Support downloading .zip of arbitrary photos, clipboard.

Now that creating zips of any photo set is easier, we can
let the user download whatever is on their clipboard.

etiquette/helpers.py

@@ -232,6 +232,18 @@ def hash_file(filepath, hasher):
 def hash_file_md5(filepath):
     return hash_file(filepath, hasher=hashlib.md5())
 
+def hash_photoset(photos):
+    '''
+    Given some photos, return a fingerprint string for that particular set.
+    '''
+    hasher = hashlib.md5()
+
+    photo_ids = sorted(set(p.id for p in photos))
+    for photo_id in photo_ids:
+        hasher.update(photo_id.encode('utf-8'))
+
+    return hasher.hexdigest()
+
 def hyphen_range(s):
     '''
     Given a string like '1-3', return numbers (1, 3) representing lower

frontends/etiquette_flask/etiquette_flask/endpoints/photo_endpoints.py

@@ -5,12 +5,15 @@ import urllib.parse
 
 import etiquette
 
+from voussoirkit import cacheclass
+
 from .. import common
 from .. import decorators
 from .. import jsonify
 
 site = common.site
 session_manager = common.session_manager
+photo_download_zip_tokens = cacheclass.Cache(maxlen=100)
 
 
 # Individual photos ################################################################################
@@ -226,6 +229,59 @@ def post_batch_photos_photo_cards():
     response = jsonify.make_json_response(divs)
     return response
 
+# Zipping ##########################################################################################
+
+@site.route('/batch/photos/download_zip/<zip_token>', methods=['GET'])
+def get_batch_photos_download_zip(zip_token):
+    '''
+    After the user has generated their zip token, they can retrieve
+    that zip file.
+    '''
+    zip_token = zip_token.split('.')[0]
+    try:
+        photo_ids = photo_download_zip_tokens[zip_token]
+    except KeyError:
+        flask.abort(404)
+
+    # Let's re-validate those IDs just in case anything has changed.
+    photos = list(common.P_photos(photo_ids, response_type='json'))
+    if not photos:
+        flask.abort(400)
+
+    streamed_zip = etiquette.helpers.zip_photos(photos)
+    download_as = zip_token + '.zip'
+    download_as = urllib.parse.quote(download_as)
+
+    outgoing_headers = {
+        'Content-Type': 'application/octet-stream',
+        'Content-Disposition': f'attachment; filename*=UTF-8\'\'{download_as}',
+    }
+    return flask.Response(streamed_zip, headers=outgoing_headers)
+
+@site.route('/batch/photos/download_zip', methods=['POST'])
+@decorators.required_fields(['photo_ids'], forbid_whitespace=True)
+def post_batch_photos_download_zip():
+    '''
+    Initiating file downloads via POST requests is a bit clunky and unreliable,
+    so the way this works is we generate a token representing the photoset
+    that they want, and then they can retrieve the zip itself via GET.
+    '''
+    photo_ids = request.form['photo_ids']
+    photo_ids = etiquette.helpers.comma_space_split(photo_ids)
+
+    photos = list(common.P_photos(photo_ids, response_type='json'))
+    if not photos:
+        flask.abort(400)
+
+    photo_ids = [p.id for p in photos]
+
+    zip_token = etiquette.helpers.hash_photoset(photos)
+    photo_download_zip_tokens[zip_token] = photo_ids
+
+    response = {'zip_token': zip_token}
+    response = jsonify.make_json_response(response)
+    return response
+
 # Search ###########################################################################################
 
 def get_search_core():

frontends/etiquette_flask/templates/clipboard.html

@@ -43,12 +43,13 @@ body
     grid-area: right;
 
     display: grid;
-    grid-template-rows: 75px 75px 75px 75px auto;
+    grid-template-rows: 75px 75px 75px 75px 75px auto;
     grid-template-areas:
         "add_tag_area"
         "remove_tag_area"
         "refresh_metadata_area"
         "searchhidden_area"
+        "download_zip_area"
         "message_area";
 
     background-color: rgba(0, 0, 0, 0.1);
@@ -73,6 +74,11 @@ body
     grid-area: searchhidden_area;
     margin: auto;
 }
+#download_zip_area
+{
+    grid-area: download_zip_area;
+    margin: auto;
+}
 #message_area
 {
     grid-area: message_area;
@@ -112,6 +118,10 @@ body
         </span>
     </div>
 
+    <div id="download_zip_area">
+        <button class="yellow_button" id="download_zip_button" onclick="submit_download_zip(download_zip_callback)">Download .zip</button>
+    </div>
+
     <div id="message_area">
     </div>
 </div>
@@ -262,6 +272,25 @@ function add_remove_callback(response)
     common.create_message_bubble(message_area, message_positivity, message_text, 8000);
 }
 
+function submit_download_zip(callback)
+{
+    if (photo_clipboard.clipboard.size == 0)
+        {return;}
+
+    var url = "/batch/photos/download_zip";
+    var photo_ids = Array.from(photo_clipboard.clipboard).join(",");
+    var data = new FormData();
+    data.append("photo_ids", photo_ids);
+    common.post(url, data, callback);
+}
+
+function download_zip_callback(response)
+{
+    var zip_token = response["data"]["zip_token"];
+    var url = `/batch/photos/download_zip/${zip_token}.zip`;
+    window.location.href = url;
+}
+
 var refresh_in_progress = false;
 function submit_refresh_metadata(callback)
 {