add Sms segments

Author: pwelter34

src/Arbiter.Communication.Azure/AzureSmsDeliveryService.cs

@@ -1,3 +1,5 @@
+using System.Globalization;
+
 using Arbiter.Communication.Extensions;
 using Arbiter.Communication.Sms;
 
@@ -41,7 +43,7 @@ public AzureSmsDeliveryService(ILogger<AzureSmsDeliveryService> logger, SmsClien
     /// </returns>
     public async Task<SmsResult> Send(SmsMessage message, CancellationToken cancellationToken = default)
     {
-        var truncatedMessage = message.Message.Truncate(20);
+        var truncatedMessage = message.Message.Truncate(50);
         var senderNumber = message.Sender.HasValue() ? message.Sender : _options.Value.SenderNumber;
 
         LogSendingSms(_logger, message.Recipient, senderNumber, truncatedMessage);
@@ -59,8 +61,9 @@ public async Task<SmsResult> Send(SmsMessage message, CancellationToken cancella
 
             if (results.Value.Successful)
             {
-                LogSmsSent(_logger, message.Recipient, truncatedMessage);
-                return SmsResult.Success("SMS sent successfully.");
+                var segments = SmsSegment.Calculate(message.Message);
+                LogSmsSent(_logger, message.Recipient, truncatedMessage, segments);
+                return SmsResult.Success("SMS sent successfully.", segments);
             }
 
             LogSmsSendError(_logger, message.Recipient, truncatedMessage);
@@ -77,8 +80,8 @@ public async Task<SmsResult> Send(SmsMessage message, CancellationToken cancella
     [LoggerMessage(1, LogLevel.Debug, "Sending SMS to '{Recipient}' from '{Sender} with message '{Message}' using Azure Communication")]
     static partial void LogSendingSms(ILogger logger, string recipient, string? sender, string message);
 
-    [LoggerMessage(2, LogLevel.Information, "Sent SMS to '{Recipient}' with message '{Message}'")]
-    static partial void LogSmsSent(ILogger logger, string recipient, string message);
+    [LoggerMessage(2, LogLevel.Information, "Sent SMS to '{Recipient}' with message '{Message}' using segments {Segments}")]
+    static partial void LogSmsSent(ILogger logger, string recipient, string message, int? segments);
 
     [LoggerMessage(3, LogLevel.Error, "Error sending SMS to '{Recipient}' with message '{Message}'")]
     static partial void LogSmsSendError(ILogger logger, string recipient, string message);

src/Arbiter.Communication.Twilio/TwilioSmsDeliveryService.cs

@@ -1,3 +1,5 @@
+using System.Globalization;
+
 using Arbiter.Communication.Extensions;
 using Arbiter.Communication.Sms;
 
@@ -44,7 +46,7 @@ public TwilioSmsDeliveryService(ILogger<TwilioSmsDeliveryService> logger, IOptio
     /// </returns>
     public async Task<SmsResult> Send(SmsMessage message, CancellationToken cancellationToken = default)
     {
-        var truncatedMessage = message.Message.Truncate(20);
+        var truncatedMessage = message.Message.Truncate(50);
         var senderNumber = message.Sender.HasValue() ? message.Sender : _options.Value.SenderNumber;
 
         _logger.LogDebug("Sending SMS to '{Recipient}' from '{Sender} with message '{Message}' using Twilio", message.Recipient, senderNumber, truncatedMessage);
@@ -67,7 +69,8 @@ public async Task<SmsResult> Send(SmsMessage message, CancellationToken cancella
             if (messageResponse.ErrorCode.HasValue)
                 return SmsResult.Fail($"SMS send failed with status {messageResponse.Status}");
 
-            return SmsResult.Success("SMS sent successfully.");
+            var segments = int.TryParse(messageResponse.NumSegments, CultureInfo.InvariantCulture, out var s) ? s : SmsSegment.Calculate(message.Message);
+            return SmsResult.Success("SMS sent successfully.", segments);
         }
         catch (Exception ex)
         {

src/Arbiter.Communication/Sms/SmsResult.cs

@@ -15,6 +15,11 @@ public readonly record struct SmsResult
     /// </summary>
     public string? Message { get; init; }
 
+    /// <summary>
+    /// Gets the number of segments the SMS message was split into, if applicable.
+    /// </summary>
+    public int? Segments { get; init; }
+
     /// <summary>
     /// Gets the exception that occurred during the SMS operation, if any.
     /// </summary>
@@ -24,9 +29,10 @@ public readonly record struct SmsResult
     /// Creates a successful <see cref="SmsResult"/> with an optional message.
     /// </summary>
     /// <param name="message">An optional message describing the success.</param>
+    /// <param name="segments">The number of segments the SMS message was split into, if applicable.</param>
     /// <returns>An <see cref="SmsResult"/> indicating success.</returns>
-    public static SmsResult Success(string? message = null)
-        => new() { Successful = true, Message = message };
+    public static SmsResult Success(string? message = null, int? segments = null)
+        => new() { Successful = true, Message = message, Segments = segments };
 
     /// <summary>
     /// Creates a failed <see cref="SmsResult"/> with an optional message and exception.

src/Arbiter.Communication/Sms/SmsSegment.cs

@@ -0,0 +1,85 @@
+// Ignore Spelling: Sms
+
+using System.Buffers;
+
+namespace Arbiter.Communication.Sms;
+
+/// <summary>
+/// Provides utilities for calculating SMS message segments based on character encoding.
+/// </summary>
+public static class SmsSegment
+{
+    // GSM-7 basic character set for O(1) lookup using SearchValues
+    private static readonly SearchValues<char> Gsm7Characters = SearchValues.Create("@£$¥èéùìòÇ\nØø\rÅåΔ_ΦΓΛΩΠΨΣΘΞÆæßÉ !\"#¤%&'()*+,-./0123456789:;<=>?¡ABCDEFGHIJKLMNOPQRSTUVWXYZÄÖÑܧ¿abcdefghijklmnopqrstuvwxyzäöñüà");
+
+    // GSM-7 extended character set (these require escape character, counting as 2 characters)
+    private static readonly SearchValues<char> Gsm7Extended = SearchValues.Create("^{}\\[~]|€");
+
+    /// <summary>
+    /// Calculates the number of SMS segments required to send the specified message.
+    /// </summary>
+    /// <param name="message">The message to calculate segments for.</param>
+    /// <returns>
+    /// The number of SMS segments required. Returns 0 if the message is null or empty.
+    /// For GSM-7 encoding: 1 segment for up to 160 characters, then 153 characters per additional segment.
+    /// For UCS-2/Unicode encoding: 1 segment for up to 70 characters, then 67 characters per additional segment.
+    /// </returns>
+    /// <remarks>
+    /// Extended GSM-7 characters (^{}\\[~]|€) count as 2 characters each due to the required escape sequence.
+    /// If any character outside the GSM-7 character set is found, UCS-2/Unicode encoding is used for the entire message.
+    /// </remarks>
+    public static int Calculate(ReadOnlySpan<char> message)
+    {
+        if (message.IsEmpty)
+            return 0;
+
+        int effectiveLength = CalculateLength(message, out bool isGsm7);
+
+        // GSM-7 encoding; Single SMS: 160 chars, Concatenated SMS: 153 chars per segment
+        // UCS-2/Unicode encoding; Single SMS: 70 chars, Concatenated SMS: 67 chars per segment
+        (int single, double concatenated) = isGsm7 ? (160, 153) : (70, 67);
+
+        if (effectiveLength <= single)
+            return 1;
+
+        return (int)Math.Ceiling(effectiveLength / concatenated);
+    }
+
+    /// <summary>
+    /// Calculates the effective length of the message and determines the encoding type.
+    /// </summary>
+    /// <param name="text">The text to calculate the length for.</param>
+    /// <param name="isGsm7">
+    /// When this method returns, contains <c>true</c> if the message can be encoded using GSM-7;
+    /// otherwise, <c>false</c> if UCS-2/Unicode encoding is required.
+    /// </param>
+    /// <returns>
+    /// The effective character length of the message. For GSM-7 encoding, extended characters count as 2.
+    /// For UCS-2/Unicode encoding, returns the actual string length.
+    /// </returns>
+    private static int CalculateLength(ReadOnlySpan<char> text, out bool isGsm7)
+    {
+        isGsm7 = true;
+        int length = 0;
+
+        foreach (char c in text)
+        {
+            if (Gsm7Characters.Contains(c))
+            {
+                length++;
+            }
+            else if (Gsm7Extended.Contains(c))
+            {
+                length += 2; // Extended characters require escape sequence
+            }
+            else
+            {
+                // Non-GSM7 character found, must use UCS-2 encoding
+                isGsm7 = false;
+                return text.Length;
+            }
+        }
+
+        return length;
+    }
+}