Implemented basic CLI based on python curses.

telematica/ass1/chat_window.py

+import curses
+
+class ChatWindow:
+    def __init__(self, main, top, left, height, width):
+        # Reference to the main window
+        self.main = main
+
+        # Command bar position
+        self.top    = top
+        self.left   = left
+        self.height = height
+        self.width  = width
+
+        # Initialise window
+        self.window = curses.newwin(height, width, top, left)
+
+        # True, if help screen is currently displayed.
+        self.displayed_help = False
+
+    def handle_close(self):
+        # If the help screen is currently displayed, hide it.
+        if self.displayed_help:
+            self.displayed_help = False
+            self.window.clear()
+            self.window.refresh()
+        else:
+            # Stop user input handler (which will exit the application).
+            self.main.quit()
+
+    def display_help(self):
+        if self.displayed_help:
+            return
+
+        self.displayed_help = True
+
+        self.window.clear()
+        help_text = 'Help screen\n' \
+            + '\n' \
+            + 'All commands listed below should be preceded by a slash:\n' \
+            + '\n' \
+            + '  Command\tDescription\n' \
+            + '  close\t\tClose visible chat window (or this help screen).\n' \
+            + '  help\t\tThis help page.\n' \
+            + '  quit\t\tQuit this chat application (shortcut: ^c).\n' \
+
+        for i, line in enumerate(help_text.split('\n')):
+            self.window.addstr(i, 0, line)
+        self.window.refresh()
+

telematica/ass1/cli.py

+import curses
+import sys
+
+from chat_window import ChatWindow
+from info_bar import InfoBar
+from command_bar import CommandBar
+
+class CLI:
+    """
+    Command line interface based on the Curses library used for the chat
+    application. This chat application is a practical assignment for the
+    University of Amsterdam's course Telematica 2011.
+    """
+
+    def __init__(self):
+        # Initialse the curses library
+        self.stdscr = curses.initscr()
+
+        # start_color() initializes eight basic colors (black, red, green,
+        # yellow, blue, magenta, cyan, and white), and two global variables in
+        # the curses module, COLORS and COLOR_PAIRS, containing the maximum
+        # number of colors and color-pairs the terminal can support. It also
+        # restores the colors on the terminal to the values they had when the
+        # terminal was just turned on.
+        self.color_count = curses.start_color()
+        curses.use_default_colors()
+
+        # Usually curses applications turn off automatic echoing of keys to the
+        # screen, in order to be able to read keys and only display them under
+        # certain circumstances.
+        curses.noecho()
+
+        # Applications will also commonly need to react to keys instantly,
+        # without requiring the Enter key to be pressed; this is called cbreak
+        # mode, as opposed to the usual buffered input mode.
+        curses.cbreak()
+
+        # Terminals usually return special keys, such as the cursor keys or
+        # navigation keys such as Page Up and Home, as a multibyte escape
+        # sequence. While you could write your application to expect such
+        # sequences and process them accordingly, curses can do it for you,
+        # returning a special value such as curses.KEY_LEFT. To get curses to do
+        # the job, you'll have to enable keypad mode.
+        self.stdscr.keypad(1)
+
+        # After setting nodelay(1), getch() for the window becomes non-blocking
+        # and returns curses.ERR (a value of -1) when no input is ready.
+        self.stdscr.nodelay(1)
+
+        # Initialise color scheme.
+        curses.init_pair(1, curses.COLOR_WHITE, curses.COLOR_BLUE)
+
+        # Window composition.
+        self.init_windows()
+
+        # Enter the user input handler loop.
+        self.init_input_handler()
+
+    def init_windows(self):
+        """
+        Initialise the window of this command line interface. The user interface
+        of this chat application consists of a main chat window, an optional
+        user list window and a command bar. The chat window does also view the
+        help screen, when the help screen is requested by the user.
+        """
+
+        self.max_y, self.max_x = self.stdscr.getmaxyx()
+        self.stdscr.refresh()
+
+        # Initalise chat window.
+        self.chat_window = ChatWindow(self, 0, 0, self.max_y - 2, self.max_x)
+
+        # Info bar between chat window and command bar
+        self.info_bar = InfoBar(self, self.max_y - 2, 0, 1, self.max_x)
+
+        # Command bar at the bottom of the screen.
+        self.command_bar = CommandBar(self, self.max_y - 1, 0, 1, self.max_x)
+
+        # set cursor position to bottom of screen.
+        self.stdscr.move(self.max_y - 1, 0)
+        self.stdscr.refresh()
+
+    def init_input_handler(self):
+        while True:
+            # KeyboardInterrupt is raised when an user presses ^C. This
+            # try/except block will catch the exception and shutdown the
+            # application gracefully.
+            try:
+                c = self.stdscr.getch()
+            except KeyboardInterrupt:
+                self.quit()
+
+            if c != curses.ERR and self.command_bar.handle_input(c):
+                break
+
+    def quit(self):
+        # Reverse the curses-friendly terminal settings.
+        curses.nocbreak();
+        self.stdscr.keypad(0);
+        curses.echo()
+
+        # Restore the terminal to its original operating mode.
+        curses.endwin()
+
+        sys.exit(0)
+
+    def __del__(self):
+        import curses
+
+        # Reverse the curses-friendly terminal settings.
+        curses.nocbreak();
+        self.stdscr.keypad(0);
+        curses.echo()
+
+        # Restore the terminal to its original operating mode.
+        curses.endwin()
+

telematica/ass1/command_bar.py

+import curses
+from curses.textpad import Textbox
+
+class CommandBar:
+    def __init__(self, main, top, left, height, width):
+        # Reference to the main window
+        self.main = main
+
+        # Command bar position
+        self.top    = top
+        self.left   = left
+        self.height = height
+        self.width  = width
+
+        # Initialise window and textbox
+        self.window = curses.newwin(height, width, top, left)
+        self.textbox = Textbox(self.window)
+
+    def handle_input(self, c):
+        #if c == ord('Q'):
+        #    return True
+        #if c == ord('q'):
+        #    return self.handle_quit()
+        #if c == ord('h'):
+        #    self.display_help()
+        #elif c == curses.KEY_HOME:
+        #    self.x = self.y = 0
+        #if 32 <= c <= 127:
+        #    self.append_command(c)
+        #elif c == 10: # Enter key
+        #    return self.execute_command()
+        self.append_command(c)
+
+    def append_command(self, c):
+        if not self.textbox.do_command(c):
+            self.execute_command()
+        self.window.refresh()
+
+    def execute_command(self, command=''):
+        if not command:
+            # Clear command bar, reset cursor and redraw the command bar.
+            command = self.textbox.gather()
+            self.window.deleteln()
+            self.window.move(0, 0)
+        # Handle the given/typed command.
+        self.handle_command(command)
+
+    def handle_command(self, command):
+        if not command:
+            return
+
+        if command[0] == '/':
+            cmd = command.split(' ', 1)[0][1:]
+            if cmd == 'help':
+                self.main.chat_window.display_help()
+            elif cmd == 'quit':
+                self.main.quit()
+            elif cmd == 'close':
+                self.main.chat_window.handle_close()
+        else:
+            pass
+

telematica/ass1/info_bar.py

+import curses
+
+class InfoBar:
+    def __init__(self, main, top, left, height, width):
+        # Reference to the main window
+        self.main = main
+
+        # Command bar position
+        self.top    = top
+        self.left   = left
+        self.height = height
+        self.width  = width
+
+        # Initialise window
+        self.window = curses.newwin(height, width, top, left)
+
+        # Display start message
+        start_message = 'Type "/connect HOST" to connect to a chat server' \
+                + ' or "/help" for help.'
+        self.display(start_message)
+
+    def display(self, msg):
+        color_pair = curses.color_pair(1)
+        try:
+            self.window.addstr(0, 0, msg.ljust(self.width), color_pair)
+        except curses.error:
+            pass
+        self.window.refresh()
+

telematica/ass1/main.py

+#!/usr/bin/env python
+
+from cli import CLI
+
+try:
+    cli = CLI()
+except Exception, e:
+    curses.nocbreak();
+    curses.echo()
+    curses.endwin()
+    print 'Error:', e
+