import re
import sys

import parsing
import evaluate
import modules
import debug
import imports

__all__ = ['complete', 'get_completion_parts', 'get_definitions',
            'set_debug_function']


class NotFoundError(Exception):
    """ A custom error to avoid catching the wrong errors """
    def __init__(self, scope, path_tuple, message=None):
        super(NotFoundError, self).__init__(message)
        self.scope = scope
        self.path_tuple = path_tuple


class Completion(object):
    def __init__(self, name, needs_dot, like_name_length):
        self.name = name
        self.needs_dot = needs_dot
        self.like_name_length = like_name_length

    @property
    def complete(self):
        dot = '.' if self.needs_dot else ''
        return dot + self.name.names[-1][self.like_name_length:]

    @property
    def description(self):
        return str(self.name.parent)

    @property
    def help(self):
        try:
            return str(self.name.parent.docstr)
        except AttributeError:
            return ''

    def get_type(self):
        return type(self.name.parent)

    def get_vim_type(self):
        """
        This is the only function, which is vim specific, it returns the vim
        type, see help(complete-items)
        """
        typ = self.get_type()
        if typ == parsing.Statement:
            return 'v'  # variable
        elif typ == parsing.Function:
            return 'f'  # function / method
        elif typ in [parsing.Class, evaluate.Instance]:
            return 't'  # typedef -> abused as class
        elif typ == parsing.Import:
            return 'd'  # define -> abused as import
        if typ == parsing.Param:
            return 'm'  # member -> abused as param
        else:
            debug.dbg('other python type: ', typ)

        return ''

    def __str__(self):
        return self.name.names[-1]


class Definition(object):
    def __init__(self, scope):
        """ The definition of a function """
        self.scope = scope

    def get_name(self):
        try:
            return self.scope.name
        except AttributeError:
            return self.scope.type

    def get_module(self):
        par = self.scope
        while True:
            if par.parent is not None:
                par = par.parent
            else:
                break

        path = str(par.path)
        try:
            return path[path.rindex('/') + 1:]
        except ValueError:
            return path

    def get_line(self):
        return self.scope.start_pos[0]

    def get_indent(self):
        return self.scope.indent

    def __str__(self):
        module = self.get_module()
        if module[0] == '/':
            position = '@%s' % (self.get_line())
        else:
            # no path - is a builtin
            position = ''
        return "%s:%s%s" % (module, self.get_name(), position)

    def __repr__(self):
        return "<%s %s>" % (self.__class__.__name__, self)


def get_completion_parts(path):
    """
    Returns the parts for the completion
    :return: tuple - (path, dot, like)
    """
    match = re.match(r'^(.*?)(\.|)(\w?[\w\d]*)$', path, flags=re.S)
    return match.groups()


def complete(source, line, column, source_path):
    """
    An auto completer for python files.

    :param source: The source code of the current file
    :type source: string
    :param line: The line to complete in.
    :type line: int
    :param col: The column to complete in.
    :type col: int
    :param source_path: The path in the os, the current module is in.
    :type source_path: str

    :return: list of Completion objects.
    :rtype: list
    """
    try:
        scopes, path, dot, like = prepare_goto(source, (line, column),
                                                source_path, True)
    except NotFoundError:
        # normally this would be used like this: `NotFoundError as exc`, but
        # this guarantues backwards compatibility with Python2.5.
        exc = sys.exc_info()[1]
        path, dot, like = exc.path_tuple
        scope_generator = evaluate.get_names_for_scope(exc.scope)
        completions = []
        for dummy, name_list in scope_generator:
            completions += name_list
        #for c in completions:
        #    if isinstance(, parsing.Function):
        #        print c.parent
    else:
        completions = []
        debug.dbg('possible scopes', scopes)
        for s in scopes:
            # TODO is this really the right way? just ignore the functions? \
            # do the magic functions first? and then recheck here?
            if not isinstance(s, evaluate.Function):
                completions += s.get_defined_names()

    completions = [c for c in completions
                            if c.names[-1].lower().startswith(like.lower())]

    _clear_caches()

    needs_dot = not dot and path
    return [Completion(c, needs_dot, len(like)) for c in set(completions)]


def prepare_goto(source, position, source_path, is_like_search):
    f = modules.ModuleWithCursor(source_path, source=source, position=position)
    scope = f.parser.user_scope

    if is_like_search:
        path = f.get_path_until_cursor()
        path, dot, like = get_completion_parts(path)
    else:
        path = f.get_path_under_cursor()

    debug.dbg('start: %s in %s' % (path, scope))

    user_stmt = f.parser.user_stmt
    if isinstance(user_stmt, parsing.Import):
        scopes = [imports.ImportPath(user_stmt, is_like_search)]
    else:
        # just parse one statement, take it and evaluate it
        r = parsing.PyFuzzyParser(path, source_path)
        try:
            stmt = r.top.statements[0]
        except IndexError:
            if is_like_search:
                path_tuple = path, dot, like
            else:
                path_tuple = ()
            raise NotFoundError(scope, path_tuple)
        else:
            stmt.start_pos = position
            stmt.parent = scope
            scopes = evaluate.follow_statement(stmt)

    if is_like_search:
        return scopes, path, dot, like
    else:
        return scopes


def get_definitions(source, line, column, source_path):
    """
    Returns the definitions of a the path under the cursor.
    This is not a goto function! This follows complicated paths and returns the
    end, not the first definition.

    :param source: The source code of the current file
    :type source: string
    :param line: The line to complete in.
    :type line: int
    :param col: The column to complete in.
    :type col: int
    :param source_path: The path in the os, the current module is in.
    :type source_path: int

    :return: list of Definition objects, which are basically scopes.
    :rtype: list
    """
    scopes = prepare_goto(source, (line, column), source_path, False)
    _clear_caches()
    return [Definition(s) for s in set(scopes)]


def set_debug_function(func_cb):
    """
    You can define a callback debug function to get all the debug messages.
    :param func_cb: The callback function for debug messages, with n params.
    """
    debug.debug_function = func_cb


def _clear_caches():
    evaluate.clear_caches()