From 81846764a1cc77db9890aaee9fd9cf25dd4db01c Mon Sep 17 00:00:00 2001
From: Ivan Habunek <ivan@habunek.com>
Date: Sun, 14 Aug 2022 10:02:41 +0200
Subject: [PATCH] Don't download already downloaded files

---
 tests/test_progress.py | 14 +++++++++++---
 twitchdl/http.py       |  6 ++++++
 twitchdl/progress.py   | 21 +++++++++++++++++----
 3 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/tests/test_progress.py b/tests/test_progress.py
index dcb711f..8b2b672 100644
--- a/tests/test_progress.py
+++ b/tests/test_progress.py
@@ -19,26 +19,32 @@ def test_downloaded():
     progress.start(3, 300)
 
     assert progress.downloaded == 0
+    assert progress.progress_bytes == 0
     assert progress.progress_perc == 0
 
     progress.advance(1, 100)
     assert progress.downloaded == 100
+    assert progress.progress_bytes == 100
     assert progress.progress_perc == 11
 
     progress.advance(2, 200)
     assert progress.downloaded == 300
+    assert progress.progress_bytes == 300
     assert progress.progress_perc == 33
 
     progress.advance(3, 150)
     assert progress.downloaded == 450
+    assert progress.progress_bytes == 450
     assert progress.progress_perc == 50
 
     progress.advance(1, 50)
     assert progress.downloaded == 500
+    assert progress.progress_bytes == 500
     assert progress.progress_perc == 55
 
     progress.abort(2)
-    assert progress.downloaded == 300
+    assert progress.downloaded == 500
+    assert progress.progress_bytes == 300
     assert progress.progress_perc == 33
 
     progress.start(2, 300)
@@ -47,14 +53,16 @@ def test_downloaded():
     progress.advance(2, 300)
     progress.advance(3, 150)
 
-    assert progress.downloaded == 900
+    assert progress.downloaded == 1100
+    assert progress.progress_bytes == 900
     assert progress.progress_perc == 100
 
     progress.end(1)
     progress.end(2)
     progress.end(3)
 
-    assert progress.downloaded == 900
+    assert progress.downloaded == 1100
+    assert progress.progress_bytes == 900
     assert progress.progress_perc == 100
 
 
diff --git a/twitchdl/http.py b/twitchdl/http.py
index 2452b6a..02b6a2a 100644
--- a/twitchdl/http.py
+++ b/twitchdl/http.py
@@ -1,6 +1,7 @@
 import asyncio
 import httpx
 import logging
+import os
 import time
 
 from typing import List, Optional, Union
@@ -91,6 +92,11 @@ async def download_with_retries(
     token_bucket: AnyTokenBucket,
 ):
     async with semaphore:
+        if os.path.exists(target):
+            size = os.path.getsize(target)
+            progress.already_downloaded(task_id, size)
+            return
+
         for n in range(RETRY_COUNT):
             try:
                 return await download(client, task_id, source, target, progress, token_bucket)
diff --git a/twitchdl/progress.py b/twitchdl/progress.py
index 5ce57c6..d34d09b 100644
--- a/twitchdl/progress.py
+++ b/twitchdl/progress.py
@@ -29,6 +29,7 @@ class Progress:
     vod_count: int
     downloaded: int = 0
     estimated_total: Optional[int] = None
+    progress_bytes: int = 0
     progress_perc: int = 0
     remaining_time: Optional[int] = None
     speed: Optional[float] = None
@@ -54,10 +55,22 @@ class Progress:
             raise ValueError(f"Task {task_id}: cannot advance, not started")
 
         self.downloaded += chunk_size
+        self.progress_bytes += chunk_size
         self.tasks[task_id].advance(chunk_size)
         self._calculate_progress()
         self.print()
 
+    def already_downloaded(self, task_id: int, size: int):
+        if task_id in self.tasks:
+            raise ValueError(f"Task {task_id}: cannot mark as downloaded, already started")
+
+        self.tasks[task_id] = Task(task_id, size)
+        self.progress_bytes += size
+        self.vod_downloaded_count += 1
+        self._calculate_total()
+        self._calculate_progress()
+        self.print()
+
     def abort(self, task_id: int):
         logger.debug(f"#{task_id} abort")
 
@@ -65,7 +78,7 @@ class Progress:
             raise ValueError(f"Task {task_id}: cannot abort, not started")
 
         del self.tasks[task_id]
-        self.downloaded = sum(t.downloaded for t in self.tasks.values())
+        self.progress_bytes = sum(t.downloaded for t in self.tasks.values())
 
         self._calculate_total()
         self._calculate_progress()
@@ -89,15 +102,15 @@ class Progress:
 
     def _calculate_progress(self):
         elapsed_time = time.time() - self.start_time
-        self.progress_perc = int(100 * self.downloaded / self.estimated_total) if self.estimated_total else 0
+        self.progress_perc = int(100 * self.progress_bytes / self.estimated_total) if self.estimated_total else 0
         self.speed = self.downloaded / elapsed_time if elapsed_time else None
-        self.remaining_time = int((self.estimated_total - self.downloaded) / self.speed) if self.estimated_total and self.speed else None
+        self.remaining_time = int((self.estimated_total - self.progress_bytes) / self.speed) if self.estimated_total and self.speed else None
 
     def print(self):
         progress = " ".join([
             f"Downloaded {self.vod_downloaded_count}/{self.vod_count} VODs",
             f"({self.progress_perc}%)",
-            f"<cyan>{format_size(self.downloaded)}</cyan>",
+            f"<cyan>{format_size(self.progress_bytes)}</cyan>",
             f"of <cyan>~{format_size(self.estimated_total)}</cyan>" if self.estimated_total else "",
             f"at <cyan>{format_size(self.speed)}/s</cyan>" if self.speed else "",
             f"remaining <cyan>~{format_duration(self.remaining_time)}</cyan>" if self.remaining_time is not None else "",