from typing import Optional

import qrcode
import qrcode.exceptions

from PyQt6.QtGui import QColor, QPen
import PyQt6.QtGui as QtGui
from PyQt6.QtCore import Qt, QRect
from PyQt6.QtWidgets import QApplication, QVBoxLayout, QHBoxLayout, QPushButton, QWidget

from electrum.i18n import _
from electrum.simple_config import SimpleConfig

from .util import WindowModalDialog, WWLabel, getSaveFileName


class QrCodeDataOverflow(qrcode.exceptions.DataOverflowError):
    pass


class QRCodeWidget(QWidget):

    def __init__(self, data=None, *, manual_size: bool = False):
        QWidget.__init__(self)
        self.data = None
        self.qr = None
        self._framesize = None  # type: Optional[int]
        self._manual_size = manual_size
        self.setData(data)

    def setData(self, data):
        if data:
            qr = qrcode.QRCode(
                error_correction=qrcode.constants.ERROR_CORRECT_L,
                box_size=10,
                border=0,
            )
            try:
                qr.add_data(data)
                qr_matrix = qr.get_matrix()  # test that data fits in QR code
            except (ValueError, qrcode.exceptions.DataOverflowError) as e:
                raise QrCodeDataOverflow() from e
            self.qr = qr
            self.data = data
            if not self._manual_size:
                k = len(qr_matrix)
                self.setMinimumSize(k * 5, k * 5)
        else:
            self.qr = None
            self.data = None

        self.update()

    def paintEvent(self, e):
        if not self.data:
            return

        black = QColor(0, 0, 0, 255)
        grey  = QColor(196, 196, 196, 255)
        white = QColor(255, 255, 255, 255)
        black_pen = QPen(black) if self.isEnabled() else QPen(grey)
        black_pen.setJoinStyle(Qt.PenJoinStyle.MiterJoin)

        if not self.qr:
            qp = QtGui.QPainter()
            qp.begin(self)
            qp.setBrush(white)
            qp.setPen(white)
            r = qp.viewport()
            qp.drawRect(0, 0, r.width(), r.height())
            qp.end()
            return

        matrix = self.qr.get_matrix()
        k = len(matrix)
        qp = QtGui.QPainter()
        qp.begin(self)
        r = qp.viewport()
        framesize = min(r.width(), r.height())
        self._framesize = framesize
        boxsize = int(framesize/(k + 2))
        if boxsize < 2:
            qp.drawText(0, 20, 'Cannot draw QR code:')
            qp.drawText(0, 40, 'Boxsize too small')
            qp.end()
            return
        size = k*boxsize
        left = (framesize - size)/2
        top = (framesize - size)/2
        # Draw white background with margin
        qp.setBrush(white)
        qp.setPen(white)
        qp.drawRect(0, 0, framesize, framesize)
        # Draw qr code
        qp.setBrush(black if self.isEnabled() else grey)
        qp.setPen(black_pen)
        for r in range(k):
            for c in range(k):
                if matrix[r][c]:
                    qp.drawRect(
                        int(left+c*boxsize), int(top+r*boxsize),
                        boxsize - 1, boxsize - 1)
        qp.end()

    def grab(self) -> QtGui.QPixmap:
        """Overrides QWidget.grab to only include the QR code itself,
        excluding horizontal/vertical stretch.
        """
        fsize = self._framesize
        if fsize is None:
            fsize = -1
        rect = QRect(0, 0, fsize, fsize)
        return QWidget.grab(self, rect)


class QRDialog(WindowModalDialog):

    def __init__(
            self,
            *,
            data,
            parent=None,
            title="",
            show_text=False,
            help_text=None,
            show_copy_text_btn=False,
            config: SimpleConfig,
    ):
        WindowModalDialog.__init__(self, parent, title)
        self.config = config

        vbox = QVBoxLayout()

        qrw = QRCodeWidget(data, manual_size=True)
        qrw.setMinimumSize(250, 250)
        vbox.addWidget(qrw, 1)

        help_text = data if show_text else help_text
        if help_text:
            text_label = WWLabel()
            text_label.setText(help_text)
            vbox.addWidget(text_label)
        hbox = QHBoxLayout()
        hbox.addStretch(1)

        def print_qr():
            filename = getSaveFileName(
                parent=self,
                title=_("Select where to save file"),
                filename="qrcode.png",
                config=self.config,
            )
            if not filename:
                return
            p = qrw.grab()
            p.save(filename, 'png')
            self.show_message(_("QR code saved to file") + " " + filename)

        def copy_image_to_clipboard():
            p = qrw.grab()
            QApplication.clipboard().setPixmap(p)
            self.show_message(_("QR code copied to clipboard"))

        def copy_text_to_clipboard():
            QApplication.clipboard().setText(data)
            self.show_message(_("Text copied to clipboard"))

        b = QPushButton(_("Copy Image"))
        hbox.addWidget(b)
        b.clicked.connect(copy_image_to_clipboard)

        if show_copy_text_btn:
            b = QPushButton(_("Copy Text"))
            hbox.addWidget(b)
            b.clicked.connect(copy_text_to_clipboard)

        b = QPushButton(_("Save"))
        hbox.addWidget(b)
        b.clicked.connect(print_qr)

        b = QPushButton(_("Close"))
        hbox.addWidget(b)
        b.clicked.connect(self.accept)
        b.setDefault(True)

        vbox.addLayout(hbox)
        self.setLayout(vbox)

        # note: the word-wrap on the text_label is causing layout sizing issues.
        #       see https://stackoverflow.com/a/25661985 and https://bugreports.qt.io/browse/QTBUG-37673
        #       workaround:
        self.setMinimumSize(self.sizeHint())