#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# This software may be modified and distributed under the terms
# of the MIT license.  See the LICENSE file for details.
#
#
# Simple TK based frontend for "pydoc" to show the help text
# for Python keywords, classes and methods in a simple text window.
#
# Should work with Python 2 and 3.
#

from __future__ import print_function

import pydoc
import sys


PY3 = sys.version_info[0] == 3

if PY3:
    from io import StringIO
    from tkinter.scrolledtext import ScrolledText
    import tkinter as tk
else:
    from ScrolledText import ScrolledText
    from StringIO import StringIO
    import Tkinter as tk


class Application(tk.Frame):

    # ----------------------------------------------------------------------
    def __init__(self, master, title, help_text):
        if PY3:
            super(Application, self).__init__(master)
        else:
            tk.Frame.__init__(self, master)
        self.master = master
        self.pack()

        self.master.title(title)

        # scrollable text widget
        self._text_widget = ScrolledText(self)
        self._text_widget.insert(tk.END, help_text)
        self._text_widget.bind('<Key>', self._exit)
        self._text_widget.bind('<Button-1>', self._hide_popup)
        self._text_widget.bind('<Button-3>', self._show_popup)

        # context menu
        menubar = tk.Menu(self.master)
        self._menu_edit = tk.Menu(menubar, tearoff=0)
        self._menu_edit.add_command(label='Copy', command=self._copy)
        self._menu_edit.add_command(label='Select All', command=self._select_all)
        self._menu_edit.add_separator()
        self._menu_edit.add_command(label='Close', command=self._exit)

        self._text_widget.pack()
        self._text_widget.focus()

    # ----------------------------------------------------------------------
    def _show_popup(self, event):
        self._menu_edit.post(event.x_root, event.y_root)

    # ----------------------------------------------------------------------
    def _hide_popup(self, event):
        self._menu_edit.unpost()

    # ----------------------------------------------------------------------
    def _copy(self):
        self._text_widget.event_generate('<<Copy>>')
        return 'break'

    # ----------------------------------------------------------------------
    def _select_all(self):
        self._text_widget.selection_clear()
        self._text_widget.tag_add(tk.SEL, '1.0', tk.END)
        return 'break'

    # ----------------------------------------------------------------------
    def _exit(self, event=None):
        self.master.destroy()
        return 'break'


class StringIOPager(StringIO):

    # ----------------------------------------------------------------------
    def __call__(self, text):
        excaped_text = pydoc.plain(text)
        self.write(excaped_text)


# ----------------------------------------------------------------------
def _get_help_text(word):
    # patch pydoc to *not* use a pager, see bpo-37755
    help_text_pager = StringIOPager()
    pydoc.pager = help_text_pager

    helper = pydoc.Helper(output=help_text_pager)
    helper.help(word)

    help_text_pager.seek(0)
    return help_text_pager.read()


# ----------------------------------------------------------------------
def main():
    try:
        word = sys.argv[1]
    except IndexError:
        print('usage: pydocw <name>', file=sys.stderr)
        sys.exit(1)

    try:
        help_text = _get_help_text(word)
    except Exception as exc:
        help_text = 'An error occurred:\n{}'.format(exc)

    title = 'PyDoc Instant Helper'
    help_text = '{}\n\n---------------------\nPress any key to quit'.format(help_text)

    root = tk.Tk()
    app = Application(root, title, help_text)
    app.mainloop()


if __name__ == '__main__':
    main()