#!/usr/bin/env python3
"""Idempotently inject the HomeDash stylesheet and script into Dashy's index.html.

Dashy's index.html does not always contain a `</body>` tag. A naive
`sed s#</body>#...#` therefore silently drops the injected script (and the
`</body>` marker itself). This script inserts before `</head>`/`</body>` when
those exist, otherwise before `</html>`, and restores a missing `</body>`.
"""
import re
import sys

CSS_TAG = '<link rel="stylesheet" href="/navi.css">'
JS_TAG = '<script src="/navi.js"></script>'

# Dashy 自带的 logo（/web-icons/favicon-*.png）会被浏览器优先选中，
# 于是站点标签栏显示上游 logo 而不是我们的纸飞机。
# 做法：删掉那些 <link rel=icon>，再显式指向我们自己的 /favicon.svg。
# 为什么用“删掉”而不是“改路径”：index.html 来自上游镜像，每次重建可能被重置，
# 删标签幂等，且不依赖上游将来还叫 web-icons。
ICON_LINK_RE = re.compile(r'[ \t]*<link[^>]*rel=["\']icon["\'][^>]*>\s*', re.I)
OUR_ICONS = ('<link rel="icon" type="image/svg+xml" href="/favicon.svg">\n'
             '<link rel="apple-touch-icon" href="/apple-touch-icon.png">')


def patch(html: str) -> str:
    html = re.sub(r'[ \t]*<link rel="stylesheet" href="/navi\.css">\s*', '', html)
    html = re.sub(r'[ \t]*<script src="/navi\.js"></script>\s*', '', html)
    html = re.sub(r'[ \t]*' + re.escape(OUR_ICONS) + r'\s*', '', html)
    html = ICON_LINK_RE.sub('', html)

    if '</head>' in html:
        html = html.replace('</head>', CSS_TAG + OUR_ICONS + '</head>', 1)

    if '</body>' in html:
        html = html.replace('</body>', JS_TAG + '</body>', 1)
    elif '</html>' in html:
        html = html.replace('</html>', JS_TAG + '\n</body>\n</html>', 1)
    else:
        html = html + '\n' + JS_TAG + '\n'
    return html


def main(path: str) -> int:
    with open(path, encoding='utf-8') as fh:
        original = fh.read()
    patched = patch(original)
    if 'href="/navi.css"' not in patched or 'src="/navi.js"' not in patched:
        print('patch failed: tags missing after patch', file=sys.stderr)
        return 1
    if 'web-icons/favicon' in patched:
        print('patch failed: upstream Dashy icon links survived', file=sys.stderr)
        return 1
    if '/favicon.svg' not in patched:
        print('patch failed: our icon link missing', file=sys.stderr)
        return 1
    with open(path, 'w', encoding='utf-8') as fh:
        fh.write(patched)
    print('patched %s (%s)' % (path, 'changed' if patched != original else 'unchanged'))
    return 0


if __name__ == '__main__':
    raise SystemExit(main(sys.argv[1] if len(sys.argv) > 1 else '/app/dashy/index.html'))