__author__ = "Johannes Köster"
__copyright__ = "Copyright 2022, Johannes Köster"
__email__ = "johannes.koester@tu-dortmund.de"
__license__ = "MIT"

import os
import time
from collections import namedtuple
import hashlib

import requests


from snakemake.remote import (
    AbstractRemoteProvider,
    check_deprecated_retry,
)
from snakemake.exceptions import WorkflowError
from snakemake.common import lazy_property


EGAFileInfo = namedtuple("EGAFileInfo", ["size", "status", "id", "checksum"])
EGAFile = namedtuple("EGAFile", ["dataset", "path"])


class RemoteProvider(AbstractRemoteProvider):
    def __init__(
        self,
        *args,
        keep_local=False,
        stay_on_remote=False,
        is_default=False,
        retry=None,
        **kwargs,
    ):
        super().__init__(
            *args,
            keep_local=keep_local,
            stay_on_remote=stay_on_remote,
            is_default=is_default,
            **kwargs,
        )
        check_deprecated_retry(retry)
        self._token = None
        self._expires = None
        self._file_cache = dict()

    def _login(self):
        if self._expires is not None and self._expires > time.time():
            # token is still valid
            return

        # token will expire in 10 minutes
        # (we stop using it 10 seconds earlier to be sure)
        self._expires = time.time() + 10 * 60 * 60 - 10

        data = {
            "grant_type": "password",
            "client_id": self._client_id(),
            "scope": "openid",
            "client_secret": self._client_secret(),
            "username": self._username(),
            "password": self._password(),
        }
        for i in range(3):
            try:
                r = requests.post(
                    "https://ega.ebi.ac.uk:8443/ega-openid-connect-server/token",
                    headers={"Content-Type": "application/x-www-form-urlencoded"},
                    data=data,
                )
            except requests.exceptions.ConnectionError as e:
                time.sleep(5)
                if i == 2:
                    raise WorkflowError("Error contacting EGA.", e)

        if r.status_code != 200:
            raise WorkflowError(f"Login to EGA failed with:\n{r.text}")
        r = r.json()
        # store session token
        try:
            self._token = r["access_token"]
        except KeyError:
            raise WorkflowError(f"Login to EGA failed:\n{r}")

    def _expire_token(self):
        self._expires = None

    @property
    def token(self):
        self._login()
        return self._token

    def api_request(
        self,
        url_suffix,
        url_prefix="https://ega.ebi.ac.uk:8051/elixir/",
        json=True,
        post=False,
        **params,
    ):
        """Make an API request.

        Args:
            url_suffix (str): Part of REST API URL right of https://ega.ebi.ac.uk:8051/elixir/
            params (dict): Parameters to pass, except session
        """

        url = url_prefix + url_suffix
        headers = (
            {"Accept": "application/json"}
            if json
            else {"Accept": "application/octet-stream"}
        )
        headers["Authorization"] = f"Bearer {self.token}"

        for i in range(3):
            try:
                if post:
                    r = requests.post(
                        url,
                        stream=not json,
                        data=params,
                        params={"session": self.token},
                        headers=headers,
                    )
                else:
                    params = dict(params)
                    params["session"] = self.token
                    r = requests.get(
                        url, stream=not json, params=params, headers=headers
                    )
            except requests.exceptions.ConnectionError as e:
                time.sleep(5)
                if i == 2:
                    raise WorkflowError("Error contacting EGA.", e)
        if r.status_code != 200:
            raise WorkflowError(
                "Access to EGA API endpoint {} failed with:\n{}".format(url, r.text)
            )
        if json:
            msg = r.json()
            return msg
        else:
            return r

    def get_files(self, dataset):
        if dataset not in self._file_cache:
            files = self.api_request(f"data/metadata/datasets/{dataset}/files")
            self._file_cache[dataset] = {
                os.path.basename(f["fileName"])[:-4]: EGAFileInfo(
                    int(f["fileSize"]), f["fileStatus"], f["fileId"], f["checksum"]
                )
                for f in files
            }
        return self._file_cache[dataset]

    @property
    def default_protocol(self):
        return "ega://"

    @property
    def available_protocols(self):
        return ["ega://"]

    @classmethod
    def _username(cls):
        return cls._credentials("EGA_USERNAME")

    @classmethod
    def _password(cls):
        return cls._credentials("EGA_PASSWORD")

    @classmethod
    def _client_id(cls):
        return cls._credentials("EGA_CLIENT_ID")

    @classmethod
    def _client_secret(cls):
        return cls._credentials("EGA_CLIENT_SECRET")

    @classmethod
    def _credentials(cls, name):
        try:
            return os.environ[name]
        except KeyError:
            raise WorkflowError(
                "$EGA_USERNAME, $EGA_PASSWORD, $EGA_CLIENT_ID, "
                "$EGA_CLIENT_SECRET must be given "
                "as environment variables."
            )


class RemoteObject(AbstractRemoteRetryObject):
    # === Implementations of abstract class members ===
    def _stats(self):
        return self.provider.get_files(self.parts.dataset)[self.parts.path]

    def exists(self):
        return self.parts.path in self.provider.get_files(self.parts.dataset)

    def size(self):
        return self._stats().size

    def mtime(self):
        # There is no mtime info provided by EGA
        # Hence, the files are always considered to be "ancient".
        return 0

    def _download(self):
        stats = self._stats()

        r = self.provider.api_request(
            f"data/files/{stats.id}?destinationFormat=plain", json=False
        )

        local_md5 = hashlib.md5()

        # download file in chunks and calculate md5 on the fly
        os.makedirs(os.path.dirname(self.local_file()), exist_ok=True)

        with open(self.local_file(), "wb") as f:
            for chunk in r.iter_content(chunk_size=1024 * 1024 * 10):
                local_md5.update(chunk)
                f.write(chunk)
        local_md5 = local_md5.hexdigest()

        if local_md5 != stats.checksum:
            raise WorkflowError(
                f"File checksums do not match for: {self.remote_file()}"
            )

    @lazy_property
    def parts(self):
        parts = self.local_file().split("/")
        if parts[0] != "ega":
            raise WorkflowError(
                "Invalid EGA remote file name. Must be 'ega/<dataset>/<filepath>'"
            )
        _, dataset, path = self.local_file().split("/", 2)
        return EGAFile(dataset, path)