#!/usr/bin/env python
# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
from __future__ import (unicode_literals, division, absolute_import,
                        print_function)

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

import copy, logging
from functools import partial
from collections import defaultdict, namedtuple
from io import BytesIO
from struct import pack

import cssutils
from lxml import etree

from calibre import isbytestring, force_unicode
from calibre.ebooks.mobi.utils import (create_text_record, to_base,
        is_guide_ref_start)
from calibre.ebooks.compression.palmdoc import compress_doc
from calibre.ebooks.oeb.base import (OEB_DOCS, OEB_STYLES, SVG_MIME, XPath,
        extract, XHTML, urlnormalize)
from calibre.ebooks.oeb.parse_utils import barename
from calibre.ebooks.mobi.writer8.skeleton import Chunker, aid_able_tags, to_href
from calibre.ebooks.mobi.writer8.index import (NCXIndex, SkelIndex,
        ChunkIndex, GuideIndex, NonLinearNCXIndex)
from calibre.ebooks.mobi.writer8.mobi import KF8Book
from calibre.ebooks.mobi.writer8.tbs import apply_trailing_byte_sequences
from calibre.ebooks.mobi.writer8.toc import TOCAdder

XML_DOCS = OEB_DOCS | {SVG_MIME}

# References to record numbers in KF8 are stored as base-32 encoded integers,
# with 4 digits
to_ref = partial(to_base, base=32, min_num_digits=4)

class KF8Writer(object):

    def __init__(self, oeb, opts, resources):
        self.oeb, self.opts, self.log = oeb, opts, oeb.log
        self.compress = not self.opts.dont_compress
        self.has_tbs = False
        self.log.info('Creating KF8 output')

        # Create an inline ToC if one does not already exist
        self.toc_adder = TOCAdder(oeb, opts)
        self.used_images = set()
        self.resources = resources
        self.flows = [None] # First flow item is reserved for the text
        self.records = [None] # Placeholder for zeroth record

        self.log('\tGenerating KF8 markup...')
        self.dup_data()
        self.cleanup_markup()
        self.replace_resource_links()
        self.extract_css_into_flows()
        self.extract_svg_into_flows()
        self.replace_internal_links_with_placeholders()
        self.insert_aid_attributes()
        self.chunk_it_up()
        # Dump the cloned data as it is no longer needed
        del self._data_cache
        self.create_text_records()
        self.log('\tCreating indices...')
        self.create_fdst_records()
        self.create_indices()
        self.create_guide()
        # We do not want to use this ToC for MOBI 6, so remove it
        self.toc_adder.remove_generated_toc()

    def dup_data(self):
        ''' Duplicate data so that any changes we make to markup/CSS only
        affect KF8 output and not MOBI 6 output '''
        self._data_cache = {}
        # Suppress cssutils logging output as it is duplicated anyway earlier
        # in the pipeline
        cssutils.log.setLevel(logging.CRITICAL)
        for item in self.oeb.manifest:
            if item.media_type in XML_DOCS:
                self._data_cache[item.href] = copy.deepcopy(item.data)
            elif item.media_type in OEB_STYLES:
                # I can't figure out how to make an efficient copy of the
                # in-memory CSSStylesheet, as deepcopy doesn't work (raises an
                # exception)
                self._data_cache[item.href] = cssutils.parseString(
                        item.data.cssText, validate=False)

    def data(self, item):
        return self._data_cache.get(item.href, item.data)

    def cleanup_markup(self):
        for item in self.oeb.spine:
            root = self.data(item)

            # Remove empty script tags as they are pointless
            for tag in XPath('//h:script')(root):
                if not tag.text and not tag.get('src', False):
                    tag.getparent().remove(tag)

    def replace_resource_links(self):
        ''' Replace links to resources (raster images/fonts) with pointers to
        the MOBI record containing the resource. The pointers are of the form:
        kindle:embed:XXXX?mime=image/* The ?mime= is apparently optional and
        not used for fonts. '''

        def pointer(item, oref):
            ref = urlnormalize(item.abshref(oref))
            idx = self.resources.item_map.get(ref, None)
            if idx is not None:
                is_image = self.resources.records[idx-1][:4] not in {b'FONT'}
                idx = to_ref(idx)
                if is_image:
                    self.used_images.add(ref)
                    return 'kindle:embed:%s?mime=%s'%(idx,
                            self.resources.mime_map[ref])
                else:
                    return 'kindle:embed:%s'%idx
            return oref

        for item in self.oeb.manifest:

            if item.media_type in XML_DOCS:
                root = self.data(item)
                for tag in XPath('//h:img|//svg:image')(root):
                    for attr, ref in tag.attrib.iteritems():
                        if attr.split('}')[-1].lower() in {'src', 'href'}:
                            tag.attrib[attr] = pointer(item, ref)

                for tag in XPath('//h:style')(root):
                    if tag.text:
                        sheet = cssutils.parseString(tag.text, validate=False)
                        replacer = partial(pointer, item)
                        cssutils.replaceUrls(sheet, replacer,
                                ignoreImportRules=True)
                        repl = sheet.cssText
                        if isbytestring(repl):
                            repl = repl.decode('utf-8')
                        tag.text = '\n'+ repl + '\n'

            elif item.media_type in OEB_STYLES:
                sheet = self.data(item)
                replacer = partial(pointer, item)
                cssutils.replaceUrls(sheet, replacer, ignoreImportRules=True)

    def extract_css_into_flows(self):
        inlines = defaultdict(list) # Ensure identical <style>s not repeated
        sheets = {}

        for item in self.oeb.manifest:
            if item.media_type in OEB_STYLES:
                data = self.data(item).cssText
                sheets[item.href] = len(self.flows)
                self.flows.append(force_unicode(data, 'utf-8'))

        for item in self.oeb.spine:
            root = self.data(item)

            for link in XPath('//h:link[@href]')(root):
                href = item.abshref(link.get('href'))
                idx = sheets.get(href, None)
                if idx is not None:
                    idx = to_ref(idx)
                    link.set('href', 'kindle:flow:%s?mime=text/css'%idx)

            for tag in XPath('//h:style')(root):
                p = tag.getparent()
                idx = p.index(tag)
                raw = tag.text
                if not raw or not raw.strip():
                    extract(tag)
                    continue
                repl = etree.Element(XHTML('link'), type='text/css',
                        rel='stylesheet')
                repl.tail='\n'
                p.insert(idx, repl)
                extract(tag)
                inlines[raw].append(repl)

        for raw, elems in inlines.iteritems():
            idx = to_ref(len(self.flows))
            self.flows.append(raw)
            for link in elems:
                link.set('href', 'kindle:flow:%s?mime=text/css'%idx)

    def extract_svg_into_flows(self):
        images = {}

        for item in self.oeb.manifest:
            if item.media_type == SVG_MIME:
                data = self.data(item)
                images[item.href] = len(self.flows)
                self.flows.append(etree.tostring(data, encoding='UTF-8',
                    with_tail=True, xml_declaration=True))

        for item in self.oeb.spine:
            root = self.data(item)

            for svg in XPath('//svg:svg')(root):
                raw = etree.tostring(svg, encoding=unicode, with_tail=False)
                idx = len(self.flows)
                self.flows.append(raw)
                p = svg.getparent()
                pos = p.index(svg)
                img = etree.Element(XHTML('img'),
                        src="kindle:flow:%s?mime=image/svg+xml"%to_ref(idx))
                p.insert(pos, img)
                extract(svg)

            for img in XPath('//h:img[@src]')(root):
                src = img.get('src')
                abshref = item.abshref(src)
                idx = images.get(abshref, None)
                if idx is not None:
                    img.set('src', 'kindle:flow:%s?mime=image/svg+xml'%
                            to_ref(idx))

    def replace_internal_links_with_placeholders(self):
        self.link_map = {}
        count = 0
        hrefs = {item.href for item in self.oeb.spine}
        for item in self.oeb.spine:
            root = self.data(item)

            for a in XPath('//h:a[@href]')(root):
                count += 1
                ref = item.abshref(a.get('href'))
                href, _, frag = ref.partition('#')
                href = urlnormalize(href)
                if href in hrefs:
                    placeholder = 'kindle:pos:fid:0000:off:%s'%to_href(count)
                    self.link_map[placeholder] = (href, frag)
                    a.set('href', placeholder)

    def insert_aid_attributes(self):
        self.id_map = {}
        for i, item in enumerate(self.oeb.spine):
            root = self.data(item)
            aidbase = i * int(1e6)
            j = 0
            for tag in root.iterdescendants(etree.Element):
                id_ = tag.attrib.get('id', None)
                if id_ is None and tag.tag == XHTML('a'):
                    # Can happen during tweaking
                    id_ = tag.attrib.get('name', None)
                    if id_ is not None:
                        tag.attrib['id'] = id_
                if id_ is not None or barename(tag.tag).lower() in aid_able_tags:
                    aid = aidbase + j
                    tag.attrib['aid'] = to_base(aid, base=32)
                    if tag.tag == XHTML('body'):
                        self.id_map[(item.href, '')] = tag.attrib['aid']
                    if id_ is not None:
                        self.id_map[(item.href, id_)] = tag.attrib['aid']

                    j += 1

    def chunk_it_up(self):
        placeholder_map = {}
        for placeholder, x in self.link_map.iteritems():
            href, frag = x
            aid = self.id_map.get(x, None)
            if aid is None:
                aid = self.id_map.get((href, ''))
            placeholder_map[placeholder] = aid
        chunker = Chunker(self.oeb, self.data, placeholder_map)

        for x in ('skel_table', 'chunk_table', 'aid_offset_map'):
            setattr(self, x, getattr(chunker, x))

        self.flows[0] = chunker.text

    def create_text_records(self):
        self.flows = [x.encode('utf-8') if isinstance(x, unicode) else x for x
                in self.flows]
        text = b''.join(self.flows)
        self.text_length = len(text)
        text = BytesIO(text)
        nrecords = 0
        records_size = 0
        self.uncompressed_record_lengths = []

        if self.compress:
            self.oeb.logger.info('\tCompressing markup...')

        while text.tell() < self.text_length:
            data, overlap = create_text_record(text)
            self.uncompressed_record_lengths.append(len(data))
            if self.compress:
                data = compress_doc(data)

            data += overlap
            data += pack(b'>B', len(overlap))

            self.records.append(data)
            records_size += len(data)
            nrecords += 1

        self.last_text_record_idx = nrecords
        self.first_non_text_record_idx = nrecords + 1
        # Pad so that the next records starts at a 4 byte boundary
        if records_size % 4 != 0:
            self.records.append(b'\x00'*(records_size % 4))
            self.first_non_text_record_idx += 1

    def create_fdst_records(self):
        FDST = namedtuple('Flow', 'start end')
        entries = []
        self.fdst_table = []
        for i, flow in enumerate(self.flows):
            start = 0 if i == 0 else self.fdst_table[-1].end
            self.fdst_table.append(FDST(start, start + len(flow)))
            entries.extend(self.fdst_table[-1])
        rec = (b'FDST' + pack(b'>LL', 12, len(self.fdst_table)) +
                pack(b'>%dL'%len(entries), *entries))
        self.fdst_records = [rec]
        self.fdst_count = len(self.fdst_table)

    def create_indices(self):
        self.skel_records = SkelIndex(self.skel_table)()
        self.chunk_records = ChunkIndex(self.chunk_table)()
        self.ncx_records = []
        toc = self.oeb.toc
        entries = []
        is_periodical = self.opts.mobi_periodical
        if toc.count() < 2:
            self.log.warn('Document has no ToC, MOBI will have no NCX index')
            return

        # Flatten the ToC into a depth first list
        fl = toc.iterdescendants()
        for i, item in enumerate(fl):
            entry = {'id': id(item), 'index': i, 'label':(item.title or
                _('Unknown')), 'children':[]}
            entry['depth'] = getattr(item, 'ncx_hlvl', 0)
            p = getattr(item, 'ncx_parent', None)
            if p is not None:
                entry['parent_id'] = p
            for child in item:
                child.ncx_parent = entry['id']
                child.ncx_hlvl = entry['depth'] + 1
                entry['children'].append(id(child))
            if is_periodical:
                if item.author:
                    entry['author'] = item.author
                if item.description:
                    entry['description'] = item.description
            entries.append(entry)
            href = item.href or ''
            href, frag = href.partition('#')[0::2]
            aid = self.id_map.get((href, frag), None)
            if aid is None:
                aid = self.id_map.get((href, ''), None)
            if aid is None:
                pos, fid = 0, 0
                chunk = self.chunk_table[pos]
                offset = chunk.insert_pos + fid
            else:
                pos, fid, offset = self.aid_offset_map[aid]

            entry['pos_fid'] = (pos, fid)
            entry['offset'] = offset

        # The Kindle requires entries to be sorted by (depth, playorder)
        # However, I cannot figure out how to deal with non linear ToCs, i.e.
        # ToCs whose nth entry at depth d has an offset after its n+k entry at
        # the same depth, so we sort on (depth, offset) instead. This re-orders
        # the ToC to be linear. A non-linear ToC causes section to section
        # jumping to not work. kindlegen somehow handles non-linear tocs, but I
        # cannot figure out how.
        original = sorted(entries,
                key=lambda entry: (entry['depth'], entry['index']))
        linearized = sorted(entries,
                key=lambda entry: (entry['depth'], entry['offset']))
        is_non_linear = original != linearized
        entries = linearized
        is_non_linear = False # False as we are using the linearized entries

        if is_non_linear:
            for entry in entries:
                entry['kind'] = 'chapter'

        for i, entry in enumerate(entries):
            entry['index'] = i
        id_to_index = {entry['id']:entry['index'] for entry in entries}

        # Write the hierarchical information
        for entry in entries:
            children = entry.pop('children')
            if children:
                entry['first_child'] = id_to_index[children[0]]
                entry['last_child'] = id_to_index[children[-1]]
            if 'parent_id' in entry:
                entry['parent'] = id_to_index[entry.pop('parent_id')]

        # Write the lengths
        def get_next_start(entry):
            enders = [e['offset'] for e in entries if e['depth'] <=
                    entry['depth'] and e['offset'] > entry['offset']]
            if enders:
                return min(enders)
            return len(self.flows[0])
        for entry in entries:
            entry['length'] = get_next_start(entry) - entry['offset']

        self.has_tbs = apply_trailing_byte_sequences(entries, self.records,
                self.uncompressed_record_lengths)
        idx_type = NonLinearNCXIndex if is_non_linear else NCXIndex
        self.ncx_records = idx_type(entries)()

    def create_guide(self):
        self.start_offset = None
        self.guide_table = []
        self.guide_records = []
        GuideRef = namedtuple('GuideRef', 'title type pos_fid')
        for ref in self.oeb.guide.values():
            href, frag = ref.href.partition('#')[0::2]
            aid = self.id_map.get((href, frag), None)
            if aid is None:
                aid = self.id_map.get((href, ''))
            if aid is None:
                continue
            pos, fid, offset = self.aid_offset_map[aid]
            if is_guide_ref_start(ref):
                self.start_offset = offset
            self.guide_table.append(GuideRef(ref.title or
                _('Unknown'), ref.type, (pos, fid)))

        if self.guide_table:
            self.guide_table.sort(key=lambda x:x.type) # Needed by the Kindle
            self.guide_records = GuideIndex(self.guide_table)()

def create_kf8_book(oeb, opts, resources, for_joint=False):
    writer = KF8Writer(oeb, opts, resources)
    return KF8Book(writer, for_joint=for_joint)

