', 'band', parentLayerParameterName='rasterlayer', allowMultiple=False, defaultValue=None))
    self.addParameter(QgsProcessingParameterRasterLayer('rasterlayer', 'layer', defaultValue=None))
    self.addParameter(QgsProcessingParameterNumber('refadd', 'refadd', type=QgsProcessingParameterNumber.Double, defaultValue=-0.1))
    self.addParameter(QgsProcessingParameterNumber('refmult', 'refmult', type=QgsProcessingParameterNumber.Double, defaultValue=2E-5))
    self.addParameter(QgsProcessingParameterNumber('sunel', 'sunel', type=QgsProcessingParameterNumber.Double, defaultValue=60))
    self.addParameter(QgsProcessingParameterRasterDestination('Reflectance', 'reflectance', createByDefault=True, defaultValue=None))

def processAlgorithm(self, parameters, context, model_feedback):
    # Use a multi-step feedback, so that individual child algorithm progress reports are adjusted for the
    # overall progress through the model
    feedback = QgsProcessingMultiStepFeedback(1, model_feedback)
    results = {}
    outputs = {}

    # Raster calculator
    alg_params = {
        'BAND_A': 1,
        'BAND_B': None,
        'BAND_C': None,
        'BAND_D': None,
        'BAND_E': None,
        'BAND_F': None,
        'FORMULA': '(A* refmult +(refadd) ) /( sin(sunel * 3.14159/180  ) )',
        'INPUT_A': parameters['rasterlayer'],
        'INPUT_B': None,
        'INPUT_C': None,
        'INPUT_D': None,
        'INPUT_E': None,
        'INPUT_F': None,
        'NO_DATA': None,
        'OPTIONS': '',
        'RTYPE': 5,
        'OUTPUT': parameters['Reflectance']
    }
    outputs['RasterCalculator'] = processing.run('gdal:rastercalculator', alg_params, context=context, feedback=feedback, is_child_algorithm=True)
    results['Reflectance'] = outputs['RasterCalculator']['OUTPUT']
    return results

def name(self):
    return 'raster calculator'

def displayName(self):
    return 'raster calculator'

def group(self):
    return 'remote sensing'

def groupId(self):
    return 'remote sensing'

def createInstance(self):
    return RasterCalculator()