from __future__ import absolute_import, division, print_function

import zipfile

from fsspec import open_files
from fsspec.archive import AbstractArchiveFileSystem
from fsspec.utils import DEFAULT_BLOCK_SIZE


class ZipFileSystem(AbstractArchiveFileSystem):
    """Read contents of ZIP archive as a file-system

    Keeps file object open while instance lives.

    This class is pickleable, but not necessarily thread-safe
    """

    root_marker = ""
    protocol = "zip"

    def __init__(
        self,
        fo="",
        mode="r",
        target_protocol=None,
        target_options=None,
        block_size=DEFAULT_BLOCK_SIZE,
        **kwargs,
    ):
        """
        Parameters
        ----------
        fo: str or file-like
            Contains ZIP, and must exist. If a str, will fetch file using
            `open_files()`, which must return one file exactly.
        mode: str
            Currently, only 'r' accepted
        target_protocol: str (optional)
            If ``fo`` is a string, this value can be used to override the
            FS protocol inferred from a URL
        target_options: dict (optional)
            Kwargs passed when instantiating the target FS, if ``fo`` is
            a string.
        """
        super().__init__(self, **kwargs)
        if mode != "r":
            raise ValueError("Only read from zip files accepted")
        if isinstance(fo, str):
            files = open_files(fo, protocol=target_protocol, **(target_options or {}))
            if len(files) != 1:
                raise ValueError(
                    'Path "{}" did not resolve to exactly'
                    'one file: "{}"'.format(fo, files)
                )
            fo = files[0]
        self.fo = fo.__enter__()  # the whole instance is a context
        self.zip = zipfile.ZipFile(self.fo)
        self.block_size = block_size
        self.dir_cache = None

    @classmethod
    def _strip_protocol(cls, path):
        # zip file paths are always relative to the archive root
        return super()._strip_protocol(path).lstrip("/")

    def _get_dirs(self):
        if self.dir_cache is None:
            files = self.zip.infolist()
            self.dir_cache = {
                dirname + "/": {"name": dirname + "/", "size": 0, "type": "directory"}
                for dirname in self._all_dirnames(self.zip.namelist())
            }
            for z in files:
                f = {s: getattr(z, s) for s in zipfile.ZipInfo.__slots__}
                f.update(
                    {
                        "name": z.filename,
                        "size": z.file_size,
                        "type": ("directory" if z.is_dir() else "file"),
                    }
                )
                self.dir_cache[f["name"]] = f

    def cat(self, path, callback=None, **kwargs):
        return self.zip.read(path)

    def _open(
        self,
        path,
        mode="rb",
        block_size=None,
        autocommit=True,
        cache_options=None,
        **kwargs,
    ):
        path = self._strip_protocol(path)
        if mode != "rb":
            raise NotImplementedError
        info = self.info(path)
        out = self.zip.open(path, "r")
        out.size = info["size"]
        out.name = info["name"]
        return out