Add params validations and remove extra params support

Remove label_name and milestone_title params support
Add mutually_exclusive validation for author_id and author_username
Add mutually_exclusive validation for assignee_id and assignee_username
Add validation to allow single value for asignee_username on CE
Add separate issue_stats_params helper for statistics params and
reuse in issues_params.

1 files changed, 190 insertions, 0 deletions

diff --git a/doc/api/issues_statistics.md b/doc/api/issues_statistics.md
new file mode 100644
index 00000000000..1eeb1338104
--- /dev/null
+++ b/doc/api/issues_statistics.md
@@ -0,0 +1,190 @@
+# Issues Statistics API
+
+Every API call to issues_statistics must be authenticated.
+
+If a user is not a member of a project and the project is private, a `GET`
+request on that project will result to a `404` status code.
+
+## Get issues statistics
+
+Gets issues count statistics on all issues the authenticated user has access to. By default it
+returns only issues created by the current user. To get all issues,
+use parameter `scope=all`.
+
+```
+GET /issues_statistics
+GET /issues_statistics?labels=foo
+GET /issues_statistics?labels=foo,bar
+GET /issues_statistics?labels=foo,bar&state=opened
+GET /issues_statistics?milestone=1.0.0
+GET /issues_statistics?milestone=1.0.0&state=opened
+GET /issues_statistics?iids[]=42&iids[]=43
+GET /issues_statistics?author_id=5
+GET /issues_statistics?assignee_id=5
+GET /issues_statistics?my_reaction_emoji=star
+GET /issues_statistics?search=foo&in=title
+GET /issues_statistics?confidential=true
+```
+
+| Attribute           | Type             | Required   | Description                                                                                                                                         |
+| ------------------- | ---------------- | ---------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. `No+Label` (Deprecated) lists all issues with no labels. Predefined names are case-insensitive. |
+| `milestone`         | string           | no         | The milestone title. `None` lists all issues with no milestone. `Any` lists all issues that have an assigned milestone.                             |
+| `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`. Defaults to `created_by_me`<br> For versions before 11.0, use the now deprecated `created-by-me` or `assigned-to-me` scopes instead.<br> _([Introduced][ce-13004] in GitLab 9.5. [Changed to snake_case][ce-18935] in GitLab 11.0)_ |
+| `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. _([Introduced][ce-13004] in GitLab 9.5)_ |
+| `author_username`   | string           | no         | Return issues created by the given `username`. Simillar to `author_id` and mutually exclusive with `author_id`. |
+| `assignee_id`       | integer          | no         | Return issues assigned to the given user `id`. Mutually exclusive with `assignee_username`. `None` returns unassigned issues. `Any` returns issues with an assignee. _([Introduced][ce-13004] in GitLab 9.5)_ |
+| `assignee_username` | Array[String]    | no         | Return issues assigned to the given `username`. Simillar to `assignee_id` and mutually exclusive with `assignee_id`. In CE version `assignee_username` array should only contain a single value or an invalid param error will be returned otherwise. |
+| `my_reaction_emoji` | string           | no         | Return issues reacted by the authenticated user by the given `emoji`. `None` returns issues not given a reaction. `Any` returns issues given at least one reaction. _([Introduced][ce-14016] in GitLab 10.0)_ |
+| `iids[]`            | Array[integer]   | no         | Return only the issues having the given `iid`                                                                                                       |
+| `search`            | string           | no         | Search issues against their `title` and `description`                                                                                               |
+| `in`                | string           | no         | Modify the scope of the `search` attribute. `title`, `description`, or a string joining them with comma. Default is `title,description`             |
+| `created_after`     | datetime         | no         | Return issues created on or after the given time                                                                                                    |
+| `created_before`    | datetime         | no         | Return issues created on or before the given time                                                                                                   |
+| `updated_after`     | datetime         | no         | Return issues updated on or after the given time                                                                                                    |
+| `updated_before`    | datetime         | no         | Return issues updated on or before the given time                                                                                                   |
+| `confidential `     | Boolean          | no         | Filter confidential or public issues.                                                                                                               |
+
+```bash
+curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/issues_statistics
+```
+
+Example response:
+
+```json
+{
+  "statistics": {
+    "counts": {
+      "all": 20,
+      "closed": 5,
+      "opened": 15
+    }
+  }
+}
+```
+
+**Note**: `assignee` column is deprecated, now we show it as a single-sized array `assignees` to conform to the GitLab EE API.
+
+**Note**: The `closed_by` attribute was [introduced in GitLab 10.6][ce-17042]. This value will only be present for issues which were closed after GitLab 10.6 and when the user account that closed the issue still exists.
+
+## List group issues
+
+Get a list of a group's issues.
+
+```
+GET /groups/:id/issues_statistics
+GET /groups/:id/issues_statistics?labels=foo
+GET /groups/:id/issues_statistics?labels=foo,bar
+GET /groups/:id/issues_statistics?labels=foo,bar&state=opened
+GET /groups/:id/issues_statistics?milestone=1.0.0
+GET /groups/:id/issues_statistics?milestone=1.0.0&state=opened
+GET /groups/:id/issues_statistics?iids[]=42&iids[]=43
+GET /groups/:id/issues_statistics?search=issue+title+or+description
+GET /groups/:id/issues_statistics?author_id=5
+GET /groups/:id/issues_statistics?assignee_id=5
+GET /groups/:id/issues_statistics?my_reaction_emoji=star
+GET /groups/:id/issues_statistics?confidential=true
+```
+
+| Attribute           | Type             | Required   | Description                                                                                                                   |
+| ------------------- | ---------------- | ---------- | ----------------------------------------------------------------------------------------------------------------------------- |
+| `id`                | integer/string   | yes        | The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user                 |
+| `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. `No+Label` (Deprecated) lists all issues with no labels. Predefined names are case-insensitive. |
+| `iids[]`            | Array[integer]   | no         | Return only the issues having the given `iid`                                                                                 |
+| `milestone`         | string           | no         | The milestone title. `None` lists all issues with no milestone. `Any` lists all issues that have an assigned milestone.       |
+| `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`.<br> For versions before 11.0, use the now deprecated `created-by-me` or `assigned-to-me` scopes instead.<br> _([Introduced][ce-13004] in GitLab 9.5. [Changed to snake_case][ce-18935] in GitLab 11.0)_ |
+| `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. _([Introduced][ce-13004] in GitLab 9.5)_ |
+| `author_username`   | string           | no         | Return issues created by the given `username`. Simillar to `author_id` and mutually exclusive with `author_id`. |
+| `assignee_id`       | integer          | no         | Return issues assigned to the given user `id`. Mutually exclusive with `assignee_username`. `None` returns unassigned issues. `Any` returns issues with an assignee. _([Introduced][ce-13004] in GitLab 9.5)_ |
+| `assignee_username` | Array[String]    | no         | Return issues assigned to the given `username`. Simillar to `assignee_id` and mutually exclusive with `assignee_id`. In CE version `assignee_username` array should only contain a single value or an invalid param error will be returned otherwise. |
+| `my_reaction_emoji` | string           | no         | Return issues reacted by the authenticated user by the given `emoji`. `None` returns issues not given a reaction. `Any` returns issues given at least one reaction. _([Introduced][ce-14016] in GitLab 10.0)_ |
+| `search`            | string           | no         | Search group issues against their `title` and `description`                                                                   |
+| `created_after`     | datetime         | no         | Return issues created on or after the given time                                                                              |
+| `created_before`    | datetime         | no         | Return issues created on or before the given time                                                                             |
+| `updated_after`     | datetime         | no         | Return issues updated on or after the given time                                                                              |
+| `updated_before`    | datetime         | no         | Return issues updated on or before the given time                                                                             |
+| `confidential `     | Boolean          | no         | Filter confidential or public issues.                                                                                         |
+
+```bash
+curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/groups/4/issues_statistics
+```
+
+Example response:
+
+```json
+{
+  "statistics": {
+    "counts": {
+      "all": 20,
+      "closed": 5,
+      "opened": 15
+    }
+  }
+}
+```
+
+**Note**: `assignee` column is deprecated, now we show it as a single-sized array `assignees` to conform to the GitLab EE API.
+
+**Note**: The `closed_by` attribute was [introduced in GitLab 10.6][ce-17042]. This value will only be present for issues which were closed after GitLab 10.6 and when the user account that closed the issue still exists.
+
+## List project issues
+
+Get a list of a project's issues.
+
+```
+GET /projects/:id/issues_statistics
+GET /projects/:id/issues_statistics?labels=foo
+GET /projects/:id/issues_statistics?labels=foo,bar
+GET /projects/:id/issues_statistics?labels=foo,bar&state=opened
+GET /projects/:id/issues_statistics?milestone=1.0.0
+GET /projects/:id/issues_statistics?milestone=1.0.0&state=opened
+GET /projects/:id/issues_statistics?iids[]=42&iids[]=43
+GET /projects/:id/issues_statistics?search=issue+title+or+description
+GET /projects/:id/issues_statistics?author_id=5
+GET /projects/:id/issues_statistics?assignee_id=5
+GET /projects/:id/issues_statistics?my_reaction_emoji=star
+GET /projects/:id/issues_statistics?confidential=true
+```
+
+| Attribute           | Type             | Required   | Description                                                                                                                   |
+| ------------------- | ---------------- | ---------- | ----------------------------------------------------------------------------------------------------------------------------- |
+| `id`                | integer/string   | yes        | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding) owned by the authenticated user               |
+| `iids[]`            | Array[integer]   | no         | Return only the milestone having the given `iid`                                                                              |
+| `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. `No+Label` (Deprecated) lists all issues with no labels. Predefined names are case-insensitive. |
+| `milestone`         | string           | no         | The milestone title. `None` lists all issues with no milestone. `Any` lists all issues that have an assigned milestone.       |
+| `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`.<br> For versions before 11.0, use the now deprecated `created-by-me` or `assigned-to-me` scopes instead.<br> _([Introduced][ce-13004] in GitLab 9.5. [Changed to snake_case][ce-18935] in GitLab 11.0)_ |
+| `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. _([Introduced][ce-13004] in GitLab 9.5)_ |
+| `author_username`   | string           | no         | Return issues created by the given `username`. Simillar to `author_id` and mutually exclusive with `author_id`. |
+| `assignee_id`       | integer          | no         | Return issues assigned to the given user `id`. Mutually exclusive with `assignee_username`. `None` returns unassigned issues. `Any` returns issues with an assignee. _([Introduced][ce-13004] in GitLab 9.5)_ |
+| `assignee_username` | Array[String]    | no         | Return issues assigned to the given `username`. Simillar to `assignee_id` and mutually exclusive with `assignee_id`. In CE version `assignee_username` array should only contain a single value or an invalid param error will be returned otherwise. |
+| `my_reaction_emoji` | string           | no         | Return issues reacted by the authenticated user by the given `emoji`. `None` returns issues not given a reaction. `Any` returns issues given at least one reaction. _([Introduced][ce-14016] in GitLab 10.0)_ |
+| `search`            | string           | no         | Search project issues against their `title` and `description`                                                                 |
+| `created_after`     | datetime         | no         | Return issues created on or after the given time                                                                              |
+| `created_before`    | datetime         | no         | Return issues created on or before the given time                                                                             |
+| `updated_after`     | datetime         | no         | Return issues updated on or after the given time                                                                              |
+| `updated_before`    | datetime         | no         | Return issues updated on or before the given time                                                                             |
+| `confidential `     | Boolean          | no         | Filter confidential or public issues.                                                                                         |
+
+
+```bash
+curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/projects/4/issues_statistics
+```
+
+Example response:
+
+```json
+{
+  "statistics": {
+    "counts": {
+      "all": 20,
+      "closed": 5,
+      "opened": 15
+    }
+  }
+}
+```
+
+**Note**: `assignee` column is deprecated, now we show it as a single-sized array `assignees` to conform to the GitLab EE API.
+
+**Note**: The `closed_by` attribute was [introduced in GitLab 10.6][ce-17042]. This value will only be present for issues which were closed after GitLab 10.6 and when the user account that closed the issue still exists.
+