import os
import json
import shutil

from urllib.request import Request
from urllib.parse import urlparse, urlunparse
from zipfile import ZipFile

from .doi import DoiProvider
from ..utils import copytree, deep_get, is_doi, normalize_doi


class Dataverse(DoiProvider):
    """Provide contents of a Dataverse dataset."""

    def __init__(self):
        data_file = os.path.join(os.path.dirname(__file__), "dataverse.json")
        with open(data_file, "r") as fp:
            self.hosts = json.load(fp)["installations"]
        super().__init__()

    def detect(self, doi, ref=None, extra_args=None):
        """Trigger this provider for things that resolve to a Dataverse dataset.

        Handles:
        - DOI pointing to {siteURL}/dataset.xhtml?persistentId={persistentId}
        - DOI pointing to {siteURL}/file.xhtml?persistentId={persistentId}&...
        - URL {siteURL}/api/access/datafile/{fileId}

        Examples:
        - https://dataverse.harvard.edu/api/access/datafile/3323458
        - doi:10.7910/DVN/6ZXAGT
        - doi:10.7910/DVN/6ZXAGT/3YRRYJ

        """
        url = self.doi2url(doi)

        # Check if the url matches any known Dataverse installation, bail if not.
        host = next((host for host in self.hosts if url.startswith(host["url"])), None)
        if host is None:
            return

        # Parse the url, to get the base for later API calls
        parsed_url = urlparse(url)

        # Corner case handling
        if parsed_url.path.startswith("/file.xhtml"):
            # There's no way of getting file information using its persistentId, the only thing we can do is assume that doi
            # is structured as "doi:<dataset_doi>/<file_doi>" and try to handle dataset that way.
            new_doi = doi.rsplit("/", 1)[0]
            if new_doi == doi:
                # tough luck :( Avoid inifite recursion and exit.
                return
            return self.detect(new_doi)
        elif parsed_url.path.startswith("/api/access/datafile"):
            # Raw url pointing to a datafile is a typical output from an External Tool integration
            entity_id = os.path.basename(parsed_url.path)
            search_query = "q=entityId:" + entity_id + "&type=file"
            # Knowing the file identifier query search api to get parent dataset
            search_url = urlunparse(
                parsed_url._replace(path="/api/search", query=search_query)
            )
            resp = self.urlopen(search_url).read()
            data = json.loads(resp.decode("utf-8"))["data"]
            if data["count_in_response"] != 1:
                self.log.debug("Dataverse search query failed!")
                self.log.debug("  - doi = " + doi)
                self.log.debug("  - url = " + url)
                self.log.debug("  - resp = " + json.dumps(data))
                return

            self.record_id = deep_get(data, "items.0.dataset_persistent_id")
        elif is_doi(doi):
            self.record_id = "doi:" + normalize_doi(doi)

        if hasattr(self, "record_id"):
            return {"record": self.record_id, "host": host}

    def fetch(self, spec, output_dir, yield_output=False):
        """Fetch and unpack a Dataverse dataset."""
        record_id = spec["record"]
        host = spec["host"]

        yield "Fetching Dataverse record {}.\n".format(record_id)
        req = Request(
            "{}/api/datasets/:persistentId?persistentId={}".format(
                host["url"], record_id
            ),
            headers={"accept": "application/json"},
        )
        resp = self.urlopen(req)
        record = json.loads(resp.read().decode("utf-8"))["data"]

        # In order to fetch entire dataset we build a list of file IDs we want to fetch
        # and then receive a zip file containing all of them.
        # TODO: Dataverse has a limit for the zipfile size (see
        # https://github.com/jupyter/repo2docker/pull/739#issuecomment-510834729)
        # If size of the dataset is grater than 100MB individual files should be downloaded.
        file_ids = [
            str(deep_get(fobj, "dataFile.id"))
            for fobj in deep_get(record, "latestVersion.files")
        ]

        req = Request(
            "{}/api/access/datafiles/{}".format(host["url"], ",".join(file_ids))
        )

        dst_fname = os.path.join(output_dir, "dataverse.zip")
        with self.urlopen(req) as src, open(dst_fname, "wb") as dst:
            yield "Fetching files bundle\n"
            shutil.copyfileobj(src, dst)

        yield "Extracting files\n"
        with ZipFile(dst_fname) as zfile:
            zfile.extractall(path=output_dir)

        os.remove(dst_fname)
        new_subdirs = os.listdir(output_dir)
        # if there is only one new subdirectory move its contents
        # to the top level directory
        if len(new_subdirs) == 1:
            d = new_subdirs[0]
            copytree(os.path.join(output_dir, d), output_dir)
            shutil.rmtree(os.path.join(output_dir, d))

    @property
    def content_id(self):
        """The Dataverse persistent identifier (could use internal dataset_id too)."""
        return self.record_id