#!/usr/bin/env python

# life.py -- A curses-based version of Conway's Game of Life.

# Contributed by AMK

#

# An empty board will be displayed, and the following commands are available:

#  E : Erase the board

#  R : Fill the board randomly

#  S : Step for a single generation

#  C : Update continuously until a key is struck

#  Q : Quit

#  Cursor keys :  Move the cursor around the board

#  Space or Enter : Toggle the contents of the cursor's position

#

# TODO :

#   Support the mouse

#   Use colour if available

#   Make board updates faster

#

import random, string, traceback

import curses

class LifeBoard:

    """Encapsulates a Life board

    Attributes:

    X,Y : horizontal and vertical size of the board

    state : dictionary mapping (x,y) to 0 or 1

    Methods:

    display(update_board) -- If update_board is true, compute the

                             next generation.  Then display the state

                             of the board and refresh the screen.

    erase() -- clear the entire board

    makeRandom() -- fill the board randomly

    set(y,x) -- set the given cell to Live; doesn't refresh the screen

    toggle(y,x) -- change the given cell from live to dead, or vice

                   versa, and refresh the screen display

    """

    def __init__(self, scr, char=ord('*')):

        """Create a new LifeBoard instance.

        scr -- curses screen object to use for display

        char -- character used to render live cells (default: '*')

        """

        self.state = {}

        self.scr = scr

        Y, X = self.scr.getmaxyx()

        self.X, self.Y = X-2, Y-2-1

        self.char = char

        self.scr.clear()

        # Draw a border around the board

        border_line = '+'+(self.X*'-')+'+'

        self.scr.addstr(0, 0, border_line)

        self.scr.addstr(self.Y+1,0, border_line)

        for y in range(0, self.Y):

            self.scr.addstr(1+y, 0, '|')

            self.scr.addstr(1+y, self.X+1, '|')

        self.scr.refresh()

    def set(self, y, x):

        """Set a cell to the live state"""

        if x<0 or self.X<=x or y<0 or self.Y<=y:

            raise ValueError, "Coordinates out of range %i,%i"% (y,x)

        self.state[x,y] = 1

    def toggle(self, y, x):

        """Toggle a cell's state between live and dead"""

        if x<0 or self.X<=x or y<0 or self.Y<=y:

            raise ValueError, "Coordinates out of range %i,%i"% (y,x)

        if self.state.has_key( (x,y) ):

            del self.state[x,y]

            self.scr.addch(y+1, x+1, ' ')

        else:

            self.state[x,y] = 1

            self.scr.addch(y+1, x+1, self.char)

        self.scr.refresh()

    def erase(self):

        """Clear the entire board and update the board display"""

        self.state = {}

        self.display(update_board=False)

    def display(self, update_board=True):

        """Display the whole board, optionally computing one generation"""

        M,N = self.X, self.Y

        if not update_board:

            for i in range(0, M):

                for j in range(0, N):

                    if self.state.has_key( (i,j) ):

                        self.scr.addch(j+1, i+1, self.char)

                    else:

                        self.scr.addch(j+1, i+1, ' ')

            self.scr.refresh()

            return

        d = {}

        self.boring = 1

        for i in range(0, M):

            L = range( max(0, i-1), min(M, i+2) )

            for j in range(0, N):

                s = 0

                live = self.state.has_key( (i,j) )

                for k in range( max(0, j-1), min(N, j+2) ):

                    for l in L:

                        if self.state.has_key( (l,k) ):

                            s += 1

                s -= live

                if s == 3:

                    # Birth

                    d[i,j] = 1

                    self.scr.addch(j+1, i+1, self.char)

                    if not live: self.boring = 0

                elif s == 2 and live: d[i,j] = 1       # Survival

                elif live:

                    # Death

                    self.scr.addch(j+1, i+1, ' ')

                    self.boring = 0

        self.state = d

        self.scr.refresh()

    def makeRandom(self):

        "Fill the board with a random pattern"

        self.state = {}

        for i in range(0, self.X):

            for j in range(0, self.Y):

                if random.random() > 0.5:

                    self.set(j,i)

def erase_menu(stdscr, menu_y):

    "Clear the space where the menu resides"

    stdscr.move(menu_y, 0)

    stdscr.clrtoeol()

    stdscr.move(menu_y+1, 0)

    stdscr.clrtoeol()

def display_menu(stdscr, menu_y):

    "Display the menu of possible keystroke commands"

    erase_menu(stdscr, menu_y)

    stdscr.addstr(menu_y, 4,

                  'Use the cursor keys to move, and space or Enter to toggle a cell.')

    stdscr.addstr(menu_y+1, 4,

                  'E)rase the board, R)andom fill, S)tep once or C)ontinuously, Q)uit')

def keyloop(stdscr):

    # Clear the screen and display the menu of keys

    stdscr.clear()

    stdscr_y, stdscr_x = stdscr.getmaxyx()

    menu_y = (stdscr_y-3)-1

    display_menu(stdscr, menu_y)

    # Allocate a subwindow for the Life board and create the board object

    subwin = stdscr.subwin(stdscr_y-3, stdscr_x, 0, 0)

    board = LifeBoard(subwin, char=ord('*'))

    board.display(update_board=False)

    # xpos, ypos are the cursor's position

    xpos, ypos = board.X//2, board.Y//2

    # Main loop:

    while (1):

        stdscr.move(1+ypos, 1+xpos)     # Move the cursor

        c = stdscr.getch()                # Get a keystroke

        if 0<c<256:

            c = chr(c)

            if c in ' \n':

                board.toggle(ypos, xpos)

            elif c in 'Cc':

                erase_menu(stdscr, menu_y)

                stdscr.addstr(menu_y, 6, ' Hit any key to stop continuously '

                              'updating the screen.')

                stdscr.refresh()

                # Activate nodelay mode; getch() will return -1

                # if no keystroke is available, instead of waiting.

                stdscr.nodelay(1)

                while (1):

                    c = stdscr.getch()

                    if c != -1:

                        break

                    stdscr.addstr(0,0, '/')

                    stdscr.refresh()

                    board.display()

                    stdscr.addstr(0,0, '+')

                    stdscr.refresh()

                stdscr.nodelay(0)       # Disable nodelay mode

                display_menu(stdscr, menu_y)

            elif c in 'Ee':

                board.erase()

            elif c in 'Qq':

                break

            elif c in 'Rr':

                board.makeRandom()

                board.display(update_board=False)

            elif c in 'Ss':

                board.display()

            else: pass                  # Ignore incorrect keys

        elif c == curses.KEY_UP and ypos>0:            ypos -= 1

        elif c == curses.KEY_DOWN and ypos<board.Y-1:  ypos += 1

        elif c == curses.KEY_LEFT and xpos>0:          xpos -= 1

        elif c == curses.KEY_RIGHT and xpos<board.X-1: xpos += 1

        else:

            # Ignore incorrect keys

            pass

def main(stdscr):

    keyloop(stdscr)                    # Enter the main loop

if __name__ == '__main__':

    curses.wrapper(main)