import math

from .. import functions as fn
from ..icons import invisibleEye
from ..Point import Point
from ..Qt import QtCore, QtGui, QtWidgets
from .BarGraphItem import BarGraphItem
from .GraphicsWidget import GraphicsWidget
from .GraphicsWidgetAnchor import GraphicsWidgetAnchor
from .LabelItem import LabelItem
from .PlotDataItem import PlotDataItem
from .ScatterPlotItem import ScatterPlotItem, drawSymbol

__all__ = ['LegendItem', 'ItemSample']


class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
    """
    Displays a legend used for describing the contents of a plot.

    LegendItems are most commonly created by calling :meth:`PlotItem.addLegend
    <pyqtgraph.PlotItem.addLegend>`.

    Note that this item should *not* be added directly to a PlotItem (via
    :meth:`PlotItem.addItem <pyqtgraph.PlotItem.addItem>`). Instead, make it a
    direct descendant of the PlotItem::

        legend.setParentItem(plotItem)

    """

    def __init__(self, size=None, offset=None, horSpacing=25, verSpacing=0,
                 pen=None, brush=None, labelTextColor=None, frame=True,
                 labelTextSize='9pt', colCount=1, sampleType=None, **kwargs):
        """
        ==============  ===============================================================
        **Arguments:**
        size            Specifies the fixed size (width, height) of the legend. If
                        this argument is omitted, the legend will automatically resize
                        to fit its contents.
        offset          Specifies the offset position relative to the legend's parent.
                        Positive values offset from the left or top; negative values
                        offset from the right or bottom. If offset is None, the
                        legend must be anchored manually by calling anchor() or
                        positioned by calling setPos().
        horSpacing      Specifies the spacing between the line symbol and the label.
        verSpacing      Specifies the spacing between individual entries of the legend
                        vertically. (Can also be negative to have them really close)
        pen             Pen to use when drawing legend border. Any single argument
                        accepted by :func:`mkPen <pyqtgraph.mkPen>` is allowed.
        brush           QBrush to use as legend background filling. Any single argument
                        accepted by :func:`mkBrush <pyqtgraph.mkBrush>` is allowed.
        labelTextColor  Pen to use when drawing legend text. Any single argument
                        accepted by :func:`mkPen <pyqtgraph.mkPen>` is allowed.
        labelTextSize   Size to use when drawing legend text. Accepts CSS style
                        string arguments, e.g. '9pt'.
        colCount        Specifies the integer number of columns that the legend should
                        be divided into. The number of rows will be calculated
                        based on this argument. This is useful for plots with many
                        curves displayed simultaneously. Default: 1 column.
        sampleType      Customizes the item sample class of the `LegendItem`.
        ==============  ===============================================================

        """
        GraphicsWidget.__init__(self)
        GraphicsWidgetAnchor.__init__(self)
        self.setFlag(self.GraphicsItemFlag.ItemIgnoresTransformations)
        self.layout = QtWidgets.QGraphicsGridLayout()
        self.layout.setVerticalSpacing(verSpacing)
        self.layout.setHorizontalSpacing(horSpacing)

        self.setLayout(self.layout)
        self.items = []
        self.size = size
        self.offset = offset
        self.frame = frame
        self.columnCount = colCount
        self.rowCount = 1
        if size is not None:
            self.setGeometry(QtCore.QRectF(0, 0, self.size[0], self.size[1]))

        if sampleType is not None:
            if not issubclass(sampleType, GraphicsWidget):
                raise RuntimeError("Only classes of type `GraphicsWidgets` "
                                   "are allowed as `sampleType`")
            self.sampleType = sampleType
        else:
            self.sampleType = ItemSample

        self.opts = {
            'pen': fn.mkPen(pen),
            'brush': fn.mkBrush(brush),
            'labelTextColor': labelTextColor,
            'labelTextSize': labelTextSize,
            'offset': offset,
        }
        self.opts.update(kwargs)

    def setSampleType(self, sample):
        """Set the new sample item claspes"""
        if sample is self.sampleType:
            return

        # Clear the legend, but before create a list of items
        items = list(self.items)
        self.sampleType = sample
        self.clear()

        # Refill the legend with the item list and new sample item
        for sample, label in items:
            plot_item = sample.item
            plot_name = label.text
            self.addItem(plot_item, plot_name)

        self.updateSize()

    def offset(self):
        """Get the offset position relative to the parent."""
        return self.opts['offset']

    def setOffset(self, offset):
        """Set the offset position relative to the parent."""
        self.opts['offset'] = offset

        offset = Point(self.opts['offset'])
        anchorx = 1 if offset[0] <= 0 else 0
        anchory = 1 if offset[1] <= 0 else 0
        anchor = (anchorx, anchory)
        self.anchor(itemPos=anchor, parentPos=anchor, offset=offset)

    def pen(self):
        """Get the QPen used to draw the border around the legend."""
        return self.opts['pen']

    def setPen(self, *args, **kargs):
        """Set the pen used to draw a border around the legend.

        Accepts the same arguments as :func:`~pyqtgraph.mkPen`.
        """
        pen = fn.mkPen(*args, **kargs)
        self.opts['pen'] = pen

        self.update()

    def brush(self):
        """Get the QBrush used to draw the legend background."""
        return self.opts['brush']

    def setBrush(self, *args, **kargs):
        """Set the brush used to draw the legend background.

        Accepts the same arguments as :func:`~pyqtgraph.mkBrush`.
        """
        brush = fn.mkBrush(*args, **kargs)
        if self.opts['brush'] == brush:
            return
        self.opts['brush'] = brush

        self.update()

    def labelTextColor(self):
        """Get the QColor used for the item labels."""
        return self.opts['labelTextColor']

    def setLabelTextColor(self, *args, **kargs):
        """Set the color of the item labels.

        Accepts the same arguments as :func:`~pyqtgraph.mkColor`.
        """
        self.opts['labelTextColor'] = fn.mkColor(*args, **kargs)
        for sample, label in self.items:
            label.setAttr('color', self.opts['labelTextColor'])

        self.update()

    def labelTextSize(self):
        """Get the `labelTextSize` used for the item labels."""
        return self.opts['labelTextSize']

    def setLabelTextSize(self, size):
        """Set the `size` of the item labels.

        Accepts the CSS style string arguments, e.g. '8pt'.
        """
        self.opts['labelTextSize'] = size
        for _, label in self.items:
            label.setAttr('size', self.opts['labelTextSize'])

        self.update()

    def setParentItem(self, p):
        """Set the parent."""
        ret = GraphicsWidget.setParentItem(self, p)
        if self.opts['offset'] is not None:
            offset = Point(self.opts['offset'])
            anchorx = 1 if offset[0] <= 0 else 0
            anchory = 1 if offset[1] <= 0 else 0
            anchor = (anchorx, anchory)
            self.anchor(itemPos=anchor, parentPos=anchor, offset=offset)
        return ret

    def addItem(self, item, name):
        """
        Add a new entry to the legend.

        ==============  ========================================================
        **Arguments:**
        item            A :class:`~pyqtgraph.PlotDataItem` from which the line
                        and point style of the item will be determined or an
                        instance of ItemSample (or a subclass), allowing the
                        item display to be customized.
        title           The title to display for this item. Simple HTML allowed.
        ==============  ========================================================
        """
        label = LabelItem(name, color=self.opts['labelTextColor'],
                          justify='left', size=self.opts['labelTextSize'])
        if isinstance(item, self.sampleType):
            sample = item
        else:
            sample = self.sampleType(item)
        self.items.append((sample, label))
        self._addItemToLayout(sample, label)
        self.updateSize()

    def _addItemToLayout(self, sample, label):
        col = self.layout.columnCount()
        row = self.layout.rowCount()
        if row:
            row -= 1
        nCol = self.columnCount * 2
        # FIRST ROW FULL
        if col == nCol:
            for col in range(0, nCol, 2):
                # FIND RIGHT COLUMN
                if not self.layout.itemAt(row, col):
                    break
            else:
                if col + 2 == nCol:
                    # MAKE NEW ROW
                    col = 0
                    row += 1
        self.layout.addItem(sample, row, col)
        self.layout.addItem(label, row, col + 1)
        # Keep rowCount in sync with the number of rows if items are added
        self.rowCount = max(self.rowCount, row + 1)

    def setColumnCount(self, columnCount):
        """change the orientation of all items of the legend
        """
        if columnCount != self.columnCount:
            self.columnCount = columnCount

            self.rowCount = math.ceil(len(self.items) / columnCount)
            for i in range(self.layout.count() - 1, -1, -1):
                self.layout.removeAt(i)  # clear layout
            for sample, label in self.items:
                self._addItemToLayout(sample, label)
            self.updateSize()

    def getLabel(self, plotItem):
        """Return the labelItem inside the legend for a given plotItem

        The label-text can be changed via labelItem.setText
        """
        out = [(it, lab) for it, lab in self.items if it.item == plotItem]
        try:
            return out[0][1]
        except IndexError:
            return None

    def removeItem(self, item):
        """Removes one item from the legend.

        ==============  ========================================================
        **Arguments:**
        item            The item to remove or its name.
        ==============  ========================================================
        """
        for sample, label in self.items:
            if sample.item is item or label.text == item:
                self.items.remove((sample, label))  # remove from itemlist
                self.layout.removeItem(sample)  # remove from layout
                sample.close()  # remove from drawing
                self.layout.removeItem(label)
                label.close()
                self.updateSize()  # redraq box
                return  # return after first match

    def clear(self):
        """Remove all items from the legend."""
        for sample, label in self.items:
            self.layout.removeItem(sample)
            sample.close()
            self.layout.removeItem(label)
            label.close()

        self.items = []
        self.updateSize()

    def updateSize(self):
        if self.size is not None:
            return
        height = 0
        width = 0
        for row in range(self.layout.rowCount()):
            row_height = 0
            col_width = 0
            for col in range(self.layout.columnCount()):
                item = self.layout.itemAt(row, col)
                if item:
                    col_width += item.width() + 3
                    row_height = max(row_height, item.height())
            width = max(width, col_width)
            height += row_height
        self.setGeometry(0, 0, width, height)
        return

    def boundingRect(self):
        return QtCore.QRectF(0, 0, self.width(), self.height())

    def paint(self, p, *args):
        if self.frame:
            p.setPen(self.opts['pen'])
            p.setBrush(self.opts['brush'])
            p.drawRect(self.boundingRect())

    def hoverEvent(self, ev):
        ev.acceptDrags(QtCore.Qt.MouseButton.LeftButton)

    def mouseDragEvent(self, ev):
        if ev.button() == QtCore.Qt.MouseButton.LeftButton:
            ev.accept()
            dpos = ev.pos() - ev.lastPos()
            self.autoAnchor(self.pos() + dpos)


class ItemSample(GraphicsWidget):
    """Class responsible for drawing a single item in a LegendItem (sans label)
    """

    def __init__(self, item):
        GraphicsWidget.__init__(self)
        self.item = item

    def boundingRect(self):
        return QtCore.QRectF(0, 0, 20, 20)

    def paint(self, p, *args):
        opts = self.item.opts
        if opts.get('antialias'):
            p.setRenderHint(p.RenderHint.Antialiasing)

        visible = self.item.isVisible()
        if not visible:
            icon = invisibleEye.qicon
            p.drawPixmap(QtCore.QPoint(1, 1), icon.pixmap(18, 18))
            return

        if not isinstance(self.item, ScatterPlotItem):
            p.setPen(fn.mkPen(opts['pen']))
            p.drawLine(0, 11, 20, 11)

            if (opts.get('fillLevel', None) is not None and
                    opts.get('fillBrush', None) is not None):
                p.setBrush(fn.mkBrush(opts['fillBrush']))
                p.setPen(fn.mkPen(opts['pen']))
                p.drawPolygon(QtGui.QPolygonF(
                    [QtCore.QPointF(2, 18), QtCore.QPointF(18, 2),
                     QtCore.QPointF(18, 18)]))

        symbol = opts.get('symbol', None)
        if symbol is not None:
            if isinstance(self.item, PlotDataItem):
                opts = self.item.scatter.opts
            p.translate(10, 10)
            drawSymbol(p, symbol, opts['size'], fn.mkPen(opts['pen']),
                       fn.mkBrush(opts['brush']))

        if isinstance(self.item, BarGraphItem):
            p.setBrush(fn.mkBrush(opts['brush']))
            p.drawRect(QtCore.QRectF(2, 2, 18, 18))

    def mouseClickEvent(self, event):
        """Use the mouseClick event to toggle the visibility of the plotItem
        """
        if event.button() == QtCore.Qt.MouseButton.LeftButton:
            visible = self.item.isVisible()
            self.item.setVisible(not visible)

        event.accept()
        self.update()
