import time
import tkinter as tk
from logging import getLogger
from tkinter import messagebox

from thonny import get_runner, get_workbench
from thonny.codeview import SyntaxText
from thonny.common import InlineCommand
from thonny.editor_helpers import get_text_filename
from thonny.languages import tr

logger = getLogger(__name__)


class OccurrencesHighlighter:
    def __init__(self, text):
        self.text: SyntaxText = text
        self._request_scheduled: bool = False
        get_workbench().bind("highlight_occurrences_response", self._handle_response, True)

    def get_positions_for(self, source, line, column):
        raise NotImplementedError()

    def get_positions(self):
        index = self.text.index("insert")

        # ignore if cursor in open string
        if self.text.tag_prevrange("open_string", index) or self.text.tag_prevrange(
            "open_string3", index
        ):
            return set()

        source = self.text.get("1.0", "end")
        index_parts = index.split(".")
        line, column = int(index_parts[0]), int(index_parts[1])

        return self.get_positions_for(source, line, column)

    def trigger(self):
        self._clear()

        if (
            not get_workbench().get_option("view.name_highlighting")
            or not self.text.is_python_text()
        ):
            return

        def consider_request():
            if time.time() - self.text.get_last_operation_time() < 0.3:
                # wait a bit more, there may be more keypresses or cursor location changes coming
                self.text.after(100, consider_request)
            else:
                try:
                    self._request()
                finally:
                    self._request_scheduled = False

        if not self._request_scheduled:
            self._request_scheduled = True
            self.text.after_idle(consider_request)

    def _clear(self) -> None:
        self.text.tag_remove("matched_name", "1.0", "end")

    def _request(self):
        self._clear()
        row, column = map(int, self.text.index("insert").split("."))
        runner = get_runner()
        if not runner or runner.is_running():
            return

        runner.send_command(
            InlineCommand(
                "highlight_occurrences",
                filename=get_text_filename(self.text),
                source=self.text.get("1.0", "end"),
                row=row,
                column=column,
                text_last_operation_time=self.text.get_last_operation_time(),
            )
        )

    def _handle_response(self, msg) -> None:
        error = getattr(msg, "error", None)
        if error:
            messagebox.showerror(tr("Error"), str(error), master=get_workbench())
            return

        if msg.text_last_operation_time != self.text.get_last_operation_time():
            # response arrived too late
            return

        try:
            if len(msg.references) > 1:
                for ref in msg.references:
                    start_index = f"{ref.row}.{ref.column}"
                    end_index = f"{ref.row}.{ref.column + ref.length}"
                    self.text.tag_add("matched_name", start_index, end_index)
        except Exception as e:
            logger.exception("Problem when updating name highlighting", exc_info=e)


def update_highlighting(event):
    if not get_workbench().ready:
        # don't slow down loading process
        return

    if not get_runner() or not get_runner().get_backend_proxy():
        # too early
        return

    assert isinstance(event.widget, tk.Text)
    text = event.widget
    if not hasattr(text, "name_highlighter"):
        text.name_highlighter = OccurrencesHighlighter(text)

    text.name_highlighter.trigger()


def load_plugin() -> None:
    wb = get_workbench()
    wb.set_default("view.name_highlighting", True)
    wb.bind_class("EditorCodeViewText", "<<CursorMove>>", update_highlighting, True)
    wb.bind_class("EditorCodeViewText", "<<TextChange>>", update_highlighting, True)
    wb.bind("<<UpdateAppearance>>", update_highlighting, True)