Adds Webhook Option

Adds webhook option on form creation, and adds validation. Updates
`SCHEMA.md`.

Signed-off-by: Hassan Abouelela <[email protected]>

3 files changed, 67 insertions, 7 deletions

diff --git a/SCHEMA.md b/SCHEMA.md
index b37ed1d..894ffec 100644
--- a/SCHEMA.md
+++ b/SCHEMA.md
@@ -12,13 +12,14 @@ In this document:
 
 ## Form
 
-| Field       | Type                                     | Description                                                                               | Example                     |
-| ----------- | ---------------------------------------- | ----------------------------------------------------------------------------------------- | --------------------------- |
-| `id`          | Unique identifier                        | A user selected, unique, descriptive identifier (used in URL routes, so no spaces)        | `"ban-appeals"`             |
-| `features`    | List of [form features](#form-features)  | A list of features to change the behaviour of the form, described in the features section | `["OPEN", "COLLECT_EMAIL"]` |
-| `questions`   | List of [form questions](#form-question) | The list of questions to render on a specific form                                        | Too long! See below         |
-| `name`        | String                                   | Name of the form                                                                          | `"Summer Code Jam 2100"` |
-| `description` | String                                   | Form description                                                                          | `"This is my amazing form description."` |
+| Field         | Type                                      | Description                                                                               | Example                                  |
+| ------------- | ----------------------------------------- | ----------------------------------------------------------------------------------------- | ---------------------------------------- |
+| `id`          | Unique identifier                         | A user selected, unique, descriptive identifier (used in URL routes, so no spaces)        | `"ban-appeals"`                          |
+| `features`    | List of [form features](#form-features)   | A list of features to change the behaviour of the form, described in the features section | `["OPEN", "COLLECT_EMAIL"]`              |
+| `meta`        | Mapping of [meta options](#meta-options)  | Meta properties for the form.                                                             | See meta-options section                 |
+| `questions`   | List of [form questions](#form-question)  | The list of questions to render on a specific form                                        | Too long! See below                      |
+| `name`        | String                                    | Name of the form                                                                          | `"Summer Code Jam 2100"`                 |
+| `description` | String                                    | Form description                                                                          | `"This is my amazing form description."` |
 
 ### Form features
 
@@ -29,6 +30,13 @@ In this document:
 | `OPEN`             | The form is currently accepting responses.                                    |
 | `COLLECT_EMAIL`    | The form should collect the email from submissions. Requires `REQUIRES_LOGIN` |
 | `DISABLE_ANTISPAM` | Disable the anti-spam checks from running on a form submission.               |
+| `WEBHOOK_ENABLED`  | The form should notify the webhook. Has no effect if no webhook is set.       |
+
+### Meta options
+| Field     | Description                         | Example                                                                                    |
+| --------- | ----------------------------------- | ------------------------------------------------------------------------------------------ |
+| `webhook` | Mapping of webhook url and message. | `"webhook": {"url": "https://discord.com/api/webhooks/id/key", "message": "Hello World!"}` |
+
 
 ### Form question
 
diff --git a/backend/constants.py b/backend/constants.py
index fdf7092..e733e53 100644
--- a/backend/constants.py
+++ b/backend/constants.py
@@ -58,3 +58,4 @@ class FormFeatures(Enum):
     OPEN = "OPEN"
     COLLECT_EMAIL = "COLLECT_EMAIL"
     DISABLE_ANTISPAM = "DISABLE_ANTISPAM"
+    WEBHOOK_ENABLED = "WEBHOOK_ENABLED"
diff --git a/backend/models/form.py b/backend/models/form.py
index cb58065..e6c56a4 100644
--- a/backend/models/form.py
+++ b/backend/models/form.py
@@ -1,5 +1,6 @@
 import typing as t
 
+import httpx
 from pydantic import BaseModel, Field, validator
 
 from backend.constants import FormFeatures
@@ -8,6 +9,55 @@ from .question import Question
 PUBLIC_FIELDS = ["id", "features", "questions", "name", "description"]
 
 
+class _WebHook(BaseModel):
+    """Schema model of discord webhooks."""
+    url: str
+    message: str
+
+    @validator("url")
+    def validate_url(cls, url: str) -> str:
+        """Checks if discord webhook urls are valid."""
+        if not isinstance(url, str):
+            raise ValueError("Webhook URL must be a string.")
+
+        if "discord.com/api/webhooks/" not in url:
+            raise ValueError("URL must be a discord webhook.")
+
+        # Attempt to connect to URL
+        try:
+            httpx.get(url).raise_for_status()
+
+        except httpx.RequestError as e:
+            # Catch exceptions in request format
+            raise ValueError(
+                f"Encountered error while trying to connect to url: `{e}`"
+            )
+
+        except httpx.HTTPStatusError as e:
+            # Catch exceptions in response
+            status = e.response.status_code
+
+            if status == 401:
+                raise ValueError(
+                    "Could not authenticate with target. Please check the webhook url."
+                )
+            elif status == 404:
+                raise ValueError(
+                    "Target could not find webhook url. Please check the webhook url."
+                )
+            else:
+                raise ValueError(
+                    f"Unknown error ({status}) while connecting to target: {e}"
+                )
+
+        return url
+
+
+class _FormMeta(BaseModel):
+    """Schema model for form meta data."""
+    webhook: _WebHook
+
+
 class Form(BaseModel):
     """Schema model for form."""
 
@@ -16,6 +66,7 @@ class Form(BaseModel):
     questions: list[Question]
     name: str
     description: str
+    meta: _FormMeta
 
     class Config:
         allow_population_by_field_name = True