import functools
import mimetypes
import os

from platypush.utils import get_mime_type

from . import MediaHandler


class FileHandler(MediaHandler):
    prefix_handlers = ['file://']

    def __init__(self, source, *args, **kwargs):
        super().__init__(source, *args, **kwargs)

        self.path = os.path.abspath(os.path.expanduser(
            self.source[len(self._matched_handler):]))
        self.filename = self.path.split('/')[-1]

        if not os.path.isfile(self.path):
            raise FileNotFoundError('{} is not a valid file'.
                                    format(self.path))

        self.mime_type = get_mime_type(source)
        if self.mime_type[:5] not in ['video', 'audio', 'image'] and self.mime_type != 'application/octet-stream':
            raise AttributeError('{} is not a valid media file (detected format: {})'.
                                 format(source, self.mime_type))

        self.extension = mimetypes.guess_extension(self.mime_type)
        if self.url:
            self.url += self.extension
        self.content_length = os.path.getsize(self.path)


    def get_data(self, from_bytes=None, to_bytes=None, chunk_size=None):
        if from_bytes is None:
            from_bytes = 0
        if to_bytes is None:
            to_bytes = os.path.getsize(self.path)
        if chunk_size is None:
            chunk_size = os.path.getsize(self.path) - from_bytes

        with open(self.path, 'rb') as f:
            f.seek(from_bytes)
            for chunk in iter(functools.partial(
                    f.read, min(to_bytes-from_bytes, chunk_size)), b''):
                yield chunk


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