import re

snap = '''- heading "Welcome" [level=1, ref=e3]
- textbox "Username" [required, ref=e9]
- link "Forgot Your Username?" [ref=e4]
- button "Next" [ref=e7]
- region "SARS AI Assistant Chat" [ref=e1]
  - button "Open SARS AI Assistant Chat" [expanded=false, ref=e2]'''

def find_ref(snap, role, name=None):
    if name is None:
        pattern = rf"\b{re.escape(role)}\b[^\n]*?[,]?\s*ref=(e\d+)\]"
    else:
        pattern = (
            rf"\b{re.escape(role)}\b[^\n]*?['\"]({re.escape(name)})['\"][^\n]*?"
            rf"[,]?\s*ref=(e\d+)\]"
        )
    m = re.search(pattern, snap, re.MULTILINE)
    if m:
        return m.group(2) if m.lastindex and m.lastindex >= 2 else m.group(1)
    return None

# Test all
cases = [
    ('textbox', 'Username', 'e9'),
    ('button', 'Next', 'e7'),
    ('link', 'Forgot Your Username?', 'e4'),
    ('heading', 'Welcome', 'e3'),
    ('region', 'SARS AI Assistant Chat', 'e1'),
    ('button', 'Open SARS AI Assistant Chat', 'e2'),
    (None, 'e9'),  # role-only
]

for c in cases:
    if c[0] is None:
        continue
    role, name, want = c
    got = find_ref(snap, role, name)
    ok = 'OK' if got == want else 'FAIL'
    print(f'{ok} find_ref({role!r}, {name!r}) = {got!r} (want {want!r})')

# Role-only
got = find_ref(snap, 'button', 'Next')  # works
print('role+name:', got)