#!/usr/bin/env python
"""A Python curses test."""

import sys, curses, curses.textpad
import curses.ascii as ascii

class Editor:
    """Editing widget using the interior of a window object."""
    def __init__(self, win, fn=None): 
        self.win = win
        maxy, maxx = win.getmaxyx()
        self.maxy = maxy - 3
        self.maxx = maxx - 1
        self.win.keypad(1)

        self.startline = 0

        if fn: 
           lines = open(fn).read().splitlines()
        else: lines = ['']
        self.lines = lines
        self.draw()

        prompt = "$[" + (" " * (self.maxx - 3)) + "]"
        self.win.addstr(self.maxy + 2, 0, prompt, curses.A_BOLD)
        msg = "Type stuff. Edit stuff. Do something like Ctrl+S to save."
        self.setStatus(msg)
        # self.win.refresh()
        self.win.move(0, 0)

    def setStatus(self, s): 
        if len(s) < self.maxx: 
           s += ' ' * ((self.maxx - len(s)) + 1)
        else: s = s[:self.maxx]
        self.win.addstr(self.maxy + 1, 0, s, curses.A_REVERSE)
        self.win.refresh()

    def draw(self): 
        for y in xrange(self.maxy + 1): 
           Y = y + self.startline
           try: line = self.lines[Y]
           except IndexError: line = ''

           if len(line) < self.maxx: 
              line += ' ' * ((self.maxx - len(line)) + 1)
           else: line = line[:self.maxx]
           self.win.addstr(y, 0, line)
        self.win.refresh()

    def insert(self, y, x, s): 
        Y = y + self.startline

        line = self.lines[Y]
        line = (line[:x] + s + line[x:])[:self.maxx]
        self.lines[Y] = line
        self.win.addstr(y, 0, line)
        self.win.refresh()
        self.win.move(y, x + len(s))

    def delete(self, y, x, i): 
        if i < 1: return
        if (y == 0) and (x == 0): return

        Y = y + self.startline
        if (x == 0) and (y > 0): 
           line = self.lines[Y]
           prev = self.lines[Y-1]
           if i != 1: 
              self.lines[Y-1] = prev[:-(i-1)] + line
           else: self.lines[Y-1] += line
           del self.lines[Y]
           self.draw()
           self.win.move(y - 1, (len(prev) - i) + 1)
        else: 
           line = self.lines[Y]
           line = (line[:(x - i)] + line[x:])[:self.maxx]
           self.lines[Y] = line

           if len(line) < self.maxx: 
              line += ' ' * ((self.maxx - len(line)) + 1)
           self.win.addstr(y, 0, line)
           self.win.refresh()
           self.win.move(y, x - i)

    def do_command(self, ch):
        "Process a single editing command."
        y, x = self.win.getyx()
        Y = y + self.startline

        if ascii.isprint(ch):
            if (y < self.maxy) or (x < self.maxx): 
                # The try-catch ignores the error we trigger from some curses
                # versions by trying to write into the lowest-rightmost spot
                # in the window.
                try: self.insert(y, x, chr(ch))
                except curses.error:
                    pass

        elif ch in (ascii.DLE, curses.KEY_UP): 
            if y > 0:
                n = len(self.lines[Y-1])
                self.win.move(y-1, x)
                if x > n: self.win.move(y-1, n)
            elif self.startline > 0: 
                self.startline -= 1
                self.draw()
                self.win.move(y, x)

        elif ch in (ascii.SO, curses.KEY_DOWN): 
            if Y < (len(self.lines) - 1) and y < self.maxy: 
                n = len(self.lines[Y+1])
                self.win.move(y+1, x)
                if x > n: self.win.move(y+1, n)
            elif Y < (len(self.lines) - 1) and y == self.maxy: 
                self.startline += 1
                self.draw()
                self.win.move(y, x)

        elif ch == 10: 
            if y < self.maxy: 
                line = self.lines[Y]
                self.lines[Y] = line[:x]
                rest = line[x:]
                self.lines.insert(Y + 1, rest)
                self.draw()                
                self.win.move(y+1, 0)

        elif ch in (ascii.STX, curses.KEY_LEFT, 
                    ascii.BS, curses.KEY_BACKSPACE, 127): 
            if x > 0:
                self.win.move(y, x-1)
            elif y == 0:
                pass
            else: self.win.move(y-1, len(self.lines[Y-1]))

            if ch in (ascii.BS, curses.KEY_BACKSPACE, 127): 
                self.delete(y, x, 1) # @@!

        elif ch in (ascii.ACK, curses.KEY_RIGHT): 
            if x < len(self.lines[Y]): 
                self.win.move(y, x+1)
            elif y == self.maxy or Y == (len(self.lines) - 1): 
                pass
            elif x >= len(self.lines[Y]): 
                self.win.move(y+1, 0)

        elif ch == 330: # Delete; delete the bit after the cursor
            if x < len(self.lines[Y]): 
                self.win.move(y, x+1)
            elif y == self.maxy or Y == (len(self.lines) - 1): 
                pass
            elif x >= len(self.lines[Y]): 
                self.win.move(y+1, 0)
            y, x = self.win.getyx()
            self.delete(y, x, 1)

        elif ch == 262: # Home; beginning of line
            self.win.move(y, 0)

        elif ch == 360: # End; end of line
            self.win.move(y, len(self.lines[Y]))

        elif ch == 17: # Ctrl+Q; Quit
            return 0

        else: 
            if y < self.maxy or x < self.maxx:
                try: self.insert(y, x, '[%r]' % ch)
                except curses.error:
                    pass
        return 1

def run(stdscr): 
   if sys.argv[1:]: 
      fn = sys.argv[1]
   else: fn = None

   editor = Editor(stdscr, fn=fn)
   while 1: 
      c = stdscr.getch()
      n = editor.do_command(c)
      if not n: break

def main(): 
   """Run run() in a curses wrapper."""
   curses.wrapper(run)

if __name__=="__main__": 
   main()