""" MP4 Parser based on:
http://download.macromedia.com/f4v/video_file_format_spec_v10_1.pdf 

@author: Alastair McCormack
@license: MIT License

The MIT License (MIT)

Copyright (c) 2015 use-sparingly

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""

import bitstring
from datetime import datetime
from collections import namedtuple
import logging
import six

log = logging.getLogger(__name__)
#log.addHandler(logging.NullHandler())
log.setLevel(logging.WARN)

class MixinDictRepr(object):
    def __repr__(self, *args, **kwargs):
        return "{class_name} : {content!r} ".format(class_name=self.__class__.__name__,
                                                    content=self.__dict__)
        
class MixinMinimalRepr(object):
    """ A minimal representaion when the payload could be large """
   
    def __repr__(self, *args, **kwargs):
        return "{class_name} : {content!r} ".format(class_name=self.__class__.__name__,
                                                    content=self.__dict__.keys())

class FragmentRunTableBox(MixinDictRepr):
    pass


class UnImplementedBox(MixinDictRepr):
    type = "na"
    pass


class MovieFragmentBox(MixinDictRepr):
    type = "moof"

class MovieBox(MixinDictRepr):
    type = "moov"

class BootStrapInfoBox(MixinDictRepr):
    type = "abst"
        
    @property
    def current_media_time(self):
        return self._current_media_time
    
    @current_media_time.setter
    def current_media_time(self, epoch_timestamp):
        """ Takes a timestamp arg and saves it as datetime """
        self._current_media_time = datetime.utcfromtimestamp(epoch_timestamp/float(self.time_scale))
        
class FragmentRandomAccessBox(MixinDictRepr):
    """ aka afra """
    type = "afra"
    
    FragmentRandomAccessBoxEntry = namedtuple("FragmentRandomAccessBoxEntry", ["time", "offset"])
    FragmentRandomAccessBoxGlobalEntry = namedtuple("FragmentRandomAccessBoxGlobalEntry", ["time", "segment_number", "fragment_number", "afra_offset", "sample_offset"])
    
    pass


class SegmentRunTable(MixinDictRepr):
    type = "asrt"

    SegmentRunTableEntry = namedtuple('SegmentRunTableEntry', ["first_segment", "fragments_per_segment"])
    pass

class FragmentRunTable(MixinDictRepr):
    type = "afrt"

    class FragmentRunTableEntry( namedtuple('FragmentRunTableEntry', 
                                       ["first_fragment", 
                                        "first_fragment_timestamp", 
                                        "fragment_duration",
                                        "discontinuity_indicator"]) ):
        
        DI_END_OF_PRESENTATION = 0
        DI_NUMBERING = 1
        DI_TIMESTAMP = 2
        DI_TIMESTAMP_AND_NUMBER = 3
        
        def __eq__(self, other):
            if self.first_fragment == other.first_fragment and \
                self.first_fragment_timestamp == other.first_fragment_timestamp and \
                self.fragment_duration == other.fragment_duration and \
                self.discontinuity_indicator == other.discontinuity_indicator:
                    return True
        
    
    def __repr__(self, *args, **kwargs):
        return str(self.__dict__)

class MediaDataBox(MixinMinimalRepr):
    """ aka mdat """
    type = "mdat"

class MovieFragmentHeader(MixinDictRepr):
    type = "mfhd"

class ProtectionSystemSpecificHeader(MixinDictRepr):
    type = "pssh"

BoxHeader = namedtuple( "BoxHeader", ["box_size", "box_type", "header_size"] )
 
    
class F4VParser(object):

    @classmethod
    def parse(cls, filename=None, bytes_input=None, file_input=None, offset_bytes=0, headers_only=False):
        """
        Parse an MP4 file or bytes into boxes


        :param filename: filename of mp4 file.
        :type filename: str.
        :param bytes_input: bytes of mp4 file.
        :type bytes_input: bytes / Python 2.x str.
        :param offset_bytes: start parsing at offset.
        :type offset_bytes: int.
        :param headers_only: Ignore data and return just headers. Useful when data is cut short
        :type: headers_only: boolean
        :return: BMFF Boxes or Headers

        """

        box_lookup = {
            BootStrapInfoBox.type:                  cls._parse_abst,
            FragmentRandomAccessBox.type:           cls._parse_afra,
            MediaDataBox.type:                      cls._parse_mdat,
            MovieFragmentBox.type:                  cls._parse_moof,
            MovieBox.type:                          cls._parse_moov,
            MovieFragmentHeader.type:               cls._parse_mfhd,
            ProtectionSystemSpecificHeader.type:    cls._parse_pssh
        }
        
        if filename:
            bs = bitstring.ConstBitStream(filename=filename, offset=offset_bytes * 8)
        elif bytes_input:
            bs = bitstring.ConstBitStream(bytes=bytes_input, offset=offset_bytes * 8)
        else:
            bs = bitstring.ConstBitStream(auto=file_input, offset=offset_bytes * 8)
        
        log.debug("Starting parse")
        log.debug("Size is %d bits", bs.len)

        while bs.pos < bs.len:
            log.debug("Byte pos before header: %d relative to (%d)", bs.bytepos, offset_bytes)
            log.debug("Reading header")
            try:
                header = cls._read_box_header(bs)
            except bitstring.ReadError as e:
                log.error("Premature end of data while reading box header")
                raise
            
            log.debug("Header type: %s", header.box_type)
            log.debug("Byte pos after header: %d relative to (%d)", bs.bytepos, offset_bytes)

            if headers_only:
                yield header

                # move pointer to next header if possible
                try:
                    bs.bytepos += header.box_size
                except ValueError:
                    log.warning("Premature end of data")
                    raise
            else:
                # Get parser method for header type
                parse_function = box_lookup.get(header.box_type, cls._parse_unimplemented)
                try:
                    yield parse_function(bs, header)
                except ValueError as e:
                    log.error("Premature end of data")
                    raise

    @classmethod
    def _is_mp4(cls, parser):
        try:
            for box in parser:
                return True
        except ValueError:
            return False

    @classmethod
    def is_mp4_s(cls, bytes_input):
        """ Is bytes_input the contents of an MP4 file

        :param bytes_input: str/bytes to check.
        :type bytes_input: str/bytes.
        :return:
        """

        parser = cls.parse(bytes_input=bytes_input, headers_only=True)
        return cls._is_mp4(parser)

    @classmethod
    def is_mp4(cls, file_input):
        """ Checks input if it's an MP4 file

        :param input: Filename or file object
        :type input: str, file
        :param state: Current state to be in.
        :type state: bool.
        :returns:  bool.
        :raises: AttributeError, KeyError
        """

        if hasattr(file_input, "read"):
           parser = cls.parse(file_input=file_input, headers_only=True)
        else:
           parser = cls.parse(filename=file_input, headers_only=True)
        return cls._is_mp4(parser)

    @staticmethod
    def _read_string(bs):
        """ read UTF8 null terminated string """
        result = bs.readto('0x00', bytealigned=True).bytes.decode("utf-8")[:-1]
        return result if result else None

    @classmethod
    def _read_count_and_string_table(cls, bs):
        """ Read a count then return the strings in a list """
        result = []
        entry_count = bs.read("uint:8")
        for _ in six.range(0, entry_count):
            result.append( cls._read_string(bs) )
        return result

    @staticmethod
    def _read_box_header(bs):
        header_start_pos = bs.bytepos
        size, box_type = bs.readlist("uint:32, bytes:4")

        # box_type should be an ASCII string. Decode as UTF-8 in case
        try:
            box_type = box_type.decode('utf-8')
        except UnicodeDecodeError:
            # we'll leave as bytes instead
            pass

        # if size == 1, then this is an extended size type.
        # Therefore read the next 64 bits as size
        if size == 1:
            size = bs.read("uint:64")
        header_end_pos = bs.bytepos
        header_size = header_end_pos - header_start_pos    
        
        return BoxHeader(box_size=size-header_size, box_type=box_type, header_size=header_size)

    @staticmethod
    def _parse_unimplemented(bs, header):
        ui = UnImplementedBox()
        ui.header = header

        bs.bytepos += header.box_size
        
        return ui

    @classmethod
    def _parse_afra(cls, bs, header):
    
        afra = FragmentRandomAccessBox()
        afra.header = header
        
        # read the entire box in case there's padding
        afra_bs = bs.read(header.box_size * 8)
        # skip Version and Flags
        afra_bs.pos += 8 + 24
        long_ids, long_offsets, global_entries, afra.time_scale, local_entry_count  = \
                afra_bs.readlist("bool, bool, bool, pad:5, uint:32, uint:32")
        
        if long_ids:
            id_bs_type = "uint:32"
        else:
            id_bs_type = "uint:16"
                
        if long_offsets:
            offset_bs_type = "uint:64"
        else:
            offset_bs_type = "uint:32"
        
        log.debug("local_access_entries entry count: %s", local_entry_count)
        afra.local_access_entries = []        
        for _ in six.range(0, local_entry_count):
            time = cls._parse_time_field(afra_bs, afra.time_scale)
            
            offset = afra_bs.read(offset_bs_type)
            
            afra_entry = \
                FragmentRandomAccessBox.FragmentRandomAccessBoxEntry(time=time, 
                                                                     offset=offset)
            afra.local_access_entries.append(afra_entry)
        
        afra.global_access_entries = []
        
        if global_entries:
            global_entry_count = afra_bs.read("uint:32")
            
            log.debug("global_access_entries entry count: %s", global_entry_count)  
            
            for _ in six.range(0, global_entry_count):
                time = cls._parse_time_field(afra_bs, afra.time_scale)
                
                segment_number = afra_bs.read(id_bs_type)
                fragment_number = afra_bs.read(id_bs_type)
                
                afra_offset = afra_bs.read(offset_bs_type)
                sample_offset = afra_bs.read(offset_bs_type)
                
                afra_global_entry = \
                    FragmentRandomAccessBox.FragmentRandomAccessBoxGlobalEntry(
                                            time=time,
                                            segment_number=segment_number,
                                            fragment_number=fragment_number,
                                            afra_offset=afra_offset,
                                            sample_offset=sample_offset)
    
                afra.global_access_entries.append(afra_global_entry)
       
        return afra

    @classmethod
    def _parse_moof(cls, bootstrap_bs, header):
        moof = MovieFragmentBox()
        moof.header = header

        box_bs = bootstrap_bs.read(moof.header.box_size * 8)

        for child_box in cls.parse(bytes_input=box_bs.bytes):
            setattr(moof, child_box.type, child_box)

        return moof

    @classmethod
    def _parse_moov(cls, bootstrap_bs, header):
        moov = MovieBox()
        moov.header = header
        psshs = []

        box_bs = bootstrap_bs.read(moov.header.box_size * 8)

        for child_box in cls.parse(bytes_input=box_bs.bytes):
            if(child_box.type == "pssh"):
                psshs.append(child_box)
            else:
                setattr(moov, child_box.type, child_box)
        setattr(moov, "pssh", psshs)

        return moov

    @classmethod
    def _parse_mfhd(cls, bootstrap_bs, header):
        mfhd = MovieFragmentHeader()
        mfhd.header = header

        box_bs = bootstrap_bs.read(mfhd.header.box_size * 8)
        return mfhd

    @staticmethod
    def _parse_pssh(bootstrap_bs, header):
        pssh = ProtectionSystemSpecificHeader()
        pssh.header = header

        box_bs = bootstrap_bs.read(pssh.header.box_size*8)
        # Payload appears to be 8 bytes in.
        data = box_bs.hex[8:]
        pssh.system_id = data[:32]
        pssh.payload = data[40:]
        return pssh

    @classmethod
    def _parse_abst(cls, bootstrap_bs, header):
        
        abst = BootStrapInfoBox()
        abst.header = header
        
        box_bs = bootstrap_bs.read(abst.header.box_size * 8)
        
        abst.version, abst.profile_raw, abst.live, abst.update, \
        abst.time_scale, abst.current_media_time, abst.smpte_timecode_offset = \
                box_bs.readlist("""pad:8, pad:24, uint:32, uint:2, bool, bool,
                                   pad:4,
                                   uint:32, uint:64, uint:64""")
        abst.movie_identifier = cls._read_string(box_bs)
        
        abst.server_entry_table = cls._read_count_and_string_table(box_bs)
        abst.quality_entry_table = cls._read_count_and_string_table(box_bs)
            
        abst.drm_data = cls._read_string(box_bs)
        abst.meta_data = cls._read_string(box_bs)
                
        abst.segment_run_tables = []
        
        segment_count = box_bs.read("uint:8")
        log.debug("segment_count: %d" % segment_count)
        for _ in six.range(0, segment_count):
            abst.segment_run_tables.append( cls._parse_asrt(box_bs) )

        abst.fragment_tables = []
        fragment_count = box_bs.read("uint:8")
        log.debug("fragment_count: %d" % fragment_count)
        for _ in xrange(0, fragment_count):
            abst.fragment_tables.append( cls._parse_afrt(box_bs) )
        
        log.debug("Finished parsing abst")
        
        return abst

    @classmethod
    def _parse_asrt(cls, box_bs):
        """ Parse asrt / Segment Run Table Box """
        
        asrt = SegmentRunTable()
        asrt.header = cls._read_box_header(box_bs)
        # read the entire box in case there's padding
        asrt_bs_box = box_bs.read(asrt.header.box_size * 8)
        
        asrt_bs_box.pos += 8
        update_flag = asrt_bs_box.read("uint:24")
        asrt.update = True if update_flag == 1 else False
        
        asrt.quality_segment_url_modifiers = cls._read_count_and_string_table(asrt_bs_box)
        
        asrt.segment_run_table_entries = []
        segment_count = asrt_bs_box.read("uint:32")
        
        for _ in six.range(0, segment_count):
            first_segment = asrt_bs_box.read("uint:32")
            fragments_per_segment = asrt_bs_box.read("uint:32")
            asrt.segment_run_table_entries.append( 
                SegmentRunTable.SegmentRunTableEntry(first_segment=first_segment,
                                                     fragments_per_segment=fragments_per_segment) )
        return asrt

    @classmethod
    def _parse_afrt(cls, box_bs):
        """ Parse afrt / Fragment Run Table Box """
        
        afrt = FragmentRunTable()
        afrt.header = cls._read_box_header(box_bs)
        # read the entire box in case there's padding
        afrt_bs_box = box_bs.read(afrt.header.box_size * 8)
        
        afrt_bs_box.pos += 8
        update_flag = afrt_bs_box.read("uint:24")
        afrt.update = True if update_flag == 1 else False
 
        afrt.time_scale = afrt_bs_box.read("uint:32")
        afrt.quality_fragment_url_modifiers = cls._read_count_and_string_table(afrt_bs_box)
        
        fragment_count = afrt_bs_box.read("uint:32")
        
        afrt.fragments = []

        for _ in six.range(0, fragment_count):
            first_fragment = afrt_bs_box.read("uint:32")
            first_fragment_timestamp_raw = afrt_bs_box.read("uint:64")
            
            try:
                first_fragment_timestamp = datetime.utcfromtimestamp(first_fragment_timestamp_raw/float(afrt.time_scale))
            except ValueError:
                # Elemental sometimes create odd timestamps
                first_fragment_timestamp = None
                
            fragment_duration = afrt_bs_box.read("uint:32")
            
            if fragment_duration == 0:
                discontinuity_indicator = afrt_bs_box.read("uint:8")
            else:
                discontinuity_indicator = None
            
            frte = FragmentRunTable.FragmentRunTableEntry(first_fragment=first_fragment,
                                                          first_fragment_timestamp=first_fragment_timestamp,
                                                          fragment_duration=fragment_duration,
                                                          discontinuity_indicator=discontinuity_indicator)
            afrt.fragments.append(frte)
        return afrt

    @staticmethod
    def _parse_mdat(box_bs, header):
        """ Parse afrt / Fragment Run Table Box """
                
        mdat = MediaDataBox()
        mdat.header = header
        mdat.payload = box_bs.read(mdat.header.box_size * 8).bytes
        return mdat

    @staticmethod
    def _parse_time_field(bs, scale):
        timestamp = bs.read("uint:64")
        return datetime.utcfromtimestamp(timestamp / float(scale) )