import datetime
import hashlib
import hmac as hmac_lib
import requests
import sys
import time

try:
    # Python 3.x
    from urllib.parse import urlparse
except ImportError:
    # Python 2.7
    from urlparse import urlparse


def oauth2(
    access_token,
    client_id,
    client_secret=None,
    refresh_token=None,
    expires_at=None,
    server="https://localbitcoins.com",
):
    conn = Connection()
    conn._set_oauth2(server, client_id, client_secret, access_token, refresh_token, expires_at)
    return conn


def hmac(hmac_key, hmac_secret, server="https://localbitcoins.com"):
    conn = Connection()
    conn._set_hmac(server, hmac_key, hmac_secret)
    return conn


class Connection:
    def __init__(self):
        self.server = None

        # OAuth2 stuff
        self.client_id = None
        self.client_secret = None
        self.access_token = None
        self.refresh_token = None
        self.expires_at = None

        # HMAC stuff
        self.hmac_key = None
        self.hmac_secret = None

    def call(self, method, url, params=None, stream=False, files=None):
        method = method.upper()
        if method not in ["GET", "POST"]:
            raise Exception("Invalid method {}!".format(method))

        if method == "GET" and files:
            raise Exception("You cannot send files with GET method!")

        if files and not isinstance(files, dict):
            raise Exception('"files" must be a dict of file objects or file contents!')

        # If URL is absolute, then convert it
        if url.startswith(self.server):
            url = url[len(self.server) :]  # noqa

        # If OAuth2
        if self.access_token:

            # If token is expiring tomorrow, then try to refresh it
            if (
                self.refresh_token
                and self.client_id
                and self.client_secret
                and (not self.expires_at or self.expires_at < datetime.datetime.utcnow() + datetime.timedelta(days=1))
            ):
                refresh_params = {
                    "refresh_token": self.refresh_token,
                    "grant_type": "refresh_token",
                    "client_id": self.client_id,
                    "client_secret": self.client_secret,
                }
                r = requests.post(self.server + "/oauth2/access_token/", data=refresh_params)
                self.access_token = r.json()["access_token"]
                self.refresh_token = r.json()["refresh_token"]
                self.expires_at = datetime.datetime.utcnow() + datetime.timedelta(seconds=int(r.json()["expires_in"]))

            headers = {
                "Authorization-Extra": "Bearer " + self.access_token,
            }

            if method == "GET":
                return requests.get(self.server + url, params=params, headers=headers, stream=stream)
            else:
                return requests.post(
                    self.server + url,
                    data=params,
                    headers=headers,
                    stream=stream,
                    files=files,
                )

        # If HMAC
        elif self.hmac_key:

            # If nonce fails, retry several times, then give up
            for retry in range(10):

                nonce = str(int(time.time() * 1000)).encode("ascii")

                # Prepare request based on method.
                if method == "POST":
                    api_request = requests.Request("POST", self.server + url, data=params, files=files).prepare()
                    params_encoded = api_request.body

                # GET method
                else:
                    api_request = requests.Request("GET", self.server + url, params=params).prepare()
                    params_encoded = urlparse(api_request.url).query

                # Calculate signature
                message = nonce + self.hmac_key + url.encode("ascii")
                if params_encoded:
                    if sys.version_info >= (3, 0) and isinstance(params_encoded, str):
                        message += params_encoded.encode("ascii")
                    else:
                        message += params_encoded
                signature = hmac_lib.new(self.hmac_secret, msg=message, digestmod=hashlib.sha256).hexdigest().upper()

                # Store signature and other stuff to headers
                api_request.headers["Apiauth-Key"] = self.hmac_key
                api_request.headers["Apiauth-Nonce"] = nonce
                api_request.headers["Apiauth-Signature"] = signature

                # Send request
                session = requests.Session()
                response = session.send(api_request, stream=stream)

                # If HMAC Nonce is already used, then wait a little and try again
                try:
                    response_json = response.json()
                    if int(response_json.get("error", {}).get("error_code")) == 42:
                        time.sleep(0.1)
                        continue
                except:  # noqa
                    # No JSONic response, or interrupt, better just give up
                    pass

                return response

            raise Exception("Nonce is too small!")

        raise Exception("No OAuth2 or HMAC connection initialized!")

    def get_access_token(self):
        return self.access_token

    def get_refresh_token(self):
        return self.refresh_token

    def get_expires_at(self):
        return self.expires_at

    def _set_oauth2(self, server, client_id, client_secret, access_token, refresh_token, expires_at):
        self.server = server
        self.client_id = client_id
        self.client_secret = client_secret
        self.access_token = access_token
        self.refresh_token = refresh_token
        self.expires_at = expires_at
        self.hmac_key = None
        self.hmac_secret = None

    def _set_hmac(self, server, hmac_key, hmac_secret):
        self.server = server
        self.client_id = None
        self.client_secret = None
        self.access_token = None
        self.refresh_token = None
        self.expires_at = None
        self.hmac_key = hmac_key.encode("ascii")
        self.hmac_secret = hmac_secret.encode("ascii")