feat(api): add repository permissions endpoints

GET/PUT/DELETE for repo-level settings.
Following existing Gitea API patterns.

Signed-off-by: SBALAVIGNESH123 <balavignesh449@gmail.com>

routers/api/v1/repo/repo_actions_permissions.go

@@ -0,0 +1,208 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"net/http"
+	
+	actions_model "code.gitea.io/gitea/models/actions"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/web"
+	api "code.gitea.io/gitea/modules/structs"
+)
+
+// GetActionsPermissions returns the Actions token permissions for a repository
+func GetActionsPermissions(ctx *context.APIContext) {
+	// swagger:operation GET /repos/{owner}/{repo}/settings/actions/permissions repository repoGetActionsPermissions
+	// ---
+	// summary: Get repository Actions token permissions
+	// 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":
+	//     "$ref": "#/responses/ActionsPermissionsResponse"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	
+	// Check if user has admin access to this repo
+	// NOTE: Only repo admins should be able to view/modify permission settings
+	// This is important for security - we don't want regular contributors
+	// to be able to grant themselves elevated permissions via Actions
+	if !ctx.Repo.IsAdmin() {
+		ctx.Error(http.StatusForbidden, "NoPermission", "You must be a repository admin to access this")
+		return
+	}
+	
+	perms, err := actions_model.GetRepoActionPermissions(ctx, ctx.Repo.Repository.ID)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "GetPermissions", err)
+		return
+	}
+	
+	// If no custom permissions are set, return the default (restricted mode)
+	// This is intentional - we want a secure default that requires explicit opt-in
+	// to more permissive settings. See: https://github.com/go-gitea/gitea/issues/24635
+	if perms == nil {
+		perms = &actions_model.ActionTokenPermission{
+			RepoID:         ctx.Repo.Repository.ID,
+			PermissionMode: actions_model.PermissionModeRestricted,
+			// Default restricted permissions - only read contents and metadata
+			ContentsRead:   true,
+			MetadataRead:   true,
+		}
+	}
+	
+	ctx.JSON(http.StatusOK, convertToAPIPermissions(perms))
+}
+
+// UpdateActionsPermissions updates the Actions token permissions for a repository
+func UpdateActionsPermissions(ctx *context.APIContext) {
+	// swagger:operation PUT /repos/{owner}/{repo}/settings/actions/permissions repository repoUpdateActionsPermissions
+	// ---
+	// summary: Update repository Actions token permissions
+	// consumes:
+	// - application/json
+	// 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
+	// - name: body
+	//   in: body
+	//   schema:
+	//     "$ref": "#/definitions/ActionsPermissions"
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/ActionsPermissionsResponse"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"
+	//   "422":
+	//     "$ref": "#/responses/validationError"
+	
+	if !ctx.Repo.IsAdmin() {
+		ctx.Error(http.StatusForbidden, "NoPermission", "You must be a repository admin to modify this")
+		return
+	}
+	
+	form := web.GetForm(ctx).(*api.ActionsPermissions)
+	
+	// Validate permission mode
+	if form.PermissionMode < 0 || form.PermissionMode > 2 {
+		ctx.Error(http.StatusUnprocessableEntity, "InvalidMode", "Permission mode must be 0 (restricted), 1 (permissive), or 2 (custom)")
+		return
+	}
+	
+	// TODO: Check if org-level permissions exist and validate against them
+	// For now, we'll implement basic validation, but we should enhance this
+	// to ensure repo settings don't exceed org caps. This is important for
+	// multi-repository organizations where admins want centralized control.
+	// See wolfogre's comment: https://github.com/go-gitea/gitea/pull/24554#issuecomment-1537040811
+	
+	perm := &actions_model.ActionTokenPermission{
+		RepoID:             ctx.Repo.Repository.ID,
+		PermissionMode:     actions_model.PermissionMode(form.PermissionMode),
+		ActionsRead:        form.ActionsRead,
+		ActionsWrite:       form.ActionsWrite,
+		ContentsRead:       form.ContentsRead,
+		ContentsWrite:      form.ContentsWrite,
+		IssuesRead:         form.IssuesRead,
+		IssuesWrite:        form.IssuesWrite,
+		PackagesRead:       form.PackagesRead,
+		PackagesWrite:      form.PackagesWrite,
+		PullRequestsRead:   form.PullRequestsRead,
+		PullRequestsWrite:  form.PullRequestsWrite,
+		MetadataRead:       true, // Always true - needed for basic operations
+	}
+	
+	if err := actions_model.CreateOrUpdateRepoPermissions(ctx, perm); err != nil {
+		ctx.Error(http.StatusInternalServerError, "UpdatePermissions", err)
+		return
+	}
+	
+	ctx.JSON(http.StatusOK, convertToAPIPermissions(perm))
+}
+
+// ResetActionsPermissions resets permissions to default (restricted mode)
+func ResetActionsPermissions(ctx *context.APIContext) {
+	// swagger:operation DELETE /repos/{owner}/{repo}/settings/actions/permissions repository repoResetActionsPermissions
+	// ---
+	// summary: Reset repository Actions permissions to default
+	// 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:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"
+	
+	if !ctx.Repo.IsAdmin() {
+		ctx.Error(http.StatusForbidden, "NoPermission", "You must be a repository admin")
+		return
+	}
+	
+	// Create default restricted permissions
+	// This is a "safe reset" - puts the repo back to secure defaults
+	defaultPerm := &actions_model.ActionTokenPermission{
+		RepoID:         ctx.Repo.Repository.ID,
+		PermissionMode: actions_model.PermissionModeRestricted,
+		ContentsRead:   true,
+		MetadataRead:   true,
+	}
+	
+	if err := actions_model.CreateOrUpdateRepoPermissions(ctx, defaultPerm); err != nil {
+		ctx.Error(http.StatusInternalServerError, "ResetPermissions", err)
+		return
+	}
+	
+	ctx.Status(http.StatusNoContent)
+}
+
+// convertToAPIPermissions converts model to API response format
+// This helper keeps our internal model separate from the API contract
+func convertToAPIPermissions(perm *actions_model.ActionTokenPermission) *api.ActionsPermissions {
+	return &api.ActionsPermissions{
+		PermissionMode:    int(perm.PermissionMode),
+		ActionsRead:       perm.ActionsRead,
+		ActionsWrite:      perm.ActionsWrite,
+		ContentsRead:      perm.ContentsRead,
+		ContentsWrite:     perm.ContentsWrite,
+		IssuesRead:        perm.IssuesRead,
+		IssuesWrite:       perm.IssuesWrite,
+		PackagesRead:      perm.PackagesRead,
+		PackagesWrite:     perm.PackagesWrite,
+		PullRequestsRead:  perm.PullRequestsRead,
+		PullRequestsWrite: perm.PullRequestsWrite,
+		MetadataRead:      perm.MetadataRead,
+	}
+}