
import os
import sys
import imp
from glob import glob

__all__ = ['PackageLoader']

class PackageLoader:
    def __init__(self, verbose=False, infunc=False):
        """ Manages loading packages.
        """

        if infunc:
            _level = 2
        else:
            _level = 1
        self.parent_frame = frame = sys._getframe(_level)
        self.parent_name = eval('__name__',frame.f_globals,frame.f_locals)
        parent_path = eval('__path__',frame.f_globals,frame.f_locals)
        if isinstance(parent_path, str):
            parent_path = [parent_path]
        self.parent_path = parent_path
        if not frame.f_locals.has_key('__all__'):
            exec('__all__ = []',frame.f_globals,frame.f_locals)
        self.parent_export_names = eval('__all__',frame.f_globals,frame.f_locals)

        self.info_modules = {}
        self.imported_packages = []
        self.verbose = None

    def _get_info_files(self, package_dir, parent_path, parent_package=None):
        """ Return list of (package name,info.py file) from parent_path subdirectories.
        """
        from glob import glob
        files = glob(os.path.join(parent_path,package_dir,'info.py'))
        for info_file in glob(os.path.join(parent_path,package_dir,'info.pyc')):
            if info_file[:-1] not in files:
                files.append(info_file)
        info_files = []
        for info_file in files:
            package_name = os.path.dirname(info_file[len(parent_path)+1:])\
                           .replace(os.sep,'.')
            if parent_package:
                package_name = parent_package + '.' + package_name
            info_files.append((package_name,info_file))
            info_files.extend(self._get_info_files('*',
                                                   os.path.dirname(info_file),
                                                   package_name))
        return info_files

    def _init_info_modules(self, packages=None):
        """Initialize info_modules = {<package_name>: <package info.py module>}.
        """
        import imp
        info_files = []
        info_modules = self.info_modules

        if packages is None:
            for path in self.parent_path:
                info_files.extend(self._get_info_files('*',path))
        else:
            for package_name in packages:
                package_dir = os.path.join(*package_name.split('.'))
                for path in self.parent_path:
                    names_files = self._get_info_files(package_dir, path)
                    if names_files:
                        info_files.extend(names_files)
                        break
                else:
                    try:
                        exec 'import %s.info as info' % (package_name)
                        info_modules[package_name] = info
                    except ImportError, msg:
                        self.warn('No scipy-style subpackage %r found in %s. '\
                                  'Ignoring: %s'\
                                  % (package_name,':'.join(self.parent_path), msg))

        for package_name,info_file in info_files:
            if info_modules.has_key(package_name):
                continue
            fullname = self.parent_name +'.'+ package_name
            if info_file[-1]=='c':
                filedescriptor = ('.pyc','rb',2)
            else:
                filedescriptor = ('.py','U',1)

            try:
                info_module = imp.load_module(fullname+'.info',
                                              open(info_file,filedescriptor[1]),
                                              info_file,
                                              filedescriptor)
            except Exception,msg:
                self.error(msg)
                info_module = None

            if info_module is None or getattr(info_module,'ignore',False):
                info_modules.pop(package_name,None)
            else:
                self._init_info_modules(getattr(info_module,'depends',[]))
                info_modules[package_name] = info_module

        return

    def _get_sorted_names(self):
        """ Return package names sorted in the order as they should be
        imported due to dependence relations between packages.
        """

        depend_dict = {}
        for name,info_module in self.info_modules.items():
            depend_dict[name] = getattr(info_module,'depends',[])
        package_names = []

        for name in depend_dict.keys():
            if not depend_dict[name]:
                package_names.append(name)
                del depend_dict[name]

        while depend_dict:
            for name, lst in depend_dict.items():
                new_lst = [n for n in lst if depend_dict.has_key(n)]
                if not new_lst:
                    package_names.append(name)
                    del depend_dict[name]
                else:
                    depend_dict[name] = new_lst

        return package_names

    def __call__(self,*packages, **options):
        """Load one or more packages into parent package top-level namespace.

    Usage:

       This function is intended to shorten the need to import many
       subpackages, say of scipy, constantly with statements such as

         import scipy.linalg, scipy.fftpack, scipy.etc...

       Instead, you can say:

         import scipy
         scipy.pkgload('linalg','fftpack',...)

       or

         scipy.pkgload()

       to load all of them in one call.

       If a name which doesn't exist in scipy's namespace is
       given, a warning is shown.

     Inputs:

       - the names (one or more strings) of all the numpy modules one
         wishes to load into the top-level namespace.

     Optional keyword inputs:

       - verbose - integer specifying verbosity level [default: -1].
                   verbose=-1 will suspend also warnings.
       - force   - when True, force reloading loaded packages
                   [default: False].
       - postpone - when True, don't load packages [default: False]

     If no input arguments are given, then all of scipy's subpackages
     are imported.

     """
        frame = self.parent_frame
        self.info_modules = {}
        if options.get('force',False):
            self.imported_packages = []
        self.verbose = verbose = options.get('verbose',-1)
        postpone = options.get('postpone',None)
        self._init_info_modules(packages or None)

        self.log('Imports to %r namespace\n----------------------------'\
                 % self.parent_name)

        for package_name in self._get_sorted_names():
            if package_name in self.imported_packages:
                continue
            info_module = self.info_modules[package_name]
            global_symbols = getattr(info_module,'global_symbols',[])
            postpone_import = getattr(info_module,'postpone_import',False)
            if (postpone and not global_symbols) \
                   or (postpone_import and postpone is not None):
                self.log('__all__.append(%r)' % (package_name))
                if '.' not in package_name:
                    self.parent_export_names.append(package_name)
                continue

            old_object = frame.f_locals.get(package_name,None)

            cmdstr = 'import '+package_name
            if self._execcmd(cmdstr):
                continue
            self.imported_packages.append(package_name)

            if verbose!=-1:
                new_object = frame.f_locals.get(package_name)
                if old_object is not None and old_object is not new_object:
                    self.warn('Overwriting %s=%s (was %s)' \
                              % (package_name,self._obj2repr(new_object),
                                 self._obj2repr(old_object)))

            if '.' not in package_name:
                self.parent_export_names.append(package_name)

            for symbol in global_symbols:
                if symbol=='*':
                    symbols = eval('getattr(%s,"__all__",None)'\
                                   % (package_name),
                                   frame.f_globals,frame.f_locals)
                    if symbols is None:
                        symbols = eval('dir(%s)' % (package_name),
                                       frame.f_globals,frame.f_locals)
                        symbols = filter(lambda s:not s.startswith('_'),symbols)
                else:
                    symbols = [symbol]

                if verbose!=-1:
                    old_objects = {}
                    for s in symbols:
                        if frame.f_locals.has_key(s):
                            old_objects[s] = frame.f_locals[s]

                cmdstr = 'from '+package_name+' import '+symbol
                if self._execcmd(cmdstr):
                    continue

                if verbose!=-1:
                    for s,old_object in old_objects.items():
                        new_object = frame.f_locals[s]
                        if new_object is not old_object:
                            self.warn('Overwriting %s=%s (was %s)' \
                                      % (s,self._obj2repr(new_object),
                                         self._obj2repr(old_object)))

                if symbol=='*':
                    self.parent_export_names.extend(symbols)
                else:
                    self.parent_export_names.append(symbol)

        return

    def _execcmd(self,cmdstr):
        """ Execute command in parent_frame."""
        frame = self.parent_frame
        try:
            exec (cmdstr, frame.f_globals,frame.f_locals)
        except Exception,msg:
            self.error('%s -> failed: %s' % (cmdstr,msg))
            return True
        else:
            self.log('%s -> success' % (cmdstr))
        return

    def _obj2repr(self,obj):
        """ Return repr(obj) with"""
        module = getattr(obj,'__module__',None)
        file = getattr(obj,'__file__',None)
        if module is not None:
            return repr(obj) + ' from ' + module
        if file is not None:
            return repr(obj) + ' from ' + file
        return repr(obj)

    def log(self,mess):
        if self.verbose>1:
            print >> sys.stderr, str(mess)
    def warn(self,mess):
        if self.verbose>=0:
            print >> sys.stderr, str(mess)
    def error(self,mess):
        if self.verbose!=-1:
            print >> sys.stderr, str(mess)

    def _get_doc_title(self, info_module):
        """ Get the title from a package info.py file.
        """
        title = getattr(info_module,'__doc_title__',None)
        if title is not None:
            return title
        title = getattr(info_module,'__doc__',None)
        if title is not None:
            title = title.lstrip().split('\n',1)[0]
            return title
        return '* Not Available *'

    def _format_titles(self,titles,colsep='---'):
        display_window_width = 70 # How to determine the correct value in runtime??
        lengths = [len(name)-name.find('.')-1 for (name,title) in titles]+[0]
        max_length = max(lengths)
        lines = []
        for (name,title) in titles:
            name = name[name.find('.')+1:]
            w = max_length - len(name)
            words = title.split()
            line = '%s%s %s' % (name,w*' ',colsep)
            tab = len(line) * ' '
            while words:
                word = words.pop(0)
                if len(line)+len(word)>display_window_width:
                    lines.append(line)
                    line = tab
                line += ' ' + word
            else:
                lines.append(line)
        return '\n'.join(lines)

    def get_pkgdocs(self):
        """ Return documentation summary of subpackages.
        """
        import sys
        self.info_modules = {}
        self._init_info_modules(None)

        titles = []
        symbols = []
        for package_name, info_module in self.info_modules.items():
            global_symbols = getattr(info_module,'global_symbols',[])
            fullname = self.parent_name +'.'+ package_name
            note = ''
            if not sys.modules.has_key(fullname):
                note = ' [*]'
            titles.append((fullname,self._get_doc_title(info_module) + note))
            if global_symbols:
                symbols.append((package_name,', '.join(global_symbols)))

        retstr = self._format_titles(titles) +\
               '\n  [*] - using a package requires explicit import (see pkgload)'


        if symbols:
            retstr += """\n\nGlobal symbols from subpackages"""\
                      """\n-------------------------------\n""" +\
                      self._format_titles(symbols,'-->')

        return retstr

class PackageLoaderDebug(PackageLoader):
    def _execcmd(self,cmdstr):
        """ Execute command in parent_frame."""
        frame = self.parent_frame
        print 'Executing',`cmdstr`,'...',
        sys.stdout.flush()
        exec (cmdstr, frame.f_globals,frame.f_locals)
        print 'ok'
        sys.stdout.flush()
        return

if int(os.environ.get('NUMPY_IMPORT_DEBUG','0')):
    PackageLoader = PackageLoaderDebug
