public static ChromePolicyUrlPattern Parse()

in sources/Google.Solutions.Platform/Net/ChromePolicyUrlPattern.cs [103:167]
57 lines of code
11 McCabe index (conditional complexity)

        public static ChromePolicyUrlPattern Parse(string pattern)
        {
            Precondition.ExpectNotEmpty(pattern, nameof(pattern));

            pattern = pattern.ToLower();

            if (pattern == All)
            {
                return new ChromePolicyUrlPattern(
                    null,   // All schemes.
                    null,   // All ports.
                    null,   // All domains.
                    true);  // All subdomains.
            }

            var colonDoubleSlashIndex = pattern.IndexOf("://");
            string? scheme;
            string patternWithoutScheme;
            if (colonDoubleSlashIndex == -1)
            {
                scheme = null;
                patternWithoutScheme = pattern;
            }
            else if (colonDoubleSlashIndex == 1 && pattern[0] == '*')
            {
                scheme = null;
                patternWithoutScheme = pattern.Substring(4);
            }
            else
            {
                scheme = pattern.Substring(0, colonDoubleSlashIndex);
                patternWithoutScheme = pattern.Substring(colonDoubleSlashIndex + 3);
            }

            var slashIndex = patternWithoutScheme.IndexOf('/');
            var domainAndPort = slashIndex >= 0
                ? patternWithoutScheme.Substring(0, slashIndex)
                : patternWithoutScheme;

            var ipv6endBracket = domainAndPort.IndexOf(']');
            var colonIndex = domainAndPort.IndexOf(':', ipv6endBracket + 1);
            var port = colonIndex >= 0
                ? domainAndPort.Substring(colonIndex + 1) == "*"
                    ? null
                    : (ushort?)ushort.Parse(domainAndPort.Substring(colonIndex + 1))
                : DefaultPortForScheme(scheme);
            var domain = colonIndex >= 0
                ? domainAndPort.Substring(0, colonIndex)
                : domainAndPort;

            if (string.IsNullOrEmpty(domain))
            {
                throw new ArgumentException("Pattern is empty", nameof(pattern));
            }

            var includeSubdomains = domain.StartsWith(SubdomainWilcard);

            return new ChromePolicyUrlPattern(
                scheme,
                port,
                includeSubdomains
                    ? domain.Substring(SubdomainWilcard.Length)
                    : domain,
                includeSubdomains);
        }