arbret/backend/validation.py
2025-12-19 10:12:55 +01:00

135 lines
3.8 KiB
Python

"""Validation utilities for user profile fields."""
import re
from email_validator import validate_email, EmailNotValidError
from bech32 import bech32_decode
def validate_contact_email(value: str | None) -> str | None:
"""
Validate contact email format.
Returns None if valid, error message if invalid.
Empty/None values are valid (field is optional).
"""
if not value:
return None
try:
validate_email(value, check_deliverability=False)
return None
except EmailNotValidError as e:
return str(e)
def validate_telegram(value: str | None) -> str | None:
"""
Validate Telegram handle.
Must start with @ if provided.
Returns None if valid, error message if invalid.
Empty/None values are valid (field is optional).
"""
if not value:
return None
if not value.startswith("@"):
return "Telegram handle must start with @"
if len(value) < 2:
return "Telegram handle must have at least one character after @"
# Telegram usernames: 5-32 characters, alphanumeric and underscores
# But we store with @, so check 6-33 total
handle = value[1:] # Remove @
if len(handle) < 5:
return "Telegram handle must be at least 5 characters (after @)"
if len(handle) > 32:
return "Telegram handle must be at most 32 characters (after @)"
if not re.match(r'^[a-zA-Z][a-zA-Z0-9_]*$', handle):
return "Telegram handle must start with a letter and contain only letters, numbers, and underscores"
return None
def validate_signal(value: str | None) -> str | None:
"""
Validate Signal username.
Any non-empty string is valid.
Returns None if valid, error message if invalid.
Empty/None values are valid (field is optional).
"""
if not value:
return None
# Signal usernames are fairly permissive, just check it's not empty
if len(value.strip()) == 0:
return "Signal username cannot be empty"
if len(value) > 64:
return "Signal username must be at most 64 characters"
return None
def validate_nostr_npub(value: str | None) -> str | None:
"""
Validate Nostr npub (public key in bech32 format).
Must be valid bech32 with 'npub' prefix.
Returns None if valid, error message if invalid.
Empty/None values are valid (field is optional).
"""
if not value:
return None
if not value.startswith("npub1"):
return "Nostr npub must start with 'npub1'"
# Decode bech32 to validate checksum
hrp, data = bech32_decode(value)
if hrp is None or data is None:
return "Invalid Nostr npub: bech32 checksum failed"
if hrp != "npub":
return "Nostr npub must have 'npub' prefix"
# npub should decode to 32 bytes (256 bits) for a public key
# In bech32, each character encodes 5 bits, so 32 bytes = 52 characters of data
if len(data) != 52:
return "Invalid Nostr npub: incorrect length"
return None
def validate_profile_fields(
contact_email: str | None = None,
telegram: str | None = None,
signal: str | None = None,
nostr_npub: str | None = None,
) -> dict[str, str]:
"""
Validate all profile fields at once.
Returns a dict of field_name -> error_message for any invalid fields.
Empty dict means all fields are valid.
"""
errors: dict[str, str] = {}
if err := validate_contact_email(contact_email):
errors["contact_email"] = err
if err := validate_telegram(telegram):
errors["telegram"] = err
if err := validate_signal(signal):
errors["signal"] = err
if err := validate_nostr_npub(nostr_npub):
errors["nostr_npub"] = err
return errors