Add the ability to pin Issues (#24406)

This adds the ability to pin important Issues and Pull Requests. You can
also move pinned Issues around to change their Position. Resolves #2175.

## Screenshots

![grafik](https://user-images.githubusercontent.com/15185051/235123207-0aa39869-bb48-45c3-abe2-ba1e836046ec.png)

![grafik](https://user-images.githubusercontent.com/15185051/235123297-152a16ea-a857-451d-9a42-61f2cd54dd75.png)

![grafik](https://user-images.githubusercontent.com/15185051/235640782-cbfe25ec-6254-479a-a3de-133e585d7a2d.png)

The Design was mostly copied from the Projects Board.

## Implementation
This uses a new `pin_order` Column in the `issue` table. If the value is
set to 0, the Issue is not pinned. If it's set to a bigger value, the
value is the Position. 1 means it's the first pinned Issue, 2 means it's
the second one etc. This is dived into Issues and Pull requests for each
Repo.

## TODO
- [x] You can currently pin as many Issues as you want. Maybe we should
add a Limit, which is configurable. GitHub uses 3, but I prefer 6, as
this is better for bigger Projects, but I'm open for suggestions.
- [x] Pin and Unpin events need to be added to the Issue history.
- [x] Tests
- [x] Migration

**The feature itself is currently fully working, so tester who may find
weird edge cases are very welcome!**

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Giteabot <teabot@gitea.io>

1 files changed, 301 insertions, 0 deletions

diff --git a/routers/api/v1/repo/issue_pin.go b/routers/api/v1/repo/issue_pin.go
new file mode 100644
index 0000000000..c96ede45f5
--- /dev/null
+++ b/routers/api/v1/repo/issue_pin.go
@@ -0,0 +1,301 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"net/http"
+
+	issues_model "code.gitea.io/gitea/models/issues"
+	"code.gitea.io/gitea/modules/context"
+	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/services/convert"
+)
+
+// PinIssue pins a issue
+func PinIssue(ctx *context.APIContext) {
+	// swagger:operation POST /repos/{owner}/{repo}/issues/{index}/pin issue pinIssue
+	// ---
+	// summary: Pin an Issue
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// - name: index
+	//   in: path
+	//   description: index of issue to pin
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	issue, err := issues_model.GetIssueByIndex(ctx.Repo.Repository.ID, ctx.ParamsInt64(":index"))
+	if err != nil {
+		if issues_model.IsErrIssueNotExist(err) {
+			ctx.NotFound()
+		} else {
+			ctx.Error(http.StatusInternalServerError, "GetIssueByIndex", err)
+		}
+		return
+	}
+
+	// If we don't do this, it will crash when trying to add the pin event to the comment history
+	err = issue.LoadRepo(ctx)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "LoadRepo", err)
+	}
+
+	err = issue.Pin(ctx, ctx.Doer)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "PinIssue", err)
+	}
+
+	ctx.Status(http.StatusNoContent)
+}
+
+// UnpinIssue unpins a Issue
+func UnpinIssue(ctx *context.APIContext) {
+	// swagger:operation DELETE /repos/{owner}/{repo}/issues/{index}/pin issue unpinIssue
+	// ---
+	// summary: Unpin an Issue
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// - name: index
+	//   in: path
+	//   description: index of issue to unpin
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	issue, err := issues_model.GetIssueByIndex(ctx.Repo.Repository.ID, ctx.ParamsInt64(":index"))
+	if err != nil {
+		if issues_model.IsErrIssueNotExist(err) {
+			ctx.NotFound()
+		} else {
+			ctx.Error(http.StatusInternalServerError, "GetIssueByIndex", err)
+		}
+		return
+	}
+
+	// If we don't do this, it will crash when trying to add the unpin event to the comment history
+	err = issue.LoadRepo(ctx)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "LoadRepo", err)
+	}
+
+	err = issue.Unpin(ctx, ctx.Doer)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "UnpinIssue", err)
+	}
+
+	ctx.Status(http.StatusNoContent)
+}
+
+// MoveIssuePin moves a pinned Issue to a new Position
+func MoveIssuePin(ctx *context.APIContext) {
+	// swagger:operation PATCH /repos/{owner}/{repo}/issues/{index}/pin/{position} issue moveIssuePin
+	// ---
+	// summary: Moves the Pin to the given Position
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// - name: index
+	//   in: path
+	//   description: index of issue
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// - name: position
+	//   in: path
+	//   description: the new position
+	//   type: integer
+	//   format: int64
+	//   required: true
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	issue, err := issues_model.GetIssueByIndex(ctx.Repo.Repository.ID, ctx.ParamsInt64(":index"))
+	if err != nil {
+		if issues_model.IsErrIssueNotExist(err) {
+			ctx.NotFound()
+		} else {
+			ctx.Error(http.StatusInternalServerError, "GetIssueByIndex", err)
+		}
+		return
+	}
+
+	err = issue.MovePin(ctx, int(ctx.ParamsInt64(":position")))
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "MovePin", err)
+	}
+
+	ctx.Status(http.StatusNoContent)
+}
+
+// ListPinnedIssues returns a list of all pinned Issues
+func ListPinnedIssues(ctx *context.APIContext) {
+	// swagger:operation GET /repos/{owner}/{repo}/issues/pinned repository repoListPinnedIssues
+	// ---
+	// summary: List a repo's pinned issues
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/IssueList"
+	issues, err := issues_model.GetPinnedIssues(ctx, ctx.Repo.Repository.ID, false)
+
+	if err == nil {
+		ctx.JSON(http.StatusOK, convert.ToAPIIssueList(ctx, issues))
+	} else {
+		ctx.Error(http.StatusInternalServerError, "LoadPinnedIssues", err)
+	}
+}
+
+// ListPinnedPullRequests returns a list of all pinned PRs
+func ListPinnedPullRequests(ctx *context.APIContext) {
+	// swagger:operation GET /repos/{owner}/{repo}/pulls/pinned repository repoListPinnedPullRequests
+	// ---
+	// summary: List a repo's pinned pull requests
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/PullRequestList"
+	issues, err := issues_model.GetPinnedIssues(ctx, ctx.Repo.Repository.ID, true)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "LoadPinnedPullRequests", err)
+	}
+
+	apiPrs := make([]*api.PullRequest, len(issues))
+	for i, currentIssue := range issues {
+		pr, err := currentIssue.GetPullRequest()
+		if err != nil {
+			ctx.Error(http.StatusInternalServerError, "GetPullRequest", err)
+			return
+		}
+
+		if err = pr.LoadIssue(ctx); err != nil {
+			ctx.Error(http.StatusInternalServerError, "LoadIssue", err)
+			return
+		}
+
+		if err = pr.LoadAttributes(ctx); err != nil {
+			ctx.Error(http.StatusInternalServerError, "LoadAttributes", err)
+			return
+		}
+
+		if err = pr.LoadBaseRepo(ctx); err != nil {
+			ctx.Error(http.StatusInternalServerError, "LoadBaseRepo", err)
+			return
+		}
+
+		if err = pr.LoadHeadRepo(ctx); err != nil {
+			ctx.Error(http.StatusInternalServerError, "LoadHeadRepo", err)
+			return
+		}
+
+		apiPrs[i] = convert.ToAPIPullRequest(ctx, pr, ctx.Doer)
+	}
+
+	ctx.JSON(http.StatusOK, &apiPrs)
+}
+
+// AreNewIssuePinsAllowed returns if new issues pins are allowed
+func AreNewIssuePinsAllowed(ctx *context.APIContext) {
+	// swagger:operation GET /repos/{owner}/{repo}/new_pin_allowed repository repoNewPinAllowed
+	// ---
+	// summary: Returns if new Issue Pins are allowed
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/RepoNewIssuePinsAllowed"
+	pinsAllowed := api.NewIssuePinsAllowed{}
+	var err error
+
+	pinsAllowed.Issues, err = issues_model.IsNewPinAllowed(ctx, ctx.Repo.Repository.ID, false)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "IsNewIssuePinAllowed", err)
+		return
+	}
+
+	pinsAllowed.PullRequests, err = issues_model.IsNewPinAllowed(ctx, ctx.Repo.Repository.ID, true)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "IsNewPullRequestPinAllowed", err)
+		return
+	}
+
+	ctx.JSON(http.StatusOK, pinsAllowed)
+}