dotfiles/dot_config/kitty/tab_bar.py

# ── tab_bar.py · kitty tab titles: repo dir, or the file nvim is editing ──
#
# kitty loads this file from the config dir and exposes `draw_title` as the
# `{custom}` field of tab_title_template (kitty/tab_bar.py:
# load_custom_draw_title). kitty still draws the powerline chrome; only the text
# inside a tab comes from here.
#
# A title is one of:
#     2  chezmoi        <- repo the tab's cwd belongs to (dir name if no repo)
#     3  astrocore.lua  <- nvim is the active process: the file it is editing
#
# No subprocesses, no timers: the repo root is found by walking up for `.git`,
# and the edited file comes from the window title nvim already sets
# (~/.config/nvim/lua/plugins/astrocore.lua, custom_title autocmd:
# "<file> | <org/repo>" or "<file> | Nvim", and "<org/repo>" / "Nvim" with no
# file). kitty repaints the tab bar whenever that title changes, so the tab
# tracks buffer switches for free.

from __future__ import annotations

import os
from typing import Any

# Nerd Font glyphs; VictorMono Nerd Font Mono covers both.
FOLDER = '\uf07b'  # nf-fa-folder
NVIM = '\ue62b'  # nf-custom-neovim

EDITORS = frozenset({'nvim', 'vim', 'nvim-qt'})
MAX_LEN = 28

# wd -> repo root (or ''), memoized: a working dir keeps its answer for the life
# of the kitty instance, so `git init` in an already-open dir needs a config
# reload (ctrl+shift+alt+, in the herdr host, ctrl+shift+f5 here) to show up.
_repo: dict[str, str] = {}


def draw_title(data: dict[str, Any]) -> str:
    tab = data['tab']
    label = ''
    if tab.active_exe in EDITORS:
        label = _nvim_file(data['title'])
        if label:
            return f'{data["index"]} {NVIM} {_elide(label)}'
    wd = tab.active_wd
    if wd:
        label = os.path.basename(_repo_root(wd) or wd.rstrip('/'))
        if wd == os.path.expanduser('~'):
            label = '~'
    return f'{data["index"]} {FOLDER} {_elide(label or data["title"])}'


def _repo_root(wd: str) -> str:
    root = _repo.get(wd)
    if root is None:
        root = ''
        path = wd
        while True:
            if os.path.exists(os.path.join(path, '.git')):
                root = path
                break
            parent = os.path.dirname(path)
            if parent == path:
                break
            path = parent
        _repo[wd] = root
    return root


def _nvim_file(title: str) -> str:
    """The file name out of an nvim window title, '' when it is editing none.

    Handles this config's "<file> | <org/repo>" / "<file> | Nvim" and nvim's own
    default "%t - Nvim" / "<file> (<dir>) - NVIM".
    """
    text = title.strip()
    for suffix in (' - NVIM', ' - Nvim', ' - nvim'):
        if text.endswith(suffix):
            text = text[: -len(suffix)]
    text = text.split(' | ', 1)[0].strip()
    if text.endswith(')') and ' (' in text:
        text = text.split(' (', 1)[0].strip()
    # Left with a bare repo slug ("org/repo") or the placeholder: no file open.
    if not text or '/' in text or text.lower() == 'nvim':
        return ''
    return text


def _elide(label: str) -> str:
    return label if len(label) <= MAX_LEN else label[: MAX_LEN - 1] + '…'