"""
Attempt to generate templates for module reference with Sphinx

To include extension modules, first identify them as valid in the
``_uri2path`` method, then handle them in the ``_parse_module_with_import``
script.

Notes
-----
This parsing is based on import and introspection of modules.
Previously functions and classes were found by parsing the text of .py files.

Extension modules should be discovered and included as well.

This is a modified version of a script originally shipped with the PyMVPA
project, then adapted for use first in NIPY and then in skimage. PyMVPA
is an MIT-licensed project.
"""

# Stdlib imports
import os
import re

from types import BuiltinFunctionType, FunctionType, ModuleType

# suppress print statements (warnings for empty files)
DEBUG = True


class ApiDocWriter:
    ''' Class for automatic detection and parsing of API docs
    to Sphinx-parsable reST format'''

    # only separating first two levels
    rst_section_levels = ['*', '=', '-', '~', '^']

    def __init__(self,
                 package_name,
                 rst_extension='.rst',
                 package_skip_patterns=None,
                 module_skip_patterns=None,
                 ):
        r''' Initialize package for parsing

        Parameters
        ----------
        package_name : string
            Name of the top-level package.  *package_name* must be the
            name of an importable package
        rst_extension : string, optional
            Extension for reST files, default '.rst'
        package_skip_patterns : None or sequence of {strings, regexps}
            Sequence of strings giving URIs of packages to be excluded
            Operates on the package path, starting at (including) the
            first dot in the package path, after *package_name* - so,
            if *package_name* is ``sphinx``, then ``sphinx.util`` will
            result in ``.util`` being passed for earching by these
            regexps.  If is None, gives default. Default is:
            ['\.tests$']
        module_skip_patterns : None or sequence
            Sequence of strings giving URIs of modules to be excluded
            Operates on the module name including preceding URI path,
            back to the first dot after *package_name*.  For example
            ``sphinx.util.console`` results in the string to search of
            ``.util.console``
            If is None, gives default. Default is:
            ['\.setup$', '\._']
        '''
        if package_skip_patterns is None:
            package_skip_patterns = ['\\.tests$']
        if module_skip_patterns is None:
            module_skip_patterns = ['\\.setup$', '\\._']
        self.package_name = package_name
        self.rst_extension = rst_extension
        self.package_skip_patterns = package_skip_patterns
        self.module_skip_patterns = module_skip_patterns

    def get_package_name(self):
        return self._package_name

    def set_package_name(self, package_name):
        ''' Set package_name

        >>> docwriter = ApiDocWriter('sphinx')
        >>> import sphinx
        >>> docwriter.root_path == sphinx.__path__[0]
        True
        >>> docwriter.package_name = 'docutils'
        >>> import docutils
        >>> docwriter.root_path == docutils.__path__[0]
        True
        '''
        # It's also possible to imagine caching the module parsing here
        self._package_name = package_name
        root_module = self._import(package_name)
        self.root_path = root_module.__path__[-1]
        self.written_modules = None

    package_name = property(get_package_name, set_package_name, None,
                            'get/set package_name')

    def _import(self, name):
        ''' Import namespace package '''
        mod = __import__(name)
        components = name.split('.')
        for comp in components[1:]:
            mod = getattr(mod, comp)
        return mod

    def _get_object_name(self, line):
        ''' Get second token in line
        >>> docwriter = ApiDocWriter('sphinx')
        >>> docwriter._get_object_name("  def func():  ")
        'func'
        >>> docwriter._get_object_name("  class Klass(object):  ")
        'Klass'
        >>> docwriter._get_object_name("  class Klass:  ")
        'Klass'
        '''
        name = line.split()[1].split('(')[0].strip()
        # in case we have classes which are not derived from object
        # ie. old style classes
        return name.rstrip(':')

    def _uri2path(self, uri):
        ''' Convert uri to absolute filepath

        Parameters
        ----------
        uri : string
            URI of python module to return path for

        Returns
        -------
        path : None or string
            Returns None if there is no valid path for this URI
            Otherwise returns absolute file system path for URI

        Examples
        --------
        >>> docwriter = ApiDocWriter('sphinx')
        >>> import sphinx
        >>> modpath = sphinx.__path__[0]
        >>> res = docwriter._uri2path('sphinx.builder')
        >>> res == os.path.join(modpath, 'builder.py')
        True
        >>> res = docwriter._uri2path('sphinx')
        >>> res == os.path.join(modpath, '__init__.py')
        True
        >>> docwriter._uri2path('sphinx.does_not_exist')

        '''
        if uri == self.package_name:
            return os.path.join(self.root_path, '__init__.py')
        path = uri.replace(self.package_name + '.', '')
        path = path.replace('.', os.path.sep)
        path = os.path.join(self.root_path, path)
        # XXX maybe check for extensions as well?
        if os.path.exists(path + '.py'): # file
            path += '.py'
        elif os.path.exists(os.path.join(path, '__init__.py')):
            path = os.path.join(path, '__init__.py')
        else:
            return None
        return path

    def _path2uri(self, dirpath):
        ''' Convert directory path to uri '''
        package_dir = self.package_name.replace('.', os.path.sep)
        relpath = dirpath.replace(self.root_path, package_dir)
        if relpath.startswith(os.path.sep):
            relpath = relpath[1:]
        return relpath.replace(os.path.sep, '.')

    def _parse_module(self, uri):
        ''' Parse module defined in *uri* '''
        filename = self._uri2path(uri)
        if filename is None:
            print(filename, 'erk')
            # nothing that we could handle here.
            return ([],[])
        with open(filename) as f:
            functions, classes = self._parse_lines(f)

        return functions, classes

    def _parse_module_with_import(self, uri):
        """Look for functions and classes in an importable module.

        Parameters
        ----------
        uri : str
            The name of the module to be parsed. This module needs to be
            importable.

        Returns
        -------
        functions : list of str
            A list of (public) function names in the module.
        classes : list of str
            A list of (public) class names in the module.
        submodules : list of str
            A list of (public) submodule names in the module.
        """
        mod = __import__(uri, fromlist=[uri.split('.')[-1]])
        # find all public objects in the module.
        obj_strs = getattr(mod, '__all__',
                           [obj for obj in dir(mod) if not obj.startswith('_')])
        functions = []
        classes = []
        submodules = []
        for obj_str in obj_strs:
            # find the actual object from its string representation
            try:
                obj = getattr(mod, obj_str)
            except AttributeError:
                continue

            # figure out if obj is a function or class
            if isinstance(obj, (FunctionType, BuiltinFunctionType)):
                functions.append(obj_str)
            elif isinstance(obj, ModuleType) and 'skimage' in mod.__name__:
                submodules.append(obj_str)
            else:
                try:
                    issubclass(obj, object)
                    classes.append(obj_str)
                except TypeError:
                    # not a function or class
                    pass
        return functions, classes, submodules

    def _parse_lines(self, linesource):
        ''' Parse lines of text for functions and classes '''
        functions = []
        classes = []
        for line in linesource:
            if line.startswith('def ') and line.count('('):
                # exclude private stuff
                name = self._get_object_name(line)
                if not name.startswith('_'):
                    functions.append(name)
            elif line.startswith('class '):
                # exclude private stuff
                name = self._get_object_name(line)
                if not name.startswith('_'):
                    classes.append(name)
            else:
                pass
        functions.sort()
        classes.sort()
        return functions, classes

    def generate_api_doc(self, uri):
        '''Make autodoc documentation template string for a module

        Parameters
        ----------
        uri : string
            python location of module - e.g 'sphinx.builder'

        Returns
        -------
        S : string
            Contents of API doc
        '''
        # get the names of all classes and functions
        functions, classes, submodules = self._parse_module_with_import(uri)
        if not (len(functions) or len(classes) or len(submodules)) and DEBUG:
            print('WARNING: Empty -', uri)
            return ''
        functions = sorted(functions)
        classes = sorted(classes)
        submodules = sorted(submodules)

        ad = '.. AUTO-GENERATED FILE -- DO NOT EDIT!\n\n'

        # Set the chapter title to read 'module' for all modules except for the
        # main packages
        title = ':mod:`' + uri + '`'
        ad += title + '\n' + self.rst_section_levels[1] * len(title) + '\n\n'

        ad += '.. automodule:: ' + uri + '\n\n'
        ad += '.. currentmodule:: ' + uri + '\n\n'
        ad += '.. autosummary::\n   :nosignatures:\n\n'
        for f in functions:
            ad += '   ' + uri + '.' + f + '\n'
        ad += '\n'
        for c in classes:
            ad += '   ' + uri + '.' + c + '\n'
        ad += '\n'
        for m in submodules:
            ad += '    ' + uri + '.' + m + '\n'
        ad += '\n'

        for f in functions:
            ad += "------------\n\n"
            # must NOT exclude from index to keep cross-refs working
            full_f = uri + '.' + f
            ad += '\n.. autofunction:: ' + full_f + '\n\n'
            ad += f'    .. minigallery:: {full_f}\n\n'
        for c in classes:
            ad += '\n.. autoclass:: ' + c + '\n'
            # must NOT exclude from index to keep cross-refs working
            ad += '  :members:\n' \
                  '  :inherited-members:\n' \
                  '  :undoc-members:\n' \
                  '  :show-inheritance:\n' \
                  '\n' \
                  '  .. automethod:: __init__\n\n'
            full_c = uri + '.' + c
            ad += f'    .. minigallery:: {full_c}\n\n'
        return ad

    def _survives_exclude(self, matchstr, match_type):
        ''' Returns True if *matchstr* does not match patterns

        ``self.package_name`` removed from front of string if present

        Examples
        --------
        >>> dw = ApiDocWriter('sphinx')
        >>> dw._survives_exclude('sphinx.okpkg', 'package')
        True
        >>> dw.package_skip_patterns.append('^\\.badpkg$')
        >>> dw._survives_exclude('sphinx.badpkg', 'package')
        False
        >>> dw._survives_exclude('sphinx.badpkg', 'module')
        True
        >>> dw._survives_exclude('sphinx.badmod', 'module')
        True
        >>> dw.module_skip_patterns.append('^\\.badmod$')
        >>> dw._survives_exclude('sphinx.badmod', 'module')
        False
        '''
        if match_type == 'module':
            patterns = self.module_skip_patterns
        elif match_type == 'package':
            patterns = self.package_skip_patterns
        else:
            raise ValueError(f'Cannot interpret match type "{match_type}"')
        # Match to URI without package name
        L = len(self.package_name)
        if matchstr[:L] == self.package_name:
            matchstr = matchstr[L:]
        for pat in patterns:
            try:
                pat.search
            except AttributeError:
                pat = re.compile(pat)
            if pat.search(matchstr):
                return False
        return True

    def discover_modules(self):
        r''' Return module sequence discovered from ``self.package_name``


        Parameters
        ----------
        None

        Returns
        -------
        mods : sequence
            Sequence of module names within ``self.package_name``

        Examples
        --------
        >>> dw = ApiDocWriter('sphinx')
        >>> mods = dw.discover_modules()
        >>> 'sphinx.util' in mods
        True
        >>> dw.package_skip_patterns.append('\.util$')
        >>> 'sphinx.util' in dw.discover_modules()
        False
        >>>
        '''
        modules = [self.package_name]
        # raw directory parsing
        for dirpath, dirnames, filenames in os.walk(self.root_path):
            # Check directory names for packages
            root_uri = self._path2uri(os.path.join(self.root_path,
                                                   dirpath))
            for dirname in dirnames[:]: # copy list - we modify inplace
                package_uri = '.'.join((root_uri, dirname))
                if (self._uri2path(package_uri) and
                    self._survives_exclude(package_uri, 'package')):
                    modules.append(package_uri)
                else:
                    dirnames.remove(dirname)
        return sorted(modules)

    def write_modules_api(self, modules, outdir):
        # write the list
        written_modules = []
        public_modules = [m for m in modules
                          if not m.split('.')[-1].startswith('_')]
        for m in public_modules:
            api_str = self.generate_api_doc(m)
            if not api_str:
                continue
            # write out to file
            outfile = os.path.join(outdir,
                                   m + self.rst_extension)
            with open(outfile, 'w') as fileobj:
                fileobj.write(api_str)
            written_modules.append(m)
        self.written_modules = written_modules

    def write_api_docs(self, outdir):
        """Generate API reST files.

        Parameters
        ----------
        outdir : string
            Directory name in which to store files
            We create automatic filenames for each module

        Returns
        -------
        None

        Notes
        -----
        Sets self.written_modules to list of written modules
        """
        if not os.path.exists(outdir):
            os.mkdir(outdir)
        # compose list of modules
        modules = self.discover_modules()
        self.write_modules_api(modules, outdir)

    def write_index(self, outdir, froot='gen', relative_to=None):
        """Make a reST API index file from written files

        Parameters
        ----------
        outdir : string
            Directory to which to write generated index file
        froot : string, optional
            root (filename without extension) of filename to write to
            Defaults to 'gen'.  We add ``self.rst_extension``.
        relative_to : string
            path to which written filenames are relative.  This
            component of the written file path will be removed from
            outdir, in the generated index.  Default is None, meaning,
            leave path as it is.
        """
        if self.written_modules is None:
            raise ValueError('No modules written')
        # Get full filename path
        path = os.path.join(outdir, froot+self.rst_extension)
        # Path written into index is relative to rootpath
        if relative_to is not None:
            relpath = (outdir + os.path.sep).replace(relative_to + os.path.sep, '')
        else:
            relpath = outdir
        print("outdir: ", relpath)
        with open(path, 'w') as idx:
            w = idx.write
            w('.. AUTO-GENERATED FILE -- DO NOT EDIT!\n\n')

            # We look at the module name.
            # If it is `skimage`, display,
            # if `skimage.submodule`, only show `submodule`,
            # if it is `skimage.submodule.subsubmodule`, ignore.

            title = "API reference"
            w(title + "\n")
            w("=" * len(title) + "\n\n")

            w('.. toctree::\n')
            w('   :maxdepth: 1\n\n')
            for f in self.written_modules:
                w(f'   {os.path.join(relpath, f)}\n\n')

            w('----------------------\n\n')
            w('.. toctree::\n')
            w('   :maxdepth: 1\n\n')
            w('   ../license\n')
