// Copyright 2016 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package repo

import (
	"errors"
	"fmt"
	"math"
	"net/http"
	"strconv"
	"strings"
	"time"

	activities_model "code.gitea.io/gitea/models/activities"
	issues_model "code.gitea.io/gitea/models/issues"
	access_model "code.gitea.io/gitea/models/perm/access"
	pull_model "code.gitea.io/gitea/models/pull"
	repo_model "code.gitea.io/gitea/models/repo"
	"code.gitea.io/gitea/models/unit"
	user_model "code.gitea.io/gitea/models/user"
	"code.gitea.io/gitea/modules/base"
	"code.gitea.io/gitea/modules/git"
	"code.gitea.io/gitea/modules/gitrepo"
	"code.gitea.io/gitea/modules/graceful"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/setting"
	api "code.gitea.io/gitea/modules/structs"
	"code.gitea.io/gitea/modules/timeutil"
	"code.gitea.io/gitea/modules/web"
	"code.gitea.io/gitea/routers/api/v1/utils"
	"code.gitea.io/gitea/routers/common"
	asymkey_service "code.gitea.io/gitea/services/asymkey"
	"code.gitea.io/gitea/services/automerge"
	"code.gitea.io/gitea/services/context"
	"code.gitea.io/gitea/services/convert"
	"code.gitea.io/gitea/services/forms"
	"code.gitea.io/gitea/services/gitdiff"
	issue_service "code.gitea.io/gitea/services/issue"
	notify_service "code.gitea.io/gitea/services/notify"
	pull_service "code.gitea.io/gitea/services/pull"
	repo_service "code.gitea.io/gitea/services/repository"
)

// ListPullRequests returns a list of all PRs
func ListPullRequests(ctx *context.APIContext) {
	// swagger:operation GET /repos/{owner}/{repo}/pulls repository repoListPullRequests
	// ---
	// summary: List a repo's 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
	// - name: base_branch
	//   in: query
	//   description: Filter by target base branch of the pull request
	//   type: string
	// - name: state
	//   in: query
	//   description: State of pull request
	//   type: string
	//   enum: [open, closed, all]
	//   default: open
	// - name: sort
	//   in: query
	//   description: Type of sort
	//   type: string
	//   enum: [oldest, recentupdate, recentclose, leastupdate, mostcomment, leastcomment, priority]
	// - name: milestone
	//   in: query
	//   description: ID of the milestone
	//   type: integer
	//   format: int64
	// - name: labels
	//   in: query
	//   description: Label IDs
	//   type: array
	//   collectionFormat: multi
	//   items:
	//     type: integer
	//     format: int64
	// - name: poster
	//   in: query
	//   description: Filter by pull request author
	//   type: string
	// - name: page
	//   in: query
	//   description: Page number of results to return (1-based)
	//   type: integer
	//   minimum: 1
	//   default: 1
	// - name: limit
	//   in: query
	//   description: Page size of results
	//   type: integer
	//   minimum: 0
	// responses:
	//   "200":
	//     "$ref": "#/responses/PullRequestList"
	//   "404":
	//     "$ref": "#/responses/notFound"
	//   "500":
	//     "$ref": "#/responses/error"

	labelIDs, err := base.StringsToInt64s(ctx.FormStrings("labels"))
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	var posterID int64
	if posterStr := ctx.FormString("poster"); posterStr != "" {
		poster, err := user_model.GetUserByName(ctx, posterStr)
		if err != nil {
			if user_model.IsErrUserNotExist(err) {
				ctx.APIError(http.StatusBadRequest, err)
			} else {
				ctx.APIErrorInternal(err)
			}
			return
		}
		posterID = poster.ID
	}
	listOptions := utils.GetListOptions(ctx)
	prs, maxResults, err := issues_model.PullRequests(ctx, ctx.Repo.Repository.ID, &issues_model.PullRequestsOptions{
		ListOptions: listOptions,
		State:       ctx.FormTrim("state"),
		SortType:    ctx.FormTrim("sort"),
		Labels:      labelIDs,
		MilestoneID: ctx.FormInt64("milestone"),
		PosterID:    posterID,
		BaseBranch:  ctx.FormTrim("base_branch"),
	})
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	apiPrs, err := convert.ToAPIPullRequests(ctx, ctx.Repo.Repository, prs, ctx.Doer)
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	ctx.SetLinkHeader(int(maxResults), listOptions.PageSize)
	ctx.SetTotalCountHeader(maxResults)
	ctx.JSON(http.StatusOK, &apiPrs)
}

// GetPullRequest returns a single PR based on index
func GetPullRequest(ctx *context.APIContext) {
	// swagger:operation GET /repos/{owner}/{repo}/pulls/{index} repository repoGetPullRequest
	// ---
	// summary: Get a pull request
	// 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: index
	//   in: path
	//   description: index of the pull request to get
	//   type: integer
	//   format: int64
	//   required: true
	// responses:
	//   "200":
	//     "$ref": "#/responses/PullRequest"
	//   "404":
	//     "$ref": "#/responses/notFound"

	pr, err := issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, ctx.PathParamInt64("index"))
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	if err = pr.LoadBaseRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	if err = pr.LoadHeadRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	// Consider API access a view for delayed checking.
	pull_service.StartPullRequestCheckOnView(ctx, pr)

	ctx.JSON(http.StatusOK, convert.ToAPIPullRequest(ctx, pr, ctx.Doer))
}

// GetPullRequest returns a single PR based on index
func GetPullRequestByBaseHead(ctx *context.APIContext) {
	// swagger:operation GET /repos/{owner}/{repo}/pulls/{base}/{head} repository repoGetPullRequestByBaseHead
	// ---
	// summary: Get a pull request by base and head
	// 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: base
	//   in: path
	//   description: base of the pull request to get
	//   type: string
	//   required: true
	// - name: head
	//   in: path
	//   description: head of the pull request to get
	//   type: string
	//   required: true
	// responses:
	//   "200":
	//     "$ref": "#/responses/PullRequest"
	//   "404":
	//     "$ref": "#/responses/notFound"

	var headRepoID int64
	var headBranch string
	head := ctx.PathParam("*")
	if strings.Contains(head, ":") {
		split := strings.SplitN(head, ":", 2)
		headBranch = split[1]
		var owner, name string
		if strings.Contains(split[0], "/") {
			split = strings.Split(split[0], "/")
			owner = split[0]
			name = split[1]
		} else {
			owner = split[0]
			name = ctx.Repo.Repository.Name
		}
		repo, err := repo_model.GetRepositoryByOwnerAndName(ctx, owner, name)
		if err != nil {
			if repo_model.IsErrRepoNotExist(err) {
				ctx.APIErrorNotFound()
			} else {
				ctx.APIErrorInternal(err)
			}
			return
		}
		headRepoID = repo.ID
	} else {
		headRepoID = ctx.Repo.Repository.ID
		headBranch = head
	}

	pr, err := issues_model.GetPullRequestByBaseHeadInfo(ctx, ctx.Repo.Repository.ID, headRepoID, ctx.PathParam("base"), headBranch)
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	if err = pr.LoadBaseRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	if err = pr.LoadHeadRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	// Consider API access a view for delayed checking.
	pull_service.StartPullRequestCheckOnView(ctx, pr)

	ctx.JSON(http.StatusOK, convert.ToAPIPullRequest(ctx, pr, ctx.Doer))
}

// DownloadPullDiffOrPatch render a pull's raw diff or patch
func DownloadPullDiffOrPatch(ctx *context.APIContext) {
	// swagger:operation GET /repos/{owner}/{repo}/pulls/{index}.{diffType} repository repoDownloadPullDiffOrPatch
	// ---
	// summary: Get a pull request diff or patch
	// produces:
	// - text/plain
	// 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 the pull request to get
	//   type: integer
	//   format: int64
	//   required: true
	// - name: diffType
	//   in: path
	//   description: whether the output is diff or patch
	//   type: string
	//   enum: [diff, patch]
	//   required: true
	// - name: binary
	//   in: query
	//   description: whether to include binary file changes. if true, the diff is applicable with `git apply`
	//   type: boolean
	// responses:
	//   "200":
	//     "$ref": "#/responses/string"
	//   "404":
	//     "$ref": "#/responses/notFound"
	pr, err := issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, ctx.PathParamInt64("index"))
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}
	var patch bool
	if ctx.PathParam("diffType") == "diff" {
		patch = false
	} else {
		patch = true
	}

	binary := ctx.FormBool("binary")

	if err := pull_service.DownloadDiffOrPatch(ctx, pr, ctx, patch, binary); err != nil {
		ctx.APIErrorInternal(err)
		return
	}
}

// CreatePullRequest does what it says
func CreatePullRequest(ctx *context.APIContext) {
	// swagger:operation POST /repos/{owner}/{repo}/pulls repository repoCreatePullRequest
	// ---
	// summary: Create a pull request
	// 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:
	//     "$ref": "#/definitions/CreatePullRequestOption"
	// responses:
	//   "201":
	//     "$ref": "#/responses/PullRequest"
	//   "403":
	//     "$ref": "#/responses/forbidden"
	//   "404":
	//     "$ref": "#/responses/notFound"
	//   "409":
	//     "$ref": "#/responses/error"
	//   "422":
	//     "$ref": "#/responses/validationError"
	//   "423":
	//     "$ref": "#/responses/repoArchivedError"

	form := *web.GetForm(ctx).(*api.CreatePullRequestOption)
	if form.Head == form.Base {
		ctx.APIError(http.StatusUnprocessableEntity, "Invalid PullRequest: There are no changes between the head and the base")
		return
	}

	var (
		repo        = ctx.Repo.Repository
		labelIDs    []int64
		milestoneID int64
	)

	// Get repo/branch information
	compareResult, closer := parseCompareInfo(ctx, form)
	if ctx.Written() {
		return
	}
	defer closer()

	if !compareResult.baseRef.IsBranch() || !compareResult.headRef.IsBranch() {
		ctx.APIError(http.StatusUnprocessableEntity, "Invalid PullRequest: base and head must be branches")
		return
	}

	// Check if another PR exists with the same targets
	existingPr, err := issues_model.GetUnmergedPullRequest(ctx, compareResult.headRepo.ID, ctx.Repo.Repository.ID,
		compareResult.headRef.ShortName(), compareResult.baseRef.ShortName(),
		issues_model.PullRequestFlowGithub,
	)
	if err != nil {
		if !issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorInternal(err)
			return
		}
	} else {
		err = issues_model.ErrPullRequestAlreadyExists{
			ID:         existingPr.ID,
			IssueID:    existingPr.Index,
			HeadRepoID: existingPr.HeadRepoID,
			BaseRepoID: existingPr.BaseRepoID,
			HeadBranch: existingPr.HeadBranch,
			BaseBranch: existingPr.BaseBranch,
		}
		ctx.APIError(http.StatusConflict, err)
		return
	}

	if len(form.Labels) > 0 {
		labels, err := issues_model.GetLabelsInRepoByIDs(ctx, ctx.Repo.Repository.ID, form.Labels)
		if err != nil {
			ctx.APIErrorInternal(err)
			return
		}

		labelIDs = make([]int64, 0, len(labels))
		for _, label := range labels {
			labelIDs = append(labelIDs, label.ID)
		}

		if ctx.Repo.Owner.IsOrganization() {
			orgLabels, err := issues_model.GetLabelsInOrgByIDs(ctx, ctx.Repo.Owner.ID, form.Labels)
			if err != nil {
				ctx.APIErrorInternal(err)
				return
			}

			orgLabelIDs := make([]int64, 0, len(orgLabels))
			for _, orgLabel := range orgLabels {
				orgLabelIDs = append(orgLabelIDs, orgLabel.ID)
			}
			labelIDs = append(labelIDs, orgLabelIDs...)
		}
	}

	if form.Milestone > 0 {
		milestone, err := issues_model.GetMilestoneByRepoID(ctx, ctx.Repo.Repository.ID, form.Milestone)
		if err != nil {
			if issues_model.IsErrMilestoneNotExist(err) {
				ctx.APIErrorNotFound()
			} else {
				ctx.APIErrorInternal(fmt.Errorf("GetMilestoneByRepoID: %w", err))
			}
			return
		}

		milestoneID = milestone.ID
	}

	var deadlineUnix timeutil.TimeStamp
	if form.Deadline != nil {
		deadlineUnix = timeutil.TimeStamp(form.Deadline.Unix())
	}

	prIssue := &issues_model.Issue{
		RepoID:       repo.ID,
		Title:        form.Title,
		PosterID:     ctx.Doer.ID,
		Poster:       ctx.Doer,
		MilestoneID:  milestoneID,
		IsPull:       true,
		Content:      form.Body,
		DeadlineUnix: deadlineUnix,
	}
	pr := &issues_model.PullRequest{
		HeadRepoID: compareResult.headRepo.ID,
		BaseRepoID: repo.ID,
		HeadBranch: compareResult.headRef.ShortName(),
		BaseBranch: compareResult.baseRef.ShortName(),
		HeadRepo:   compareResult.headRepo,
		BaseRepo:   repo,
		MergeBase:  compareResult.compareInfo.MergeBase,
		Type:       issues_model.PullRequestGitea,
	}

	// Get all assignee IDs
	assigneeIDs, err := issues_model.MakeIDsFromAPIAssigneesToAdd(ctx, form.Assignee, form.Assignees)
	if err != nil {
		if user_model.IsErrUserNotExist(err) {
			ctx.APIError(http.StatusUnprocessableEntity, fmt.Sprintf("Assignee does not exist: [name: %s]", err))
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}
	// Check if the passed assignees is assignable
	for _, aID := range assigneeIDs {
		assignee, err := user_model.GetUserByID(ctx, aID)
		if err != nil {
			ctx.APIErrorInternal(err)
			return
		}

		valid, err := access_model.CanBeAssigned(ctx, assignee, repo, true)
		if err != nil {
			ctx.APIErrorInternal(err)
			return
		}
		if !valid {
			ctx.APIError(http.StatusUnprocessableEntity, repo_model.ErrUserDoesNotHaveAccessToRepo{UserID: aID, RepoName: repo.Name})
			return
		}
	}

	prOpts := &pull_service.NewPullRequestOptions{
		Repo:        repo,
		Issue:       prIssue,
		LabelIDs:    labelIDs,
		PullRequest: pr,
		AssigneeIDs: assigneeIDs,
	}
	prOpts.Reviewers, prOpts.TeamReviewers = parseReviewersByNames(ctx, form.Reviewers, form.TeamReviewers)
	if ctx.Written() {
		return
	}

	if err := pull_service.NewPullRequest(ctx, prOpts); err != nil {
		if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) {
			ctx.APIError(http.StatusBadRequest, err)
		} else if errors.Is(err, user_model.ErrBlockedUser) {
			ctx.APIError(http.StatusForbidden, err)
		} else if errors.Is(err, issues_model.ErrMustCollaborator) {
			ctx.APIError(http.StatusForbidden, err)
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	log.Trace("Pull request created: %d/%d", repo.ID, prIssue.ID)
	ctx.JSON(http.StatusCreated, convert.ToAPIPullRequest(ctx, pr, ctx.Doer))
}

// EditPullRequest does what it says
func EditPullRequest(ctx *context.APIContext) {
	// swagger:operation PATCH /repos/{owner}/{repo}/pulls/{index} repository repoEditPullRequest
	// ---
	// summary: Update a pull request. If using deadline only the date will be taken into account, and time of day ignored.
	// 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: index
	//   in: path
	//   description: index of the pull request to edit
	//   type: integer
	//   format: int64
	//   required: true
	// - name: body
	//   in: body
	//   schema:
	//     "$ref": "#/definitions/EditPullRequestOption"
	// responses:
	//   "201":
	//     "$ref": "#/responses/PullRequest"
	//   "403":
	//     "$ref": "#/responses/forbidden"
	//   "404":
	//     "$ref": "#/responses/notFound"
	//   "409":
	//     "$ref": "#/responses/error"
	//   "412":
	//     "$ref": "#/responses/error"
	//   "422":
	//     "$ref": "#/responses/validationError"

	form := web.GetForm(ctx).(*api.EditPullRequestOption)
	pr, err := issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, ctx.PathParamInt64("index"))
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	err = pr.LoadIssue(ctx)
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	issue := pr.Issue
	issue.Repo = ctx.Repo.Repository

	if err := issue.LoadAttributes(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	if !issue.IsPoster(ctx.Doer.ID) && !ctx.Repo.CanWrite(unit.TypePullRequests) {
		ctx.Status(http.StatusForbidden)
		return
	}

	if len(form.Title) > 0 {
		err = issue_service.ChangeTitle(ctx, issue, ctx.Doer, form.Title)
		if err != nil {
			ctx.APIErrorInternal(err)
			return
		}
	}
	if form.Body != nil {
		err = issue_service.ChangeContent(ctx, issue, ctx.Doer, *form.Body, issue.ContentVersion)
		if err != nil {
			if errors.Is(err, issues_model.ErrIssueAlreadyChanged) {
				ctx.APIError(http.StatusBadRequest, err)
				return
			}

			ctx.APIErrorInternal(err)
			return
		}
	}

	// Update or remove deadline if set
	if form.Deadline != nil || form.RemoveDeadline != nil {
		var deadlineUnix timeutil.TimeStamp
		if (form.RemoveDeadline == nil || !*form.RemoveDeadline) && !form.Deadline.IsZero() {
			deadline := time.Date(form.Deadline.Year(), form.Deadline.Month(), form.Deadline.Day(),
				23, 59, 59, 0, form.Deadline.Location())
			deadlineUnix = timeutil.TimeStamp(deadline.Unix())
		}

		if err := issues_model.UpdateIssueDeadline(ctx, issue, deadlineUnix, ctx.Doer); err != nil {
			ctx.APIErrorInternal(err)
			return
		}
		issue.DeadlineUnix = deadlineUnix
	}

	// Add/delete assignees

	// Deleting is done the GitHub way (quote from their api documentation):
	// https://developer.github.com/v3/issues/#edit-an-issue
	// "assignees" (array): Logins for Users to assign to this issue.
	// Pass one or more user logins to replace the set of assignees on this Issue.
	// Send an empty array ([]) to clear all assignees from the Issue.

	if ctx.Repo.CanWrite(unit.TypePullRequests) && (form.Assignees != nil || len(form.Assignee) > 0) {
		err = issue_service.UpdateAssignees(ctx, issue, form.Assignee, form.Assignees, ctx.Doer)
		if err != nil {
			if user_model.IsErrUserNotExist(err) {
				ctx.APIError(http.StatusUnprocessableEntity, fmt.Sprintf("Assignee does not exist: [name: %s]", err))
			} else if errors.Is(err, user_model.ErrBlockedUser) {
				ctx.APIError(http.StatusForbidden, err)
			} else {
				ctx.APIErrorInternal(err)
			}
			return
		}
	}

	if ctx.Repo.CanWrite(unit.TypePullRequests) && form.Milestone != 0 &&
		issue.MilestoneID != form.Milestone {
		oldMilestoneID := issue.MilestoneID
		issue.MilestoneID = form.Milestone
		issue.Milestone, err = issues_model.GetMilestoneByRepoID(ctx, ctx.Repo.Repository.ID, form.Milestone)
		if err != nil {
			ctx.APIErrorInternal(err)
			return
		}
		if err = issue_service.ChangeMilestoneAssign(ctx, issue, ctx.Doer, oldMilestoneID); err != nil {
			ctx.APIErrorInternal(err)
			return
		}
	}

	if ctx.Repo.CanWrite(unit.TypePullRequests) && form.Labels != nil {
		labels, err := issues_model.GetLabelsInRepoByIDs(ctx, ctx.Repo.Repository.ID, form.Labels)
		if err != nil {
			ctx.APIErrorInternal(err)
			return
		}

		if ctx.Repo.Owner.IsOrganization() {
			orgLabels, err := issues_model.GetLabelsInOrgByIDs(ctx, ctx.Repo.Owner.ID, form.Labels)
			if err != nil {
				ctx.APIErrorInternal(err)
				return
			}

			labels = append(labels, orgLabels...)
		}

		if err = issues_model.ReplaceIssueLabels(ctx, issue, labels, ctx.Doer); err != nil {
			ctx.APIErrorInternal(err)
			return
		}
	}

	if form.State != nil {
		if pr.HasMerged {
			ctx.APIError(http.StatusPreconditionFailed, "cannot change state of this pull request, it was already merged")
			return
		}

		state := api.StateType(*form.State)
		closeOrReopenIssue(ctx, issue, state)
		if ctx.Written() {
			return
		}
	}

	// change pull target branch
	if !pr.HasMerged && len(form.Base) != 0 && form.Base != pr.BaseBranch {
		if !gitrepo.IsBranchExist(ctx, ctx.Repo.Repository, form.Base) {
			ctx.APIError(http.StatusNotFound, fmt.Errorf("new base '%s' not exist", form.Base))
			return
		}
		if err := pull_service.ChangeTargetBranch(ctx, pr, ctx.Doer, form.Base); err != nil {
			if issues_model.IsErrPullRequestAlreadyExists(err) {
				ctx.APIError(http.StatusConflict, err)
				return
			} else if issues_model.IsErrIssueIsClosed(err) {
				ctx.APIError(http.StatusUnprocessableEntity, err)
				return
			} else if pull_service.IsErrPullRequestHasMerged(err) {
				ctx.APIError(http.StatusConflict, err)
				return
			}
			ctx.APIErrorInternal(err)
			return
		}
		notify_service.PullRequestChangeTargetBranch(ctx, ctx.Doer, pr, form.Base)
	}

	// update allow edits
	if form.AllowMaintainerEdit != nil {
		if err := pull_service.SetAllowEdits(ctx, ctx.Doer, pr, *form.AllowMaintainerEdit); err != nil {
			if errors.Is(err, pull_service.ErrUserHasNoPermissionForAction) {
				ctx.APIError(http.StatusForbidden, fmt.Sprintf("SetAllowEdits: %s", err))
				return
			}
			ctx.APIErrorInternal(err)
			return
		}
	}

	// Refetch from database
	pr, err = issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, pr.Index)
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	// TODO this should be 200, not 201
	ctx.JSON(http.StatusCreated, convert.ToAPIPullRequest(ctx, pr, ctx.Doer))
}

// IsPullRequestMerged checks if a PR exists given an index
func IsPullRequestMerged(ctx *context.APIContext) {
	// swagger:operation GET /repos/{owner}/{repo}/pulls/{index}/merge repository repoPullRequestIsMerged
	// ---
	// summary: Check if a pull request has been merged
	// 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: index
	//   in: path
	//   description: index of the pull request
	//   type: integer
	//   format: int64
	//   required: true
	// responses:
	//   "204":
	//     description: pull request has been merged
	//   "404":
	//     description: pull request has not been merged

	pr, err := issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, ctx.PathParamInt64("index"))
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	if pr.HasMerged {
		ctx.Status(http.StatusNoContent)
	}
	ctx.APIErrorNotFound()
}

// MergePullRequest merges a PR given an index
func MergePullRequest(ctx *context.APIContext) {
	// swagger:operation POST /repos/{owner}/{repo}/pulls/{index}/merge repository repoMergePullRequest
	// ---
	// summary: Merge a pull request
	// 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: index
	//   in: path
	//   description: index of the pull request to merge
	//   type: integer
	//   format: int64
	//   required: true
	// - name: body
	//   in: body
	//   schema:
	//     $ref: "#/definitions/MergePullRequestOption"
	// responses:
	//   "200":
	//     "$ref": "#/responses/empty"
	//   "404":
	//     "$ref": "#/responses/notFound"
	//   "405":
	//     "$ref": "#/responses/empty"
	//   "409":
	//     "$ref": "#/responses/error"
	//   "423":
	//     "$ref": "#/responses/repoArchivedError"

	form := web.GetForm(ctx).(*forms.MergePullRequestForm)

	pr, err := issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, ctx.PathParamInt64("index"))
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound("GetPullRequestByIndex", err)
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	if err := pr.LoadHeadRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	if err := pr.LoadIssue(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	pr.Issue.Repo = ctx.Repo.Repository

	if ctx.IsSigned {
		// Update issue-user.
		if err = activities_model.SetIssueReadBy(ctx, pr.Issue.ID, ctx.Doer.ID); err != nil {
			ctx.APIErrorInternal(err)
			return
		}
	}

	manuallyMerged := repo_model.MergeStyle(form.Do) == repo_model.MergeStyleManuallyMerged

	mergeCheckType := pull_service.MergeCheckTypeGeneral
	if form.MergeWhenChecksSucceed {
		mergeCheckType = pull_service.MergeCheckTypeAuto
	}
	if manuallyMerged {
		mergeCheckType = pull_service.MergeCheckTypeManually
	}

	// start with merging by checking
	if err := pull_service.CheckPullMergeable(ctx, ctx.Doer, &ctx.Repo.Permission, pr, mergeCheckType, form.ForceMerge); err != nil {
		if errors.Is(err, pull_service.ErrIsClosed) {
			ctx.APIErrorNotFound()
		} else if errors.Is(err, pull_service.ErrNoPermissionToMerge) {
			ctx.APIError(http.StatusMethodNotAllowed, "User not allowed to merge PR")
		} else if errors.Is(err, pull_service.ErrHasMerged) {
			ctx.APIError(http.StatusMethodNotAllowed, "The PR is already merged")
		} else if errors.Is(err, pull_service.ErrIsWorkInProgress) {
			ctx.APIError(http.StatusMethodNotAllowed, "Work in progress PRs cannot be merged")
		} else if errors.Is(err, pull_service.ErrNotMergeableState) {
			ctx.APIError(http.StatusMethodNotAllowed, "Please try again later")
		} else if errors.Is(err, pull_service.ErrNotReadyToMerge) {
			ctx.APIError(http.StatusMethodNotAllowed, err)
		} else if asymkey_service.IsErrWontSign(err) {
			ctx.APIError(http.StatusMethodNotAllowed, err)
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	// handle manually-merged mark
	if manuallyMerged {
		if err := pull_service.MergedManually(ctx, pr, ctx.Doer, ctx.Repo.GitRepo, form.MergeCommitID); err != nil {
			if pull_service.IsErrInvalidMergeStyle(err) {
				ctx.APIError(http.StatusMethodNotAllowed, fmt.Errorf("%s is not allowed an allowed merge style for this repository", repo_model.MergeStyle(form.Do)))
				return
			}
			if strings.Contains(err.Error(), "Wrong commit ID") {
				ctx.JSON(http.StatusConflict, err)
				return
			}
			ctx.APIErrorInternal(err)
			return
		}
		ctx.Status(http.StatusOK)
		return
	}

	if len(form.Do) == 0 {
		form.Do = string(repo_model.MergeStyleMerge)
	}

	message := strings.TrimSpace(form.MergeTitleField)
	if len(message) == 0 {
		message, _, err = pull_service.GetDefaultMergeMessage(ctx, ctx.Repo.GitRepo, pr, repo_model.MergeStyle(form.Do))
		if err != nil {
			ctx.APIErrorInternal(err)
			return
		}
	}

	form.MergeMessageField = strings.TrimSpace(form.MergeMessageField)
	if len(form.MergeMessageField) > 0 {
		message += "\n\n" + form.MergeMessageField
	}

	deleteBranchAfterMerge, err := pull_service.ShouldDeleteBranchAfterMerge(ctx, form.DeleteBranchAfterMerge, ctx.Repo.Repository, pr)
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	if form.MergeWhenChecksSucceed {
		scheduled, err := automerge.ScheduleAutoMerge(ctx, ctx.Doer, pr, repo_model.MergeStyle(form.Do), message, deleteBranchAfterMerge)
		if err != nil {
			if pull_model.IsErrAlreadyScheduledToAutoMerge(err) {
				ctx.APIError(http.StatusConflict, err)
				return
			}
			ctx.APIErrorInternal(err)
			return
		} else if scheduled {
			// nothing more to do ...
			ctx.Status(http.StatusCreated)
			return
		}
	}

	if err := pull_service.Merge(ctx, pr, ctx.Doer, ctx.Repo.GitRepo, repo_model.MergeStyle(form.Do), form.HeadCommitID, message, false); err != nil {
		if pull_service.IsErrInvalidMergeStyle(err) {
			ctx.APIError(http.StatusMethodNotAllowed, fmt.Errorf("%s is not allowed an allowed merge style for this repository", repo_model.MergeStyle(form.Do)))
		} else if pull_service.IsErrMergeConflicts(err) {
			conflictError := err.(pull_service.ErrMergeConflicts)
			ctx.JSON(http.StatusConflict, conflictError)
		} else if pull_service.IsErrRebaseConflicts(err) {
			conflictError := err.(pull_service.ErrRebaseConflicts)
			ctx.JSON(http.StatusConflict, conflictError)
		} else if pull_service.IsErrMergeUnrelatedHistories(err) {
			conflictError := err.(pull_service.ErrMergeUnrelatedHistories)
			ctx.JSON(http.StatusConflict, conflictError)
		} else if git.IsErrPushOutOfDate(err) {
			ctx.APIError(http.StatusConflict, "merge push out of date")
		} else if pull_service.IsErrSHADoesNotMatch(err) {
			ctx.APIError(http.StatusConflict, "head out of date")
		} else if git.IsErrPushRejected(err) {
			errPushRej := err.(*git.ErrPushRejected)
			if len(errPushRej.Message) == 0 {
				ctx.APIError(http.StatusConflict, "PushRejected without remote error message")
			} else {
				ctx.APIError(http.StatusConflict, "PushRejected with remote message: "+errPushRej.Message)
			}
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}
	log.Trace("Pull request merged: %d", pr.ID)

	if deleteBranchAfterMerge {
		if err = repo_service.DeleteBranchAfterMerge(ctx, ctx.Doer, pr.ID, nil); err != nil {
			// no way to tell users that what error happens, and the PR has been merged, so ignore the error
			log.Debug("DeleteBranchAfterMerge: pr %d, err: %v", pr.ID, err)
		}
	}

	ctx.Status(http.StatusOK)
}

type parseCompareInfoResult struct {
	headRepo    *repo_model.Repository
	headGitRepo *git.Repository
	compareInfo *pull_service.CompareInfo
	baseRef     git.RefName
	headRef     git.RefName
}

// parseCompareInfo returns non-nil if it succeeds, it always writes to the context and returns nil if it fails
func parseCompareInfo(ctx *context.APIContext, form api.CreatePullRequestOption) (result *parseCompareInfoResult, closer func()) {
	var err error
	// Get compared branches information
	// format: <base branch>...[<head repo>:]<head branch>
	// base<-head: master...head:feature
	// same repo: master...feature
	baseRepo := ctx.Repo.Repository
	baseRefToGuess := form.Base

	headUser := ctx.Repo.Owner
	headRefToGuess := form.Head
	if headInfos := strings.Split(form.Head, ":"); len(headInfos) == 1 {
		// If there is no head repository, it means pull request between same repository.
		// Do nothing here because the head variables have been assigned above.
	} else if len(headInfos) == 2 {
		// There is a head repository (the head repository could also be the same base repo)
		headRefToGuess = headInfos[1]
		headUser, err = user_model.GetUserOrOrgByName(ctx, headInfos[0])
		if err != nil {
			if user_model.IsErrUserNotExist(err) {
				ctx.APIErrorNotFound("GetUserByName")
			} else {
				ctx.APIErrorInternal(err)
			}
			return nil, nil
		}
	} else {
		ctx.APIErrorNotFound()
		return nil, nil
	}

	isSameRepo := ctx.Repo.Owner.ID == headUser.ID

	var headRepo *repo_model.Repository
	if isSameRepo {
		headRepo = baseRepo
	} else {
		headRepo, err = common.FindHeadRepo(ctx, baseRepo, headUser.ID)
		if err != nil {
			ctx.APIErrorInternal(err)
			return nil, nil
		}
		if headRepo == nil {
			ctx.APIErrorNotFound("head repository not found")
			return nil, nil
		}
	}

	var headGitRepo *git.Repository
	if isSameRepo {
		headGitRepo = ctx.Repo.GitRepo
		closer = func() {} // no need to close the head repo because it shares the base repo
	} else {
		headGitRepo, err = gitrepo.OpenRepository(ctx, headRepo)
		if err != nil {
			ctx.APIErrorInternal(err)
			return nil, nil
		}
		closer = func() { _ = headGitRepo.Close() }
	}
	defer func() {
		if result == nil && !isSameRepo {
			_ = headGitRepo.Close()
		}
	}()

	// user should have permission to read baseRepo's codes and pulls, NOT headRepo's
	permBase, err := access_model.GetUserRepoPermission(ctx, baseRepo, ctx.Doer)
	if err != nil {
		ctx.APIErrorInternal(err)
		return nil, nil
	}

	if !permBase.CanRead(unit.TypeCode) {
		log.Trace("Permission Denied: User %-v cannot create/read pull requests or cannot read code in Repo %-v\nUser in baseRepo has Permissions: %-+v", ctx.Doer, baseRepo, permBase)
		ctx.APIErrorNotFound("Can't read pulls or can't read UnitTypeCode")
		return nil, nil
	}

	// user should have permission to read headRepo's codes
	// TODO: could the logic be simplified if the headRepo is the same as the baseRepo? Need to think more about it.
	permHead, err := access_model.GetUserRepoPermission(ctx, headRepo, ctx.Doer)
	if err != nil {
		ctx.APIErrorInternal(err)
		return nil, nil
	}
	if !permHead.CanRead(unit.TypeCode) {
		log.Trace("Permission Denied: User: %-v cannot read code in Repo: %-v\nUser in headRepo has Permissions: %-+v", ctx.Doer, headRepo, permHead)
		ctx.APIErrorNotFound("Can't read headRepo UnitTypeCode")
		return nil, nil
	}

	baseRef := ctx.Repo.GitRepo.UnstableGuessRefByShortName(baseRefToGuess)
	headRef := headGitRepo.UnstableGuessRefByShortName(headRefToGuess)

	log.Trace("Repo path: %q, base ref: %q->%q, head ref: %q->%q", ctx.Repo.GitRepo.Path, baseRefToGuess, baseRef, headRefToGuess, headRef)

	baseRefValid := baseRef.IsBranch() || baseRef.IsTag() || git.IsStringLikelyCommitID(git.ObjectFormatFromName(ctx.Repo.Repository.ObjectFormatName), baseRef.ShortName())
	headRefValid := headRef.IsBranch() || headRef.IsTag() || git.IsStringLikelyCommitID(git.ObjectFormatFromName(headRepo.ObjectFormatName), headRef.ShortName())
	// Check if base&head ref are valid.
	if !baseRefValid || !headRefValid {
		ctx.APIErrorNotFound()
		return nil, nil
	}

	compareInfo, err := pull_service.GetCompareInfo(ctx, baseRepo, headRepo, headGitRepo, baseRef.ShortName(), headRef.ShortName(), false, false)
	if err != nil {
		ctx.APIErrorInternal(err)
		return nil, nil
	}

	result = &parseCompareInfoResult{headRepo: headRepo, headGitRepo: headGitRepo, compareInfo: compareInfo, baseRef: baseRef, headRef: headRef}
	return result, closer
}

// UpdatePullRequest merge PR's baseBranch into headBranch
func UpdatePullRequest(ctx *context.APIContext) {
	// swagger:operation POST /repos/{owner}/{repo}/pulls/{index}/update repository repoUpdatePullRequest
	// ---
	// summary: Merge PR's baseBranch into headBranch
	// 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: index
	//   in: path
	//   description: index of the pull request to get
	//   type: integer
	//   format: int64
	//   required: true
	// - name: style
	//   in: query
	//   description: how to update pull request
	//   type: string
	//   enum: [merge, rebase]
	// responses:
	//   "200":
	//     "$ref": "#/responses/empty"
	//   "403":
	//     "$ref": "#/responses/forbidden"
	//   "404":
	//     "$ref": "#/responses/notFound"
	//   "409":
	//     "$ref": "#/responses/error"
	//   "422":
	//     "$ref": "#/responses/validationError"

	pr, err := issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, ctx.PathParamInt64("index"))
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	if pr.HasMerged {
		ctx.APIError(http.StatusUnprocessableEntity, err)
		return
	}

	if err = pr.LoadIssue(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	if pr.Issue.IsClosed {
		ctx.APIError(http.StatusUnprocessableEntity, err)
		return
	}

	if err = pr.LoadBaseRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	if err = pr.LoadHeadRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	rebase := ctx.FormString("style") == "rebase"

	allowedUpdateByMerge, allowedUpdateByRebase, err := pull_service.IsUserAllowedToUpdate(ctx, pr, ctx.Doer)
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	if (!allowedUpdateByMerge && !rebase) || (rebase && !allowedUpdateByRebase) {
		ctx.Status(http.StatusForbidden)
		return
	}

	// default merge commit message
	message := fmt.Sprintf("Merge branch '%s' into %s", pr.BaseBranch, pr.HeadBranch)

	if err = pull_service.Update(graceful.GetManager().ShutdownContext(), pr, ctx.Doer, message, rebase); err != nil {
		if pull_service.IsErrMergeConflicts(err) {
			ctx.APIError(http.StatusConflict, "merge failed because of conflict")
			return
		} else if pull_service.IsErrRebaseConflicts(err) {
			ctx.APIError(http.StatusConflict, "rebase failed because of conflict")
			return
		}
		ctx.APIErrorInternal(err)
		return
	}

	ctx.Status(http.StatusOK)
}

// MergePullRequest cancel an auto merge scheduled for a given PullRequest by index
func CancelScheduledAutoMerge(ctx *context.APIContext) {
	// swagger:operation DELETE /repos/{owner}/{repo}/pulls/{index}/merge repository repoCancelScheduledAutoMerge
	// ---
	// summary: Cancel the scheduled auto merge for the given pull request
	// 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: index
	//   in: path
	//   description: index of the pull request to merge
	//   type: integer
	//   format: int64
	//   required: true
	// responses:
	//   "204":
	//     "$ref": "#/responses/empty"
	//   "403":
	//     "$ref": "#/responses/forbidden"
	//   "404":
	//     "$ref": "#/responses/notFound"
	//   "423":
	//     "$ref": "#/responses/repoArchivedError"

	pullIndex := ctx.PathParamInt64("index")
	pull, err := issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, pullIndex)
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
			return
		}
		ctx.APIErrorInternal(err)
		return
	}

	exist, autoMerge, err := pull_model.GetScheduledMergeByPullID(ctx, pull.ID)
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	if !exist {
		ctx.APIErrorNotFound()
		return
	}

	if ctx.Doer.ID != autoMerge.DoerID {
		allowed, err := pull_service.IsUserAllowedToMerge(ctx, pull, ctx.Repo.Permission, ctx.Doer)
		if err != nil {
			ctx.APIErrorInternal(err)
			return
		}
		if !allowed {
			ctx.APIError(http.StatusForbidden, "user has no permission to cancel the scheduled auto merge")
			return
		}
	}

	if err := automerge.RemoveScheduledAutoMerge(ctx, ctx.Doer, pull); err != nil {
		ctx.APIErrorInternal(err)
	} else {
		ctx.Status(http.StatusNoContent)
	}
}

// GetPullRequestCommits gets all commits associated with a given PR
func GetPullRequestCommits(ctx *context.APIContext) {
	// swagger:operation GET /repos/{owner}/{repo}/pulls/{index}/commits repository repoGetPullRequestCommits
	// ---
	// summary: Get commits for a pull request
	// 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: index
	//   in: path
	//   description: index of the pull request to get
	//   type: integer
	//   format: int64
	//   required: true
	// - name: page
	//   in: query
	//   description: page number of results to return (1-based)
	//   type: integer
	// - name: limit
	//   in: query
	//   description: page size of results
	//   type: integer
	// - name: verification
	//   in: query
	//   description: include verification for every commit (disable for speedup, default 'true')
	//   type: boolean
	// - name: files
	//   in: query
	//   description: include a list of affected files for every commit (disable for speedup, default 'true')
	//   type: boolean
	// responses:
	//   "200":
	//     "$ref": "#/responses/CommitList"
	//   "404":
	//     "$ref": "#/responses/notFound"

	pr, err := issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, ctx.PathParamInt64("index"))
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	if err := pr.LoadBaseRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	var prInfo *pull_service.CompareInfo
	baseGitRepo, closer, err := gitrepo.RepositoryFromContextOrOpen(ctx, pr.BaseRepo)
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	defer closer.Close()

	if pr.HasMerged {
		prInfo, err = pull_service.GetCompareInfo(ctx, pr.BaseRepo, pr.BaseRepo, baseGitRepo, pr.MergeBase, pr.GetGitHeadRefName(), false, false)
	} else {
		prInfo, err = pull_service.GetCompareInfo(ctx, pr.BaseRepo, pr.BaseRepo, baseGitRepo, pr.BaseBranch, pr.GetGitHeadRefName(), false, false)
	}
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	commits := prInfo.Commits

	listOptions := utils.GetListOptions(ctx)

	totalNumberOfCommits := len(commits)
	totalNumberOfPages := int(math.Ceil(float64(totalNumberOfCommits) / float64(listOptions.PageSize)))

	userCache := make(map[string]*user_model.User)

	start, limit := listOptions.GetSkipTake()

	limit = min(limit, totalNumberOfCommits-start)
	limit = max(limit, 0)

	verification := ctx.FormString("verification") == "" || ctx.FormBool("verification")
	files := ctx.FormString("files") == "" || ctx.FormBool("files")

	apiCommits := make([]*api.Commit, 0, limit)
	for i := start; i < start+limit; i++ {
		apiCommit, err := convert.ToCommit(ctx, ctx.Repo.Repository, baseGitRepo, commits[i], userCache,
			convert.ToCommitOptions{
				Stat:         true,
				Verification: verification,
				Files:        files,
			})
		if err != nil {
			ctx.APIErrorInternal(err)
			return
		}
		apiCommits = append(apiCommits, apiCommit)
	}

	ctx.SetLinkHeader(totalNumberOfCommits, listOptions.PageSize)
	ctx.SetTotalCountHeader(int64(totalNumberOfCommits))

	ctx.RespHeader().Set("X-Page", strconv.Itoa(listOptions.Page))
	ctx.RespHeader().Set("X-PerPage", strconv.Itoa(listOptions.PageSize))
	ctx.RespHeader().Set("X-PageCount", strconv.Itoa(totalNumberOfPages))
	ctx.RespHeader().Set("X-HasMore", strconv.FormatBool(listOptions.Page < totalNumberOfPages))
	ctx.AppendAccessControlExposeHeaders("X-Page", "X-PerPage", "X-PageCount", "X-HasMore")

	ctx.JSON(http.StatusOK, &apiCommits)
}

// GetPullRequestFiles gets all changed files associated with a given PR
func GetPullRequestFiles(ctx *context.APIContext) {
	// swagger:operation GET /repos/{owner}/{repo}/pulls/{index}/files repository repoGetPullRequestFiles
	// ---
	// summary: Get changed files for a pull request
	// 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: index
	//   in: path
	//   description: index of the pull request to get
	//   type: integer
	//   format: int64
	//   required: true
	// - name: skip-to
	//   in: query
	//   description: skip to given file
	//   type: string
	// - name: whitespace
	//   in: query
	//   description: whitespace behavior
	//   type: string
	//   enum: [ignore-all, ignore-change, ignore-eol, show-all]
	// - name: page
	//   in: query
	//   description: page number of results to return (1-based)
	//   type: integer
	// - name: limit
	//   in: query
	//   description: page size of results
	//   type: integer
	// responses:
	//   "200":
	//     "$ref": "#/responses/ChangedFileList"
	//   "404":
	//     "$ref": "#/responses/notFound"

	pr, err := issues_model.GetPullRequestByIndex(ctx, ctx.Repo.Repository.ID, ctx.PathParamInt64("index"))
	if err != nil {
		if issues_model.IsErrPullRequestNotExist(err) {
			ctx.APIErrorNotFound()
		} else {
			ctx.APIErrorInternal(err)
		}
		return
	}

	if err := pr.LoadBaseRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	if err := pr.LoadHeadRepo(ctx); err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	baseGitRepo := ctx.Repo.GitRepo

	var prInfo *pull_service.CompareInfo
	if pr.HasMerged {
		prInfo, err = pull_service.GetCompareInfo(ctx, pr.BaseRepo, pr.BaseRepo, baseGitRepo, pr.MergeBase, pr.GetGitHeadRefName(), false, false)
	} else {
		prInfo, err = pull_service.GetCompareInfo(ctx, pr.BaseRepo, pr.BaseRepo, baseGitRepo, pr.BaseBranch, pr.GetGitHeadRefName(), false, false)
	}
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	headCommitID, err := baseGitRepo.GetRefCommitID(pr.GetGitHeadRefName())
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	startCommitID := prInfo.MergeBase
	endCommitID := headCommitID

	maxLines := setting.Git.MaxGitDiffLines

	// FIXME: If there are too many files in the repo, may cause some unpredictable issues.
	diff, err := gitdiff.GetDiffForAPI(ctx, baseGitRepo,
		&gitdiff.DiffOptions{
			BeforeCommitID:     startCommitID,
			AfterCommitID:      endCommitID,
			SkipTo:             ctx.FormString("skip-to"),
			MaxLines:           maxLines,
			MaxLineCharacters:  setting.Git.MaxGitDiffLineCharacters,
			MaxFiles:           -1, // GetDiff() will return all files
			WhitespaceBehavior: gitdiff.GetWhitespaceFlag(ctx.FormString("whitespace")),
		})
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}

	diffShortStat, err := gitdiff.GetDiffShortStat(baseGitRepo, startCommitID, endCommitID)
	if err != nil {
		ctx.APIErrorInternal(err)
		return
	}
	listOptions := utils.GetListOptions(ctx)

	totalNumberOfFiles := diffShortStat.NumFiles
	totalNumberOfPages := int(math.Ceil(float64(totalNumberOfFiles) / float64(listOptions.PageSize)))

	start, limit := listOptions.GetSkipTake()

	limit = min(limit, totalNumberOfFiles-start)

	limit = max(limit, 0)

	apiFiles := make([]*api.ChangedFile, 0, limit)
	for i := start; i < start+limit; i++ {
		// refs/pull/1/head stores the HEAD commit ID, allowing all related commits to be found in the base repository.
		// The head repository might have been deleted, so we should not rely on it here.
		apiFiles = append(apiFiles, convert.ToChangedFile(diff.Files[i], pr.BaseRepo, endCommitID))
	}

	ctx.SetLinkHeader(totalNumberOfFiles, listOptions.PageSize)
	ctx.SetTotalCountHeader(int64(totalNumberOfFiles))

	ctx.RespHeader().Set("X-Page", strconv.Itoa(listOptions.Page))
	ctx.RespHeader().Set("X-PerPage", strconv.Itoa(listOptions.PageSize))
	ctx.RespHeader().Set("X-PageCount", strconv.Itoa(totalNumberOfPages))
	ctx.RespHeader().Set("X-HasMore", strconv.FormatBool(listOptions.Page < totalNumberOfPages))
	ctx.AppendAccessControlExposeHeaders("X-Page", "X-PerPage", "X-PageCount", "X-HasMore")

	ctx.JSON(http.StatusOK, &apiFiles)
}
