import curses
import random
import sys
import re

ESCAPE = 27
LETTERS = range(97, 122)
NUMBERS = range(48, 57)


class CheekyFSM(object):
    def __init__(self):
        self.lastkey = -1
        self.buffer = ""
        self.message = ""
        self.edges = {}
        self.state = "A"
        self.history = " "*30

    def show_edges(self):
        """ Print the help menu """
        y, x = self.w.getmaxyx()
        for index, ((start, end), prob) in enumerate(self.edges.items()):
            self.w.addstr(10 + index, 2, f"{start} -> {end} : {prob}%")

    def update(self):
        """ Update the FSM """
        edges = list(self.edges.items())
        random.shuffle(edges)
        for ((start, end), prob) in edges:
            if start == self.state:
                if random.randint(0, 100) < prob:
                    self.state = end

        self.history = self.history[1:] + self.state

    def show_state(self):
        """ Show the state of the machine """
        self.w.addstr(2, 2, f"Tempo: 120bpm")
        self.w.addstr(4, 2, f"State: {self.state}")
        self.w.addstr(5, 2, f"History: {self.history}")

        offset = 6
        for ((start, end), prob) in self.edges.items():
            if start == self.state:
                self.w.addstr(offset, 2,
                              f"Going to {end} with probability {prob}%")
                offset += 1

    def show_status(self):
        """ Print the status bar """
        y, x = self.w.getmaxyx()
        self.w.addstr(y - 2, 2, f"> {self.buffer}", curses.A_BOLD)

    def quit(self):
        """ Quit the program """
        curses.nocbreak()
        self.w.keypad(False)
        curses.echo()
        curses.endwin()
        sys.exit(0)

    def process_key(self):
        """ Process a key """
        key = self.w.getch()
        self.lastkey = key
        if key == ESCAPE:
            quit(self.w)
        elif key in LETTERS:
            self.buffer += chr(key).upper()
        elif key in NUMBERS:
            self.buffer += chr(key)
        elif key == 10:
            self.accept()
        elif key == 263 and len(self.buffer) > 0:
            self.buffer = self.buffer[:-1]

    def accept(self):
        """ Accept the string """
        match = re.match(r"([A-Z])([A-Z])(\d+)", self.buffer)
        if not match:
            self.message = "  Invalid command :("
        else:
            groups = match.groups()
            start = groups[0]
            end = groups[1]
            prob = int(groups[2])
            self.modify(start, end, prob)
        self.buffer = ""

    def modify(self, start, end, prob):
        """ Make a modification """
        key = (start, end)
        self.edges[key] = prob
        self.message = f"  {start} -> {end} : {prob}%"
        if prob == 0 and key in self.edges:
            self.message = f"  {start} -> {end} : deleted"
            del self.edges[key]

    def loop(self, w):
        """ Run the loop """
        self.w = w
        curses.curs_set(0)  # invisible
        w.timeout(100)
        while True:
            w.clear()
            self.show_edges()
            self.show_status()
            self.show_state()
            self.update()
            w.refresh()
            self.process_key()


if __name__ == "__main__":
    fsm = CheekyFSM()
    curses.wrapper(fsm.loop)