# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Print an AST tree in a form more readable than ast.dump."""

import gast


class PrettyPrinter(gast.NodeVisitor):
    """Print AST nodes."""

    def __init__(self, color, noanno):
        self.indent_lvl = 0
        self.result = ""
        self.color = color
        self.noanno = noanno

    def _color(self, string, color, attrs=None):
        return string

    def _type(self, node):
        return self._color(node.__class__.__name__, None, ["bold"])

    def _field(self, name):
        return self._color(name, "blue")

    def _value(self, name):
        return self._color(name, "magenta")

    def _warning(self, name):
        return self._color(name, "red")

    def _indent(self):
        return self._color("| " * self.indent_lvl, None, ["dark"])

    def _print(self, s):
        self.result += s
        self.result += "\n"

    def generic_visit(self, node, name=None):
        # In very rare instances, a list can contain something other than a Node.
        # e.g. Global contains a list of strings.
        if isinstance(node, str):
            if name:
                self._print('%s%s="%s"' % (self._indent(), name, node))
            else:
                self._print('%s"%s"' % (self._indent(), node))
            return

        if node._fields:
            cont = ":"
        else:
            cont = "()"

        if name:
            self._print(
                "%s%s=%s%s"
                % (self._indent(), self._field(name), self._type(node), cont)
            )
        else:
            self._print("%s%s%s" % (self._indent(), self._type(node), cont))

        self.indent_lvl += 1
        for f in node._fields:
            if self.noanno and f.startswith("__"):
                continue
            if not hasattr(node, f):
                self._print("%s%s" % (self._indent(), self._warning("%s=<unset>" % f)))
                continue
            v = getattr(node, f)
            if isinstance(v, list):
                if v:
                    self._print("%s%s=[" % (self._indent(), self._field(f)))
                    self.indent_lvl += 1
                    for n in v:
                        if n is not None:
                            self.generic_visit(n)
                        else:
                            self._print("%sNone" % (self._indent()))
                    self.indent_lvl -= 1
                    self._print("%s]" % (self._indent()))
                else:
                    self._print("%s%s=[]" % (self._indent(), self._field(f)))
            elif isinstance(v, tuple):
                if v:
                    self._print("%s%s=(" % (self._indent(), self._field(f)))
                    self.indent_lvl += 1
                    for n in v:
                        if n is not None:
                            self.generic_visit(n)
                        else:
                            self._print("%sNone" % (self._indent()))
                    self.indent_lvl -= 1
                    self._print("%s)" % (self._indent()))
                else:
                    self._print("%s%s=()" % (self._indent(), self._field(f)))
            elif isinstance(v, gast.AST):
                self.generic_visit(v, f)
            elif isinstance(v, bytes):
                self._print(
                    "%s%s=%s"
                    % (self._indent(), self._field(f), self._value('b"%s"' % v))
                )
            elif isinstance(v, str):
                self._print(
                    "%s%s=%s"
                    % (self._indent(), self._field(f), self._value('u"%s"' % v))
                )
            else:
                self._print(
                    "%s%s=%s" % (self._indent(), self._field(f), self._value(v))
                )
        self.indent_lvl -= 1


def fmt(node, color=True, noanno=False):
    printer = PrettyPrinter(color, noanno)
    if isinstance(node, (list, tuple)):
        for n in node:
            printer.visit(n)
    else:
        printer.visit(node)
    return printer.result
