#!/usr/bin/env python3

# HACK: seems 'requests' module bundled with blender isn't bundled with 'idna' module. So force system python for now
import sys
sys.path.insert(0, '/usr/lib/python3.6/site-packages')

from pathlib import Path
import requests
import json
import logging

log = logging.getLogger(__name__)
# log.level = logging.DEBUG

class RepositoryError(Exception):
    """
    Superclass for repository-related exceptions
    """

class MissingURLError(RepositoryError):
    """
    Thrown when the repository needs a URL but doesn't have one
    """

# class RepositoryNotFound(

class Package:
    """
    Stores package methods and metadata
    """

    def __init__(self, package_dict:dict = None):
        self.from_dict(package_dict)

    def to_dict(self) -> dict:
        """
        Return a dict representation of the package
        """
        return {
                'bl_info': self.bl_info,
                'url': self.url,
                }

    def from_dict(self, package_dict: dict):
        """
        Get attributes from a dict such as produced by `to_dict`
        """
        if package_dict is None:
            package_dict = {}

        for attr in ('name', 'url', 'bl_info'):
            setattr(self, attr, package_dict.get(attr))


class Repository:
    """
    Stores repository metadata (including packages)
    """

    def __init__(self, repo_dict:dict = None):
        self.from_dict(repo_dict)

    def refresh(self):
        """
        Requests repo.json from URL and embeds etag/last-modification headers
        """

        log.debug(self.url)
        if self.url is None:
            raise MissingURLError("Cannot refresh repository without a URL")


        log.debug("Refreshing repository from %s", self.url)
        req_headers = {}

        # Do things this way to avoid adding empty objects/None to the req_headers dict
        if self._headers:
            try:
                req_headers['If-None-Match'] = self._headers['etag']
            except KeyError:
                pass
            try:
                req_headers['If-Modified-Since'] = self._headers['last-modified']
            except KeyError:
                pass

        #try
        resp = requests.get(self.url, headers=req_headers)

        repodict = json.loads(resp.json())
        repodict['etag'] = resp.headers.get('etag')
        repodict['last-modified'] = resp.headers.get('last-modified')

        self.from_dict(repodict)


    def to_dict(self) -> dict:
        """
        Return a dict representation of the repository
        """
        return {
                'name':     self.name,
                'packages': [p.to_dict() for p in self.packages],
                'url':      self.url,
                '_headers': self._headers,
                }

    def from_dict(self, repodict: dict):
        """
        Get attributes from a dict such as produced by `to_dict`
        """
        if repodict is None:
            repodict = {}

        for attr in ('name', 'url', 'packages', '_headers'):
            if attr == 'package':
                value = set(Package(pkg) for pkg in repodict.get('packages', []))
            else:
                value = repodict.get(attr)

            setattr(self, attr, value)

    def dump(self, path: Path):
        """
        Dump repository as a repo.json file in 'path'
        """
        with (path / 'repo.json').open('w', encoding='utf-8') as repo_file:
            json.dump(self.to_dict(), repo_file, indent=4, sort_keys=True)
        log.info("repo.json written to %s" % path)