import os
import re
import argparse
from sys import exit

NUMBERED_INTERFACE_TYPES = (
    'bond', 'br', 'dum', 'en', 'ersp', 'eth', 'gnv', 'ifb', 'ipoe', 'lan',
    'l2tp', 'l2tpeth', 'macsec', 'peth', 'ppp', 'pppoe', 'pptp', 'sstp',
    'sstpc', 'tun', 'veth', 'vpptap', 'vpptun', 'vti', 'vtun', 'vxlan',
    'wg', 'wlan', 'wwan',
)

NAMED_INTERFACE_TYPES = (
    'pod-',
)

# Validate numbered interface prefixes with optional sub interfaces and optional wildcard
# Example:
#  eth*
#  eth0
#  eth0*
#  eth0.0
#  eth0.0*
NUMBERED_INTERFACE_RE = re.compile(r'^('
    + '|'.join(sorted(map(re.escape, NUMBERED_INTERFACE_TYPES), key=len, reverse=True))
    + r')(\d+(?:\.\d+)?\*?|\*)$')

# Validate named interface prefixes with optional wildcard
# Example:
#  pod-*
#  pod-network
#  pod-network*
NAMED_INTERFACE_RE = re.compile(r'^('
    + '|'.join(sorted(map(re.escape, NAMED_INTERFACE_TYPES), key=len, reverse=True))
    + r')([A-Za-z0-9._-]+\*?|\*)$')

# Validate generic interface names (must exist in /sys/class/net
GENERIC_RE = re.compile(r'^[A-Za-z0-9._-]+$')

if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument("--allow-wildcard", action='store_true', help="Allow wildcards")
    parser.add_argument("name", type=str)
    args = parser.parse_args()

    if args.name == 'lo':
        exit(0)

    if len(args.name) > 15:
        print(f'Error: {args.name} is longer than 15 characters')
        exit(1)

    wildcard = args.name.endswith('*')

    if NUMBERED_INTERFACE_RE.match(args.name) or NAMED_INTERFACE_RE.match(args.name):
        if args.allow_wildcard or not wildcard:
            exit(0)
        print(f'Error: {args.name} is not a valid interface name')
        exit(1)
    
    if GENERIC_RE.match(args.name) and os.path.isdir(f'/sys/class/net/{args.name}'):
        exit(0)

    print(f'Error: {args.name} interface does not exist')
    exit(1)