"""
Key bindings for auto suggestion (for fish-style auto suggestion).
"""
from __future__ import unicode_literals

import re

from prompt_toolkit2.application.current import get_app
from prompt_toolkit2.filters import Condition, emacs_mode
from prompt_toolkit2.key_binding.key_bindings import KeyBindings

__all__ = [
    'load_auto_suggest_bindings',
]


def load_auto_suggest_bindings():
    """
    Key bindings for accepting auto suggestion text.

    (This has to come after the Vi bindings, because they also have an
    implementation for the "right arrow", but we really want the suggestion
    binding when a suggestion is available.)
    """
    key_bindings = KeyBindings()
    handle = key_bindings.add

    @Condition
    def suggestion_available():
        app = get_app()
        return (app.current_buffer.suggestion is not None and
                app.current_buffer.suggestion.text and
                app.current_buffer.document.is_cursor_at_the_end)

    @handle('c-f', filter=suggestion_available)
    @handle('c-e', filter=suggestion_available)
    @handle('right', filter=suggestion_available)
    def _(event):
        " Accept suggestion. "
        b = event.current_buffer
        suggestion = b.suggestion

        if suggestion:
            b.insert_text(suggestion.text)

    @handle('escape', 'f', filter=suggestion_available & emacs_mode)
    def _(event):
        " Fill partial suggestion. "
        b = event.current_buffer
        suggestion = b.suggestion

        if suggestion:
            t = re.split(r'(\S+\s+)', suggestion.text)
            b.insert_text(next(x for x in t if x))

    return key_bindings
