import threading
import curses

################################################################################
# Command line class, will run in its own thread                               #
# Does not contain any actual commands, this just takes user input             #
# Commands must be registered before they can be used                          #
# When registering a command: pass the key, a poiner to the function, and      #
#    a help message                                                            #
# This does have a built-in help function, which displays the help messages    #
#    for registered commands.  The help function can be overridden if needed   #
################################################################################


class CLine(threading.Thread):
	# Initialize ncurses stuff
	def __init__(self):
		threading.Thread.__init__(self)
		self.stdscr = curses.initscr()
		self.maxSize = self.stdscr.getmaxyx()
		curses.cbreak()
		curses.noecho()
		self.stdscr.keypad(1)
		self.input = ""
		self.pos = (0,0) # REMEMBER: (y,x)
		self.start()
		self.cmnds = dict()


	# Reverse ncurses stuff (returns screen to normal)
	# THIS MUST BE CALLED BEFORE EXITING!!!
	def quit(self):
		curses.nocbreak()
		curses.echo()
		self.stdscr.keypad(0)
		curses.endwin()


	# Print the prompt
	def prompt(self):
		(y,x) = self.stdscr.getyx()
		self.stdscr.addstr(y,0,">>> ")
		self.stdscr.refresh()


	# Run the command line
	def run(self):
		try:
			self.prompt()
			while(True):
				# Enter key pressed
				c = self.stdscr.getch()
				if c==10:
					self.enter()
				elif c==127:
					self.backspace()
				else:
					self.input+=curses.keyname(c)
					self.changeline()
		finally:
			self.quit()


	# Enter key pressed
	# Returns true if we keep going
	def enter(self):
		self.input = self.input.strip().lower()
		if self.input=="":
			return
		elif self.input in self.cmnds.keys():
			self.cmnds[self.input][0]()
			self.advanceLine()
			self.prompt()
			self.input = ""
		elif self.input == "help":
			self.printHelp()
			self.input = ""


	# Backspace key pressed
	def backspace(self):
		(y,x) = self.stdscr.getyx()
		if self.input != "":
			self.stdscr.move(y,x-1)
			self.stdscr.delch()
			self.input=self.input[0:len(self.input)-1]


	# Advance cursor to next line
	def advanceLine(self):
		(y,x) = self.stdscr.getyx()
		if y==self.maxSize[0]-1:
			self.stdscr.move(0,0)
			self.stdscr.deleteln()
		else:
			y+=1
		self.stdscr.move(y,0)


	# Change the current line to reflect self.input
	def changeline(self):
		(y,x) = self.stdscr.getyx()
		self.stdscr.deleteln()
		self.stdscr.move(y,0)
		self.prompt()
		self.stdscr.addstr(self.input)


	# Print lines to the screen
	def printLines(self,lines):
		#self.advanceLine()
		for line in lines:
			self.printLine(line)
		self.advanceLine()
		self.prompt()


	# Print a single line on the screen
	def printLine(self,line):
		(y,x) = self.stdscr.getyx()
		self.advanceLine()
		(y,x) = self.stdscr.getyx()
		self.stdscr.addstr(line)
		#self.stdscr.move(y+1,x)
		self.stdscr.refresh()


	# Associate a command with a function
	def register(self,command,func,help):
		self.cmnds[command]=(func,help)


	# Scan through keys and print help messages
	def printHelp(self):
		lines = []
		keys = self.cmnds.keys()
		keys.sort()
		for cmnd in keys:
			lines+=[cmnd+"\t"+self.cmnds[cmnd][1]]
		self.printLines(lines)