from typing import Optional, List

from highlight import Highlight
from highlighted_range import HighlightedRange
from line import Line
from PyQt6.QtCore import *
from PyQt6.QtGui import *
from PyQt6.QtWidgets import *

from settings import Settings


class HighlightSelection(Highlight):
    start_byte = 0
    end_byte = 0

    def set_start(self, start_byte):
        self.start_byte = start_byte

    def set_end_byte(self, end_byte):
        self.end_byte = end_byte

    def compute_highlight(self, line: Line) -> Optional[List[HighlightedRange]]:
        begin = min(self.start_byte, self.end_byte)
        end = max(self.start_byte, self.end_byte)

        if line.intersects(begin, end):
            if line.includes_byte(begin):
                start_byte_in_line = begin - line.byte_offset()
            else:
                start_byte_in_line = 0

            if line.includes_byte(end):
                length_in_bytes = end - line.byte_offset() - start_byte_in_line
            else:
                # renders the highlighting to the end of the line
                # this is how selections usually behave
                length_in_bytes = Settings.max_line_length() - start_byte_in_line

            start_char = line.byte_index_to_char_index(start_byte_in_line)
            end_char = line.byte_index_to_char_index(start_byte_in_line+length_in_bytes)
            length_in_chars = end_char - start_char

            #print("selected: %s" % (line.substr(start_char, length_in_chars)))

            return [HighlightedRange(start_char, length_in_chars, brush=QBrush(QColor(156, 215, 255)), pen=Qt.PenStyle.NoPen)]
        else:
            return None