from __future__ import unicode_literals

import base64
import io
import itertools
import os
from struct import unpack, pack
import time
import xml.etree.ElementTree as etree

from .common import FileDownloader
from .http import HttpFD
from ..utils import (
    compat_urllib_request,
    compat_urlparse,
    format_bytes,
    encodeFilename,
    sanitize_open,
)


class FlvReader(io.BytesIO):
    """
    Reader for Flv files
    The file format is documented in https://www.adobe.com/devnet/f4v.html
    """

    # Utility functions for reading numbers and strings
    def read_unsigned_long_long(self):
        return unpack('!Q', self.read(8))[0]

    def read_unsigned_int(self):
        return unpack('!I', self.read(4))[0]

    def read_unsigned_char(self):
        return unpack('!B', self.read(1))[0]

    def read_string(self):
        res = b''
        while True:
            char = self.read(1)
            if char == b'\x00':
                break
            res += char
        return res

    def read_box_info(self):
        """
        Read a box and return the info as a tuple: (box_size, box_type, box_data)
        """
        real_size = size = self.read_unsigned_int()
        box_type = self.read(4)
        header_end = 8
        if size == 1:
            real_size = self.read_unsigned_long_long()
            header_end = 16
        return real_size, box_type, self.read(real_size-header_end)

    def read_asrt(self):
        # version
        self.read_unsigned_char()
        # flags
        self.read(3)
        quality_entry_count = self.read_unsigned_char()
        # QualityEntryCount
        for i in range(quality_entry_count):
            self.read_string()

        segment_run_count = self.read_unsigned_int()
        segments = []
        for i in range(segment_run_count):
            first_segment = self.read_unsigned_int()
            fragments_per_segment = self.read_unsigned_int()
            segments.append((first_segment, fragments_per_segment))

        return {
            'segment_run': segments,
        }

    def read_afrt(self):
        # version
        self.read_unsigned_char()
        # flags
        self.read(3)
        # time scale
        self.read_unsigned_int()

        quality_entry_count = self.read_unsigned_char()
        # QualitySegmentUrlModifiers
        for i in range(quality_entry_count):
            self.read_string()

        fragments_count = self.read_unsigned_int()
        fragments = []
        for i in range(fragments_count):
            first = self.read_unsigned_int()
            first_ts = self.read_unsigned_long_long()
            duration = self.read_unsigned_int()
            if duration == 0:
                discontinuity_indicator = self.read_unsigned_char()
            else:
                discontinuity_indicator = None
            fragments.append({
                'first': first,
                'ts': first_ts,
                'duration': duration,
                'discontinuity_indicator': discontinuity_indicator,
            })

        return {
            'fragments': fragments,
        }

    def read_abst(self):
        # version
        self.read_unsigned_char()
        # flags
        self.read(3)
        # BootstrapinfoVersion
        bootstrap_info_version = self.read_unsigned_int()
        # Profile,Live,Update,Reserved
        self.read(1)
        # time scale
        self.read_unsigned_int()
        # CurrentMediaTime
        self.read_unsigned_long_long()
        # SmpteTimeCodeOffset
        self.read_unsigned_long_long()
        # MovieIdentifier
        movie_identifier = self.read_string()
        server_count = self.read_unsigned_char()
        # ServerEntryTable
        for i in range(server_count):
            self.read_string()
        quality_count = self.read_unsigned_char()
        # QualityEntryTable
        for i in range(server_count):
            self.read_string()
        # DrmData
        self.read_string()
        # MetaData
        self.read_string()

        segments_count = self.read_unsigned_char()
        segments = []
        for i in range(segments_count):
            box_size, box_type, box_data = self.read_box_info()
            assert box_type == b'asrt'
            segment = FlvReader(box_data).read_asrt()
            segments.append(segment)
        fragments_run_count = self.read_unsigned_char()
        fragments = []
        for i in range(fragments_run_count):
            box_size, box_type, box_data = self.read_box_info()
            assert box_type == b'afrt'
            fragments.append(FlvReader(box_data).read_afrt())

        return {
            'segments': segments,
            'fragments': fragments,
        }

    def read_bootstrap_info(self):
        total_size, box_type, box_data = self.read_box_info()
        assert box_type == b'abst'
        return FlvReader(box_data).read_abst()


def read_bootstrap_info(bootstrap_bytes):
    return FlvReader(bootstrap_bytes).read_bootstrap_info()


def build_fragments_list(boot_info):
    """ Return a list of (segment, fragment) for each fragment in the video """
    res = []
    segment_run_table = boot_info['segments'][0]
    # I've only found videos with one segment
    segment_run_entry = segment_run_table['segment_run'][0]
    n_frags = segment_run_entry[1]
    fragment_run_entry_table = boot_info['fragments'][0]['fragments']
    first_frag_number = fragment_run_entry_table[0]['first']
    for (i, frag_number) in zip(range(1, n_frags+1), itertools.count(first_frag_number)):
        res.append((1, frag_number))
    return res


def write_flv_header(stream, metadata):
    """Writes the FLV header and the metadata to stream"""
    # FLV header
    stream.write(b'FLV\x01')
    stream.write(b'\x05')
    stream.write(b'\x00\x00\x00\x09')
    # FLV File body
    stream.write(b'\x00\x00\x00\x00')
    # FLVTAG
    # Script data
    stream.write(b'\x12')
    # Size of the metadata with 3 bytes
    stream.write(pack('!L', len(metadata))[1:])
    stream.write(b'\x00\x00\x00\x00\x00\x00\x00')
    stream.write(metadata)
    # Magic numbers extracted from the output files produced by AdobeHDS.php
    #(https://github.com/K-S-V/Scripts)
    stream.write(b'\x00\x00\x01\x73')


def _add_ns(prop):
    return '{http://ns.adobe.com/f4m/1.0}%s' % prop


class HttpQuietDownloader(HttpFD):
    def to_screen(self, *args, **kargs):
        pass


class F4mFD(FileDownloader):
    """
    A downloader for f4m manifests or AdobeHDS.
    """

    def real_download(self, filename, info_dict):
        man_url = info_dict['url']
        self.to_screen('[download] Downloading f4m manifest')
        manifest = self.ydl.urlopen(man_url).read()
        self.report_destination(filename)
        http_dl = HttpQuietDownloader(self.ydl, {'continuedl': True, 'quiet': True, 'noprogress': True})

        doc = etree.fromstring(manifest)
        formats = [(int(f.attrib.get('bitrate', -1)), f) for f in doc.findall(_add_ns('media'))]
        formats = sorted(formats, key=lambda f: f[0])
        rate, media = formats[-1]
        base_url = compat_urlparse.urljoin(man_url, media.attrib['url'])
        bootstrap = base64.b64decode(doc.find(_add_ns('bootstrapInfo')).text)
        metadata = base64.b64decode(media.find(_add_ns('metadata')).text)
        boot_info = read_bootstrap_info(bootstrap)
        fragments_list = build_fragments_list(boot_info)
        total_frags = len(fragments_list)

        tmpfilename = self.temp_name(filename)
        (dest_stream, tmpfilename) = sanitize_open(tmpfilename, 'wb')
        write_flv_header(dest_stream, metadata)

        # This dict stores the download progress, it's updated by the progress
        # hook
        state = {
            'downloaded_bytes': 0,
            'frag_counter': 0,
        }
        start = time.time()

        def frag_progress_hook(status):
            frag_total_bytes = status.get('total_bytes', 0)
            estimated_size = (state['downloaded_bytes'] +
                (total_frags - state['frag_counter']) * frag_total_bytes)
            if status['status'] == 'finished':
                state['downloaded_bytes'] += frag_total_bytes
                state['frag_counter'] += 1
                progress = self.calc_percent(state['frag_counter'], total_frags)
                byte_counter = state['downloaded_bytes']
            else:
                frag_downloaded_bytes = status['downloaded_bytes']
                byte_counter = state['downloaded_bytes'] + frag_downloaded_bytes
                frag_progress = self.calc_percent(frag_downloaded_bytes,
                    frag_total_bytes)
                progress = self.calc_percent(state['frag_counter'], total_frags)
                progress += frag_progress / float(total_frags)

            eta = self.calc_eta(start, time.time(), estimated_size, byte_counter)
            self.report_progress(progress, format_bytes(estimated_size),
                status.get('speed'), eta)
        http_dl.add_progress_hook(frag_progress_hook)

        frags_filenames = []
        for (seg_i, frag_i) in fragments_list:
            name = 'Seg%d-Frag%d' % (seg_i, frag_i)
            url = base_url + name
            frag_filename = '%s-%s' % (tmpfilename, name)
            success = http_dl.download(frag_filename, {'url': url})
            if not success:
                return False
            with open(frag_filename, 'rb') as down:
                down_data = down.read()
                reader = FlvReader(down_data)
                while True:
                    _, box_type, box_data = reader.read_box_info()
                    if box_type == b'mdat':
                        dest_stream.write(box_data)
                        break
            frags_filenames.append(frag_filename)

        self.report_finish(format_bytes(state['downloaded_bytes']), time.time() - start)

        self.try_rename(tmpfilename, filename)
        for frag_file in frags_filenames:
            os.remove(frag_file)

        fsize = os.path.getsize(encodeFilename(filename))
        self._hook_progress({
            'downloaded_bytes': fsize,
            'total_bytes': fsize,
            'filename': filename,
            'status': 'finished',
        })

        return True