import re
from os.path import join
import logging

from .xml import read_xml, parse_metadata_schema, Parameter
from .context import Context
from .source import Source
from .exceptions import RegistrationError


logger = logging.getLogger(__name__)

class RegistrationScheme:
    def get_context(self):
        raise NotImplementedError


def parse_datetime(value):
    return value


def pairwise(iterable):
    "s -> (s0,s1), (s2,s3), (s4, s5), ..."
    a = iter(iterable)
    return zip(a, a)


def parse_footprint(value):
    coord_list = ','.join(
        f'{x} {y}'
        for y, x in pairwise(value.split())
    )
    return f'POLYGON(({coord_list}))'


class Sentinel2RegistrationScheme(RegistrationScheme):
    MTD_MSIL2A_SCHEMA = {
        'begin_time': Parameter('/n1:Level-2A_User_Product/n1:General_Info/Product_Info/PRODUCT_START_TIME/text()', False, parse_datetime),
        'end_time': Parameter('/n1:Level-2A_User_Product/n1:General_Info/Product_Info/PRODUCT_STOP_TIME/text()', False, parse_datetime),
        'identifier': Parameter('/n1:Level-2A_User_Product/n1:General_Info/Product_Info/PRODUCT_URI/text()'),
        'footprint': Parameter('/n1:Level-2A_User_Product/n1:Geometric_Info/Product_Footprint/Product_Footprint/Global_Footprint/EXT_POS_LIST/text()', False, parse_footprint),
        'level': Parameter('/n1:Level-2A_User_Product/n1:General_Info/Product_Info/PROCESSING_LEVEL/text()'),
        'type': Parameter('/n1:Level-2A_User_Product/n1:General_Info/Product_Info/PRODUCT_TYPE/text()'),
        'generation_time': Parameter('/n1:Level-2A_User_Product/n1:General_Info/Product_Info/GENERATION_TIME/text()', False, parse_datetime),
        'cloud_cover': Parameter('/n1:Level-2A_User_Product/n1:Quality_Indicators_Info/Cloud_Coverage_Assessment/text()'),
        'image_file_paths': Parameter('/n1:Level-2A_User_Product/n1:General_Info/Product_Info/Product_Organisation/Granule_List/Granule/IMAGE_FILE/text()', True),
    }

    MTD_TL_SCHEMA = {
        'mask_file_paths': Parameter('/n1:Level-2A_Tile_ID/n1:Quality_Indicators_Info/Pixel_Level_QI/MASK_FILENAME/text()', True),
    }

    MTD_MSIL2A_NAMESPACES = {
        'n1': "https://psd-14.sentinel2.eo.esa.int/PSD/User_Product_Level-2A.xsd"
    }

    MTD_TL_NAMESPACES = {
        'n1': 'https://psd-14.sentinel2.eo.esa.int/PSD/S2_PDI_Level-2A_Tile_Metadata.xsd'
    }

    def get_context(self, source: Source, path: str):
        metadata_file = join(path, 'MTD_MSIL2A.xml')
        tree = read_xml(source, metadata_file)

        # get product metadata
        metadata = parse_metadata_schema(tree, self.MTD_MSIL2A_SCHEMA, self.MTD_MSIL2A_NAMESPACES)

        band_re = re.compile(r'.*([A-Z0-9]{3}_[0-9]{2}m)$')
        raster_files = {
            band_re.match(image_file_path).groups()[0]: f'{join(path, image_file_path)}.jp2'
            for image_file_path in metadata['image_file_paths']
        }

        # get granule metadata
        mtd_files = source.list_files(join(path, 'GRANULE'), '*/MTD_TL.xml')
        logger.info(f'{mtd_files}')
        tl_tree = read_xml(source, mtd_files[0])
        tile_metadata = parse_metadata_schema(tl_tree, self.MTD_TL_SCHEMA, self.MTD_TL_NAMESPACES)

        mask_type_re = re.compile(r'.*/MSK_([A-Z]*)_([A-Z0-9]{3}).[a-z0-9]+$')
        mask_files = {
            mask_type_re.match(mask_file_path).groups()[0]: join(path, mask_file_path)
            for mask_file_path in tile_metadata['mask_file_paths']
            if mask_type_re.match(mask_file_path) is not None
        }

        return Context(
            identifier=metadata['identifier'],
            path=path,
            product_type=metadata['type'],
            product_level=metadata['level'],
            raster_files=raster_files,
            mask_files=mask_files,
            metadata_files=[metadata_file],
            metadata={
                'begin_time': metadata['begin_time'],
                'end_time': metadata['end_time'],
                'generation_time': metadata['generation_time'],
                'cloud_cover': metadata['cloud_cover'],
                'footprint': metadata['footprint'],
            }
        )



class GSCRegistrationScheme(RegistrationScheme):
    pass


REGISTRATION_SCHEMES = {
    'gsc': GSCRegistrationScheme,
    'sentinel-2': Sentinel2RegistrationScheme,
}

def get_scheme(config: dict, path: str) -> RegistrationScheme:
    cfg_schemes = config['schemes']

    for cfg_scheme in cfg_schemes:
        if cfg_scheme['filter']:
            if re.match(cfg_scheme['filter'], path):
                break
        else:
            break
    else:
        # no source found
        raise RegistrationError(f'Could not find a suitable scheme for the path {path}')

    return REGISTRATION_SCHEMES[cfg_scheme['type']](
        *cfg_scheme.get('args', []),
        **cfg_scheme.get('kwargs', {}),
    )