"""prompt-toolkit utilities

Everything in this module is a private API,
not to be used outside IPython.
"""

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

import unicodedata
from wcwidth import wcwidth

from IPython.core.completer import (
    provisionalcompleter, cursor_to_position,
    _deduplicate_completions)
from prompt_toolkit.completion import Completer, Completion
from prompt_toolkit.layout.lexers import Lexer
from prompt_toolkit.layout.lexers import PygmentsLexer

import pygments.lexers as pygments_lexers

_completion_sentinel = object()

def _elide(string, *, min_elide=30):
    """
    If a string is long enough, and has at least 2 dots,
    replace the middle part with ellipses.

    For example:
    """
    if len(string) < min_elide:
        return string

    parts = string.split('.')

    if len(parts) <= 3:
        return string

    return '{}.{}\N{HORIZONTAL ELLIPSIS}{}.{}'.format(parts[0], parts[1][0], parts[-2][-1], parts[-1])




class IPythonPTCompleter(Completer):
    """Adaptor to provide IPython completions to prompt_toolkit"""
    def __init__(self, ipy_completer=None, shell=None, patch_stdout=None):
        if shell is None and ipy_completer is None:
            raise TypeError("Please pass shell=an InteractiveShell instance.")
        self._ipy_completer = ipy_completer
        self.shell = shell
        if patch_stdout is None:
            raise TypeError("Please pass patch_stdout")
        self.patch_stdout = patch_stdout

    @property
    def ipy_completer(self):
        if self._ipy_completer:
            return self._ipy_completer
        else:
            return self.shell.Completer

    def get_completions(self, document, complete_event):
        if not document.current_line.strip():
            return
        # Some bits of our completion system may print stuff (e.g. if a module
        # is imported). This context manager ensures that doesn't interfere with
        # the prompt.

        with self.patch_stdout(), provisionalcompleter():
            body = document.text
            cursor_row = document.cursor_position_row
            cursor_col = document.cursor_position_col
            cursor_position = document.cursor_position
            offset = cursor_to_position(body, cursor_row, cursor_col)
            yield from self._get_completions(body, offset, cursor_position, self.ipy_completer)

    @staticmethod
    def _get_completions(body, offset, cursor_position, ipyc):
        """
        Private equivalent of get_completions() use only for unit_testing.
        """
        debug = getattr(ipyc, 'debug', False)
        completions = _deduplicate_completions(
            body, ipyc.completions(body, offset))
        for c in completions:
            if not c.text:
                # Guard against completion machinery giving us an empty string.
                continue
            text = unicodedata.normalize('NFC', c.text)
            # When the first character of the completion has a zero length,
            # then it's probably a decomposed unicode character. E.g. caused by
            # the "\dot" completion. Try to compose again with the previous
            # character.
            if wcwidth(text[0]) == 0:
                if cursor_position + c.start > 0:
                    char_before = body[c.start - 1]
                    fixed_text = unicodedata.normalize(
                        'NFC', char_before + text)

                    # Yield the modified completion instead, if this worked.
                    if wcwidth(text[0:1]) == 1:
                        yield Completion(fixed_text, start_position=c.start - offset - 1)
                        continue

            # TODO: Use Jedi to determine meta_text
            # (Jedi currently has a bug that results in incorrect information.)
            # meta_text = ''
            # yield Completion(m, start_position=start_pos,
            #                  display_meta=meta_text)
            display_text = c.text

            if c.type == 'function':
                display_text = display_text + '()'

            yield Completion(c.text, start_position=c.start - offset, display=_elide(display_text), display_meta=c.type)

class IPythonPTLexer(Lexer):
    """
    Wrapper around PythonLexer and BashLexer.
    """
    def __init__(self):
        l = pygments_lexers
        self.python_lexer = PygmentsLexer(l.Python3Lexer)
        self.shell_lexer = PygmentsLexer(l.BashLexer)

        self.magic_lexers = {
            'HTML': PygmentsLexer(l.HtmlLexer),
            'html': PygmentsLexer(l.HtmlLexer),
            'javascript': PygmentsLexer(l.JavascriptLexer),
            'js': PygmentsLexer(l.JavascriptLexer),
            'perl': PygmentsLexer(l.PerlLexer),
            'ruby': PygmentsLexer(l.RubyLexer),
            'latex': PygmentsLexer(l.TexLexer),
        }

    def lex_document(self, cli, document):
        text = document.text.lstrip()

        lexer = self.python_lexer

        if text.startswith('!') or text.startswith('%%bash'):
            lexer = self.shell_lexer

        elif text.startswith('%%'):
            for magic, l in self.magic_lexers.items():
                if text.startswith('%%' + magic):
                    lexer = l
                    break

        return lexer.lex_document(cli, document)