Add option to skip downloading locally existing files

Author: marioba

src/bin/qfieldcloud-cli

@@ -293,14 +293,18 @@ def upload_files(ctx, project_id, project_path, filter_glob, throw_on_error):
     "--throw-on-error/--no-throw-on-error",
     help="If any project file downloads fails stop downloading the rest. Default: False",
 )
+@click.option(
+    "--skip-existing/--no-skip-existing",
+    help="Skip files if they already exist locally with same sha256 hash. Default: False",
+)
 @click.pass_context
-def download_files(ctx, project_id, local_dir, filter_glob, throw_on_error):
+def download_files(ctx, project_id, local_dir, filter_glob, throw_on_error, skip_existing):
     """Download QFieldCloud project files."""
 
     log(f'Downloading project "{project_id}" files to {local_dir}…')
 
     files = ctx.obj["client"].download_project(
-        project_id, local_dir, filter_glob, throw_on_error, show_progress=True
+        project_id, local_dir, filter_glob, throw_on_error, skip_existing, show_progress=True,
     )
 
     if ctx.obj["format_json"]:

src/qfieldcloud_sdk/sdk.py

@@ -278,6 +278,7 @@ def download_project(
         local_dir: str,
         filter_glob: str = None,
         throw_on_error: bool = False,
+        skip_existing: bool = False,
         show_progress: bool = False,
     ) -> List[Dict]:
         """Download the specified project files into the destination dir.
@@ -297,6 +298,7 @@ def download_project(
             local_dir,
             filter_glob,
             throw_on_error,
+            skip_existing,
             show_progress,
         )
 
@@ -477,6 +479,7 @@ def download_files(
         local_dir: str,
         filter_glob: str = None,
         throw_on_error: bool = False,
+        skip_existing: bool = False,
         show_progress: bool = False,
     ) -> List[Dict]:
         """Download project files.
@@ -489,6 +492,7 @@ def download_files(
             filter_glob (str, optional): Download only files matching the glob pattern. If None download all. Defaults to None.
             throw_on_error (bool, optional): Throw if download error occurres. Defaults to False.
             show_progress (bool, optional): Show progress bar in the console. Defaults to False.
+            skip_existing (bool, optional): Skip files if they already exist locally with same sha256 hash. Defaults to False.
 
         Raises:
             QFieldCloudException: if throw_on_error is True, throw an error if a download request fails.
@@ -504,6 +508,19 @@ def download_files(
         for file in files:
             if fnmatch.fnmatch(file["name"], filter_glob):
                 file["status"] = FileTransferStatus.PENDING
+
+                local_filename = Path(f'{local_dir}/{file["name"]}')
+                if skip_existing and local_filename.exists():
+
+                    sha256_hash = hashlib.sha256()
+                    with open(local_filename, 'rb') as f:
+                        for byte_block in iter(lambda: f.read(4096),b""):
+                            sha256_hash.update(byte_block)
+
+                    if file['sha256'] == sha256_hash.hexdigest():
+                        logging.info(f'Skip file "{file["name"]}" because it already exists locally')
+                        continue
+
                 files_to_download.append(file)
 
         for file in files_to_download: