prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  We need a new API that displays concordances information for all chants in the database
  In an email from Jan:
  
  > The intensive process of getting all the data from CD via individual json-cid requests (59.000+) is running already on the 3rd day (and not finished yet) but this will not keep the Cantus data fresh in the Cantus Index API in the long term.
  > 
  > The solution would be to regularly create a large JSON file export of all the CD chants (with the same fields as in json-cid exports) and make it available as a file to download. An example of such json export is here: https://austriamanus.org/files/concordances-export.json
  > This kind of data transfer works also with the MMMO database which has approximately half the amount of data compared to a CD. I believe it would also be the best solution for CD.
  
  This will not be difficult. We can use the code in our `json-con` API, but return all chants rather than filtering them by Cantus ID.
  
  What's a good path for this API to live at? `/json-concordances-export`?
  
  </issue>
  <code>
  [start of django/cantusdb_project/main_app/management/commands/update_cached_concordances.py]
  1 import ujson
  2 import os
  3 from sys import stdout
  4 from datetime import datetime
  5 from collections import defaultdict
  6 from django.db.models.query import QuerySet
  7 from django.core.management.base import BaseCommand
  8 from main_app.models import Chant
  9 
  10 
  11 class Command(BaseCommand):
  12     def handle(self, *args, **kwargs) -> None:
  13         CACHE_DIR: str = "api_cache"
  14         FILEPATH: str = f"{CACHE_DIR}/concordances.json"
  15         start_time: str = datetime.now().isoformat()
  16         stdout.write(f"Running update_cached_concordances at {start_time}.\n")
  17         concordances: dict = get_concordances()
  18         write_time: str = datetime.now().isoformat()
  19         metadata: dict = {
  20             "last_updated": write_time,
  21         }
  22         data_and_metadata: dict = {
  23             "data": concordances,
  24             "metadata": metadata,
  25         }
  26         stdout.write(f"Attempting to make directory at {CACHE_DIR} to hold cache: ")
  27         try:
  28             os.mkdir(CACHE_DIR)
  29             stdout.write(f"successfully created directory at {CACHE_DIR}.\n")
  30         except FileExistsError:
  31             stdout.write(f"directory at {CACHE_DIR} already exists.\n")
  32         stdout.write(f"Writing concordances to {FILEPATH} at {write_time}.\n")
  33         with open(FILEPATH, "w") as json_file:
  34             ujson.dump(data_and_metadata, json_file)
  35         end_time = datetime.now().isoformat()
  36         stdout.write(
  37             f"Concordances successfully written to {FILEPATH} at {end_time}.\n\n"
  38         )
  39 
  40 
  41 def get_concordances() -> dict:
  42     DOMAIN: str = "https://cantusdatabase.org"
  43 
  44     stdout.write("Querying database for published chants\n")
  45     published_chants: QuerySet[Chant] = Chant.objects.filter(source__published=True)
  46     values: QuerySet[dict] = published_chants.select_related(
  47         "source",
  48         "feast",
  49         "genre",
  50         "office",
  51     ).values(
  52         "id",
  53         "source_id",
  54         "source__siglum",
  55         "folio",
  56         "c_sequence",
  57         "incipit",
  58         "feast__name",
  59         "genre__name",
  60         "office__name",
  61         "position",
  62         "cantus_id",
  63         "image_link",
  64         "mode",
  65         "manuscript_full_text_std_spelling",
  66         "volpiano",
  67     )
  68 
  69     stdout.write("Processing chants\n")
  70     concordances: defaultdict = defaultdict(list)
  71     for chant in values:
  72         source_id: int = chant["source_id"]
  73         source_absolute_url: str = f"{DOMAIN}/source/{source_id}/"
  74         chant_id: int = chant["id"]
  75         chant_absolute_url: str = f"{DOMAIN}/chant/{chant_id}/"
  76 
  77         concordances[chant["cantus_id"]].append(
  78             {
  79                 "siglum": chant["source__siglum"],
  80                 "srclink": source_absolute_url,
  81                 "chantlink": chant_absolute_url,
  82                 "folio": chant["folio"],
  83                 "sequence": chant["c_sequence"],
  84                 "incipit": chant["incipit"],
  85                 "feast": chant["feast__name"],
  86                 "genre": chant["genre__name"],
  87                 "office": chant["office__name"],
  88                 "position": chant["position"],
  89                 "cantus_id": chant["cantus_id"],
  90                 "image": chant["image_link"],
  91                 "mode": chant["mode"],
  92                 "full_text": chant["manuscript_full_text_std_spelling"],
  93                 "melody": chant["volpiano"],
  94                 "db": "CD",
  95             }
  96         )
  97 
  98     stdout.write(f"All chants processed - found {len(concordances)} Cantus IDs\n")
  99 
  100     return dict(concordances)
  101
  [end of django/cantusdb_project/main_app/management/commands/update_cached_concordances.py]
  </code>
  
  I need you to solve this issue by generating a single patch file that I can apply directly to this repository using git apply. Please respond with a single patch file in the following format.
  <patch>
  diff --git a/file.py b/file.py
  --- a/file.py
  +++ b/file.py
  @@ -1,27 +1,35 @@
   def euclidean(a, b):
  -    while b:
  -        a, b = b, a % b
  -    return a
  +    if b == 0:
  +        return a
  +    return euclidean(b, a % b)
   
   
   def bresenham(x0, y0, x1, y1):
       points = []
       dx = abs(x1 - x0)
       dy = abs(y1 - y0)
  -    sx = 1 if x0 < x1 else -1
  -    sy = 1 if y0 < y1 else -1
  -    err = dx - dy
  +    x, y = x0, y0
  +    sx = -1 if x0 > x1 else 1
  +    sy = -1 if y0 > y1 else 1
   
  -    while True:
  -        points.append((x0, y0))
  -        if x0 == x1 and y0 == y1:
  -            break
  -        e2 = 2 * err
  -        if e2 > -dy:
  -            err -= dy
  -            x0 += sx
  -        if e2 < dx:
  -            err += dx
  -            y0 += sy
  +    if dx > dy:
  +        err = dx / 2.0
  +        while x != x1:
  +            points.append((x, y))
  +            err -= dy
  +            if err < 0:
  +                y += sy
  +                err += dx
  +            x += sx
  +    else:
  +        err = dy / 2.0
  +        while y != y1:
  +            points.append((x, y))
  +            err -= dx
  +            if err < 0:
  +                x += sx
  +                err += dy
  +            y += sy
  +
  +    points.append((x, y))
       return points
  
  </patch>
golden_diff: diff --git a/django/cantusdb_project/main_app/management/commands/update_cached_concordances.py b/django/cantusdb_project/main_app/management/commands/update_cached_concordances.py
  --- a/django/cantusdb_project/main_app/management/commands/update_cached_concordances.py
  +++ b/django/cantusdb_project/main_app/management/commands/update_cached_concordances.py
  @@ -1,6 +1,7 @@
   import ujson
   import os
   from sys import stdout
  +from typing import Optional
   from datetime import datetime
   from collections import defaultdict
   from django.db.models.query import QuerySet
  @@ -8,10 +9,27 @@
   from main_app.models import Chant
   
   
  +# Usage: `python manage.py update_cached_concordances`
  +# or `python manage.py update_cached_concordances -d "/path/to/directory/in/which/to/save/concordances"`
  +
  +
   class Command(BaseCommand):
  +    def add_arguments(self, parser):
  +        parser.add_argument(
  +            "-d",
  +            "--directory",
  +            help="Optional filepath specifying a directory to output concordances",
  +            type=str,
  +        )
  +
       def handle(self, *args, **kwargs) -> None:
  -        CACHE_DIR: str = "api_cache"
  -        FILEPATH: str = f"{CACHE_DIR}/concordances.json"
  +        cache_dir: Optional[str] = kwargs["directory"]
  +        if not cache_dir:
  +            # this default directory should match the value in docker-compose.yml,
  +            # at services:django:volumes:api_cache_volume
  +            cache_dir = "/resources/api_cache"
  +
  +        filepath: str = f"{cache_dir}/concordances.json"
           start_time: str = datetime.now().isoformat()
           stdout.write(f"Running update_cached_concordances at {start_time}.\n")
           concordances: dict = get_concordances()
  @@ -23,22 +41,29 @@
               "data": concordances,
               "metadata": metadata,
           }
  -        stdout.write(f"Attempting to make directory at {CACHE_DIR} to hold cache: ")
  +        stdout.write(f"Attempting to make directory at {cache_dir} to hold cache: ")
           try:
  -            os.mkdir(CACHE_DIR)
  -            stdout.write(f"successfully created directory at {CACHE_DIR}.\n")
  +            os.mkdir(cache_dir)
  +            stdout.write(f"successfully created directory at {cache_dir}.\n")
           except FileExistsError:
  -            stdout.write(f"directory at {CACHE_DIR} already exists.\n")
  -        stdout.write(f"Writing concordances to {FILEPATH} at {write_time}.\n")
  -        with open(FILEPATH, "w") as json_file:
  +            stdout.write(f"directory at {cache_dir} already exists.\n")
  +        stdout.write(f"Writing concordances to {filepath} at {write_time}.\n")
  +        with open(filepath, "w") as json_file:
               ujson.dump(data_and_metadata, json_file)
           end_time = datetime.now().isoformat()
           stdout.write(
  -            f"Concordances successfully written to {FILEPATH} at {end_time}.\n\n"
  +            f"Concordances successfully written to {filepath} at {end_time}.\n\n"
           )
   
   
   def get_concordances() -> dict:
  +    """Fetch all published chants in the database, group them by Cantus ID, and return
  +    a dictionary containing information on each of these chants.
  +
  +    Returns:
  +        dict: A dictionary where each key is a Cantus ID and each value is a list all
  +          published chants in the database with that Cantus ID.
  +    """
       DOMAIN: str = "https://cantusdatabase.org"
   
       stdout.write("Querying database for published chants\n")
  
verification_info: {"golden_diff": "diff --git a/django/cantusdb_project/main_app/management/commands/update_cached_concordances.py b/django/cantusdb_project/main_app/management/commands/update_cached_concordances.py\n--- a/django/cantusdb_project/main_app/management/commands/update_cached_concordances.py\n+++ b/django/cantusdb_project/main_app/management/commands/update_cached_concordances.py\n@@ -1,6 +1,7 @@\n import ujson\n import os\n from sys import stdout\n+from typing import Optional\n from datetime import datetime\n from collections import defaultdict\n from django.db.models.query import QuerySet\n@@ -8,10 +9,27 @@\n from main_app.models import Chant\n \n \n+# Usage: `python manage.py update_cached_concordances`\n+# or `python manage.py update_cached_concordances -d \"/path/to/directory/in/which/to/save/concordances\"`\n+\n+\n class Command(BaseCommand):\n+    def add_arguments(self, parser):\n+        parser.add_argument(\n+            \"-d\",\n+            \"--directory\",\n+            help=\"Optional filepath specifying a directory to output concordances\",\n+            type=str,\n+        )\n+\n     def handle(self, *args, **kwargs) -> None:\n-        CACHE_DIR: str = \"api_cache\"\n-        FILEPATH: str = f\"{CACHE_DIR}/concordances.json\"\n+        cache_dir: Optional[str] = kwargs[\"directory\"]\n+        if not cache_dir:\n+            # this default directory should match the value in docker-compose.yml,\n+            # at services:django:volumes:api_cache_volume\n+            cache_dir = \"/resources/api_cache\"\n+\n+        filepath: str = f\"{cache_dir}/concordances.json\"\n         start_time: str = datetime.now().isoformat()\n         stdout.write(f\"Running update_cached_concordances at {start_time}.\\n\")\n         concordances: dict = get_concordances()\n@@ -23,22 +41,29 @@\n             \"data\": concordances,\n             \"metadata\": metadata,\n         }\n-        stdout.write(f\"Attempting to make directory at {CACHE_DIR} to hold cache: \")\n+        stdout.write(f\"Attempting to make directory at {cache_dir} to hold cache: \")\n         try:\n-            os.mkdir(CACHE_DIR)\n-            stdout.write(f\"successfully created directory at {CACHE_DIR}.\\n\")\n+            os.mkdir(cache_dir)\n+            stdout.write(f\"successfully created directory at {cache_dir}.\\n\")\n         except FileExistsError:\n-            stdout.write(f\"directory at {CACHE_DIR} already exists.\\n\")\n-        stdout.write(f\"Writing concordances to {FILEPATH} at {write_time}.\\n\")\n-        with open(FILEPATH, \"w\") as json_file:\n+            stdout.write(f\"directory at {cache_dir} already exists.\\n\")\n+        stdout.write(f\"Writing concordances to {filepath} at {write_time}.\\n\")\n+        with open(filepath, \"w\") as json_file:\n             ujson.dump(data_and_metadata, json_file)\n         end_time = datetime.now().isoformat()\n         stdout.write(\n-            f\"Concordances successfully written to {FILEPATH} at {end_time}.\\n\\n\"\n+            f\"Concordances successfully written to {filepath} at {end_time}.\\n\\n\"\n         )\n \n \n def get_concordances() -> dict:\n+    \"\"\"Fetch all published chants in the database, group them by Cantus ID, and return\n+    a dictionary containing information on each of these chants.\n+\n+    Returns:\n+        dict: A dictionary where each key is a Cantus ID and each value is a list all\n+          published chants in the database with that Cantus ID.\n+    \"\"\"\n     DOMAIN: str = \"https://cantusdatabase.org\"\n \n     stdout.write(\"Querying database for published chants\\n\")\n", "issue": "We need a new API that displays concordances information for all chants in the database\nIn an email from Jan:\r\n\r\n> The intensive process of getting all the data from CD via individual json-cid requests (59.000+) is running already on the 3rd day (and not finished yet) but this will not keep the Cantus data fresh in the Cantus Index API in the long term.\r\n> \r\n> The solution would be to regularly create a large JSON file export of all the CD chants (with the same fields as in json-cid exports) and make it available as a file to download. An example of such json export is here: https://austriamanus.org/files/concordances-export.json\r\n> This kind of data transfer works also with the MMMO database which has approximately half the amount of data compared to a CD. I believe it would also be the best solution for CD.\r\n\r\nThis will not be difficult. We can use the code in our `json-con` API, but return all chants rather than filtering them by Cantus ID.\r\n\r\nWhat's a good path for this API to live at? `/json-concordances-export`?\n", "before_files": [{"content": "import ujson\nimport os\nfrom sys import stdout\nfrom datetime import datetime\nfrom collections import defaultdict\nfrom django.db.models.query import QuerySet\nfrom django.core.management.base import BaseCommand\nfrom main_app.models import Chant\n\n\nclass Command(BaseCommand):\n    def handle(self, *args, **kwargs) -> None:\n        CACHE_DIR: str = \"api_cache\"\n        FILEPATH: str = f\"{CACHE_DIR}/concordances.json\"\n        start_time: str = datetime.now().isoformat()\n        stdout.write(f\"Running update_cached_concordances at {start_time}.\\n\")\n        concordances: dict = get_concordances()\n        write_time: str = datetime.now().isoformat()\n        metadata: dict = {\n            \"last_updated\": write_time,\n        }\n        data_and_metadata: dict = {\n            \"data\": concordances,\n            \"metadata\": metadata,\n        }\n        stdout.write(f\"Attempting to make directory at {CACHE_DIR} to hold cache: \")\n        try:\n            os.mkdir(CACHE_DIR)\n            stdout.write(f\"successfully created directory at {CACHE_DIR}.\\n\")\n        except FileExistsError:\n            stdout.write(f\"directory at {CACHE_DIR} already exists.\\n\")\n        stdout.write(f\"Writing concordances to {FILEPATH} at {write_time}.\\n\")\n        with open(FILEPATH, \"w\") as json_file:\n            ujson.dump(data_and_metadata, json_file)\n        end_time = datetime.now().isoformat()\n        stdout.write(\n            f\"Concordances successfully written to {FILEPATH} at {end_time}.\\n\\n\"\n        )\n\n\ndef get_concordances() -> dict:\n    DOMAIN: str = \"https://cantusdatabase.org\"\n\n    stdout.write(\"Querying database for published chants\\n\")\n    published_chants: QuerySet[Chant] = Chant.objects.filter(source__published=True)\n    values: QuerySet[dict] = published_chants.select_related(\n        \"source\",\n        \"feast\",\n        \"genre\",\n        \"office\",\n    ).values(\n        \"id\",\n        \"source_id\",\n        \"source__siglum\",\n        \"folio\",\n        \"c_sequence\",\n        \"incipit\",\n        \"feast__name\",\n        \"genre__name\",\n        \"office__name\",\n        \"position\",\n        \"cantus_id\",\n        \"image_link\",\n        \"mode\",\n        \"manuscript_full_text_std_spelling\",\n        \"volpiano\",\n    )\n\n    stdout.write(\"Processing chants\\n\")\n    concordances: defaultdict = defaultdict(list)\n    for chant in values:\n        source_id: int = chant[\"source_id\"]\n        source_absolute_url: str = f\"{DOMAIN}/source/{source_id}/\"\n        chant_id: int = chant[\"id\"]\n        chant_absolute_url: str = f\"{DOMAIN}/chant/{chant_id}/\"\n\n        concordances[chant[\"cantus_id\"]].append(\n            {\n                \"siglum\": chant[\"source__siglum\"],\n                \"srclink\": source_absolute_url,\n                \"chantlink\": chant_absolute_url,\n                \"folio\": chant[\"folio\"],\n                \"sequence\": chant[\"c_sequence\"],\n                \"incipit\": chant[\"incipit\"],\n                \"feast\": chant[\"feast__name\"],\n                \"genre\": chant[\"genre__name\"],\n                \"office\": chant[\"office__name\"],\n                \"position\": chant[\"position\"],\n                \"cantus_id\": chant[\"cantus_id\"],\n                \"image\": chant[\"image_link\"],\n                \"mode\": chant[\"mode\"],\n                \"full_text\": chant[\"manuscript_full_text_std_spelling\"],\n                \"melody\": chant[\"volpiano\"],\n                \"db\": \"CD\",\n            }\n        )\n\n    stdout.write(f\"All chants processed - found {len(concordances)} Cantus IDs\\n\")\n\n    return dict(concordances)\n", "path": "django/cantusdb_project/main_app/management/commands/update_cached_concordances.py"}]}