#!/usr/bin/env python

# Copyright (c) 2017, DIANA-HEP
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import os.path

import numpy

import uproot.source.chunked

class XRootDSource(uproot.source.chunked.ChunkedSource):
    # makes __doc__ attribute mutable before Python 3.3
    __metaclass__ = type.__new__(type, "type", (uproot.source.chunked.ChunkedSource.__metaclass__,), {})

    def __init__(self, path, *args, **kwds):
        self._size = None
        super(XRootDSource, self).__init__(path, *args, **kwds)

    @staticmethod
    def defaults(path):
        return XRootDSource(path, chunkbytes=16*1024, limitbytes=16*1024**2)

    def _open(self):
        try:
            import pyxrootd.client
        except ImportError:
            raise ImportError("\n\nInstall pyxrootd package from source and configure PYTHONPATH and LD_LIBRARY_PATH:\n\n    http://xrootd.org/dload.html\n\nAlternatively, try a conda package:\n\n    https://anaconda.org/search?q=xrootd")

        if self._source is None or not self._source.is_open():
            self._source = pyxrootd.client.File()
            status, dummy = self._source.open(self.path)
            if status.get("error", None):
                raise OSError(status["message"])
            status, info = self._source.stat()
            if status.get("error", None):
                raise OSError(status["message"])
            self._size = info["size"]

    def size(self):
        if self._size is None:
            self._open()
        return self._size

    def threadlocal(self):
        out = XRootDSource.__new__(self.__class__)
        out.path = self.path
        out._chunkbytes = self._chunkbytes
        if isinstance(self.cache, (uproot.cache.memorycache.ThreadSafeMemoryCache, uproot.cache.memorycache.ThreadSafeDict)):
            out.cache = self.cache
        else:
            out.cache = {}
        out._source = None             # XRootD connections are *not shared* among threads
        return out

    def _read(self, chunkindex):
        self._open()
        status, data = self._source.read(chunkindex * self._chunkbytes, self._chunkbytes)
        if status.get("error", None):
            raise OSError(status["message"])
        return numpy.frombuffer(data, dtype=numpy.uint8)

    def __del__(self):
        if self._source is not None:
            self._source.close()
    
    def dismiss(self):
        pass
