many fixes and improvements - rework for modules/ and common/

feat(emailer): add Postmark and Resend providers

backend/Infrastructure/Security/PasswordGenerator.cs

@@ -0,0 +1,76 @@
+using System.Security.Cryptography;
+using System.Text;
+
+namespace Hutopy.Infrastructure.Security;
+
+// If we need to add special characters we can alternate between 2 pools.
+public static class PasswordGenerator
+{
+    private const string LowerLetters = "abcdefghijklmnopqrstuvwxyz";
+    private const string UpperLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    private const string Numbers = "0123456789";
+    private const string SpecialCharacters = "!@#$%^&*()_+-=[];',./`~{}|:\"<>?";
+
+    private static readonly Random Random = new();
+
+    public static string Next(
+        int length = 15,
+        bool requireNumber = true,
+        bool requireLowercase = true,
+        bool requireCapital = true,
+        bool requireSpecialCharacter = true)
+    {
+        // Create pools based on the requirements
+        var characterPool = new StringBuilder();
+
+        if (requireNumber)
+            characterPool.Append(LowerLetters);
+        
+        if (requireCapital)
+            characterPool.Append(UpperLetters);
+
+        if (requireNumber)
+            characterPool.Append(Numbers);
+
+        if (requireSpecialCharacter)
+            characterPool.Append(SpecialCharacters);
+
+        // Ensure that the length is within the specified bounds
+        var password = new char[length];
+
+        // Ensure at least one character from each required category is included
+        int index = 0;
+        
+        if (requireLowercase)
+            password[index++] = LowerLetters[Random.Next(LowerLetters.Length)];
+        
+        if (requireCapital)
+            password[index++] = UpperLetters[Random.Next(UpperLetters.Length)];
+        
+        if (requireNumber)
+            password[index++] = Numbers[Random.Next(Numbers.Length)];
+        
+        if (requireSpecialCharacter)
+            password[index++] = SpecialCharacters[Random.Next(SpecialCharacters.Length)];
+        
+        // Fill the rest with the password
+        for (int i = index; i < length; i++)
+        {
+            password[i] = characterPool[RandomNumberGenerator.GetInt32(characterPool.Length)];
+        }
+
+        // Shuffle the password to randomize the placement of the required characters
+        Shuffle(password);
+        return new string(password);
+    }
+
+    private static void Shuffle(
+        char[] array)
+    {
+        for (int i = array.Length - 1; i > 0; i--)
+        {
+            int j = Random.Next(i + 1);
+            (array[i], array[j]) = (array[j], array[i]); // Swap elements
+        }
+    }
+}