from enum import Enum
from math import trunc

import pyqtgraph as pg

from callbacks import CallbackDispatcher, CallbackType
from detektor_plot import DetektorPlot
from detektor_data import DetektorContainer


class DetektorRegionState(Enum):
    UNSET = 1
    SET = 4
    COPIED = 5


class DetektorRegion(pg.LinearRegionItem):
    """Encapsulates a linear region that snaps to discrete X-axis values and shows a context menu."""

    # in which mode the region is
    _state: DetektorRegionState = DetektorRegionState.UNSET
    _plot: DetektorPlot = None

    # the start and end is integer, not a label (time)
    _start_position: int = 0
    _end_position: int = 0

    def __init__(self, plot: DetektorPlot):
        super().__init__()

        # reference to the chart so we can add and remove the widget
        self._plot = plot

        # move the rectangle behind the plot lines
        self.setZValue(-10)

        # color is the same for selecting and hovering
        grid_color = pg.mkBrush((100, 100, 250, 50))
        self.setBrush(grid_color)
        self.setHoverBrush(grid_color)

        self.setAcceptHoverEvents(True)

        # callback for changing the width
        self.sigRegionChanged.connect(self.snap_to_x_labels)

    @property
    def state(self):
        return self._state

    @state.setter
    def state(self, v: DetektorRegionState):
        """ Sets state and calls hooks if it changes from the previous one """
        if v != self._state:
            self._state = v

            CallbackDispatcher().call(CallbackType.REGION_STATE)

    def set(self):
        """ Displays region occupying roughly a third of the actual view range """
        self.state = DetektorRegionState.SET
        x_range, y_range = self._plot.view_box.viewRange()
        x_min, x_max = x_range
        third = (x_max - x_min) / 3
        self.setRegion([x_min + third, x_max - third])
        self.display()

    def unset(self):
        self.state = DetektorRegionState.UNSET
        self.hide()

    def get_safe_region(self):
        start, end = self.getRegion()
        if start < 0:
            start = 0
        if end > DetektorContainer().get().data_count()-1:
            end = DetektorContainer().get().data_count()

        return trunc(start), trunc(end)

    def delete(self):
        """ Deletes data by cutting the region without keeping it """
        start, end = self.get_safe_region()
        DetektorContainer().duplicate()
        DetektorContainer().get().cut(start, end)

        self.state = DetektorRegionState.UNSET
        self.hide()

    def copy(self):
        """ Copies the data """
        start, end = self.get_safe_region()
        DetektorContainer().get().copy(start, end)

        self.state = DetektorRegionState.COPIED

    def cut(self):
        """ Cuts the data and hiding the region """
        start, end = self.get_safe_region()
        DetektorContainer().duplicate()
        DetektorContainer().get().cut(start, end)

        self.state = DetektorRegionState.COPIED
        self.hide()

    def paste_end(self):
        DetektorContainer().duplicate()
        DetektorContainer().get().paste(
            DetektorContainer().get().data_count()
        )

        self.unset()

    def paste_after(self):
        _, end = self.get_safe_region()
        DetektorContainer().duplicate()
        DetektorContainer().get().paste(end)

        self.unset()

    def paste_at(self):
        cursor_x = self._plot.cursorLine.getXPos()
        DetektorContainer().duplicate()
        DetektorContainer().get().paste(cursor_x)

        self.unset()

    def snap_to_x_labels(self):
        """Snaps the region boundaries to the nearest discrete X-axis values."""
        min_x, max_x = self.getRegion()
        self.setRegion([int(round(min_x)), int(round(max_x))])

    def display(self):
        """ Adds the region to the plot """
        self._plot.graphWidget.addItem(self)

    def hide(self):
        """ Removes the region from the plot """
        self._plot.graphWidget.removeItem(self)