Fix libpq parsing and refactors/code cleanup

pgLabII.PgUtils/ConnectionStrings/CodecCommon.cs

@@ -0,0 +1,101 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using Npgsql;
+
+namespace pgLabII.PgUtils.ConnectionStrings;
+
+/// <summary>
+/// Shared helper utilities for codecs to reduce duplication (SSL mode mapping, host:port parsing/formatting,
+/// URL query parsing, and .NET/libpq quoting helpers).
+/// </summary>
+internal static class CodecCommon
+{
+    // SSL mapping
+    public static SslMode ParseSslModeLoose(string s)
+        => s.Trim().ToLowerInvariant() switch
+        {
+            "disable" => SslMode.Disable,
+            "allow" => SslMode.Allow,
+            "prefer" => SslMode.Prefer,
+            "require" => SslMode.Require,
+            "verify-ca" or "verifyca" => SslMode.VerifyCA,
+            "verify-full" or "verifyfull" => SslMode.VerifyFull,
+            _ => throw new ArgumentException($"Not a valid SSL Mode: {s}")
+        };
+
+    public static string FormatSslModeUrlLike(SslMode mode) => mode switch
+    {
+        SslMode.Disable => "disable",
+        SslMode.Allow => "allow",
+        SslMode.Prefer => "prefer",
+        SslMode.Require => "require",
+        SslMode.VerifyCA => "verify-ca",
+        SslMode.VerifyFull => "verify-full",
+        _ => "prefer"
+    };
+   
+
+    // host:port parsing for plain or [IPv6]:port
+    public static void ParseHostPort(string hostPart, out string host, out ushort? port)
+    {
+        host = hostPart;
+        port = null;
+        if (string.IsNullOrWhiteSpace(hostPart)) 
+            return;
+        
+        if (hostPart[0] == '[')
+        {
+            int end = hostPart.IndexOf(']');
+            if (end > 0)
+            {
+                host = hostPart[1..end];
+                if (end + 1 < hostPart.Length && hostPart[end + 1] == ':')
+                {
+                    string ps = hostPart[(end + 2)..];
+                    if (ushort.TryParse(ps, NumberStyles.Integer, CultureInfo.InvariantCulture, out var p))
+                        port = p;
+                }
+            }
+            return;
+        }
+        int colon = hostPart.LastIndexOf(':');
+        if (colon > 0 && colon < hostPart.Length - 1)
+        {
+            var ps = hostPart.Substring(colon + 1);
+            if (ushort.TryParse(ps, NumberStyles.Integer, CultureInfo.InvariantCulture, out var p))
+            {
+                host = hostPart.Substring(0, colon);
+                port = p;
+            }
+        }
+    }
+
+    public static string FormatHost(HostEndpoint h)
+    {
+        var host = h.Host;
+        if (host.Contains(':') && !host.StartsWith("[")) 
+            host = "[" + host + "]"; // IPv6
+        
+        return h.Port.HasValue ? host + ":" + h.Port.Value.ToString(CultureInfo.InvariantCulture) : host;
+    }
+    
+    public static string[] SplitHosts(string hostList)
+        => hostList.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+
+    public static Dictionary<string, string> ParseQuery(string query)
+    {
+        var dict = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+        if (string.IsNullOrEmpty(query)) return dict;
+        foreach (var kv in query.Split('&', StringSplitOptions.RemoveEmptyEntries))
+        {
+            var parts = kv.Split('=', 2);
+            var key = Uri.UnescapeDataString(parts[0]);
+            var val = parts.Length > 1 ? Uri.UnescapeDataString(parts[1]) : string.Empty;
+            dict[key] = val;
+        }
+        return dict;
+    }
+}