from urllib import request
from io import TextIOWrapper
from itertools import groupby
import re
import json

META_RELEASE_WORD_MATCHER = r'(^\Dist\:\s|Name:\s|Version:\s|Date:\s|Supported:\s|Description:\s|Release\-File\:\s|ReleaseNotes:\s|ReleaseNotesHtml\:\s|UpgradeTool:\s|UpgradeToolSignature:\s)'
META_SPACE_MATCHER = r'^\s'

class SourceMetaRelease:

    def __init__(self):
        self.meta_release_url = 'http://changelogs.ubuntu.com/meta-release'

    def meta_release_parse(self):
        """ Returns the meta_release_file parsed as a list of dicts """
        with request.urlopen(self.meta_release_url) as response:
            index_counter = 0
            lines = TextIOWrapper(response, encoding='utf-8')
            stripped_lines = [
                    re.split(META_RELEASE_WORD_MATCHER, l.strip())[1::] for l in
                    lines ]
            grouped_lines = [list(group) for key, group in
                    groupby(stripped_lines, lambda x: x == []) if not key]
            list_of_dicts = []

            for group in grouped_lines:
                d = {}
                # list of each group
                for arr in group:
                    arr_per_group = len(group)
                    k = arr[0].lower().replace(":", "").strip()
                    v = arr[1].strip()

                    # this builds up our dict by adding one k,v pair per key
                    d[f"{k}"] = v

                    list_of_dicts.append(d) if arr_per_group == len(d.keys()) else None 

            return list_of_dicts
                 

class MetaRelease:
    """ 
    MetaRelease(): an object for holding onto the contents of a
    meta_release entry 
    """ 
    def __init__(self, dist=None, name=None, version=None, date=None,
            supported=None, description=None, release_file=None,
            release_notes=None, release_notes_html=None, 
            upgrade_tool=None, upgrade_tool_signature=None):
        
        self.dist = dist
        self.name = name
        self.version = version
        self.supported = supported
        self.description = description
        self.release_file = release_file
        self.release_notes = release_notes
        self.release_notes_html = release_notes_html
        self.upgrade_tool = upgrade_tool
        self.upgrade_tool_signature = upgrade_tool_signature
    
    def to_json(self):
        return json.dumps(self, default=lambda o: o.__dict__,
                indent=4)


if __name__ == '__main__':
    meta_release = SourceMetaRelease().meta_release_parse()
    for d in meta_release:
        keys = d.keys()
        meta_release_obj = MetaRelease(
                dist = d['dist'] if 'dist' in keys else None,
                name = d['name'] if 'name' in keys else None,
                version = d['version'] if 'version' in keys else None,
                supported = d['supported'] if 'supported' in keys else None,
                description = d['description'] if 'description' in keys else None,
                release_file = d['release-file'] if 'release-file' in keys else None,
                release_notes = d['releasenotes'] if 'releasenotes' in keys else None,
                release_notes_html = d['releasenoteshtml'] if 'releasenoteshtml' in keys else None,
                upgrade_tool = d['upgradetool'] if 'upgradetool' in keys else None,
                upgrade_tool_signature = d['upgradetoolsignature'] if 'upgradetoolsignature' in keys else None
                )

        print(meta_release_obj.to_json())