"""Collect information on document sections and Pygame API objects

The following persistent Pygame specific environment structures are built:

pyg_sections: [{'docname': <docname>,
                'fullname': <fullname>,
                'refid': <ref>},
               ...]
    all Pygame api sections in the documents in order processed.
pyg_descinfo_tbl: {<id>: {'fullname': <fullname>,
                          'desctype': <type>,
                          'summary': <summary>,
                          'signatures': <sigs>,
                          'children': <toc>,
                          'refid': <ref>,
                          'docname': <docname>},
                   ...}
    object specific information, including a list of direct children, if any.

<docname>: (str) the simple document name without path or extension.
<fullname>: (str) a fully qualified object name. It is a unique identifier.
<ref>: (str) an id usable as local uri reference.
<id>: (str) unique desc id, the first entry in the ids attribute list.
<type>: (str) an object's type: the desctype attribute.
<summary>: (str) a summary line as identified by a :summaryline: role.
           This corresponds to the first line of a docstring.
<sigs>: (list of str) an object's signatures, in document order.
<toc>: (list of str) refids of an object's children, in document order.

"""

from ext.utils import (Visitor, get_fullname, get_refid, as_refid,
                       geterror, GetError, EMPTYSTR, as_unicode)

from collections import deque


MODULE_ID_PREFIX = as_unicode(r'module-')


def setup(app):
    app.connect('env-purge-doc', prep_document_info)
    app.connect('doctree-read', collect_document_info)


def prep_document_info(app, env, docname):
    try:
        env.pyg_sections = [e for e in env.pyg_sections
                            if e['docname'] != docname]
    except AttributeError:
        pass
    except KeyError:
        pass
    try:
        descinfo_tbl = env.pyg_descinfo_tbl
    except AttributeError:
        pass
    else:
        to_remove = [k for k, v in descinfo_tbl.items()
                     if v['docname'] == docname]
        for k in to_remove:
            del descinfo_tbl[k]


def collect_document_info(app, doctree):
    doctree.walkabout(CollectInfo(app, doctree))

class CollectInfo(Visitor):

    """Records the information for a document"""
    
    desctypes = set(['data', 'function', 'exception', 'class',
                     'attribute', 'method', 'staticmethod', 'classmethod'])

    def __init__(self, app, document_node):
        super(CollectInfo, self).__init__(app, document_node)
        self.docname = self.env.docname
        self.summary_stack = deque()
        self.sig_stack = deque()
        self.desc_stack = deque()
        try:
            self.env.pyg_sections
        except AttributeError:
            self.env.pyg_sections = []
        try:
            self.env.pyg_descinfo_tbl
        except AttributeError:
            self.env.pyg_descinfo_tbl = {}

    def visit_section(self, node):
        if not node['names']:
            raise self.skip_node
        self._push()
        
    def depart_section(self, node):
        """Record section info"""

        summary, sigs, child_descs = self._pop()
        if not node.children:
            return
        if node['ids'][0].startswith(MODULE_ID_PREFIX):
            self._add_section(node)
            self._add_descinfo(node, summary, sigs, child_descs)
        elif child_descs:
            # No section level introduction: use the first toplevel directive
            # instead.
            desc_node = child_descs[0]
            summary = get_descinfo(desc_node, self.env).get('summary', EMPTYSTR)
            self._add_section(desc_node)
            self._add_descinfo_entry(node, get_descinfo(desc_node, self.env))
        
    def visit_desc(self, node):
        """Prepare to collect a summary and toc for this description"""
        
        if node.get('desctype', '') not in self.desctypes:
            raise self.skip_node
        self._push()
        
    def depart_desc(self, node):
        """Record descinfo information and add descinfo to parent's toc"""
        
        self._add_descinfo(node, *self._pop())
        self._add_desc(node)

    def visit_inline(self, node):
        """Collect a summary or signature"""

        if 'summaryline' in node['classes']:
            self._add_summary(node)
        elif 'signature' in node['classes']:
            self._add_sig(node)
        raise self.skip_departure

    def _add_section(self, node): 
        entry = {'docname': self.docname,
                 'fullname': get_fullname(node),
                 'refid': get_refid(node)}
        self.env.pyg_sections.append(entry)

    def _add_descinfo(self, node, summary, sigs, child_descs):
        entry = {'fullname': get_fullname(node),
                 'desctype': node.get('desctype', 'module'),
                 'summary': summary,
                 'signatures': sigs,
                 'children': [get_refid(n) for n in child_descs],
                 'refid': get_refid(node),
                 'docname': self.docname}
        self._add_descinfo_entry(node, entry)

    def _add_descinfo_entry(self, node, entry):
        key = get_refid(node)
        if key.startswith(MODULE_ID_PREFIX):
            key = key[len(MODULE_ID_PREFIX):]
        self.env.pyg_descinfo_tbl[key] = entry

    def _push(self):
        self.summary_stack.append(EMPTYSTR)
        self.sig_stack.append([])
        self.desc_stack.append([])

    def _pop(self):
        return (self.summary_stack.pop(),
                self.sig_stack.pop(),
                self.desc_stack.pop())

    def _add_desc(self, desc_node):
        self.desc_stack[-1].append(desc_node)

    def _add_summary(self, text_element_node):
        self.summary_stack[-1] = text_element_node[0].astext()

    def _add_sig(self, text_element_node):
        self.sig_stack[-1].append(text_element_node[0].astext())

def tour_descinfo(fn, node, env):
    try:
        descinfo = get_descinfo(node, env)
    except GetError:
        return
    fn(descinfo)
    for refid in descinfo['children']:
        tour_descinfo_refid(fn, refid, env)

def tour_descinfo_refid(fn, refid, env):
    descinfo = env.pyg_descinfo_tbl[refid]  # A KeyError would mean a bug.
    fn(descinfo)
    for refid in descinfo['children']:
        tour_descinfo_refid(fn, refid, env)

def get_descinfo(node, env):
    return get_descinfo_refid(get_refid(node), env)

def get_descinfo_refid(refid, env):
    if refid.startswith(MODULE_ID_PREFIX):
        refid = refid[len(MODULE_ID_PREFIX):]
    try:
        return env.pyg_descinfo_tbl[refid]
    except KeyError:
        raise GetError("Not found")
