Implement Bogus for name generation & Region specific usernames for vault items

util/Seeder/Data/CipherUsernameGenerator.cs

@@ -0,0 +1,67 @@
+using Bit.Seeder.Data.Enums;
+
+namespace Bit.Seeder.Data;
+
+/// <summary>
+/// Generates deterministic usernames for companies using configurable patterns.
+/// Uses Bogus library for locale-aware name generation while maintaining determinism
+/// through pre-generated arrays indexed by a seed.
+/// </summary>
+internal sealed class CipherUsernameGenerator
+{
+    private const int _namePoolSize = 1500;
+
+    private readonly Random _random;
+
+    private readonly UsernamePattern _pattern;
+
+    private readonly string[] _firstNames;
+
+    private readonly string[] _lastNames;
+
+    public CipherUsernameGenerator(
+        int seed,
+        UsernamePatternType patternType = UsernamePatternType.FirstDotLast,
+        GeographicRegion? region = null)
+    {
+        _random = new Random(seed);
+        _pattern = UsernamePatterns.GetPattern(patternType);
+
+        // Pre-generate arrays from Bogus for deterministic index-based access
+        var provider = new BogusNameProvider(region ?? GeographicRegion.Global, seed);
+        _firstNames = Enumerable.Range(0, _namePoolSize).Select(_ => provider.FirstName()).ToArray();
+        _lastNames = Enumerable.Range(0, _namePoolSize).Select(_ => provider.LastName()).ToArray();
+    }
+
+    public string Generate(Company company)
+    {
+        var firstName = _firstNames[_random.Next(_firstNames.Length)];
+        var lastName = _lastNames[_random.Next(_lastNames.Length)];
+        return _pattern.Generate(firstName, lastName, company.Domain);
+    }
+
+    /// <summary>
+    /// Generates username using index for deterministic selection across cipher iterations.
+    /// </summary>
+    public string GenerateByIndex(Company company, int index)
+    {
+        var firstName = _firstNames[index % _firstNames.Length];
+        var lastName = _lastNames[(index * 7) % _lastNames.Length]; // Prime multiplier for variety
+        return _pattern.Generate(firstName, lastName, company.Domain);
+    }
+
+    /// <summary>
+    /// Combines deterministic index with random offset for controlled variety.
+    /// </summary>
+    public string GenerateVaried(Company company, int index)
+    {
+        var offset = _random.Next(10);
+        var firstName = _firstNames[(index + offset) % _firstNames.Length];
+        var lastName = _lastNames[(index * 7 + offset) % _lastNames.Length];
+        return _pattern.Generate(firstName, lastName, company.Domain);
+    }
+
+    public string GetFirstName(int index) => _firstNames[index % _firstNames.Length];
+
+    public string GetLastName(int index) => _lastNames[(index * 7) % _lastNames.Length];
+}