Method Override feature (HPH-35) (#279)

Document and implement a new feature named Method Override.

Check details of the feature from the provided Markdown documentation
file.

docs/api/description.md

@@ -0,0 +1,120 @@
+# Parkkihubi REST APIs
+
+## Different APIs
+
+Parkkihubi has four different REST APIs:
+
+* [Operator API](../operator/)
+
+  Operator API can be used to manage parking events and parking permits.
+  The API is designed to be used by parking operators and other parking
+  service providers.
+
+* [Enforcement API](../enforcement/)
+
+  Enforcement API can be used to check validity of parkings in relation
+  to the operator created parking events and parking permits.  The API
+  is designed to be used by a system which serves the parking
+  enforcement personnel.
+
+* [Public API](../public/)
+
+  Public API can be used to get some statistics about the parking areas.
+  The API is designed to be available for anyone.
+
+  **NOTE!** The public API is on very initial state. Backward
+  incompatible changes are possible.
+
+* Monitoring API
+
+  Monitoring API can be used to monitor the status of the Parkkihubi.
+  The API is designed to be used by the Parkkihubi Dashboard.
+
+## Object Model
+
+### Parking (Event)
+
+Parking is a parking event created by a parking operator.  It has a
+start time and an end time.  The parking can be either paid or free
+(e.g. a parking disc parking).  Parkkihubi doesn't handle or record
+parking payments at the moment.
+
+Parkings record an actual parking event that is happening in the real
+world (or has happened when looking back in time for statistics). They
+are usually created in real time when the parking event starts.  The end
+time is usually updated when the parking event ends. (Parkings cannot be
+created postactively after the parking event has started, because the
+parking enforcement personnel wouldn't be able to check them in real
+time.)
+
+### Parking Permit
+
+Parking Permit is a permit created by a parking operator.  It has a list
+of subjects (i.e. registration numbers) and a list of permitted areas.
+Each assigned subject and area in the permit has a separate validity
+period.  A parking is valid by the permit when the registration number
+and the area match and their corresponding validity periods cover the
+parking time.
+
+Parking permits should be created in advance, before the parking events
+start.  They are also used to check if a parking event is valid or not,
+but with the permits the actual parking times are not recorded.  Parking
+permits are usually created for a longer period of time (e.g. a month or
+a year).
+
+### Permit Series
+
+Permits are grouped into permit series.  Permit series ara used as a
+mechanism to allow activating and deactivating permits in bulk.
+
+## Method Override
+
+Parkkihubi REST APIs support using the Method Override.
+
+### What Is Method Override?
+
+Method Override is a way to override the HTTP method of a request. This
+is useful when you want to perform an action of a different HTTP method
+than the one the client is using, e.g. when you want to perform a
+`PATCH` request but the client only supports `GET` and `POST`.
+
+### How To Use the Method Override in Parkkihubi
+
+Parkkihubi supports using a `method` query parameter for overriding the
+HTTP method of a request.  For example, if you want to perform a `PATCH`
+request, you can send a `POST` request with a `method=PATCH` query
+parameter.
+
+#### Example
+
+Here is an example of how to use the Method Override to update a parking
+end time, which would normally be done with a `PATCH` request, but is
+here done with a `POST` request instead.
+
+```bash
+ID=abcd1234-1234-1234-1234-123456789012  # A parking ID
+
+curl -X POST \
+  -H "Content-Type: application/json" \
+  -d '{"time_end": "2023-10-20T17:00:00+0300"}' \
+  "https://testapi.parkkiopas.fi/operator/v1/parking/$ID/?method=PATCH"
+```
+
+For comparison here is how it would look like without the Method
+Override:
+
+```bash
+curl -X PATCH \
+  -H "Content-Type: application/json" \
+  -d '{"time_end": "2023-10-20T17:00:00+0300"}' \
+  "https://testapi.parkkiopas.fi/operator/v1/parking/$ID/"
+```
+
+### Limitations
+
+The Method Override is only supported when the carrying request is using
+`POST` method and `application/json` content type.  It can only be used
+to override the method to `PATCH`, `PUT` or `DELETE`.
+
+It is not possible to override the method to `GET` or `POST`, since
+these are assumed to be universally supported by clients.

docs/api/enforcement.yaml

@@ -1,8 +1,8 @@
 openapi: 3.0.1
 info:
   title: Parkkihubi Enforcement API
-  description: >-
-    Parkkihubi Enforcement REST API Documentation
+  description:
+    $ref: ./description.md
   version: "1.2.0"
 servers:
   - url: https://api.parkkiopas.fi/enforcement/v1/

docs/api/operator.yaml

@@ -1,8 +1,8 @@
 openapi: 3.0.1
 info:
   title: Parkkihubi Operator API
-  description: >-
-    Parkkihubi Operator REST API Documentation
+  description:
+    $ref: ./description.md
   version: "1.2.0"
 servers:
   - url: https://api.parkkiopas.fi/operator/v1/

docs/api/public.yaml

@@ -2,11 +2,8 @@ swagger: '2.0'
 
 info:
   title: Parkkihubi Public API
-  description: |
-    Parkkihubi public REST API Documentation
-
-    **NOTE!** The public API is on very initial state. Backward
-    incompatible changes are possible.
+  description:
+    $ref: ./description.md
   version: "1.0.0"
 
 host: pubapi.parkkiopas.fi

docs/doc-generator/package.json

@@ -1,10 +1,10 @@
 {
   "name": "parkkihubi-doc-generator-utils",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "description": "Parkkihubi Documentation Generator Utils",
   "author": "",
   "license": "MIT",
   "dependencies": {
-    "redoc-cli": "^0.8.4"
+    "@redocly/cli": "*"
   }
 }