Add paste service utility (#179)

4 files changed, 118 insertions, 2 deletions

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 1817102e..dda1012e 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -3,6 +3,8 @@
 
 Changelog
 =========
+- :release:`9.7.0 <10th June 2023>`
+- :feature:`179` Add paste service utility to upload text to our paste service.
 - :feature:`176` Migrate repo to use ruff for linting
 
 
diff --git a/pydis_core/utils/__init__.py b/pydis_core/utils/__init__.py
index 8a61082a..0ca265c9 100644
--- a/pydis_core/utils/__init__.py
+++ b/pydis_core/utils/__init__.py
@@ -1,7 +1,8 @@
 """Useful utilities and tools for Discord bot development."""
 
 from pydis_core.utils import (
-    _monkey_patches, caching, channel, commands, cooldown, function, interactions, logging, members, regex, scheduling
+    _monkey_patches, caching, channel, commands, cooldown, function, interactions, logging, members, paste_service,
+    regex, scheduling
 )
 from pydis_core.utils._extensions import unqualify
 
@@ -32,6 +33,7 @@ __all__ = [
     interactions,
     logging,
     members,
+    paste_service,
     regex,
     scheduling,
     unqualify,
diff --git a/pydis_core/utils/paste_service.py b/pydis_core/utils/paste_service.py
new file mode 100644
index 00000000..227197e5
--- /dev/null
+++ b/pydis_core/utils/paste_service.py
@@ -0,0 +1,112 @@
+from typing import TypedDict
+
+from aiohttp import ClientConnectorError, ClientSession
+
+from pydis_core.utils import logging
+
+log = logging.get_logger(__name__)
+
+FAILED_REQUEST_ATTEMPTS = 3
+MAX_PASTE_SIZE = 128 * 1024  # 128kB
+"""The maximum allows size of a paste, in bytes."""
+
+
+class PasteResponse(TypedDict):
+    """
+    A successful response from the paste service.
+
+    args:
+        link: The URL to the saved paste.
+        removal: The URL to delete the saved paste.
+    """
+
+    link: str
+    removal: str
+
+
+class PasteUploadError(Exception):
+    """Raised when an error is encountered uploading to the paste service."""
+
+
+class PasteTooLongError(Exception):
+    """Raised when content is too large to upload to the paste service."""
+
+
+async def send_to_paste_service(
+    *,
+    contents: str,
+    paste_url: str,
+    http_session: ClientSession,
+    file_name: str = "",
+    lexer: str = "python",
+    max_size: int = MAX_PASTE_SIZE,
+) -> PasteResponse:
+    """
+    Upload some contents to the paste service.
+
+    Args:
+        contents: The content to upload to the paste service.
+        paste_url: The base url to the paste service.
+        http_session (aiohttp.ClientSession): The session to use when POSTing the content to the paste service.
+        file_name: The name of the file to save to the paste service.
+        lexer: The lexer to save the content with.
+        max_size: The max number of bytes to be allowed. Anything larger than :obj:`MAX_PASTE_SIZE` will be rejected.
+
+    Raises:
+        :exc:`ValueError`: ``max_length`` greater than the maximum allowed by the paste service.
+        :exc:`PasteTooLongError`: ``contents`` too long to upload.
+        :exc:`PasteUploadError`: Uploading failed.
+
+    Returns:
+        A :obj:`TypedDict` containing both the URL of the paste, and a URL to remove the paste.
+    """
+    if max_size > MAX_PASTE_SIZE:
+        raise ValueError(f"`max_length` must not be greater than {MAX_PASTE_SIZE}")
+
+    contents_size = len(contents.encode())
+    if contents_size > max_size:
+        log.info("Contents too large to send to paste service.")
+        raise PasteTooLongError(f"Contents of size {contents_size} greater than maximum size {max_size}")
+
+    log.debug(f"Sending contents of size {contents_size} bytes to paste service.")
+    payload = {
+        "expiry": "1month",
+        "long": "on",  # Use a longer URI for the paste.
+        "files": [
+            {"name": file_name, "lexer": lexer, "content": contents},
+        ]
+    }
+    for attempt in range(1, FAILED_REQUEST_ATTEMPTS + 1):
+        try:
+            async with http_session.post(f"{paste_url}/api/v1/paste", json=payload) as response:
+                response_json = await response.json()
+        except ClientConnectorError:
+            log.warning(
+                f"Failed to connect to paste service at url {paste_url}, "
+                f"trying again ({attempt}/{FAILED_REQUEST_ATTEMPTS})."
+            )
+            continue
+        except Exception:
+            log.exception(
+                f"An unexpected error has occurred during handling of the request, "
+                f"trying again ({attempt}/{FAILED_REQUEST_ATTEMPTS})."
+            )
+            continue
+
+        if response.status == 400:
+            log.warning(
+                f"Paste service returned error {response_json['message']} with status code {response.status}, "
+                f"trying again ({attempt}/{FAILED_REQUEST_ATTEMPTS})."
+            )
+            continue
+
+        if response.status == 200:
+            log.info(f"Successfully uploaded contents to {response_json['link']}.")
+            return PasteResponse(link=response_json["link"], removal=response_json["removal"])
+
+        log.warning(
+            f"Got unexpected JSON response from paste service: {response_json}\n"
+            f"trying again ({attempt}/{FAILED_REQUEST_ATTEMPTS})."
+        )
+
+    raise PasteUploadError("Failed to upload contents to paste service")
diff --git a/pyproject.toml b/pyproject.toml
index 641fda7f..dc64789e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "pydis_core"
-version = "9.6.0"
+version = "9.7.0"
 description = "PyDis core provides core functionality and utility to the bots of the Python Discord community."
 authors = ["Python Discord <[email protected]>"]
 license = "MIT"