__license__   = 'GPL v3'
__copyright__ = '2008, Ashish Kulkarni <kulkarni.ashish@gmail.com>'
'''Read meta information from RB files'''

import struct
import sys

from calibre import prints
from calibre.ebooks.metadata import MetaInformation, string_to_authors

MAGIC = b'\xb0\x0c\xb0\x0c\x02\x00NUVO\x00\x00\x00\x00'


def get_metadata(stream):
    """ Return metadata as a L{MetaInfo} object """
    title = 'Unknown'
    mi = MetaInformation(title, ['Unknown'])
    stream.seek(0)
    try:
        if not stream.read(14) == MAGIC:
            print('Couldn\'t read RB header from file', file=sys.stderr)
            return mi
        stream.read(10)

        def read_i32():
            return struct.unpack('<I', stream.read(4))[0]

        stream.seek(read_i32())
        toc_count = read_i32()

        for i in range(toc_count):
            stream.read(32)
            length, offset, flag = read_i32(), read_i32(), read_i32()
            if flag == 2:
                break
        else:
            print('Couldn\'t find INFO from RB file', file=sys.stderr)
            return mi

        stream.seek(offset)
        info = stream.read(length).decode('utf-8', 'replace').splitlines()
        for line in info:
            if '=' not in line:
                continue
            key, value = line.split('=')
            if key.strip() == 'TITLE':
                mi.title = value.strip()
            elif key.strip() == 'AUTHOR':
                mi.authors = string_to_authors(value)
    except Exception as err:
        msg = 'Couldn\'t read metadata from rb: %s with error %s'%(mi.title, str(err))
        prints(msg, file=sys.stderr)
        raise
    return mi
