import sys
import math
import operator
from PyQt4.Qt import QApplication, QWidget, QGridLayout, QVBoxLayout, QHBoxLayout
from PyQt4.QtGui import QPushButton, QLineEdit, QSizePolicy, QRegExpValidator, QLabel
from PyQt4.QtCore import QObject, SIGNAL, QRegExp, Qt

class PinButton(QPushButton):
    def __init__(self, password, encoded_value):
        super(PinButton, self).__init__()
        self.password = password
        self.encoded_value = encoded_value

        QObject.connect(self, SIGNAL('clicked()'), self._pressed)

    def _pressed(self):
        self.password.setText(self.password.text() + str(self.encoded_value))
        self.password.setFocus()

class PinMatrixWidget(QWidget):
    '''
        Displays widget with nine blank buttons and password box.
        Encodes button clicks into sequence of numbers for passing
        into PinAck messages of Trezor.

        show_strength=True may be useful for entering new PIN
    '''
    def __init__(self, show_strength=True, parent=None):
        super(PinMatrixWidget, self).__init__(parent)
        
        self.password = QLineEdit()
        self.password.setValidator(QRegExpValidator(QRegExp('[1-9]+'), None))
        self.password.setEchoMode(QLineEdit.Password)
        QObject.connect(self.password, SIGNAL('textChanged(QString)'), self._password_changed)

        self.strength = QLabel()
        self.strength.setMinimumWidth(75)
        self.strength.setAlignment(Qt.AlignCenter)
        self._set_strength(0)

        grid = QGridLayout()
        grid.setSpacing(0)
        for x in range(9):
            button = PinButton(self.password, x + 1)
            button.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
            button.setFocusPolicy(Qt.NoFocus)
            grid.addWidget(button, x / 3, x % 3)

        hbox = QHBoxLayout()
        hbox.addWidget(self.password)
        if show_strength:
            hbox.addWidget(self.strength)

        vbox = QVBoxLayout()
        vbox.addLayout(grid)
        vbox.addLayout(hbox)
        self.setLayout(vbox)

    def _set_strength(self, strength):
        if strength < 3000:
            self.strength.setText('weak')
            self.strength.setStyleSheet("QLabel { color : #d00; }")
        elif strength < 60000:
            self.strength.setText('fine')
            self.strength.setStyleSheet("QLabel { color : #db0; }")
        elif strength < 360000:
            self.strength.setText('strong')
            self.strength.setStyleSheet("QLabel { color : #0a0; }")
        else:
            self.strength.setText('ULTIMATE')
            self.strength.setStyleSheet("QLabel { color : #000; font-weight: bold;}")

    def _password_changed(self, password):
        self._set_strength(self.get_strength())

    def get_strength(self):
        digits = len(set(str(self.password.text())))
        strength = math.factorial(9) / math.factorial(9 - digits)
        return strength

    def get_value(self):
        return self.password.text()

if __name__ == '__main__':
    '''
        Demo application showing PinMatrix widget in action
    '''
    a = QApplication(sys.argv)

    matrix = PinMatrixWidget()

    def clicked():
        print "PinMatrix value is", matrix.get_value()
        print "Possible button combinations:", matrix.get_strength()
        sys.exit()

    ok = QPushButton('OK')
    QObject.connect(ok, SIGNAL('clicked()'), clicked)

    vbox = QVBoxLayout()
    vbox.addWidget(matrix)
    vbox.addWidget(ok)

    w = QWidget()
    w.setLayout(vbox)
    w.move(100, 100)
    w.show()

    a.exec_()