"""Django's sphinx extension."""
import json
import os
import re

from docutils import nodes
from docutils.parsers.rst import directives
from sphinx import addnodes
from sphinx.builders.html import StandaloneHTMLBuilder
from sphinx.domains.std import Cmdoption
from sphinx.util.compat import Directive
from sphinx.util.console import bold
from sphinx.util.nodes import set_source_info
from sphinx.writers.html import SmartyPantsHTMLTranslator

# RE for option descriptions without a '--' prefix
simple_option_desc_re = re.compile(
    r'([-_a-zA-Z0-9]+)(\s*.*?)(?=,\s+(?:/|-|--)|$)')


def setup(app):
    app.add_crossref_type(
        directivename="setting",
        rolename="setting",
        indextemplate="pair: %s; setting",
    )
    app.add_crossref_type(
        directivename="templatetag",
        rolename="ttag",
        indextemplate="pair: %s; template tag"
    )
    app.add_crossref_type(
        directivename="templatefilter",
        rolename="tfilter",
        indextemplate="pair: %s; template filter"
    )
    app.add_crossref_type(
        directivename="fieldlookup",
        rolename="lookup",
        indextemplate="pair: %s; field lookup type",
    )
    app.add_description_unit(
        directivename="django-admin",
        rolename="djadmin",
        indextemplate="pair: %s; django-admin command",
        parse_node=parse_django_admin_node,
    )
    app.add_directive('django-admin-option', Cmdoption)
    app.add_config_value('django_next_version', '0.0', True)
    app.add_builder(DjangoStandaloneHTMLBuilder)

    # register the snippet directive
    app.add_directive('snippet', SnippetWithFilename)
    # register a node for snippet directive so that the xml parser
    # knows how to handle the enter/exit parsing event
    app.add_node(snippet_with_filename,
                 html=(visit_snippet, depart_snippet_literal),
                 latex=(visit_snippet_latex, depart_snippet_latex),
                 man=(visit_snippet_literal, depart_snippet_literal),
                 text=(visit_snippet_literal, depart_snippet_literal),
                 texinfo=(visit_snippet_literal, depart_snippet_literal))
    return {'parallel_read_safe': True}


class snippet_with_filename(nodes.literal_block):
    """
    Subclass the literal_block to override the visit/depart event handlers
    """
    pass


def visit_snippet_literal(self, node):
    """
    default literal block handler
    """
    self.visit_literal_block(node)


def depart_snippet_literal(self, node):
    """
    default literal block handler
    """
    self.depart_literal_block(node)


def visit_snippet(self, node):
    """
    HTML document generator visit handler
    """
    lang = self.highlightlang
    linenos = node.rawsource.count('\n') >= self.highlightlinenothreshold - 1
    fname = node['filename']
    highlight_args = node.get('highlight_args', {})
    if 'language' in node:
        # code-block directives
        lang = node['language']
        highlight_args['force'] = True
    if 'linenos' in node:
        linenos = node['linenos']

    def warner(msg):
        self.builder.warn(msg, (self.builder.current_docname, node.line))

    highlighted = self.highlighter.highlight_block(node.rawsource, lang,
                                                   warn=warner,
                                                   linenos=linenos,
                                                   **highlight_args)
    starttag = self.starttag(node, 'div', suffix='',
                             CLASS='highlight-%s snippet' % lang)
    self.body.append(starttag)
    self.body.append('<div class="snippet-filename">%s</div>\n''' % (fname,))
    self.body.append(highlighted)
    self.body.append('</div>\n')
    raise nodes.SkipNode


def visit_snippet_latex(self, node):
    """
    Latex document generator visit handler
    """
    code = node.rawsource.rstrip('\n')

    lang = self.hlsettingstack[-1][0]
    linenos = code.count('\n') >= self.hlsettingstack[-1][1] - 1
    fname = node['filename']
    highlight_args = node.get('highlight_args', {})
    if 'language' in node:
        # code-block directives
        lang = node['language']
        highlight_args['force'] = True
    if 'linenos' in node:
        linenos = node['linenos']

    def warner(msg):
        self.builder.warn(msg, (self.curfilestack[-1], node.line))

    hlcode = self.highlighter.highlight_block(code, lang, warn=warner,
                                              linenos=linenos,
                                              **highlight_args)

    self.body.append(
        '\n{\\colorbox[rgb]{0.9,0.9,0.9}'
        '{\\makebox[\\textwidth][l]'
        '{\\small\\texttt{%s}}}}\n' % (
            # Some filenames have '_', which is special in latex.
            fname.replace('_', r'\_'),
        )
    )

    if self.table:
        hlcode = hlcode.replace('\\begin{Verbatim}',
                                '\\begin{OriginalVerbatim}')
        self.table.has_problematic = True
        self.table.has_verbatim = True

    hlcode = hlcode.rstrip()[:-14]  # strip \end{Verbatim}
    hlcode = hlcode.rstrip() + '\n'
    self.body.append('\n' + hlcode + '\\end{%sVerbatim}\n' %
                     (self.table and 'Original' or ''))

    # Prevent rawsource from appearing in output a second time.
    raise nodes.SkipNode


def depart_snippet_latex(self, node):
    """
    Latex document generator depart handler.
    """
    pass


class SnippetWithFilename(Directive):
    """
    The 'snippet' directive that allows to add the filename (optional)
    of a code snippet in the document. This is modeled after CodeBlock.
    """
    has_content = True
    optional_arguments = 1
    option_spec = {'filename': directives.unchanged_required}

    def run(self):
        code = '\n'.join(self.content)

        literal = snippet_with_filename(code, code)
        if self.arguments:
            literal['language'] = self.arguments[0]
        literal['filename'] = self.options['filename']
        set_source_info(self, literal)
        return [literal]


class VersionDirective(Directive):
    has_content = True
    required_arguments = 1
    optional_arguments = 1
    final_argument_whitespace = True
    option_spec = {}

    def run(self):
        if len(self.arguments) > 1:
            msg = """Only one argument accepted for directive '{directive_name}::'.
            Comments should be provided as content,
            not as an extra argument.""".format(directive_name=self.name)
            raise self.error(msg)

        env = self.state.document.settings.env
        ret = []
        node = addnodes.versionmodified()
        ret.append(node)

        if self.arguments[0] == env.config.django_next_version:
            node['version'] = "Development version"
        else:
            node['version'] = self.arguments[0]

        node['type'] = self.name
        if self.content:
            self.state.nested_parse(self.content, self.content_offset, node)
        env.note_versionchange(node['type'], node['version'], node, self.lineno)
        return ret


class DjangoHTMLTranslator(SmartyPantsHTMLTranslator):
    """
    Django-specific reST to HTML tweaks.
    """

    # Don't use border=1, which docutils does by default.
    def visit_table(self, node):
        self.context.append(self.compact_p)
        self.compact_p = True
        self._table_row_index = 0  # Needed by Sphinx
        self.body.append(self.starttag(node, 'table', CLASS='docutils'))

    def depart_table(self, node):
        self.compact_p = self.context.pop()
        self.body.append('</table>\n')

    def visit_desc_parameterlist(self, node):
        self.body.append('(')  # by default sphinx puts <big> around the "("
        self.first_param = 1
        self.optional_param_level = 0
        self.param_separator = node.child_text_separator
        self.required_params_left = sum([isinstance(c, addnodes.desc_parameter)
                                         for c in node.children])

    def depart_desc_parameterlist(self, node):
        self.body.append(')')

    #
    # Turn the "new in version" stuff (versionadded/versionchanged) into a
    # better callout -- the Sphinx default is just a little span,
    # which is a bit less obvious that I'd like.
    #
    # FIXME: these messages are all hardcoded in English. We need to change
    # that to accommodate other language docs, but I can't work out how to make
    # that work.
    #
    version_text = {
        'versionchanged': 'Changed in Django %s',
        'versionadded': 'New in Django %s',
    }

    def visit_versionmodified(self, node):
        self.body.append(
            self.starttag(node, 'div', CLASS=node['type'])
        )
        version_text = self.version_text.get(node['type'])
        if version_text:
            title = "%s%s" % (
                version_text % node['version'],
                ":" if len(node) else "."
            )
            self.body.append('<span class="title">%s</span> ' % title)

    def depart_versionmodified(self, node):
        self.body.append("</div>\n")

    # Give each section a unique ID -- nice for custom CSS hooks
    def visit_section(self, node):
        old_ids = node.get('ids', [])
        node['ids'] = ['s-' + i for i in old_ids]
        node['ids'].extend(old_ids)
        SmartyPantsHTMLTranslator.visit_section(self, node)
        node['ids'] = old_ids


def parse_django_admin_node(env, sig, signode):
    command = sig.split(' ')[0]
    env.ref_context['std:program'] = command
    title = "django-admin %s" % sig
    signode += addnodes.desc_name(title, title)
    return command


class DjangoStandaloneHTMLBuilder(StandaloneHTMLBuilder):
    """
    Subclass to add some extra things we need.
    """

    name = 'djangohtml'

    def finish(self):
        super(DjangoStandaloneHTMLBuilder, self).finish()
        self.info(bold("writing templatebuiltins.js..."))
        xrefs = self.env.domaindata["std"]["objects"]
        templatebuiltins = {
            "ttags": [n for ((t, n), (l, a)) in xrefs.items()
                      if t == "templatetag" and l == "ref/templates/builtins"],
            "tfilters": [n for ((t, n), (l, a)) in xrefs.items()
                         if t == "templatefilter" and l == "ref/templates/builtins"],
        }
        outfilename = os.path.join(self.outdir, "templatebuiltins.js")
        with open(outfilename, 'w') as fp:
            fp.write('var django_template_builtins = ')
            json.dump(templatebuiltins, fp)
            fp.write(';\n')
