"""
Module to define and register Terminal IPython shortcuts with
:mod:`prompt_toolkit`
"""

# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.

import warnings
import signal
import sys
from typing import Callable


from prompt_toolkit.application.current import get_app
from prompt_toolkit.enums import DEFAULT_BUFFER, SEARCH_BUFFER
from prompt_toolkit.filters import (has_focus, has_selection, Condition,
    vi_insert_mode, emacs_insert_mode, has_completions, vi_mode)
from prompt_toolkit.key_binding.bindings.completion import display_completions_like_readline
from prompt_toolkit.key_binding import KeyBindings

from IPython.utils.decorators import undoc

@undoc
@Condition
def cursor_in_leading_ws():
    before = get_app().current_buffer.document.current_line_before_cursor
    return (not before) or before.isspace()


def create_ipython_shortcuts(shell):
    """Set up the prompt_toolkit keyboard shortcuts for IPython"""

    kb = KeyBindings()
    insert_mode = vi_insert_mode | emacs_insert_mode

    if getattr(shell, 'handle_return', None):
        return_handler = shell.handle_return(shell)
    else:
        return_handler = newline_or_execute_outer(shell)

    kb.add('enter', filter=(has_focus(DEFAULT_BUFFER)
                            & ~has_selection
                            & insert_mode
                        ))(return_handler)

    def reformat_and_execute(event):
        reformat_text_before_cursor(event.current_buffer, event.current_buffer.document, shell)
        event.current_buffer.validate_and_handle()

    kb.add('escape', 'enter', filter=(has_focus(DEFAULT_BUFFER)
                            & ~has_selection
                            & insert_mode
                                      ))(reformat_and_execute)

    kb.add('c-\\')(force_exit)

    kb.add('c-p', filter=(vi_insert_mode & has_focus(DEFAULT_BUFFER))
                )(previous_history_or_previous_completion)

    kb.add('c-n', filter=(vi_insert_mode & has_focus(DEFAULT_BUFFER))
                )(next_history_or_next_completion)

    kb.add('c-g', filter=(has_focus(DEFAULT_BUFFER) & has_completions)
                )(dismiss_completion)

    kb.add('c-c', filter=has_focus(DEFAULT_BUFFER))(reset_buffer)

    kb.add('c-c', filter=has_focus(SEARCH_BUFFER))(reset_search_buffer)

    supports_suspend = Condition(lambda: hasattr(signal, 'SIGTSTP'))
    kb.add('c-z', filter=supports_suspend)(suspend_to_bg)

    # Ctrl+I == Tab
    kb.add('tab', filter=(has_focus(DEFAULT_BUFFER)
                          & ~has_selection
                          & insert_mode
                          & cursor_in_leading_ws
                        ))(indent_buffer)
    kb.add('c-o', filter=(has_focus(DEFAULT_BUFFER) & emacs_insert_mode)
           )(newline_autoindent_outer(shell.input_transformer_manager))

    kb.add('f2', filter=has_focus(DEFAULT_BUFFER))(open_input_in_editor)

    if shell.display_completions == 'readlinelike':
        kb.add('c-i', filter=(has_focus(DEFAULT_BUFFER)
                              & ~has_selection
                              & insert_mode
                              & ~cursor_in_leading_ws
                        ))(display_completions_like_readline)

    if sys.platform == 'win32':
        kb.add('c-v', filter=(has_focus(DEFAULT_BUFFER) & ~vi_mode))(win_paste)

    return kb


def reformat_text_before_cursor(buffer, document, shell):
    text = buffer.delete_before_cursor(len(document.text[:document.cursor_position]))
    try:
        formatted_text = shell.reformat_handler(text)
        buffer.insert_text(formatted_text)
    except Exception as e:
        buffer.insert_text(text)


def newline_or_execute_outer(shell):

    def newline_or_execute(event):
        """When the user presses return, insert a newline or execute the code."""
        b = event.current_buffer
        d = b.document

        if b.complete_state:
            cc = b.complete_state.current_completion
            if cc:
                b.apply_completion(cc)
            else:
                b.cancel_completion()
            return

        # If there's only one line, treat it as if the cursor is at the end.
        # See https://github.com/ipython/ipython/issues/10425
        if d.line_count == 1:
            check_text = d.text
        else:
            check_text = d.text[:d.cursor_position]
        status, indent = shell.check_complete(check_text)
       
        # if all we have after the cursor is whitespace: reformat current text
        # before cursor
        after_cursor = d.text[d.cursor_position:]
        reformatted = False
        if not after_cursor.strip():
            reformat_text_before_cursor(b, d, shell)
            reformatted = True
        if not (d.on_last_line or
                d.cursor_position_row >= d.line_count - d.empty_line_count_at_the_end()
                ):
            if shell.autoindent:
                b.insert_text('\n' + indent)
            else:
                b.insert_text('\n')
            return

        if (status != 'incomplete') and b.accept_handler:
            if not reformatted:
                reformat_text_before_cursor(b, d, shell)
            b.validate_and_handle()
        else:
            if shell.autoindent:
                b.insert_text('\n' + indent)
            else:
                b.insert_text('\n')
    return newline_or_execute


def previous_history_or_previous_completion(event):
    """
    Control-P in vi edit mode on readline is history next, unlike default prompt toolkit.

    If completer is open this still select previous completion.
    """
    event.current_buffer.auto_up()


def next_history_or_next_completion(event):
    """
    Control-N in vi edit mode on readline is history previous, unlike default prompt toolkit.

    If completer is open this still select next completion.
    """
    event.current_buffer.auto_down()


def dismiss_completion(event):
    b = event.current_buffer
    if b.complete_state:
        b.cancel_completion()


def reset_buffer(event):
    b = event.current_buffer
    if b.complete_state:
        b.cancel_completion()
    else:
        b.reset()


def reset_search_buffer(event):
    if event.current_buffer.document.text:
        event.current_buffer.reset()
    else:
        event.app.layout.focus(DEFAULT_BUFFER)

def suspend_to_bg(event):
    event.app.suspend_to_background()

def force_exit(event):
    """
    Force exit (with a non-zero return value)
    """
    sys.exit("Quit")

def indent_buffer(event):
    event.current_buffer.insert_text(' ' * 4)

@undoc
def newline_with_copy_margin(event):
    """
    DEPRECATED since IPython 6.0

    See :any:`newline_autoindent_outer` for a replacement.

    Preserve margin and cursor position when using
    Control-O to insert a newline in EMACS mode
    """
    warnings.warn("`newline_with_copy_margin(event)` is deprecated since IPython 6.0. "
      "see `newline_autoindent_outer(shell)(event)` for a replacement.",
                  DeprecationWarning, stacklevel=2)

    b = event.current_buffer
    cursor_start_pos = b.document.cursor_position_col
    b.newline(copy_margin=True)
    b.cursor_up(count=1)
    cursor_end_pos = b.document.cursor_position_col
    if cursor_start_pos != cursor_end_pos:
        pos_diff = cursor_start_pos - cursor_end_pos
        b.cursor_right(count=pos_diff)

def newline_autoindent_outer(inputsplitter) -> Callable[..., None]:
    """
    Return a function suitable for inserting a indented newline after the cursor.

    Fancier version of deprecated ``newline_with_copy_margin`` which should
    compute the correct indentation of the inserted line. That is to say, indent
    by 4 extra space after a function definition, class definition, context
    manager... And dedent by 4 space after ``pass``, ``return``, ``raise ...``.
    """

    def newline_autoindent(event):
        """insert a newline after the cursor indented appropriately."""
        b = event.current_buffer
        d = b.document

        if b.complete_state:
            b.cancel_completion()
        text = d.text[:d.cursor_position] + '\n'
        _, indent = inputsplitter.check_complete(text)
        b.insert_text('\n' + (' ' * (indent or 0)), move_cursor=False)

    return newline_autoindent


def open_input_in_editor(event):
    event.app.current_buffer.open_in_editor()


if sys.platform == 'win32':
    from IPython.core.error import TryNext
    from IPython.lib.clipboard import (ClipboardEmpty,
                                       win32_clipboard_get,
                                       tkinter_clipboard_get)

    @undoc
    def win_paste(event):
        try:
            text = win32_clipboard_get()
        except TryNext:
            try:
                text = tkinter_clipboard_get()
            except (TryNext, ClipboardEmpty):
                return
        except ClipboardEmpty:
            return
        event.current_buffer.insert_text(text.replace('\t', ' ' * 4))
