import os

from ebook_converter import _ent_pat, walk, xml_entity_to_unicode
from ebook_converter.customize.conversion import InputFormatPlugin, OptionRecommendation


__license__ = 'GPL 3'
__copyright__ = '2009, John Schember <john@nachtimwald.com>'
__docformat__ = 'restructuredtext en'

MD_EXTENSIONS = {
    'abbr': 'Abbreviations',
    'admonition': 'Support admonitions',
    'attr_list': 'Add attribute to HTML tags',
    'codehilite': 'Add code highlighting via Pygments',
    'def_list': 'Definition lists',
    'extra': 'Enables various common extensions',
    'fenced_code': 'Alternative code block syntax',
    'footnotes': 'Footnotes',
    'legacy_attrs': 'Use legacy element attributes',
    'legacy_em': 'Use legacy underscore handling for connected words',
    'meta': 'Metadata in the document',
    'nl2br': 'Treat newlines as hard breaks',
    'sane_lists': 'Do not allow mixing list types',
    'smarty': 'Use markdown\'s internal smartypants parser',
    'tables': 'Support tables',
    'toc': 'Generate a table of contents',
    'wikilinks': 'Wiki style links',
}


class TXTInput(InputFormatPlugin):

    name        = 'TXT Input'
    author      = 'John Schember'
    description = 'Convert TXT files to HTML'
    file_types  = {'txt', 'txtz', 'text', 'md', 'textile', 'markdown'}
    commit_name = 'txt_input'
    ui_data = {
        'md_extensions': MD_EXTENSIONS,
        'paragraph_types': {
            'auto': 'Try to auto detect paragraph type',
            'block': 'Treat a blank line as a paragraph break',
            'single': 'Assume every line is a paragraph',
            'print': 'Assume every line starting with 2+ spaces or a tab '
                     'starts a paragraph',
            'unformatted': 'Most lines have hard line breaks, few/no blank '
                           'lines or indents',
            'off': 'Don\'t modify the paragraph structure',
        },
        'formatting_types': {
            'auto': 'Automatically decide which formatting processor to use',
            'plain': 'No formatting',
            'heuristic': 'Use heuristics to determine chapter headings, '
                         'italics, etc.',
            'textile': 'Use the TexTile markup language',
            'markdown': 'Use the Markdown markup language'
        },
    }

    options = {
        OptionRecommendation(name='formatting_type', recommended_value='auto',
            choices=list(ui_data['formatting_types']),
            help='Formatting used within the document.\n'
                 '* auto: {auto}\n'
                 '* plain: {plain}\n'
                 '* heuristic: {heuristic}\n'
                 '* textile: {textile}\n'
                 '* markdown: {markdown}\n'
                 'To learn more about markdown see '
                 '{url}'.format(url='https://daringfireball.net/projects/'
                                    'markdown/',
                                **ui_data['formatting_types'])
        ),
        OptionRecommendation(name='paragraph_type', recommended_value='auto',
            choices=list(ui_data['paragraph_types']),
            help='Paragraph structure to assume. The value of "off" is useful '
                 'for formatted documents such as Markdown or Textile. '
                 'Choices are:\n'
                 '* auto: {auto}\n'
                 '* block: {block}\n'
                 '* single: {single}\n'
                 '* print:  {print}\n'
                 '* unformatted: {unformatted}\n'
                 '* off: {off}'.format(**ui_data['paragraph_types'])
        ),
        OptionRecommendation(name='preserve_spaces', recommended_value=False,
            help='Normally extra spaces are condensed into a single space. '
                 'With this option all spaces will be displayed.'),
        OptionRecommendation(name='txt_in_remove_indents', recommended_value=False,
            help='Normally extra space at the beginning of lines is retained. '
                 'With this option they will be removed.'),
        OptionRecommendation(name="markdown_extensions",
            recommended_value='footnotes, tables, toc',
            help='Enable extensions to markdown syntax. Extensions are '
                 'formatting that is not part of the standard markdown '
                 'format. The extensions enabled by default: %default.\nTo '
                 'learn more about markdown extensions, see {}\nThis should '
                 'be a comma separated list of extensions to enable:'
                 '\n'.format('https://python-markdown.github.io/extensions/') +
                             '\n'.join('* %s: %s' % (k, MD_EXTENSIONS[k])
                                       for k in sorted(MD_EXTENSIONS))),
    }

    def shift_file(self, fname, data):
        name, ext = os.path.splitext(fname)
        candidate = os.path.join(self.output_dir, fname)
        c = 0
        while os.path.exists(candidate):
            c += 1
            candidate = os.path.join(self.output_dir, '{}-{}{}'.format(name, c, ext))
        ans = candidate
        with open(ans, 'wb') as f:
            f.write(data)
        return f.name

    def fix_resources(self, html, base_dir):
        from html5_parser import parse
        root = parse(html)
        changed = False
        for img in root.xpath('//img[@src]'):
            src = img.get('src')
            prefix = src.split(':', 1)[0].lower()
            if prefix not in ('file', 'http', 'https', 'ftp') and not os.path.isabs(src):
                src = os.path.join(base_dir, src)
                if os.access(src, os.R_OK):
                    with open(src, 'rb') as f:
                        data = f.read()
                    f = self.shift_file(os.path.basename(src), data)
                    changed = True
                    img.set('src', os.path.basename(f))
        if changed:
            from lxml import etree
            html = etree.tostring(root, encoding='unicode')
        return html

    def convert(self, stream, options, file_ext, log,
                accelerators):
        from ebook_converter.ebooks.conversion.preprocess import DocAnalysis, Dehyphenator
        from ebook_converter.ebooks.chardet import detect
        from ebook_converter.utils.zipfile import ZipFile
        from ebook_converter.ebooks.txt.processor import (convert_basic,
                convert_markdown_with_metadata, separate_paragraphs_single_line,
                separate_paragraphs_print_formatted, preserve_spaces,
                detect_paragraph_type, detect_formatting_type,
                normalize_line_endings, convert_textile, remove_indents,
                block_to_single_line, separate_hard_scene_breaks)

        self.log = log
        txt = b''
        log.debug('Reading text from file...')
        length = 0
        base_dir = self.output_dir = os.getcwd()

        # Extract content from zip archive.
        if file_ext == 'txtz':
            zf = ZipFile(stream)
            zf.extractall('.')

            for x in walk('.'):
                if os.path.splitext(x)[1].lower() in ('.txt', '.text'):
                    with open(x, 'rb') as tf:
                        txt += tf.read() + b'\n\n'
        else:
            if getattr(stream, 'name', None):
                base_dir = os.path.dirname(stream.name)
            txt = stream.read()
            if file_ext in {'md', 'textile', 'markdown'}:
                options.formatting_type = {'md': 'markdown'}.get(file_ext, file_ext)
                log.info('File extension indicates particular formatting. '
                        'Forcing formatting type to: %s'%options.formatting_type)
                options.paragraph_type = 'off'

        # Get the encoding of the document.
        if options.input_encoding:
            ienc = options.input_encoding
            log.debug('Using user specified input encoding of %s' % ienc)
        else:
            det_encoding = detect(txt[:4096])
            det_encoding, confidence = det_encoding['encoding'], det_encoding['confidence']
            if det_encoding and det_encoding.lower().replace('_', '-').strip() in (
                    'gb2312', 'chinese', 'csiso58gb231280', 'euc-cn', 'euccn',
                    'eucgb2312-cn', 'gb2312-1980', 'gb2312-80', 'iso-ir-58'):
                # Microsoft Word exports to HTML with encoding incorrectly set to
                # gb2312 instead of gbk. gbk is a superset of gb2312, anyway.
                det_encoding = 'gbk'
            ienc = det_encoding
            log.debug('Detected input encoding as %s with a confidence of %s%%' % (ienc, confidence * 100))
        if not ienc:
            ienc = 'utf-8'
            log.debug('No input encoding specified and could not auto detect using %s' % ienc)
        # Remove BOM from start of txt as its presence can confuse markdown
        import codecs
        for bom in (codecs.BOM_UTF16_LE, codecs.BOM_UTF16_BE, codecs.BOM_UTF8, codecs.BOM_UTF32_LE, codecs.BOM_UTF32_BE):
            if txt.startswith(bom):
                txt = txt[len(bom):]
                break
        txt = txt.decode(ienc, 'replace')

        # Replace entities
        txt = _ent_pat.sub(xml_entity_to_unicode, txt)

        # Normalize line endings
        txt = normalize_line_endings(txt)

        # Determine the paragraph type of the document.
        if options.paragraph_type == 'auto':
            options.paragraph_type = detect_paragraph_type(txt)
            if options.paragraph_type == 'unknown':
                log.debug('Could not reliably determine paragraph type using block')
                options.paragraph_type = 'block'
            else:
                log.debug('Auto detected paragraph type as %s' % options.paragraph_type)

        # Detect formatting
        if options.formatting_type == 'auto':
            options.formatting_type = detect_formatting_type(txt)
            log.debug('Auto detected formatting as %s' % options.formatting_type)

        if options.formatting_type == 'heuristic':
            setattr(options, 'enable_heuristics', True)
            setattr(options, 'unwrap_lines', False)
            setattr(options, 'smarten_punctuation', True)

        # Reformat paragraphs to block formatting based on the detected type.
        # We don't check for block because the processor assumes block.
        # single and print at transformed to block for processing.
        if options.paragraph_type == 'single':
            txt = separate_paragraphs_single_line(txt)
        elif options.paragraph_type == 'print':
            txt = separate_hard_scene_breaks(txt)
            txt = separate_paragraphs_print_formatted(txt)
            txt = block_to_single_line(txt)
        elif options.paragraph_type == 'unformatted':
            from ebook_converter.ebooks.conversion.utils import HeuristicProcessor
            # unwrap lines based on punctuation
            docanalysis = DocAnalysis('txt', txt)
            length = docanalysis.line_length(.5)
            preprocessor = HeuristicProcessor(options, log=getattr(self, 'log', None))
            txt = preprocessor.punctuation_unwrap(length, txt, 'txt')
            txt = separate_paragraphs_single_line(txt)
        elif options.paragraph_type == 'block':
            txt = separate_hard_scene_breaks(txt)
            txt = block_to_single_line(txt)

        if getattr(options, 'enable_heuristics', False) and getattr(options, 'dehyphenate', False):
            docanalysis = DocAnalysis('txt', txt)
            if not length:
                length = docanalysis.line_length(.5)
            dehyphenator = Dehyphenator(options.verbose, log=self.log)
            txt = dehyphenator(txt,'txt', length)

        # User requested transformation on the text.
        if options.txt_in_remove_indents:
            txt = remove_indents(txt)

        # Preserve spaces will replace multiple spaces to a space
        # followed by the &nbsp; entity.
        if options.preserve_spaces:
            txt = preserve_spaces(txt)

        # Process the text using the appropriate text processor.
        self.shifted_files = []
        try:
            html = ''
            input_mi = None
            if options.formatting_type == 'markdown':
                log.debug('Running text through markdown conversion...')
                try:
                    input_mi, html = convert_markdown_with_metadata(txt, extensions=[x.strip() for x in options.markdown_extensions.split(',') if x.strip()])
                except RuntimeError:
                    raise ValueError('This txt file has malformed markup, it cannot be'
                        ' converted by calibre. See https://daringfireball.net/projects/markdown/syntax')
                html = self.fix_resources(html, base_dir)
            elif options.formatting_type == 'textile':
                log.debug('Running text through textile conversion...')
                html = convert_textile(txt)
                html = self.fix_resources(html, base_dir)
            else:
                log.debug('Running text through basic conversion...')
                flow_size = getattr(options, 'flow_size', 0)
                html = convert_basic(txt, epub_split_size_kb=flow_size)

            # Run the HTMLized text through the html processing plugin.
            from ebook_converter.customize.ui import plugin_for_input_format
            html_input = plugin_for_input_format('html')
            for opt in html_input.options:
                setattr(options, opt.option.name, opt.recommended_value)
            options.input_encoding = 'utf-8'
            htmlfile = self.shift_file('index.html', html.encode('utf-8'))
            odi = options.debug_pipeline
            options.debug_pipeline = None
            # Generate oeb from html conversion.
            oeb = html_input.convert(open(htmlfile, 'rb'), options, 'html', log, {})
            options.debug_pipeline = odi
        finally:
            for x in self.shifted_files:
                os.remove(x)

        # Set metadata from file.
        if input_mi is None:
            from ebook_converter.customize.ui import get_file_type_metadata
            input_mi = get_file_type_metadata(stream, file_ext)
        from ebook_converter.ebooks.oeb.transforms.metadata import meta_info_to_oeb_metadata
        meta_info_to_oeb_metadata(input_mi, oeb.metadata, log)
        self.html_postprocess_title = input_mi.title

        return oeb

    def postprocess_book(self, oeb, opts, log):
        for item in oeb.spine:
            if hasattr(item.data, 'xpath'):
                for title in item.data.xpath('//*[local-name()="title"]'):
                    if title.text == 'Unknown':
                        title.text = self.html_postprocess_title