import json
import os

'''
minpackage = {'id':        target_id,
              'thumb':     package['thumb'],
              'subtitles': package['subtitles'],
              'sources':   package['sources']}
'''

class Updater:
    def __init__(self, storage, jsonfile):
        self.storage = storage
        self.jsonfile = jsonfile

    def integrate_update(self, package):
        if package['origin'] != 'update':
            return package
        orig_id = package['orig_id']
        workbase = package['workbase']
        origbase = os.path.join(self.storage, orig_id)
        origjson = os.path.join(origbase, self.jsonfile)
        origpackage = None
        if not os.path.isfile(origjson):
            raise UpdateException(json.dumps(package),
                                  f'{origjson} not found.')
        with open(origjson) as f:
            origpackage = json.load(f)

        # Import untouched items from the original
        for key in ['thumb', 'subtitles']:
            if key not in package:
                # has to use .get() due to subs not always being there
                # should change to origpackage[key]
                origvalue = origpackage.get(key, '')
                package[key] = origvalue
                if origvalue:
                    self._copy(origbase, workbase, origvalue)
        # deal with the sources
        # list modified sources by name
        updatesources = {source['name']: source
                         for source in package['sources']}
        # list original sources by name
        origsources = {source['name']: source
                         for source in origpackage['sources']}
        # prepare a fresh collection of sources
        combosources = {}
        for sourcename, origsource in origsources.items():
            if sourcename in updatesources:
                # the source has been modified, copy untouched items
                updatesource = updatesources[sourcename]
                combosources[sourcename] = updatesource
                # name and playAudio are mandatory and can be ignored
                if 'poster' not in updatesource:
                    # copy the unchanged poster
                    combosources[sourcename]['poster'] = origsource['poster']
                    self._copy(origbase, workbase, origsource['poster'])
                if 'video' not in updatesource:
                    # copy the unchanged video files
                    combosources[sourcename]['video'] = origsource['video']
                    for variant in origsource['video']:
                        self._copy(origbase, workbase, variant)
            elif sourcename not in package['delete']:
                # the source was untouched, copy everything
                combosources[sourcename] = origsource
                self._copy(origbase, workbase, origsource['poster'])
                for variant in origsource['video'].values():
                    self._copy(origbase, workbase, variant)
        package['sources'] = combosources
        return package

    def _copy(self, orig, dest, item):
        return shutil.copy(os.path.join(orig, item),
                           os.path.join(dest, item))


class UpdateException(Exception):
    def __init__(self, package, message):
        self.package = package
        self.message = message