splitting large files

xlib/file/SplittedFile.py

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+import itertools
+from pathlib import Path
+from typing import List
+
+
+class SplittedFile:
+    @staticmethod
+    def split(filepath : Path, part_size : int, delete_original = False):
+        """
+        splits a file to the parts
+        
+        raises:
+            Exception
+            FileNotFoundError
+        """
+        if part_size == 0:
+            raise Exception(f'part_size == 0')
+        
+        if filepath.exists():
+            filesize = filepath.stat().st_size
+            
+            n_parts = filesize // part_size
+            
+            if filesize - part_size*n_parts != 0:
+                n_parts += 1
+            
+            if n_parts > 100:
+                raise Exception('n_parts > 100')
+                   
+            b = filepath.read_bytes()
+            for n in range(n_parts):
+                part_filepath = filepath.parent / (filepath.name + f'.part{n}')
+                part_filepath.write_bytes(b[n*part_size:(n+1)*part_size])
+            
+            
+            if delete_original:
+                filepath.unlink()
+        else:
+            raise FileNotFoundError()
+        
+    
+    @staticmethod
+    def merge(filepath : Path, delete_parts = False):
+        """
+        if filepath does not exist, merges parts of file if they exist
+        
+        example
+        
+        filename.ext.part0
+        filename.ext.part1
+        ...
+        merged to filename.ext
+        """
+        if filepath.exists():
+            return
+        
+        parts : List[Path] = []
+        for n in itertools.count(start=0):
+            part_filepath = filepath.parent / (filepath.name + f'.part{n}')
+            if part_filepath.exists():
+                parts.append(part_filepath)
+            else:
+                break
+        
+        if len(parts) != 0:
+            bytes_parts = []
+            for part_filepath in parts:
+                bytes_parts.append( part_filepath.read_bytes() )
+            
+            b = b''.join(bytes_parts)
+            
+            filepath.write_bytes(b)
+            
+            if delete_parts:
+                for part_filepath in parts:
+                    part_filepath.unlink()