Align defaults for datasource settings

Previously we had two different defaults for the edition setting:
* one default was set to CEE but was only applied if the datasource
  settings page was opened and was only applied to the backend after
  "save" was pressed.
* the other default setting was set to RAW and was applied in the
  backend

If you use a provisioned datasource and did not specify the edition
explicitly, you saw "CEE" chosen in the UI, but the backend actually
used the "RAW" edition.

In order to align this, we chose to set both defaults to CEE.

**If you use checkmk raw edition and a provisioned datasource or created
the datasource with an very old version of this plugin** you have to take
manual action:
* if you use a provisioned datasource: specify the edition explicitly
* if you used a old version of this plugin to create the datasource:
  open the datasource settings, make sure the RAW edition is chosen, and
  save the settings.

You can use the following python script to check if you are affected:
(You can only be affected if you use the plugin to fetch matrices from
checkmk raw edition.)

```
import requests

GRAFANA_URL = "http://127.0.0.1:3000/"  # with closing slash

URL = f"{GRAFANA_URL}api/datasources"

GRAFANA_USER = "admin"
GRAFANA_PASSWORD = "password"
data_sources = requests.get(URL, auth=(GRAFANA_USER, GRAFANA_PASSWORD))

for data_source in data_sources.json():
    if data_source["type"] in {"tribe-29-checkmk-datasource", "checkmk-cloud-datasource"}:
        json_data = data_source["jsonData"]
        if "edition" not in json_data:
            print("found affected data_source:")
            print(f'  name: {data_source["name"]}')
            print(f'  id: {data_source["id"]}')
            print(f'  uid: {data_source["uid"]}')
```

src/DataSource.ts

@@ -12,6 +12,7 @@ import { MetricFindQuery, RequestSpec } from './RequestSpec';
 import RestApiBackend from './backend/rest';
 import { Backend } from './backend/types';
 import WebApiBackend from './backend/web';
+import { Settings } from './settings';
 import { Backend as BackendType, CmkQuery, DataSourceOptions, Edition, ResponseDataAutocomplete } from './types';
 import { AutoCompleteParams } from './ui/autocomplete';
 import { createCmkContext } from './utils';
@@ -20,11 +21,13 @@ import { WebApiResponse } from './webapi';
 export class DataSource extends DataSourceApi<CmkQuery> {
   webBackend: WebApiBackend;
   restBackend: RestApiBackend;
+  settings: Settings;
 
   constructor(private instanceSettings: DataSourceInstanceSettings<DataSourceOptions>) {
     super(instanceSettings);
     this.webBackend = new WebApiBackend(this);
     this.restBackend = new RestApiBackend(this);
+    this.settings = new Settings(instanceSettings.jsonData);
   }
 
   async query(dataQueryRequest: DataQueryRequest<CmkQuery>): Promise<DataQueryResponse> {
@@ -94,14 +97,12 @@ export class DataSource extends DataSourceApi<CmkQuery> {
     return this.instanceSettings.url;
   }
 
-  // TODO: Move config default values to a central place instead of scattering it in getEdition and getBackendType
-
   getEdition(): Edition {
-    return this.instanceSettings.jsonData.edition ?? 'RAW';
+    return this.settings.edition;
   }
 
   getBackendType(): BackendType {
-    return this.instanceSettings.jsonData.backend ?? 'rest';
+    return this.settings.backend;
   }
 
   getBackend(): Backend {
@@ -112,10 +113,6 @@ export class DataSource extends DataSourceApi<CmkQuery> {
   }
 
   getUsername(): string {
-    const username = this.instanceSettings.jsonData.username;
-    if (typeof username === 'string') {
-      return username;
-    }
-    throw Error('Impossible');
+    return this.settings.username;
   }
 }

src/settings.ts

@@ -0,0 +1,27 @@
+import { Backend as BackendType, DataSourceOptions, Edition } from './types';
+
+export class Settings {
+  protected settings: DataSourceOptions;
+
+  constructor(settings: DataSourceOptions) {
+    this.settings = settings;
+  }
+
+  get edition(): Edition {
+    // cloud instances of this plugin don't save the edition and use this default
+    return this.settings.edition ?? 'CEE';
+  }
+
+  get backend(): BackendType {
+    // cloud instances of this plugin don't save the backend and use this default
+    return this.settings.backend ?? 'rest';
+  }
+
+  get url(): string | undefined {
+    return this.settings.url;
+  }
+
+  get username(): string {
+    return this.settings.username ?? '';
+  }
+}

src/ui/ConfigEditor.tsx

@@ -2,6 +2,7 @@ import { DataSourcePluginOptionsEditorProps, SelectableValue } from '@grafana/da
 import { Alert, FieldSet, InlineField, LegacyForms, Select } from '@grafana/ui';
 import React, { ChangeEvent, useCallback } from 'react';
 
+import { Settings } from '../settings';
 import { Backend, DataSourceOptions, Edition, SecureJsonData } from '../types';
 
 const { SecretFormField, FormField } = LegacyForms;
@@ -107,14 +108,7 @@ export const ConfigEditor = (props: Props) => {
   const { options } = props;
   const { jsonData, secureJsonFields } = options;
   const secureJsonData = options.secureJsonData || {};
-
-  if (!jsonData.edition) {
-    onEditionChange(cmkEditions[0]);
-  }
-
-  if (!jsonData.backend) {
-    onBackendChange(cmkBackends[0]);
-  }
+  const settings = new Settings(jsonData);
 
   return (
     <>
@@ -125,7 +119,7 @@ export const ConfigEditor = (props: Props) => {
             labelWidth={6}
             inputWidth={20}
             onChange={onUrlChange}
-            value={jsonData.url || ''}
+            value={settings.url || ''}
             tooltip="Which Checkmk Server to connect to. (Example: https://checkmk.server/site)"
             data-test-id="checkmk-url"
           />
@@ -137,7 +131,7 @@ export const ConfigEditor = (props: Props) => {
                 width={32}
                 options={cmkEditions}
                 onChange={onEditionChange}
-                value={jsonData.edition}
+                value={settings.edition}
                 placeholder="Select your checkmk edition"
                 inputId="checkmk-edition"
               />
@@ -151,7 +145,7 @@ export const ConfigEditor = (props: Props) => {
                 width={32}
                 options={cmkBackends}
                 onChange={onBackendChange}
-                value={jsonData.backend}
+                value={settings.backend}
                 placeholder="Select your checkmk version"
                 inputId="checkmk-version"
               />
@@ -177,7 +171,7 @@ export const ConfigEditor = (props: Props) => {
             labelWidth={6}
             inputWidth={20}
             onChange={onUsernameChange}
-            value={jsonData.username || ''}
+            value={settings.username}
             tooltip="A checkmk monitoring user. Don't use 'automation' user, because it has admin rights."
             data-test-id="checkmk-username"
           />

tests/unit/CloudEdition.test.tsx

@@ -44,11 +44,6 @@ describe('Cloud Edition Restrictions', () => {
       expect(screen.queryByLabelText('Edition')).toBeNull();
       expect(screen.queryByLabelText('Version')).toBeNull();
     });
-
-    it('sets the non configurable values to the defaults', () => {
-      expect(onOptionsChange).toHaveBeenCalledWith(expect.objectContaining({ jsonData: { backend: 'rest' } }));
-      expect(onOptionsChange).toHaveBeenCalledWith(expect.objectContaining({ jsonData: { edition: 'CEE' } }));
-    });
   });
 
   describe('RestApiBackend', () => {