From 5626e9432ae27cdbc7442eb87eee17bd40d6cacc Mon Sep 17 00:00:00 2001
From: Mirko Da Corte <mirko@etherna.io>
Date: Sun, 4 Aug 2024 18:02:29 +0200
Subject: [PATCH] add ToLocalUFile feature

---
 src/UniversalFiles/IUFileProvider.cs |  8 +++++++
 src/UniversalFiles/UFileProvider.cs  | 33 ++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/src/UniversalFiles/IUFileProvider.cs b/src/UniversalFiles/IUFileProvider.cs
index 4cef673..2c4ec5c 100644
--- a/src/UniversalFiles/IUFileProvider.cs
+++ b/src/UniversalFiles/IUFileProvider.cs
@@ -12,10 +12,18 @@
 // You should have received a copy of the GNU Lesser General Public License along with UniversalFiles.
 // If not, see <https://www.gnu.org/licenses/>.
 
+using System.Threading.Tasks;
+
 namespace Etherna.UniversalFiles
 {
     public interface IUFileProvider
     {
         UFile BuildNewUFile(UUri uuri);
+
+        Task<BasicUFile> ToLocalUFileAsync(
+            UFile inputUFile,
+            UUriKind allowedUriKinds = UUriKind.All,
+            string? baseDirectory = null,
+            BasicUUri? outputUUri = null);
     }
 }
\ No newline at end of file
diff --git a/src/UniversalFiles/UFileProvider.cs b/src/UniversalFiles/UFileProvider.cs
index 4799d7b..95f7fc8 100644
--- a/src/UniversalFiles/UFileProvider.cs
+++ b/src/UniversalFiles/UFileProvider.cs
@@ -14,7 +14,9 @@
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Net.Http;
+using System.Threading.Tasks;
 
 namespace Etherna.UniversalFiles
 {
@@ -39,5 +41,36 @@ public UFile BuildNewUFile(UUri uuri)
         
         public void RegisterUUriType<TUUri>(Func<TUUri, UFile> builder) where TUUri : UUri =>
             uFileBuilders[typeof(TUUri)] = uuri => builder((TUUri)uuri);
+
+        public async Task<BasicUFile> ToLocalUFileAsync(
+            UFile inputUFile,
+            UUriKind allowedUriKinds = UUriKind.All,
+            string? baseDirectory = null,
+            BasicUUri? outputUUri = null)
+        {
+            ArgumentNullException.ThrowIfNull(inputUFile, nameof(inputUFile));
+
+            // If it's already a local file, skip file retrieve.
+            if (inputUFile is BasicUFile basicUFile &&
+                (basicUFile.FileUri.UriKind & allowedUriKinds & UUriKind.Local) != 0)
+                return basicUFile;
+            
+            if (outputUUri != null && outputUUri.UriKind != UUriKind.LocalAbsolute)
+                throw new InvalidOperationException("If provided, output uuri must be local and absolute");
+
+            if (outputUUri is null)
+            {
+                var fileName = await inputUFile.TryGetFileNameAsync().ConfigureAwait(false);
+                outputUUri = fileName is null ?
+                    new BasicUUri(Path.GetTempFileName()) :
+                    new BasicUUri(Path.Join(Path.GetTempPath(), fileName));
+            }
+
+            using var inputFileStream = (await inputUFile.ReadToStreamAsync(allowedUriKinds, baseDirectory).ConfigureAwait(false)).Stream;
+            using var outputFileStream = new FileStream(outputUUri.ToAbsoluteUri().Item1, FileMode.Create);
+            await inputFileStream.CopyToAsync(outputFileStream).ConfigureAwait(false);
+
+            return (BasicUFile)BuildNewUFile(outputUUri);
+        }
     }
 }
\ No newline at end of file