feat: DTOSS-9159 file-level validation of NBSS Appointment event files

Author: ianfnelson

src/ServiceLayer.Mesh/FileTypes/NbssAppointmentEvents/Validation/FileValidator.cs

@@ -0,0 +1,122 @@
+using System.Text.RegularExpressions;
+using ServiceLayer.Mesh.FileTypes.NbssAppointmentEvents.Models;
+
+namespace ServiceLayer.Mesh.FileTypes.NbssAppointmentEvents.Validation;
+
+public partial class FileValidator : IFileValidator
+{
+    private readonly HeaderFieldRegexValidator _headerExtractIdValidator = new(
+        x => x.ExtractId, "Extract ID", ExtractIdRegex(),
+        ErrorCodes.MissingExtractId, ErrorCodes.InvalidExtractId);
+
+    private readonly HeaderFieldRegexValidator _headerIdRecordCountValidator = new(
+        x => x.RecordCount, "Record count", RecordCountRegex(),
+        ErrorCodes.MissingRecordCount, ErrorCodes.InvalidRecordCount);
+
+    public IEnumerable<ValidationError> Validate(ParsedFile file)
+    {
+        foreach (var error in ValidateHeaderPresence(file))
+        {
+            yield return error;
+        }
+
+        foreach (var error in ValidateTrailerPresence(file))
+        {
+            yield return error;
+        }
+
+        foreach (var error in ValidateExtractId(file))
+        {
+            yield return error;
+        }
+
+        foreach (var error in ValidateRecordCount(file))
+        {
+            yield return error;
+        }
+    }
+
+    private static IEnumerable<ValidationError> ValidateHeaderPresence(ParsedFile file)
+    {
+        if (file.FileHeader == null)
+        {
+            yield return new ValidationError
+            {
+                Code = ErrorCodes.MissingHeader,
+                Error = "Header is missing",
+                Scope = ValidationErrorScope.File
+            };
+        }
+    }
+
+    private static IEnumerable<ValidationError> ValidateTrailerPresence(ParsedFile file)
+    {
+        if (file.FileTrailer == null)
+        {
+            yield return new ValidationError
+            {
+                Code = ErrorCodes.MissingTrailer,
+                Error = "Trailer is missing",
+                Scope = ValidationErrorScope.File
+            };
+        }
+    }
+
+    private IEnumerable<ValidationError> ValidateExtractId(ParsedFile file)
+    {
+        if (file.FileHeader == null) yield break;
+
+        foreach (var error in _headerExtractIdValidator.Validate(file))
+        {
+            yield return error;
+        }
+
+        if (file.FileTrailer != null && file.FileHeader.ExtractId != file.FileTrailer.ExtractId)
+        {
+            yield return new ValidationError
+            {
+                Field = "Extract ID",
+                Code = ErrorCodes.InconsistentExtractId,
+                Error = "Extract ID does not match value in header",
+                Scope = ValidationErrorScope.Trailer
+            };
+        }
+    }
+
+    private IEnumerable<ValidationError> ValidateRecordCount(ParsedFile file)
+    {
+        if (file.FileHeader == null) yield break;
+
+        var headerRecordCountErrors = _headerIdRecordCountValidator.Validate(file).ToList();
+
+        foreach (var error in headerRecordCountErrors)
+        {
+            yield return error;
+        }
+
+        if (file.FileTrailer != null && file.FileHeader.RecordCount != file.FileTrailer.RecordCount)
+        {
+            yield return new ValidationError
+            {
+                Field = "Record count",
+                Code = ErrorCodes.InconsistentRecordCount,
+                Error = "Record count does not match value in header",
+                Scope = ValidationErrorScope.Trailer
+            };
+        } else if (headerRecordCountErrors.Count == 0 && file.DataRecords.Count != int.Parse(file.FileHeader.RecordCount!))
+        {
+            yield return new ValidationError
+            {
+                Code = ErrorCodes.UnexpectedRecordCount,
+                Error = "Record count does not match value in header and trailer",
+                Scope = ValidationErrorScope.File
+            };
+        }
+    }
+
+    [GeneratedRegex(@"^\d{8}$")]
+    private static partial Regex ExtractIdRegex();
+
+    [GeneratedRegex(@"^(?!000000)\d{6}$")]
+    private static partial Regex RecordCountRegex();
+}

src/ServiceLayer.Mesh/FileTypes/NbssAppointmentEvents/Validation/HeaderFieldRegexValidator.cs

@@ -0,0 +1,43 @@
+using System.Linq.Expressions;
+using System.Text.RegularExpressions;
+using ServiceLayer.Mesh.FileTypes.NbssAppointmentEvents.Models;
+
+namespace ServiceLayer.Mesh.FileTypes.NbssAppointmentEvents.Validation;
+
+public class HeaderFieldRegexValidator(
+    Expression<Func<FileHeaderRecord, string?>> fieldSelector,
+    string fieldName,
+    Regex pattern,
+    string errorCodeMissing,
+    string errorCodeInvalidFormat)
+    : IFileValidator
+{
+    public IEnumerable<ValidationError> Validate(ParsedFile file)
+    {
+        var header = file.FileHeader!;
+        var value = fieldSelector.Compile().Invoke(header);
+
+        if (value == null)
+        {
+            yield return new ValidationError
+            {
+                Scope = ValidationErrorScope.Header,
+                Field = fieldName,
+                Error = $"{fieldName} is missing",
+                Code = errorCodeMissing,
+            };
+            yield break;
+        }
+
+        if (!pattern.IsMatch(value))
+        {
+            yield return new ValidationError
+            {
+                Scope = ValidationErrorScope.Header,
+                Field = fieldName,
+                Error = $"{fieldName} is in an invalid format",
+                Code = errorCodeInvalidFormat,
+            };
+        }
+    }
+}

src/ServiceLayer.Mesh/FileTypes/NbssAppointmentEvents/Validation/ValidatorRegistry.cs

@@ -1,4 +1,3 @@
-using System.Runtime.InteropServices.JavaScript;
 using System.Text.RegularExpressions;
 
 namespace ServiceLayer.Mesh.FileTypes.NbssAppointmentEvents.Validation;
@@ -69,7 +68,7 @@ public static IEnumerable<IRecordValidator> GetAllRecordValidators()
 
     public static IEnumerable<IFileValidator> GetAllFileValidators()
     {
-        return [];
+        return [new FileValidator()];
     }
 
     [GeneratedRegex(@"^[BCU]$", RegexOptions.Compiled)]

src/ServiceLayer.Mesh/ValidationError.cs

@@ -4,7 +4,7 @@ public class ValidationError
 {
     public int? RowNumber { get; set; }
 
-    public required string Field { get; set; }
+    public string? Field { get; set; }
 
     public required string Code { get; set; }
 

tests/ServiceLayer.Mesh.Tests/FileTypes/NbssAppointmentEvents/TestDataBuilder.cs

@@ -12,7 +12,7 @@ public static ParsedFile BuildValidParsedFile(int numberOfRecords = 3)
             ExtractId = "00000107",
             TransferStartDate = "20250519",
             TransferStartTime = "153806",
-            RecordCount = numberOfRecords.ToString()
+            RecordCount = numberOfRecords.ToString("D6")
         };
 
         var trailer = new FileTrailerRecord
@@ -21,7 +21,7 @@ public static ParsedFile BuildValidParsedFile(int numberOfRecords = 3)
             ExtractId = "00000107",
             TransferEndDate = "20250519",
             TransferEndTime = "153957",
-            RecordCount = numberOfRecords.ToString()
+            RecordCount = numberOfRecords.ToString("D6")
         };
 
         var dataRecords = Enumerable.Range(1, numberOfRecords)