sshtui/sshtui

#!/usr/bin/env python3
import subprocess, curses
from pathlib import Path

# constants
KEY_BINDINGS = {  # can be extended
    "\n": 'ssh -i {identity} {user}@{server} -p {port}'
}
HELP_TEXT = "letters: filter mode, Esc: exit filter/exit sshtui, Enter: connect to server, arrows/PgUp/PgDn/Home/End: navigation"
MOUSE_ENABLED = True
SCREEN = curses.initscr()  # screen initialization, needed for ROWS_HEIGHT working
HEADER_HEIGHT = 4  # in rows
FOOTER_HEIGHT = 3
ROWS_HEIGHT = curses.LINES - HEADER_HEIGHT - FOOTER_HEIGHT - 3   # maximum number of visible rows indices
WIDTH = curses.COLS


# classes
class CircularList:
    def __init__(self, elements):
        self.elements = elements
        self.size = len(elements)
        self.index = 0

    def __getitem__(self, index):
        start, stop, step = index.indices(self.size)
        return [self.elements[(self.index + i) % self.size] for i in range(start, stop, step)]

    def shift(self, steps):
        self.index = (self.index + steps) % self.size


class Menu:
    def __init__(self, title: str, rows: list, begin_x: int, width: int, rows_height: int):
        self.title = title
        self.rows = rows  # all rows
        self.filter = ""  # filter for rows
        self.filtered_rows = CircularList([x for x in self.rows if self.filter in x.lower()])  # filtered rows
        self.visible_rows = lambda: self.filtered_rows[:rows_height]  # visible rows
        self.visible_row_index = 0  # index of the selected visible row
        # selected row from visible rows
        self.selected_row = lambda: self.visible_rows()[self.visible_row_index] if self.visible_rows() else None
        self.rows_height = rows_height
        self.width = width
        self.begin_x = begin_x
        self.win = curses.newwin(curses.LINES - FOOTER_HEIGHT, width, 0, begin_x)


# helper functions
def draw_row(window: curses.window, text: str, y: int, x: int, selected: bool = False):
    window.addstr(y, x, text, curses.A_REVERSE | curses.A_BOLD if selected else curses.A_NORMAL)
    window.clrtoeol()
    window.refresh()


def draw_rows(menu: Menu):
    for index, row in enumerate(menu.visible_rows()):
        draw_row(menu.win, row, index + HEADER_HEIGHT, 2, selected=True if row == menu.selected_row() else False)


def draw_menu(menu: Menu):
    menu.win.clear()  # clear menu window
    draw_row(menu.win, menu.title, 1, 2)  # draw title
    draw_rows(menu)  # draw menu rows
    draw_row(menu.win, f"filter: {menu.filter}" if menu.filter else "", curses.LINES - FOOTER_HEIGHT - 2, 2)  # draw filter row



def handle_key_bindings(key: str, user: str, server: str, port: str, identity: str):
    if not server:
        return
    curses.def_prog_mode()  # save the previous terminal state
    curses.endwin()  # without this, there are problems after exiting vim
    command = KEY_BINDINGS[key].format(user=user, server=server, identity=identity, port=port)
    try:
        subprocess.call(command, shell=True)
    except:
        pass
    curses.reset_prog_mode()  # restore the previous terminal state
    SCREEN.refresh()
    enable_mouse_support()


def handle_filter_state(key: str, menu: Menu):
    if key in ["KEY_BACKSPACE", "\x08"] and not menu.filter:
        return
    elif key == "\x1b" and not menu.filter:
        globals().update(selected_menu=None)  # exit
    elif key == "\x1b":
        menu.filter = ""  # Escape key exits filter mode
    elif key in ["KEY_BACKSPACE", "\x08"]:
        menu.filter = menu.filter[:-1]  # Backspace key deletes a character (\x08 is also Backspace)
    elif key.isalnum():
        menu.filter += key.lower()
    menu.visible_row_index = 0
    menu.filtered_rows = CircularList([x for x in menu.rows if menu.filter in x.lower()])  # update filtered rows
    draw_menu(menu)


def handle_mouse(menu: Menu):
    if not MOUSE_ENABLED:
        return
    try:
        mouse_info = curses.getmouse()
    except curses.error:  # this fixes scrolling error
        return
    row_number = mouse_info[2] - HEADER_HEIGHT
    column_number = mouse_info[1]
    char_int = menu.win.inch(mouse_info[2], column_number - menu.begin_x - 1) # get char from current mouse position
    char_str = chr(char_int & 0xFF)
    if not char_str or ord(char_str) > 127 or ' ' in char_str:
        return
    if 0 <= row_number < len(menu.visible_rows()):
        menu.visible_row_index = row_number
        draw_rows(menu)  # this will change selected row in menu


def handle_vertical_navigation(key: str, menu: Menu):
    if len(menu.visible_rows()) <= 1:
        return
    keys_numbers = {"KEY_DOWN": 1, "KEY_UP": -1, "KEY_NPAGE": 1, "KEY_PPAGE": -1, 'KEY_HOME': 0, 'KEY_END': -1}
    if key in ["KEY_DOWN", "KEY_UP"]:
        if menu.filtered_rows.size > menu.rows_height:
            menu.filtered_rows.shift(keys_numbers[key])
        else:
            menu.visible_row_index = (menu.visible_row_index + keys_numbers[key]) % menu.filtered_rows.size  # index of the selected visible row
    elif key in ["KEY_NPAGE", "KEY_PPAGE"]:
        menu.filtered_rows.shift(keys_numbers[key] * len(menu.visible_rows()))
    elif key in ['KEY_HOME','KEY_END']:
        menu.visible_row_index = keys_numbers[key]
    draw_rows(menu)


def catch_input(menu: Menu):
    key = SCREEN.getkey()
    if key in ["KEY_UP", "KEY_DOWN", "KEY_NPAGE", "KEY_PPAGE", "KEY_HOME", "KEY_END"]:
        handle_vertical_navigation(key, menu)
    elif key == "KEY_MOUSE":
        handle_mouse(menu)
    elif key in KEY_BINDINGS.keys():
        handle_key_bindings(key, user(), server(), port(), identity())
    elif key in ["\x1b", "KEY_BACKSPACE", "\x08"] or key.isalnum():  # \x1b - escape, \x08 - backspace
        handle_filter_state(key, menu)


def enable_mouse_support():
    curses.mousemask(curses.REPORT_MOUSE_POSITION)  # mouse tracking
    print('\033[?1003h') # enable mouse tracking with the XTERM API. That's the magic


def get_servers() -> dict:
    with open(f"{str(Path.home())}/.ssh/config", "r") as f:
        lines = f.readlines()
    current_host = None
    hosts = {}
    for line in lines:
        line = line.strip()
        if line.startswith("Host "):
            current_host = line.split()[1]
            hosts[current_host] = {}
        elif line and line[0].isupper():
            key, value = line.split(" ")
            key = key.strip()
            value = value.strip()
            hosts[current_host][key] = value
    return hosts


def init_menus():
    global menus, selected_menu, user, server, identity, port
    menu_title = '{: <20s} {: <20s} {: <30s} {: <8s} {}'.format("Name", "User", "Host", "Port", "Identity")
    menu_rows = []
    for host, params in get_servers().items():
        user = params['User']
        server = params['HostName']
        port = params.get('Port', "22")
        identity = params.get('IdentityFile', '~/.ssh/id_rsa')
        menu_rows.append(f"{host: <20s} {user: <20s} {server: <30s} {port: <8s} {identity}")
    menus = [Menu(menu_title, menu_rows, 0, WIDTH, ROWS_HEIGHT)]
    selected_menu = menus[0]
    user = lambda: menus[0].selected_row().split()[-4] if menus[0].selected_row() else None
    server = lambda: menus[0].selected_row().split()[-3] if menus[0].selected_row() else None
    port = lambda: menus[0].selected_row().split()[-2] if menus[0].selected_row() else None
    identity = lambda: menus[0].selected_row().split()[-1] if menus[0].selected_row() else None
    SCREEN.refresh()  # I don't know why this is needed but it doesn't work without it
    SCREEN.keypad(True)  # needed for arrow keys
    curses.set_escdelay(1)  # reduce Escape delay to 1 ms (curses can't set it to 0)
    curses.curs_set(0)  # make the cursor invisible
    curses.use_default_colors()  # don't change the terminal color
    curses.noecho()  # don't output characters at the top
    enable_mouse_support()


def main(screen):
    init_menus()
    for menu in menus:  # draw the main windows
        draw_menu(menu)
    draw_row(curses.newwin(3, curses.COLS, curses.LINES - FOOTER_HEIGHT, 0), HELP_TEXT, 1, 2)  # and the help window
    while selected_menu:
        catch_input(selected_menu)  # if a menu is selected, catch user input


if __name__ == "__main__":
    curses.wrapper(main)
    subprocess.run("tput reset", shell=True)