Let API create and edit system webhooks, attempt 2 (#33180)

This PR fixes inconsistencies between system and default webhooks in the
Gitea API. (See also #26418)
- A system webhook is a webhook that captures events for all
repositories.
- A default webhook is copied to a new repository when it is created. 

Before this PR `POST /api/v1/admin/hooks/` creates default webhooks (if
not configured otherwise) and `GET /api/v1/admin/hooks/` returns system
webhooks.

The PR introduces an optional query parameter to `GET
/api/v1/admin/hooks/` to enable selecting if either default, system or
both kind of webhooks should be retrieved. By default the flag is set to
return system webhooks keep current behaviour.

## Examples

### System Webhooks

#### Create

```
POST /api/v1/admin/hooks/

{
  "type": "gitea",
  "active": false,
  "branch_filter": "*",
  "events": [ "create", "..." ],
  "config": {
    "url": "http://...",
    "content_type": "json",
    "secret": "secret",
    "is_system_webhook": true // <-- controls hook type
  }
}
```

#### List
```
GET/api/v1/admin/hooks?type=system //type argument is optional here since it's the default
```

#### Others
The other relevant endpoints work as expected by referencing the hook by
id
```
GET /api/v1/admin/hooks/:id
PATCH /api/v1/admin/hooks/:id
DELETE /api/v1/admin/hooks/:id
```


### Default Webhooks

#### Create
```
POST /api/v1/admin/hooks/

{
  "type": "gitea",
  "active": false,
  "branch_filter": "*",
  "events": [ "create", "..." ],
  "config": {
    "url": "http://...",
    "content_type": "json",
    "secret": "secret",
    "is_system_webhook": false // optional, as false is the default value
  }
}
```

#### List
```
GET/api/v1/admin/hooks?type=default
```

#### Others
The other relevant endpoints work as expected by referencing the hook by
id
```
GET /api/v1/admin/hooks/:id
PATCH /api/v1/admin/hooks/:id
DELETE /api/v1/admin/hooks/:id
```

5 files changed, 103 insertions, 1 deletions

diff --git a/models/fixtures/webhook.yml b/models/fixtures/webhook.yml
index f62bae1f31..ebc4062b60 100644
--- a/models/fixtures/webhook.yml
+++ b/models/fixtures/webhook.yml
@@ -22,6 +22,7 @@
   content_type: 1 # json
   events: '{"push_only":false,"send_everything":false,"choose_events":false,"events":{"create":false,"push":true,"pull_request":true}}'
   is_active: true
+
 -
   id: 4
   repo_id: 2
@@ -29,3 +30,23 @@
   content_type: 1 # json
   events: '{"push_only":true,"branch_filter":"{master,feature*}"}'
   is_active: true
+
+-
+  id: 5
+  repo_id: 0
+  owner_id: 0
+  url: www.example.com/url5
+  content_type: 1 # json
+  events: '{"push_only":true,"branch_filter":"{master,feature*}"}'
+  is_active: true
+  is_system_webhook: true
+
+-
+  id: 6
+  repo_id: 0
+  owner_id: 0
+  url: www.example.com/url6
+  content_type: 1 # json
+  events: '{"push_only":true,"branch_filter":"{master,feature*}"}'
+  is_active: true
+  is_system_webhook: false
diff --git a/models/webhook/webhook_system.go b/models/webhook/webhook_system.go
index a2a9ee321a..58d9d4a5c1 100644
--- a/models/webhook/webhook_system.go
+++ b/models/webhook/webhook_system.go
@@ -11,6 +11,19 @@ import (
 	"code.gitea.io/gitea/modules/optional"
 )
 
+// GetSystemOrDefaultWebhooks returns webhooks by given argument or all if argument is missing.
+func GetSystemOrDefaultWebhooks(ctx context.Context, isSystemWebhook optional.Option[bool]) ([]*Webhook, error) {
+	webhooks := make([]*Webhook, 0, 5)
+	if !isSystemWebhook.Has() {
+		return webhooks, db.GetEngine(ctx).Where("repo_id=? AND owner_id=?", 0, 0).
+			Find(&webhooks)
+	}
+
+	return webhooks, db.GetEngine(ctx).
+		Where("repo_id=? AND owner_id=? AND is_system_webhook=?", 0, 0, isSystemWebhook.Value()).
+		Find(&webhooks)
+}
+
 // GetDefaultWebhooks returns all admin-default webhooks.
 func GetDefaultWebhooks(ctx context.Context) ([]*Webhook, error) {
 	webhooks := make([]*Webhook, 0, 5)
diff --git a/models/webhook/webhook_system_test.go b/models/webhook/webhook_system_test.go
new file mode 100644
index 0000000000..96157ed9c9
--- /dev/null
+++ b/models/webhook/webhook_system_test.go
@@ -0,0 +1,37 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package webhook
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unittest"
+	"code.gitea.io/gitea/modules/optional"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetSystemOrDefaultWebhooks(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	hooks, err := GetSystemOrDefaultWebhooks(db.DefaultContext, optional.None[bool]())
+	assert.NoError(t, err)
+	if assert.Len(t, hooks, 2) {
+		assert.Equal(t, int64(5), hooks[0].ID)
+		assert.Equal(t, int64(6), hooks[1].ID)
+	}
+
+	hooks, err = GetSystemOrDefaultWebhooks(db.DefaultContext, optional.Some(true))
+	assert.NoError(t, err)
+	if assert.Len(t, hooks, 1) {
+		assert.Equal(t, int64(5), hooks[0].ID)
+	}
+
+	hooks, err = GetSystemOrDefaultWebhooks(db.DefaultContext, optional.Some(false))
+	assert.NoError(t, err)
+	if assert.Len(t, hooks, 1) {
+		assert.Equal(t, int64(6), hooks[0].ID)
+	}
+}
diff --git a/routers/api/v1/admin/hooks.go b/routers/api/v1/admin/hooks.go
index 6b4689047b..c812ca182d 100644
--- a/routers/api/v1/admin/hooks.go
+++ b/routers/api/v1/admin/hooks.go
@@ -34,11 +34,30 @@ func ListHooks(ctx *context.APIContext) {
 	//   in: query
 	//   description: page size of results
 	//   type: integer
+	// - type: string
+	//   enum:
+	//     - system
+	//     - default
+	//     - all
+	//   description: system, default or both kinds of webhooks
+	//   name: type
+	//   default: system
+	//   in: query
+	//
 	// responses:
 	//   "200":
 	//     "$ref": "#/responses/HookList"
 
-	sysHooks, err := webhook.GetSystemWebhooks(ctx, optional.None[bool]())
+	// for compatibility the default value is true
+	isSystemWebhook := optional.Some(true)
+	typeValue := ctx.FormString("type")
+	if typeValue == "default" {
+		isSystemWebhook = optional.Some(false)
+	} else if typeValue == "all" {
+		isSystemWebhook = optional.None[bool]()
+	}
+
+	sysHooks, err := webhook.GetSystemOrDefaultWebhooks(ctx, isSystemWebhook)
 	if err != nil {
 		ctx.Error(http.StatusInternalServerError, "GetSystemWebhooks", err)
 		return
diff --git a/templates/swagger/v1_json.tmpl b/templates/swagger/v1_json.tmpl
index fb37d45ce8..8082fc594a 100644
--- a/templates/swagger/v1_json.tmpl
+++ b/templates/swagger/v1_json.tmpl
@@ -234,6 +234,18 @@
             "description": "page size of results",
             "name": "limit",
             "in": "query"
+          },
+          {
+            "enum": [
+              "system",
+              "default",
+              "all"
+            ],
+            "type": "string",
+            "default": "system",
+            "description": "system, default or both kinds of webhooks",
+            "name": "type",
+            "in": "query"
           }
         ],
         "responses": {