import sys
import httplib
import simplejson
from urlparse import urlparse, urlunparse
from cgi import parse_qs # 2.5 compat
from urllib import urlencode

GITHUB_URL = "http://github.com"

URL_PREFIX = "http://github.com/api/v2/json"

class GithubError(Exception):
    """An error occured when making a request to the Github API."""

class GithubRequest(object):
    github_url = GITHUB_URL
    url_format = "%(github_url)s/api/%(api_version)s/%(api_format)s"
    api_version = "v2"
    api_format = "json"
    GithubError = GithubError

    connector_for_scheme = {
        "http": httplib.HTTPConnection,
        "https": httplib.HTTPSConnection,
    }

    def __init__(self, username, api_token, url_prefix=None, debug=False):
        self.username = username
        self.api_token = api_token
        self.url_prefix = url_prefix
        self.debug = debug
        if not self.url_prefix:
            self.url_prefix = self.url_format % {
                "github_url": self.github_url,
                "api_version": self.api_version,
                "api_format": self.api_format,
            }

    def encode_authentication_data(self, extra_post_data):
        post_data = {"login": self.username,
                     "token": self.api_token}
        post_data.update(extra_post_data) 
        return urlencode(post_data)

    def get(self, *path_components):
        path_components = filter(None, path_components)
        return self.make_request("/".join(path_components))

    def post(self, *path_components, **extra_post_data):
        path_components = filter(None, path_components)
        return self.make_request("/".join(path_components), extra_post_data,
            method="POST")

    def make_request(self, path, extra_post_data=None, method="GET"):
        extra_post_data = extra_post_data or {}
        url = "/".join([self.url_prefix, path])
        return self.raw_request(url, extra_post_data, method=method)

    def raw_request(self, url, extra_post_data, method="GET"):
        resource = urlparse(url)
        scheme, netloc, path, params, query, fragment = urlparse(url)
        hostname = netloc.split(':')[0]
        post_data = None
        headers = self.http_headers
        headers["Accept"] = "text/html"
        method = method.upper()
        if extra_post_data or method == "POST":
            post_data = self.encode_authentication_data(extra_post_data)
            headers["Content-Length"] = str(len(post_data))
        else:
            path = urlunparse((scheme, netloc, path, params,
                self.encode_authentication_data(parse_qs(query)),
                fragment))
        connector = self.connector_for_scheme[scheme]
        connection = connector(hostname)
        connection.request(method, path, post_data, headers)
        response = connection.getresponse()
        response_text = response.read()
        if self.debug:
            sys.stderr.write("URL:[%s] POST_DATA:%s RESPONSE_TEXT: [%s]\n" % (
                                path, post_data, response_text))
        if response.status >= 400:
            raise RuntimeError("unexpected response from github.com %d: %r" % (
                               response.status, response_text))
        json = simplejson.loads(response_text)
        if json.get("error"):
            raise self.GithubError(json["error"][0]["error"])

        return json

    @property
    def http_headers(self):
        return {"User-Agent": "pygithub2 v1",
                "Accept-Encoding": "application/json"}