import math
import sys
from PyQt5.QtWidgets import *


# Logic of the Program
class Button:
    def __init__(self, text, results):
        self.b = QPushButton(str(text))
        self.text = text
        self.results = results
        self.b.clicked.connect(lambda: self.handleInput(self.text))

    # How the program handles having its buttons pushed
    def handleInput(self, v):

        # If the equals sign is pressed, evaluatate the results of the QLineEdit
        if v == "=":
            res = eval(self.results.text())
            self.results.setText(str(res))

        # If the AC button is pressed, set the results to an empty string (essentially clearing the equation)
        elif v == "AC":
            self.results.setText("")

        # If square root is pressed use function in the math module
        elif v == "√":
            value = float(self.results.text())
            self.results.setText(str(math.sqrt(value)))

        # If DEL is selected, subtract one from the line edit
        elif v == "DEL":
            current_value = self.results.text()
            self.results.setText(current_value[:-1])

        # If a number button is pressed, set the text to the value of that number
        else:
            current_value = self.results.text()
            new_value = current_value + str(v)
            self.results.setText(new_value)


# Design of the Program
class Application(QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Peter's Homemade Calculator")
        self.CreateApp()

    # Designing the layout of the app
    def CreateApp(self):

        # Create our grid
        grid = QGridLayout()

        # Also allows the text box for manual input
        results = QLineEdit()

        # List of buttons before initializing them
        buttons = ["AC", "√", "DEL", "/",
                   7, 8, 9, "*",
                   4, 5, 6, "-",
                   1, 2, 3, "+",
                   0, ".", "="]

        # Adding the dimensions of each button to the widget. In column and row 1 [0],
        # the button row is 1 column tall and 4 wide
        grid.addWidget(results, 0, 0, 1, 4)

        row = 1
        column = 0

        # Creating the loop to generate buttons.
        for button in buttons:
            # If column after 3, return to start new row
            if column > 3:
                column = 0
                row += 1

            # Instantiating the button object. Giving the properties button and results
            button_object = Button(button, results)

            if button == 0:
                grid.addWidget(button_object.b, row, column, 1, 2)
                column += 1
            else:
                grid.addWidget(button_object.b, row, column, 1, 1)

            column += 1

        # Tells the program to set the layout to our grid object
        self.setLayout(grid)

        # Shows the application
        self.show()


# Runs the program
if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = Application()
    sys.exit(app.exec())