"""Completer implementation to use with prompt_toolkit."""
import os

from prompt_toolkit.application.current import get_app
from prompt_toolkit.auto_suggest import AutoSuggestFromHistory
from prompt_toolkit.completion import Completer, Completion

from xonsh.built_ins import XSH
from xonsh.completers.tools import RichCompletion


class PromptToolkitCompleter(Completer):
    """Simple prompt_toolkit Completer object.

    It just redirects requests to normal Xonsh completer.
    """

    def __init__(self, completer, ctx, shell):
        """Takes instance of xonsh.completer.Completer, the xonsh execution
        context, and the shell instance itself.
        """
        self.completer = completer
        self.ctx = ctx
        self.shell = shell
        self.hist_suggester = AutoSuggestFromHistory()

    def get_completions(self, document, complete_event):
        """Returns a generator for list of completions."""
        env = XSH.env
        should_complete = complete_event.completion_requested or env.get(
            "UPDATE_COMPLETIONS_ON_KEYPRESS"
        )
        #  Only generate completions when the user hits tab.
        if not should_complete or self.completer is None:
            return
        # generate actual completions
        line = document.current_line

        endidx = document.cursor_position_col
        line_ex = XSH.aliases.expand_alias(line, endidx)

        begidx = line[:endidx].rfind(" ") + 1 if line[:endidx].rfind(" ") >= 0 else 0
        prefix = line[begidx:endidx]
        expand_offset = len(line_ex) - len(line)

        multiline_text = document.text
        cursor_index = document.cursor_position
        if line != line_ex:
            line_start = cursor_index - len(document.current_line_before_cursor)
            multiline_text = (
                multiline_text[:line_start]
                + line_ex
                + multiline_text[line_start + len(line) :]
            )
            cursor_index += expand_offset

        # get normal completions
        completions, plen = self.completer.complete(
            prefix,
            line_ex,
            begidx + expand_offset,
            endidx + expand_offset,
            self.ctx,
            multiline_text=multiline_text,
            cursor_index=cursor_index,
        )

        # completions from auto suggest
        sug_comp = None
        if env.get("AUTO_SUGGEST") and env.get("AUTO_SUGGEST_IN_COMPLETIONS"):
            sug_comp = self.suggestion_completion(document, line)
            if sug_comp is None:
                pass
            elif len(completions) == 0:
                plen = len(prefix)
                completions = (sug_comp,)
            else:
                completions = set(completions)
                completions.discard(sug_comp)
                completions = (sug_comp,) + tuple(sorted(completions))
        # reserve space, if needed.
        if len(completions) <= 1:
            pass
        elif len(os.path.commonprefix(completions)) <= len(prefix):
            self.reserve_space()
        # Find common prefix (strip quoting)
        c_prefix = os.path.commonprefix([a.strip("'\"") for a in completions])
        # Find last split symbol, do not trim the last part
        while c_prefix:
            if c_prefix[-1] in r"/\.:@,":
                break
            c_prefix = c_prefix[:-1]
        # yield completions
        if sug_comp is None:
            pre = min(document.cursor_position_col - begidx, len(c_prefix))
        else:
            pre = len(c_prefix)
        for comp in completions:
            # do not display quote
            if isinstance(comp, RichCompletion):
                # ptk doesn't render newlines. This can be removed once it is supported.
                desc = (
                    comp.description.replace(os.linesep, " ")
                    if comp.description
                    else None
                )
                yield Completion(
                    comp,
                    -comp.prefix_len if comp.prefix_len is not None else -plen,
                    display=comp.display or comp[pre:].strip("'\""),
                    display_meta=desc,
                    style=comp.style or "",
                )
            elif isinstance(comp, Completion):
                yield comp
            else:
                disp = comp[pre:].strip("'\"")
                yield Completion(comp, -plen, display=disp)

    def suggestion_completion(self, document, line):
        """Provides a completion based on the current auto-suggestion."""
        app = self.shell.prompter.app
        sug = self.hist_suggester.get_suggestion(app.current_buffer, document)
        if sug is None:
            return None
        comp, _, _ = sug.text.partition(" ")
        _, _, prev = line.rpartition(" ")
        return prev + comp

    def reserve_space(self):
        """Adjust the height for showing autocompletion menu."""
        app = get_app()
        render = app.renderer

        window = None
        try:
            # this raises error sometimes when COMPLETE_WHILE_TYPE is enabled
            window = app.layout.current_window
        except Exception:
            pass

        if window and window.render_info:
            h = window.render_info.content_height
            r = XSH.env.get("COMPLETIONS_MENU_ROWS")
            size = h + r
            last_h = render._last_screen.height if render._last_screen else 0
            last_h = max(render._min_available_height, last_h)
            if last_h < size:
                if render._last_screen:
                    render._last_screen.height = size
