import re

with open('_get_instance_details.php', 'r', encoding='utf-8') as f:
    content = f.read()

def replace_checkbox(m):
    block = m.group(0)
    return re.sub(
        r'<input type="checkbox" id="<\?= htmlspecialchars\(\$fieldName\) \?>"',
        r'<input type="hidden" name="<?= htmlspecialchars($fieldName) ?>" value="0">\n                                    <input type="checkbox" id="<?= htmlspecialchars($fieldName) ?>" name="<?= htmlspecialchars($fieldName) ?>"',
        block
    )

content = re.sub(
    r"<\?php if \(\$field\['type'\] === 'checkbox'\): \?>.*?<\?php else: \?>", 
    replace_checkbox, 
    content, 
    flags=re.DOTALL
)

with open('_get_instance_details.php', 'w', encoding='utf-8') as f:
    f.write(content)
print("Hidden inputs added.")