#!/usr/bin/env python


__license__   = 'GPL v3'
__copyright__ = '2012, Kovid Goyal <kovid@kovidgoyal.net>'
__docformat__ = 'restructuredtext en'

import os
import struct
import sys
import textwrap

from calibre import CurrentDir
from calibre.ebooks.mobi.debug import format_bytes
from calibre.ebooks.mobi.debug.containers import ContainerHeader
from calibre.ebooks.mobi.debug.headers import TextRecord
from calibre.ebooks.mobi.debug.index import GuideIndex, NCXIndex, SECTIndex, SKELIndex
from calibre.ebooks.mobi.reader.headers import NULL_INDEX
from calibre.ebooks.mobi.utils import RECORD_SIZE, decode_tbs, read_font_record
from calibre.utils.imghdr import what
from polyglot.builtins import print_to_binary_file


class FDST:

    def __init__(self, raw):
        if raw[:4] != b'FDST':
            raise ValueError('KF8 does not have a valid FDST record')
        self.sec_off, self.num_sections = struct.unpack_from(b'>LL', raw, 4)
        if self.sec_off != 12:
            raise ValueError('FDST record has unknown extra fields')
        secf = b'>%dL' % (self.num_sections*2)
        secs = struct.unpack_from(secf, raw, self.sec_off)
        rest = raw[self.sec_off+struct.calcsize(secf):]
        if rest:
            raise ValueError('FDST record has trailing data: '
                    f'{format_bytes(rest)}')
        self.sections = tuple(zip(secs[::2], secs[1::2]))

    def __str__(self):
        ans = ['FDST record']
        def a(k, v):
            return ans.append(f'{k}: {v}')
        a('Offset to sections', self.sec_off)
        a('Number of section records', self.num_sections)
        ans.append(f'**** {len(self.sections)} Sections ****')
        for sec in self.sections:
            ans.append(f'Start: {sec[0]:>20} End: {sec[1]}')

        return '\n'.join(ans)


class File:

    def __init__(self, skel, skeleton, text, first_aid, sections):
        self.name = f'part{skel.file_number:04}'
        self.skeleton, self.text, self.first_aid = skeleton, text, first_aid
        self.sections = sections

    def dump(self, ddir):
        with open(os.path.join(ddir, self.name + '.html'), 'wb') as f:
            f.write(self.text)
        base = os.path.join(ddir, self.name + '-parts')
        os.mkdir(base)
        with CurrentDir(base):
            with open('skeleton.html', 'wb') as f:
                f.write(self.skeleton)
            for i, text in enumerate(self.sections):
                with open(f'sect-{i:04}.html', 'wb') as f:
                    f.write(text)


class MOBIFile:

    def __init__(self, mf):
        self.mf = mf
        h, h8 = mf.mobi_header, mf.mobi8_header
        first_text_record = 1
        offset = 0
        self.resource_ranges = [(h8.first_resource_record, h8.last_resource_record, h8.first_image_index)]
        if mf.kf8_type == 'joint':
            offset = h.exth.kf8_header_index
            self.resource_ranges.insert(0, (h.first_resource_record, h.last_resource_record, h.first_image_index))

        self.text_records = [TextRecord(i, r, h8.extra_data_flags,
            mf.decompress8) for i, r in
            enumerate(mf.records[first_text_record+offset:
                first_text_record+offset+h8.number_of_text_records])]

        self.raw_text = b''.join(r.raw for r in self.text_records)
        self.header = self.mf.mobi8_header
        self.extract_resources(mf.records)
        self.read_fdst()
        self.read_indices()
        self.build_files()
        self.read_tbs()

    def print_header(self, f=sys.stdout):
        p = print_to_binary_file(f)
        p(str(self.mf.palmdb))
        p()
        p('Record headers:')
        for i, r in enumerate(self.mf.records):
            p(f'{i:6}. {r.header}')

        p()
        p(str(self.mf.mobi8_header))

    def read_fdst(self):
        self.fdst = None

        if self.header.fdst_idx != NULL_INDEX:
            idx = self.header.fdst_idx
            self.fdst = FDST(self.mf.records[idx].raw)
            if self.fdst.num_sections != self.header.fdst_count:
                raise ValueError('KF8 Header contains invalid FDST count')

    def read_indices(self):
        self.skel_index = SKELIndex(self.header.skel_idx, self.mf.records,
                self.header.encoding)
        self.sect_index = SECTIndex(self.header.sect_idx, self.mf.records,
                self.header.encoding)
        self.ncx_index = NCXIndex(self.header.primary_index_record,
                self.mf.records, self.header.encoding)
        self.guide_index = GuideIndex(self.header.oth_idx, self.mf.records,
                self.header.encoding)

    def build_files(self):
        text = self.raw_text
        self.files = []
        for skel in self.skel_index.records:
            sects = [x for x in self.sect_index.records if x.file_number == skel.file_number]
            skeleton = text[skel.start_position:skel.start_position+skel.length]
            ftext = skeleton
            first_aid = sects[0].toc_text
            sections = []

            for sect in sects:
                start_pos = skel.start_position + skel.length + sect.start_pos
                sect_text = text[start_pos:start_pos+sect.length]
                insert_pos = sect.insert_pos - skel.start_position
                ftext = ftext[:insert_pos] + sect_text + ftext[insert_pos:]
                sections.append(sect_text)

            self.files.append(File(skel, skeleton, ftext, first_aid, sections))

    def dump_flows(self, ddir):
        boundaries = [(0, len(self.raw_text))]
        if self.fdst is not None:
            boundaries = self.fdst.sections
        for i, x in enumerate(boundaries):
            start, end = x
            raw = self.raw_text[start:end]
            with open(os.path.join(ddir, f'flow{i:04}.txt'), 'wb') as f:
                f.write(raw)

    def extract_resources(self, records):
        self.resource_map = []
        self.containers = []
        known_types = {b'FLIS', b'FCIS', b'SRCS',
                    b'\xe9\x8e\r\n', b'RESC', b'BOUN', b'FDST', b'DATP',
                    b'AUDI', b'VIDE', b'CRES', b'CONT', b'CMET', b'PAGE'}
        container = None

        for i, rec in enumerate(records):
            for (l, r, offset) in self.resource_ranges:
                if l <= i <= r:
                    resource_index = i + 1
                    if offset is not None and resource_index >= offset:
                        resource_index -= offset
                    break
            else:
                continue
            sig = rec.raw[:4]
            payload = rec.raw
            ext = 'dat'
            prefix = 'binary'
            suffix = ''
            if sig in {b'HUFF', b'CDIC', b'INDX'}:
                continue
            # TODO: Ignore CNCX records as well
            if sig == b'FONT':
                font = read_font_record(rec.raw)
                if font['err']:
                    raise ValueError('Failed to read font record: {} Headers: {}'.format(
                        font['err'], font['headers']))
                payload = (font['font_data'] if font['font_data'] else
                        font['raw_data'])
                prefix, ext = 'fonts', font['ext']
            elif sig == b'CONT':
                if payload == b'CONTBOUNDARY':
                    self.containers.append(container)
                    container = None
                    continue
                container = ContainerHeader(payload)
            elif sig == b'CRES':
                container.resources.append(payload)
                if container.is_image_container:
                    payload = payload[12:]
                    q = what(None, payload)
                    if q:
                        prefix, ext = 'hd-images', q
                        resource_index = len(container.resources)
            elif sig == b'\xa0\xa0\xa0\xa0' and len(payload) == 4:
                if container is None:
                    print('Found an end of container record with no container, ignoring')
                else:
                    container.resources.append(None)
                continue
            elif sig not in known_types:
                if container is not None and len(container.resources) == container.num_of_resource_records:
                    container.add_hrefs(payload)
                    continue
                q = what(None, rec.raw)
                if q:
                    prefix, ext = 'images', q

            if prefix == 'binary':
                if sig == b'\xe9\x8e\r\n':
                    suffix = '-EOF'
                elif sig in known_types:
                    suffix = '-' + sig.decode('ascii')

            self.resource_map.append((f'{prefix}/{resource_index:06}{suffix}.{ext}',
                payload))

    def read_tbs(self):
        from calibre.ebooks.mobi.writer8.tbs import (
            DOC,
            Entry,
            NegativeStrandIndex,
            calculate_all_tbs,
            collect_indexing_data,
            encode_strands_as_sequences,
            sequences_to_bytes,
        )
        entry_map = []
        for index in self.ncx_index:
            vals = list(index)[:-1] + [None, None, None, None]
            entry_map.append(Entry(*(vals[:12])))

        indexing_data = collect_indexing_data(entry_map, list(map(len,
            self.text_records)))
        self.indexing_data = [DOC + '\n' +textwrap.dedent('''\
                Index Entry lines are of the form:
                depth:index_number [action] parent (index_num-parent) Geometry

                Where Geometry is the start and end of the index entry w.r.t
                the start of the text record.

                ''')]

        tbs_type = 8
        try:
            calculate_all_tbs(indexing_data)
        except NegativeStrandIndex:
            calculate_all_tbs(indexing_data, tbs_type=5)
            tbs_type = 5

        for i, strands in enumerate(indexing_data):
            rec = self.text_records[i]
            tbs_bytes = rec.trailing_data.get('indexing', b'')
            desc = [f'Record #{i}']
            for s, strand in enumerate(strands):
                desc.append(f'Strand {s}')
                for entries in strand.values():
                    for e in entries:
                        desc.append(
                        ' {}{} [{:<9}] parent: {} ({}) Geometry: ({}, {})'.format(
                            e.depth * ('  ') + '- ', e.index, e.action, e.parent,
                            e.index-(e.parent or 0), e.start-i*RECORD_SIZE,
                            e.start+e.length-i*RECORD_SIZE))
            desc.append('TBS Bytes: ' + format_bytes(tbs_bytes))
            flag_sz = 3
            sequences = []
            otbs = tbs_bytes
            while tbs_bytes:
                try:
                    val, extra, consumed = decode_tbs(tbs_bytes, flag_size=flag_sz)
                except Exception:
                    break
                flag_sz = 4
                tbs_bytes = tbs_bytes[consumed:]
                extra = {bin(k):v for k, v in extra.items()}
                sequences.append((val, extra))
            for j, seq in enumerate(sequences):
                desc.append(f'Sequence #{j}: {seq[0]!r} {seq[1]!r}')
            if tbs_bytes:
                desc.append(f'Remaining bytes: {format_bytes(tbs_bytes)}')
            calculated_sequences = encode_strands_as_sequences(strands,
                    tbs_type=tbs_type)
            try:
                calculated_bytes = sequences_to_bytes(calculated_sequences)
            except Exception:
                calculated_bytes = b'failed to calculate tbs bytes'
            if calculated_bytes != otbs:
                print(f'WARNING: TBS mismatch for record {i}')
                desc.append('WARNING: TBS mismatch!')
                desc.append(f'Calculated sequences: {calculated_sequences!r}')
            desc.append('')
            self.indexing_data.append('\n'.join(desc))


def inspect_mobi(mobi_file, ddir):
    f = MOBIFile(mobi_file)
    with open(os.path.join(ddir, 'header.txt'), 'wb') as out:
        f.print_header(f=out)

    alltext = os.path.join(ddir, 'raw_text.html')
    with open(alltext, 'wb') as of:
        of.write(f.raw_text)

    for x in ('text_records', 'images', 'fonts', 'binary', 'files', 'flows', 'hd-images',):
        os.mkdir(os.path.join(ddir, x))

    for rec in f.text_records:
        rec.dump(os.path.join(ddir, 'text_records'))

    for href, payload in f.resource_map:
        with open(os.path.join(ddir, href), 'wb') as fo:
            fo.write(payload)

    for i, container in enumerate(f.containers):
        with open(os.path.join(ddir, f'container{i + 1}.txt'), 'wb') as cf:
            cf.write(str(container).encode('utf-8'))

    if f.fdst:
        with open(os.path.join(ddir, 'fdst.record'), 'wb') as fo:
            fo.write(str(f.fdst).encode('utf-8'))

    with open(os.path.join(ddir, 'skel.record'), 'wb') as fo:
        fo.write(str(f.skel_index).encode('utf-8'))

    with open(os.path.join(ddir, 'chunks.record'), 'wb') as fo:
        fo.write(str(f.sect_index).encode('utf-8'))

    with open(os.path.join(ddir, 'ncx.record'), 'wb') as fo:
        fo.write(str(f.ncx_index).encode('utf-8'))

    with open(os.path.join(ddir, 'guide.record'), 'wb') as fo:
        fo.write(str(f.guide_index).encode('utf-8'))

    with open(os.path.join(ddir, 'tbs.txt'), 'wb') as fo:
        fo.write(('\n'.join(f.indexing_data)).encode('utf-8'))

    for part in f.files:
        part.dump(os.path.join(ddir, 'files'))

    f.dump_flows(os.path.join(ddir, 'flows'))
