parse nef file scripts (#3482)

* parse nef file scripts

* nef file path support

---------

Co-authored-by: Vitor Nazário Coelho <vncoelho@gmail.com>

src/Neo.CLI/CLI/MainService.Tools.cs

@@ -14,10 +14,12 @@
 using Neo.Extensions;
 using Neo.IO;
 using Neo.SmartContract;
+using Neo.VM;
 using Neo.Wallets;
 using System;
 using System.Collections.Generic;
 using System.Globalization;
+using System.IO;
 using System.Linq;
 using System.Numerics;
 using System.Reflection;
@@ -441,6 +443,58 @@ private static string Base64Fixed(string str)
             }
         }
 
+        /// <summary>
+        /// Base64 .nef file Analysis
+        /// </summary>
+        [ParseFunction("Base64 .nef file Analysis")]
+        private string? NefFileAnalyis(string base64)
+        {
+            byte[] nefData;
+            if (File.Exists(base64))  // extension name not considered
+                nefData = File.ReadAllBytes(base64);
+            else
+            {
+                try
+                {
+                    nefData = Convert.FromBase64String(base64);
+                }
+                catch { return null; }
+            }
+            NefFile nef;
+            Script script;
+            bool verifyChecksum = false;
+            bool strictMode = false;
+            try
+            {
+                nef = NefFile.Parse(nefData, true);
+                verifyChecksum = true;
+            }
+            catch (FormatException)
+            {
+                nef = NefFile.Parse(nefData, false);
+            }
+            catch { return null; }
+            try
+            {
+                script = new Script(nef.Script, true);
+                strictMode = true;
+            }
+            catch (BadScriptException)
+            {
+                script = new Script(nef.Script, false);
+            }
+            catch { return null; }
+            string? result = ScriptsToOpCode(Convert.ToBase64String(nef.Script.ToArray()));
+            if (result == null)
+                return null;
+            string prefix = $"\r\n# Compiler: {nef.Compiler}";
+            if (!verifyChecksum)
+                prefix += $"\r\n# Warning: Invalid .nef file checksum";
+            if (!strictMode)
+                prefix += $"\r\n# Warning: Failed in {nameof(strictMode)}";
+            return prefix + result;
+        }
+
         /// <summary>
         /// Checks if the string is null or cannot be printed.
         /// </summary>