🦺 added validators for query-params

Co-authored-by: Sindre Kjelsrud <kjelsrudsindre@gmail.com>

backend/Util/Validators.cs

@@ -0,0 +1,56 @@
+namespace backend;
+
+public static class QueryParameterValidators
+{
+    private static readonly string[] sortTypes = new[]
+    {
+        "titleasc", "titledesc", "yearasc", "yeardesc"
+    };
+
+    private static readonly string[] movieTypes = new[]
+    {
+        "movie", "series", "episode"
+    };
+
+
+    // Assuming `s` is a non-nullable parameter and can be any string
+    // If there are specific requirements for `s`, additional validation can be added
+    public static bool IsValidS(string s)
+    {
+        return !string.IsNullOrWhiteSpace(s);
+    }
+
+    // Assuming `type` can be any string but you might want to limit it to specific values
+    // If there are predefined types, you can replace the body with something like: return new List<string> { "type1", "type2" }.Contains(type);
+    public static bool IsValidType(string? type)
+    {
+        return string.IsNullOrWhiteSpace(type) || movieTypes.Contains(type.ToLower());
+    }
+
+    // For `year`, assuming it's a 4 digit representation of a year
+    public static bool IsValidYear(string? year)
+    {
+        if (string.IsNullOrWhiteSpace(year)) return true;
+
+        return int.TryParse(year, out int parsedYear) && parsedYear > 1900 && parsedYear <= DateTime.Now.Year;
+    }
+
+    // Assuming `sort` can be any string but you might want to limit it to specific values
+    // If there are predefined sorts, you can replace the body with something like: return new List<string> { "asc", "desc" }.Contains(sort);
+    public static bool IsValidSort(string? sort)
+    {
+        return string.IsNullOrWhiteSpace(sort) || sortTypes.Contains(sort.ToLower());
+    }
+
+    // Assuming `pageNumber` should be 1 or more
+    public static bool IsValidPageNumber(int pageNumber)
+    {
+        return pageNumber > 0;
+    }
+
+    // Assuming `pageSize` should be between 1 to 100 (or any other limits you might want to set)
+    public static bool IsValidPageSize(int pageSize)
+    {
+        return pageSize > 0 && pageSize <= 100; // you can adjust the upper limit as per requirements
+    }
+}