textual-textarea with some vim bindings

vim-textarea.py

# /// script
# requires-python = ">=3.13"
# dependencies = [
#     "textual",
# ]
# ///

from enum import Enum
from textual.events import Key
from textual.app import App
from textual.reactive import reactive
from textual.widgets import TextArea
# from textual.document._document import Location

TEXT = """\
def hello(name):
    print("hello" + name)

def goodbye(name):
    print("goodbye" + name)
"""

class MODES(str, Enum):
    NORMAL = 'normal'
    VISUAL = 'visual'
    INSERT = 'insert'

class VimText(TextArea):
    mode: reactive(MODES) = reactive(MODES.NORMAL)
    last_keys: reactive(str) = reactive('')
    def on_mount(self):
        ...

    def watch_mode(self):
        self.border_title = self.mode
        match self.mode:
            case MODES.NORMAL: 
                self.read_only = True
            case MODES.INSERT: 
                self.read_only = False

    def _on_key(self, event:Key):

        ## Switch Modes

        if self.mode == MODES.NORMAL:
            # Go to Insert Mode
            if event.character in ['i', 'I', 'a', 'A', 's', 'S', 'o', 'O']:
                self._move_to_insert_mode(character_pressed=event.character)
                event.prevent_default()
            # Navigate
            if event.character in ['h', 'j', 'k', 'l', 'w', 'b']:
                self._navigate_cursor(character_pressed=event.character)
            event.prevent_default()

        elif self.mode == MODES.INSERT:
            if event.key in ["escape", "ctrl+c"]:
                self.mode = MODES.NORMAL
                event.prevent_default()
            if event.character in ["(", "[", "{", "'", '"', "`"]:
                self._auto_close_brackets_and_quotes(character_pressed=event.character)
                event.prevent_default()

    def _move_to_insert_mode(self, character_pressed):
        match character_pressed:
            case "i":
                self.move_cursor_relative(columns=0)
            case "I":
                self.move_cursor(location=self.get_cursor_line_start_location())
            case "a":
                self.move_cursor_relative(columns=+1)
            case "A":
                self.move_cursor(location=self.get_cursor_line_end_location())
            case "s":
                self.replace("", *self.selection)
            case "S":
                # doesnt work
                self._delete_cursor_line()
            case "o":
                self.move_cursor(location=self.get_cursor_line_end_location())
                self.insert("\n")
            case "O":
                self.move_cursor_relative(rows=-1)
                self.move_cursor(location=self.get_cursor_line_end_location())
                self.insert("\n")

        self.mode = MODES.INSERT

    def _navigate_cursor(self, character_pressed):
        self.cursor_blink = False
        match character_pressed:
            case "h":
                self.move_cursor_relative(columns=-1)
            case "j":
                self.move_cursor_relative(rows=+1)
            case "k":
                self.move_cursor_relative(rows=-1)
            case "l":
                self.move_cursor_relative(columns=+1)
            case "w":
                self.action_cursor_word_right()
                self.move_cursor_relative(columns=+1)
            case "b":
                self.action_cursor_word_left()
        self.cursor_blink = True

    def _auto_close_brackets_and_quotes(self, character_pressed):
        match character_pressed:
            case "(":
                self.insert("()")
            case "[":
                self.insert("[]")
            case "{":
                self.insert("{}")
            case "'":
                self.insert("''")
            case '"':
                self.insert('""')
            case '`':
                self.insert('``')
        self.move_cursor_relative(columns=-1)


class VimApp(App):
    CSS = """
    VimText {
        border:orange;
    }
    """
    def compose(self):
        yield VimText(TEXT)

def main():
    app = VimApp()
    app.run()


if __name__ == '__main__':
    main()