renumbering chapters >= 19

20-futures/getflags/flags2_sequential.py

@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+
+"""Download flags of countries (with error handling).
+
+Sequential version
+
+Sample run::
+
+    $ python3 flags2_sequential.py -s DELAY b
+    DELAY site: http://localhost:8002/flags
+    Searching for 26 flags: from BA to BZ
+    1 concurrent connection will be used.
+    --------------------
+    17 flags downloaded.
+    9 not found.
+    Elapsed time: 13.36s
+
+"""
+
+from collections import Counter
+
+import requests
+import tqdm  # type: ignore
+
+from flags2_common import main, save_flag, HTTPStatus, Result
+
+DEFAULT_CONCUR_REQ = 1
+MAX_CONCUR_REQ = 1
+
+# tag::FLAGS2_BASIC_HTTP_FUNCTIONS[]
+def get_flag(base_url: str, cc: str) -> bytes:
+    url = f'{base_url}/{cc}/{cc}.gif'.lower()
+    resp = requests.get(url)
+    if resp.status_code != 200:  # <1>
+        resp.raise_for_status()
+    return resp.content
+
+def download_one(cc: str, base_url: str, verbose: bool = False):
+    try:
+        image = get_flag(base_url, cc)
+    except requests.exceptions.HTTPError as exc:  # <2>
+        res = exc.response
+        if res.status_code == 404:
+            status = HTTPStatus.not_found  # <3>
+            msg = 'not found'
+        else:  # <4>
+            raise
+    else:
+        save_flag(image, f'{cc}.gif')
+        status = HTTPStatus.ok
+        msg = 'OK'
+
+    if verbose:  # <5>
+        print(cc, msg)
+
+    return Result(status, cc)  # <6>
+# end::FLAGS2_BASIC_HTTP_FUNCTIONS[]
+
+# tag::FLAGS2_DOWNLOAD_MANY_SEQUENTIAL[]
+def download_many(cc_list: list[str],
+                  base_url: str,
+                  verbose: bool,
+                  _unused_concur_req: int) -> Counter[int]:
+    counter: Counter[int] = Counter()  # <1>
+    cc_iter = sorted(cc_list)  # <2>
+    if not verbose:
+        cc_iter = tqdm.tqdm(cc_iter)  # <3>
+    for cc in cc_iter:  # <4>
+        try:
+            res = download_one(cc, base_url, verbose)  # <5>
+        except requests.exceptions.HTTPError as exc:  # <6>
+            error_msg = 'HTTP error {res.status_code} - {res.reason}'
+            error_msg = error_msg.format(res=exc.response)
+        except requests.exceptions.ConnectionError:  # <7>
+            error_msg = 'Connection error'
+        else:  # <8>
+            error_msg = ''
+            status = res.status
+
+        if error_msg:
+            status = HTTPStatus.error  # <9>
+        counter[status] += 1           # <10>
+        if verbose and error_msg:      # <11>
+            print(f'*** Error for {cc}: {error_msg}')
+
+    return counter  # <12>
+# end::FLAGS2_DOWNLOAD_MANY_SEQUENTIAL[]
+
+if __name__ == '__main__':
+    main(download_many, DEFAULT_CONCUR_REQ, MAX_CONCUR_REQ)