from __future__ import unicode_literals

from .common import PostProcessor
from ..compat import compat_os_name
from ..utils import (
    hyphenate_date,
    write_xattr,
    XAttrMetadataError,
    XAttrUnavailableError,
)


class XAttrMetadataPP(PostProcessor):

    #
    # More info about extended attributes for media:
    #   http://freedesktop.org/wiki/CommonExtendedAttributes/
    #   http://www.freedesktop.org/wiki/PhreedomDraft/
    #   http://dublincore.org/documents/usageguide/elements.shtml
    #
    # TODO:
    #  * capture youtube keywords and put them in 'user.dublincore.subject' (comma-separated)
    #  * figure out which xattrs can be used for 'duration', 'thumbnail', 'resolution'
    #

    def run(self, info):
        """Set extended attributes on downloaded file (if xattr support is found)."""

        # Write the metadata to the file's xattrs
        self._downloader.to_screen("[metadata] Writing metadata to file's xattrs")

        filename = info["filepath"]

        try:
            xattr_mapping = {
                "user.xdg.referrer.url": "webpage_url",
                # 'user.xdg.comment':            'description',
                "user.dublincore.title": "title",
                "user.dublincore.date": "upload_date",
                "user.dublincore.description": "description",
                "user.dublincore.contributor": "uploader",
                "user.dublincore.format": "format",
            }

            num_written = 0
            for xattrname, infoname in xattr_mapping.items():

                value = info.get(infoname)

                if value:
                    if infoname == "upload_date":
                        value = hyphenate_date(value)

                    byte_value = value.encode("utf-8")
                    write_xattr(filename, xattrname, byte_value)
                    num_written += 1

            return [], info

        except XAttrUnavailableError as e:
            self._downloader.report_error(str(e))
            return [], info

        except XAttrMetadataError as e:
            if e.reason == "NO_SPACE":
                self._downloader.report_warning(
                    "There's no disk space left, disk quota exceeded or filesystem xattr limit exceeded. "
                    + (
                        ("Some " if num_written else "")
                        + "extended attributes are not written."
                    ).capitalize()
                )
            elif e.reason == "VALUE_TOO_LONG":
                self._downloader.report_warning(
                    "Unable to write extended attributes due to too long values."
                )
            else:
                msg = "This filesystem doesn't support extended attributes. "
                if compat_os_name == "nt":
                    msg += "You need to use NTFS."
                else:
                    msg += "(You may have to enable them in your /etc/fstab)"
                self._downloader.report_error(msg)
            return [], info
