"""
Tools for working with code.
"""

import sys
import os
import inspect
import ast
import textwrap
import importlib
from collections import defaultdict, OrderedDict
from six import iteritems, next

import networkx as nx


def _get_long_name(node):
    # If the node is an Attribute or Name node that is composed
    # only of other Attribute or Name nodes, then return the full
    # dotted name for this node. Otherwise, i.e., if this node
    # contains Subscripts or Calls, return None.
    if isinstance(node, ast.Name):
        return node.id
    elif not isinstance(node, ast.Attribute):
        return None
    val = node.value
    parts = [node.attr]
    while True:
        if isinstance(val, ast.Attribute):
            parts.append(val.attr)
            val = val.value
        elif isinstance(val, ast.Name):
            parts.append(val.id)
            break
        else:  # it's more than just a simple dotted name
            return None
    return '.'.join(parts[::-1])


class _SelfCallCollector(ast.NodeVisitor):
    """
    An ast.NodeVisitor that records calls to self.* methods.
    """

    def __init__(self, class_):
        super(_SelfCallCollector, self).__init__()
        self.self_calls = defaultdict(list)
        self.class_ = class_
        self.mro = inspect.getmro(class_)
        self.mro_names = set([c.__name__ for c in self.mro])

    def visit_Call(self, node):  # (func, args, keywords, starargs, kwargs)
        fncname = _get_long_name(node.func)
        class_ = self.class_
        if fncname is not None:
            if fncname.startswith('self.') and len(fncname.split('.')) == 2:
                shortfnc = fncname.split('.')[1]
                if shortfnc not in self.self_calls[class_]:
                    self.self_calls[class_].append(shortfnc)
                for arg in node.args:
                    self.visit(arg)
            # check for Class.func(inst) form for base class method call
            elif (len(fncname.split('.')) == 2 and fncname.split('.')[0] in self.mro_names and
                  node.args and isinstance(node.args[0], ast.Name) and node.args[0].id == 'self'):
                cname, func = fncname.split('.')
                for c in self.mro:
                    if c.__name__ == cname:
                        sub_mro = inspect.getmro(c)
                        for sub_c in sub_mro:
                            if func in sub_c.__dict__:
                                c = sub_c
                                break
                        if func not in self.self_calls[c]:
                            self.self_calls[c].append(func)
                        for arg in node.args:
                            self.visit(arg)
                        break
                else:
                    self.generic_visit(node)
            else:
                self.generic_visit(node)
        # check for super(Class, self) call
        elif isinstance(node.func, ast.Attribute) and isinstance(node.func.value, ast.Call):
            callnode = node.func.value
            n = _get_long_name(callnode.func)
            # if this is a 'super' call, get the base of the specified class
            if n == 'super':  # this only works for a single call level
                sup_1 = _get_long_name(callnode.args[1])
                sup_0 = _get_long_name(callnode.args[0])
                if sup_1 == 'self' and sup_0 is not None and len(sup_0.split('.')) == 1:
                    for i, c in enumerate(self.mro[:-1]):
                        if sup_0 == c.__name__:
                            # we need super of the specified class
                            sub_mro = inspect.getmro(c)
                            for sub_c in sub_mro:
                                if sub_c is not c:
                                    c = sub_c
                                    break
                            fn = node.func.attr
                            if fn not in self.self_calls[c]:
                                self.self_calls[c].append(fn)
                            for arg in node.args:
                                self.visit(arg)
                            break
                    else:
                        self.generic_visit(node)
            else:
                self.generic_visit(node)
        else:
            self.generic_visit(node)


def _find_owning_class(mro, func_name):
    """
    Return the full funcname and class where the function is first found in the class MRO.
    """
    # TODO: this won't work for classes with __slots__

    for c in mro:
        if func_name in c.__dict__:
            return '.'.join((c.__name__, func_name)), c

    return None, None


def _get_nested_calls(starting_class, class_, func_name, parent, graph, seen):
    """
    Parse the AST of the given method and all 'self' methods it calls and record owning classes.
    """
    func = getattr(class_, func_name)
    src = inspect.getsource(func)
    dedented_src = textwrap.dedent(src)

    node = ast.parse(dedented_src, mode='exec')
    visitor = _SelfCallCollector(starting_class)
    visitor.visit(node)

    seen.add('.'.join((class_.__name__, func_name)))

    # now find the actual owning class for each call
    for klass, funcset in iteritems(visitor.self_calls):
        mro = inspect.getmro(klass)
        for f in funcset:
            full, c = _find_owning_class(mro, f)
            if full is not None:
                graph.add_edge(parent, full)
                if full not in seen:
                    _get_nested_calls(starting_class, c, f, full, graph, seen)


def get_nested_calls(class_, method_name, stream=sys.stdout):
    """
    Display the call tree for the specified class method and all 'self' class methods it calls.

    Parameters
    ----------
    class_ : class
        The starting class.
    method_name : str
        The name of the class method.
    stream : file-like
        The output stream where output will be displayed.

    Returns
    -------
    networkx.DiGraph
        A graph containing edges from methods to their sub-methods.
    """
    # moved this class def in here to keep the numpy doc scraper from barfing due to
    # stuff in nx.DiGraph.
    class OrderedDiGraph(nx.DiGraph):
        """
        A DiGraph using OrderedDicts for internal storage.
        """

        node_dict_factory = OrderedDict
        adjlist_dict_factory = OrderedDict
        edge_attr_dict_factory = OrderedDict

    graph = OrderedDiGraph()
    seen = set()

    full, klass = _find_owning_class(inspect.getmro(class_), method_name)
    if full is None:
        print("Can't find function '%s' in class '%s'." % (method_name, class_.__name__))
    else:
        graph.add_edge(None, full)
        parent = full
        _get_nested_calls(class_, klass, method_name, parent, graph, seen)

    if graph and stream is not None:
        seen = set([None])
        stack = [(0, iter(graph[None]))]
        while stack:
            depth, children = stack[-1]
            try:
                n = next(children)
                stream.write("%s%s\n" % ('  ' * depth, n))
                if n not in seen:
                    stack.append((depth + 1, iter(graph[n])))
                    seen.add(n)
            except StopIteration:
                stack.pop()

    return graph


def _calltree_setup_parser(parser):
    """
    Set up the command line options for the 'openmdao call_tree' command line tool.
    """
    parser.add_argument('method_path', nargs=1, help='Full module path to desired class method.')
    parser.add_argument('-o', '--outfile', action='store', dest='outfile',
                        default='stdout', help='Output file.  Defaults to stdout.')


def _calltree_exec(options):
    """
    Process command line args and call get_nested_calls on the specified class method.
    """
    parts = options.method_path[0].split('.')
    if len(parts) < 3:
        raise RuntimeError("You must supply the full module path to the function, "
                           "for example:  openmdao.api.Group._setup.")

    class_name = parts[-2]
    func_name = parts[-1]
    modpath = '.'.join(parts[:-2])

    sys.path.append(os.getcwd())

    mod = importlib.import_module(modpath)
    klass = getattr(mod, class_name)

    stream_map = {'stdout': sys.stdout, 'stderr': sys.stderr}
    stream = stream_map.get(options.outfile)
    if stream is None:
        stream = open(options.outfile, 'w')

    get_nested_calls(klass, func_name, stream)


if __name__ == '__main__':
    import openmdao.api as om

    get_nested_calls(om.LinearBlockGS, 'solve')
