// Copyright 2019 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package pull

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"slices"
	"strings"
	"time"
	"unicode"
	"unicode/utf8"

	"gitea.dev/models/db"
	git_model "gitea.dev/models/git"
	issues_model "gitea.dev/models/issues"
	"gitea.dev/models/organization"
	access_model "gitea.dev/models/perm/access"
	repo_model "gitea.dev/models/repo"
	"gitea.dev/models/unit"
	user_model "gitea.dev/models/user"
	"gitea.dev/modules/base"
	"gitea.dev/modules/container"
	"gitea.dev/modules/git"
	"gitea.dev/modules/git/gitcmd"
	"gitea.dev/modules/gitrepo"
	"gitea.dev/modules/globallock"
	"gitea.dev/modules/graceful"
	"gitea.dev/modules/log"
	repo_module "gitea.dev/modules/repository"
	"gitea.dev/modules/setting"
	"gitea.dev/modules/util"
	git_service "gitea.dev/services/git"
	issue_service "gitea.dev/services/issue"
	notify_service "gitea.dev/services/notify"
)

func getPullWorkingLockKey(prID int64) string {
	return fmt.Sprintf("pull_working_%d", prID)
}

type NewPullRequestOptions struct {
	Repo            *repo_model.Repository
	Issue           *issues_model.Issue
	LabelIDs        []int64
	AttachmentUUIDs []string
	PullRequest     *issues_model.PullRequest
	AssigneeIDs     []int64
	Reviewers       []*user_model.User
	TeamReviewers   []*organization.Team
	ProjectIDs      []int64
}

// NewPullRequest creates new pull request with labels for repository.
func NewPullRequest(ctx context.Context, opts *NewPullRequestOptions) error {
	repo, issue, labelIDs, uuids, pr, assigneeIDs := opts.Repo, opts.Issue, opts.LabelIDs, opts.AttachmentUUIDs, opts.PullRequest, opts.AssigneeIDs
	if err := issue.LoadPoster(ctx); err != nil {
		return err
	}

	if user_model.IsUserBlockedBy(ctx, issue.Poster, repo.OwnerID) || user_model.IsUserBlockedBy(ctx, issue.Poster, assigneeIDs...) {
		return user_model.ErrBlockedUser
	}

	// user should be a collaborator or a member of the organization for base repo
	canCreate := issue.Poster.IsAdmin || pr.Flow == issues_model.PullRequestFlowAGit
	canAssignProject := canCreate
	if !canCreate {
		canCreate, err := repo_model.IsOwnerMemberCollaborator(ctx, repo, issue.Poster.ID)
		if err != nil {
			return err
		}
		canAssignProject = canCreate

		if !canCreate {
			// or user should have write permission in the head repo
			if err := pr.LoadHeadRepo(ctx); err != nil {
				return err
			}
			perm, err := access_model.GetDoerRepoPermission(ctx, pr.HeadRepo, issue.Poster)
			if err != nil {
				return err
			}
			if !perm.CanWrite(unit.TypeCode) {
				return issues_model.ErrMustCollaborator
			}
			canAssignProject = perm.CanWrite(unit.TypeProjects)
		}
	}

	if err := checkPullRequestBranchMergeable(ctx, pr); err != nil {
		return err
	}

	assigneeCommentMap := make(map[int64]*issues_model.Comment)
	assignees := make(map[int64]*user_model.User)
	var reviewNotifiers []*issue_service.ReviewRequestNotifier
	if err := db.WithTx(ctx, func(ctx context.Context) error {
		if err := issues_model.NewPullRequest(ctx, repo, issue, labelIDs, uuids, pr); err != nil {
			return err
		}

		for _, assigneeID := range assigneeIDs {
			assignee, err := user_model.GetUserByID(ctx, assigneeID)
			if err != nil {
				log.Error("GetUserByID: %v", err)
				continue
			}
			comment, err := issue_service.AddAssigneeIfNotAssigned(ctx, issue, issue.Poster, assignee)
			if err != nil {
				return err
			}
			assignees[assigneeID] = assignee
			assigneeCommentMap[assigneeID] = comment
		}

		if len(opts.ProjectIDs) > 0 && canAssignProject {
			if err := issues_model.IssueAssignOrRemoveProject(ctx, issue, issue.Poster, opts.ProjectIDs); err != nil {
				return err
			}
		}

		pr.Issue = issue
		issue.PullRequest = pr

		var err error
		if pr.Flow == issues_model.PullRequestFlowGithub {
			err = PushToBaseRepo(ctx, pr)
		} else {
			err = UpdateRef(ctx, pr)
		}
		if err != nil {
			return err
		}

		// Update Commit Divergence
		err = syncCommitDivergence(ctx, pr)
		if err != nil {
			return err
		}

		// add first push codes comment
		if _, _, err := CreatePushPullComment(ctx, issue.Poster, pr, git.BranchPrefix+pr.BaseBranch, pr.GetGitHeadRefName(), false); err != nil {
			return err
		}

		if !pr.IsWorkInProgress(ctx) {
			reviewNotifiers, err = issue_service.PullRequestCodeOwnersReview(ctx, pr)
			if err != nil {
				return err
			}
		}
		return nil
	}); err != nil {
		// cleanup: this will only remove the reference, the real commit will be clean up when next GC
		if err1 := gitrepo.RemoveRef(ctx, pr.BaseRepo, pr.GetGitHeadRefName()); err1 != nil {
			log.Error("RemoveRef: %v", err1)
		}
		return err
	}

	issue_service.ReviewRequestNotify(ctx, issue, issue.Poster, reviewNotifiers)

	// Request reviews, these should be requested before other notifications because they will add request reviews record
	// on database
	permDoer, err := access_model.GetDoerRepoPermission(ctx, repo, issue.Poster)
	if err != nil {
		return err
	}
	for _, reviewer := range opts.Reviewers {
		if _, err = issue_service.ReviewRequest(ctx, pr.Issue, issue.Poster, &permDoer, reviewer, true); err != nil {
			return err
		}
	}
	for _, teamReviewer := range opts.TeamReviewers {
		if _, err = issue_service.TeamReviewRequest(ctx, pr.Issue, issue.Poster, teamReviewer, true); err != nil {
			return err
		}
	}

	mentions, err := issues_model.FindAndUpdateIssueMentions(ctx, issue, issue.Poster, issue.Content)
	if err != nil {
		return err
	}
	notify_service.NewPullRequest(ctx, pr, mentions)
	if len(issue.Labels) > 0 {
		notify_service.IssueChangeLabels(ctx, issue.Poster, issue, issue.Labels, nil)
	}
	if issue.Milestone != nil {
		notify_service.IssueChangeMilestone(ctx, issue.Poster, issue, 0)
	}
	for _, assignee := range assignees {
		notify_service.IssueChangeAssignee(ctx, issue.Poster, issue, assignee, false, assigneeCommentMap[assignee.ID])
	}

	return nil
}

// ErrPullRequestHasMerged represents a "PullRequestHasMerged"-error
type ErrPullRequestHasMerged struct {
	ID         int64
	IssueID    int64
	HeadRepoID int64
	BaseRepoID int64
	HeadBranch string
	BaseBranch string
}

// IsErrPullRequestHasMerged checks if an error is a ErrPullRequestHasMerged.
func IsErrPullRequestHasMerged(err error) bool {
	_, ok := err.(ErrPullRequestHasMerged)
	return ok
}

// Error does pretty-printing :D
func (err ErrPullRequestHasMerged) Error() string {
	return fmt.Sprintf("pull request has merged [id: %d, issue_id: %d, head_repo_id: %d, base_repo_id: %d, head_branch: %s, base_branch: %s]",
		err.ID, err.IssueID, err.HeadRepoID, err.BaseRepoID, err.HeadBranch, err.BaseBranch)
}

// ChangeTargetBranch changes the target branch of this pull request, as the given user.
func ChangeTargetBranch(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.User, targetBranch string) (err error) {
	releaser, err := globallock.Lock(ctx, getPullWorkingLockKey(pr.ID))
	if err != nil {
		log.Error("lock.Lock(): %v", err)
		return fmt.Errorf("lock.Lock: %w", err)
	}
	defer releaser()

	// Current target branch is already the same
	if pr.BaseBranch == targetBranch {
		return nil
	}

	if pr.Issue.IsClosed {
		return issues_model.ErrIssueIsClosed{
			ID:     pr.Issue.ID,
			RepoID: pr.Issue.RepoID,
			Index:  pr.Issue.Index,
			IsPull: true,
		}
	}

	if pr.HasMerged {
		return ErrPullRequestHasMerged{
			ID:         pr.ID,
			IssueID:    pr.Index,
			HeadRepoID: pr.HeadRepoID,
			BaseRepoID: pr.BaseRepoID,
			HeadBranch: pr.HeadBranch,
			BaseBranch: pr.BaseBranch,
		}
	}

	exist, err := git_model.IsBranchExist(ctx, pr.BaseRepoID, targetBranch)
	if err != nil {
		return err
	}
	if !exist {
		return git_model.ErrBranchNotExist{
			RepoID:     pr.BaseRepoID,
			BranchName: targetBranch,
		}
	}

	// Check if branches are equal
	branchesEqual, err := IsHeadEqualWithBranch(ctx, pr, targetBranch)
	if err != nil {
		return err
	}
	if branchesEqual {
		return git_model.ErrBranchesEqual{
			HeadBranchName: pr.HeadBranch,
			BaseBranchName: targetBranch,
		}
	}

	// Check if pull request for the new target branch already exists
	existingPr, err := issues_model.GetUnmergedPullRequest(ctx, pr.HeadRepoID, pr.BaseRepoID, pr.HeadBranch, targetBranch, issues_model.PullRequestFlowGithub)
	if existingPr != nil {
		return issues_model.ErrPullRequestAlreadyExists{
			ID:         existingPr.ID,
			IssueID:    existingPr.Index,
			HeadRepoID: existingPr.HeadRepoID,
			BaseRepoID: existingPr.BaseRepoID,
			HeadBranch: existingPr.HeadBranch,
			BaseBranch: existingPr.BaseBranch,
		}
	}
	if err != nil && !issues_model.IsErrPullRequestNotExist(err) {
		return err
	}

	// Set new target branch
	oldBranch := pr.BaseBranch
	pr.BaseBranch = targetBranch

	// Refresh patch
	if err := checkPullRequestBranchMergeable(ctx, pr); err != nil {
		return err
	}

	// Update target branch, PR diff and status
	// This is the same as markPullRequestAsMergeable in check service, but also updates base_branch
	if pr.Status == issues_model.PullRequestStatusChecking {
		pr.Status = issues_model.PullRequestStatusMergeable
	}

	// add first push codes comment
	return db.WithTx(ctx, func(ctx context.Context) error {
		// The UPDATE acquires the transaction lock, if the UPDATE succeeds, it should have updated one row (the "base_branch" is changed)
		// If no row is updated, it means the PR has been merged or closed in the meantime
		updated, err := pr.UpdateColsIfNotMerged(ctx, "merge_base", "status", "conflicted_files", "changed_protected_files", "base_branch")
		if err != nil {
			return err
		}
		if updated == 0 {
			return util.ErrorWrap(util.ErrInvalidArgument, "pull request status has changed")
		}

		if err := syncCommitDivergence(ctx, pr); err != nil {
			return fmt.Errorf("syncCommitDivergence: %w", err)
		}

		// Create comment
		options := &issues_model.CreateCommentOptions{
			Type:   issues_model.CommentTypeChangeTargetBranch,
			Doer:   doer,
			Repo:   pr.Issue.Repo,
			Issue:  pr.Issue,
			OldRef: oldBranch,
			NewRef: targetBranch,
		}
		if _, err = issues_model.CreateComment(ctx, options); err != nil {
			return fmt.Errorf("CreateChangeTargetBranchComment: %w", err)
		}

		// Delete all old push comments and insert new push comments
		if _, err := db.GetEngine(ctx).Where("issue_id = ?", pr.IssueID).
			And("type = ?", issues_model.CommentTypePullRequestPush).
			NoAutoCondition().
			Delete(new(issues_model.Comment)); err != nil {
			return err
		}

		_, _, err = CreatePushPullComment(ctx, doer, pr, git.BranchPrefix+pr.BaseBranch, pr.GetGitHeadRefName(), false)
		return err
	})
}

func checkForInvalidation(ctx context.Context, requests issues_model.PullRequestList, repoID int64, doer *user_model.User, branch string) error {
	repo, err := repo_model.GetRepositoryByID(ctx, repoID)
	if err != nil {
		return fmt.Errorf("GetRepositoryByIDCtx: %w", err)
	}
	gitRepo, err := gitrepo.OpenRepository(ctx, repo)
	if err != nil {
		return fmt.Errorf("gitrepo.OpenRepository: %w", err)
	}
	go func() {
		// FIXME: graceful: We need to tell the manager we're doing something...
		err := InvalidateCodeComments(ctx, requests, doer, repo, gitRepo, branch)
		if err != nil {
			log.Error("PullRequestList.InvalidateCodeComments: %v", err)
		}
		gitRepo.Close()
	}()
	return nil
}

type TestPullRequestOptions struct {
	RepoID      int64
	Doer        *user_model.User
	Branch      string
	IsSync      bool // True means it's a pull request synchronization, false means it's triggered for pull request merging or updating
	IsForcePush bool
	OldCommitID string
	NewCommitID string
}

// AddTestPullRequestTask adds new test tasks by given head/base repository and head/base branch,
// and generate new patch for testing as needed.
func AddTestPullRequestTask(opts TestPullRequestOptions) {
	log.Trace("AddTestPullRequestTask [head_repo_id: %d, head_branch: %s]: finding pull requests", opts.RepoID, opts.Branch)
	graceful.GetManager().RunWithShutdownContext(func(ctx context.Context) {
		// this function does a lot of operations to various models, if the process gets killed in the middle,
		// there is no way to recover at the moment. The best workaround is to let end user push again.
		repo, err := repo_model.GetRepositoryByID(ctx, opts.RepoID)
		if err != nil {
			log.Error("GetRepositoryByID: %v", err)
			return
		}
		// GetUnmergedPullRequestsByHeadInfo() only return open and unmerged PR.
		headBranchPRs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(ctx, opts.RepoID, opts.Branch)
		if err != nil {
			log.Error("Find pull requests [head_repo_id: %d, head_branch: %s]: %v", opts.RepoID, opts.Branch, err)
			return
		}

		for _, pr := range headBranchPRs {
			log.Trace("Updating PR[%d]: composing new test task", pr.ID)
			pr.HeadRepo = repo // avoid loading again
			if pr.Flow == issues_model.PullRequestFlowGithub {
				if err := PushToBaseRepo(ctx, pr); err != nil {
					log.Error("PushToBaseRepo: %v", err)
					continue
				}
			} else {
				continue
			}

			// create push comment before check pull request status,
			// then when the status is mergeable, the comment is already in database, to make testing easy and stable
			comment, commentCreated, err := CreatePushPullComment(ctx, opts.Doer, pr, opts.OldCommitID, opts.NewCommitID, opts.IsForcePush)
			if err != nil {
				log.Error("CreatePushPullComment: %v", err)
			} else if commentCreated {
				notify_service.PullRequestPushCommits(ctx, opts.Doer, pr, comment)
			}
			// The caller can be in a goroutine or a "push queue", "conflict check" can be time-consuming,
			// and the concurrency should be limited, so the conflict check will be done in another queue
			StartPullRequestCheckImmediately(ctx, pr)
		}

		if opts.IsSync {
			if err = headBranchPRs.LoadAttributes(ctx); err != nil {
				log.Error("PullRequestList.LoadAttributes: %v", err)
			}
			if invalidationErr := checkForInvalidation(ctx, headBranchPRs, opts.RepoID, opts.Doer, opts.Branch); invalidationErr != nil {
				log.Error("checkForInvalidation: %v", invalidationErr)
			}
			if err == nil {
				for _, pr := range headBranchPRs {
					objectFormat := git.ObjectFormatFromName(pr.BaseRepo.ObjectFormatName)
					if opts.NewCommitID != "" && opts.NewCommitID != objectFormat.EmptyObjectID().String() {
						changed, newMergeBase, err := checkIfPRContentChanged(ctx, pr, opts.OldCommitID, opts.NewCommitID)
						if err != nil {
							log.Error("checkIfPRContentChanged: %v", err)
						}
						if newMergeBase != "" && pr.MergeBase != newMergeBase {
							pr.MergeBase = newMergeBase
							if _, err := pr.UpdateColsIfNotMerged(ctx, "merge_base"); err != nil {
								log.Error("Update merge base for %-v: %v", pr, err)
							}
						}
						if changed {
							// Mark old reviews as stale if diff to mergebase has changed
							if err := issues_model.MarkReviewsAsStale(ctx, pr.IssueID); err != nil {
								log.Error("MarkReviewsAsStale: %v", err)
							}

							// dismiss all approval reviews if protected branch rule item enabled.
							pb, err := git_model.GetFirstMatchProtectedBranchRule(ctx, pr.BaseRepoID, pr.BaseBranch)
							if err != nil {
								log.Error("GetFirstMatchProtectedBranchRule: %v", err)
							}
							if pb != nil && pb.DismissStaleApprovals {
								if err := DismissApprovalReviews(ctx, opts.Doer, pr); err != nil {
									log.Error("DismissApprovalReviews: %v", err)
								}
							}
						}
						if err := issues_model.MarkReviewsAsNotStale(ctx, pr.IssueID, opts.NewCommitID); err != nil {
							log.Error("MarkReviewsAsNotStale: %v", err)
						}
						if err = syncCommitDivergence(ctx, pr); err != nil {
							log.Error("syncCommitDivergence: %v", err)
						}
					}

					if !pr.IsWorkInProgress(ctx) {
						reviewNotifiers, err := issue_service.PullRequestCodeOwnersReview(ctx, pr)
						if err != nil {
							log.Error("PullRequestCodeOwnersReview: %v", err)
						}
						if len(reviewNotifiers) > 0 {
							issue_service.ReviewRequestNotify(ctx, pr.Issue, opts.Doer, reviewNotifiers)
						}
					}

					notify_service.PullRequestSynchronized(ctx, opts.Doer, pr, opts.OldCommitID, opts.NewCommitID)
				}
			}
		}

		log.Trace("AddTestPullRequestTask [base_repo_id: %d, base_branch: %s]: finding pull requests", opts.RepoID, opts.Branch)
		// The base repositories of baseBranchPRs are the same one (opts.RepoID)
		baseBranchPRs, err := issues_model.GetUnmergedPullRequestsByBaseInfo(ctx, opts.RepoID, opts.Branch)
		if err != nil {
			log.Error("Find pull requests [base_repo_id: %d, base_branch: %s]: %v", opts.RepoID, opts.Branch, err)
			return
		}
		for _, pr := range baseBranchPRs {
			pr.BaseRepo = repo // avoid loading again
			err = syncCommitDivergence(ctx, pr)
			if err != nil {
				if errors.Is(err, util.ErrNotExist) {
					log.Warn("Cannot test PR %s/%d with base=%s head=%s: no longer exists", pr.BaseRepo.FullName(), pr.IssueID, pr.BaseBranch, pr.HeadBranch)
				} else {
					log.Error("syncCommitDivergence: %v", err)
				}
				continue
			}
			StartPullRequestCheckDelayable(ctx, pr)
		}
	})
}

// checkIfPRContentChanged checks if diff to target branch has changed by push
// A commit can be considered to leave the PR untouched if the patch/diff with its merge base is unchanged
func checkIfPRContentChanged(ctx context.Context, pr *issues_model.PullRequest, oldCommitID, newCommitID string) (hasChanged bool, mergeBase string, err error) {
	prCtx, cancel, err := createTemporaryRepoForPR(ctx, pr) // FIXME: why it still needs to create a temp repo, since the alongside calls like GetDiverging doesn't do so anymore
	if err != nil {
		log.Error("CreateTemporaryRepoForPR %-v: %v", pr, err)
		return false, "", err
	}
	defer cancel()

	mergeBase, err = gitrepo.MergeBase(ctx, pr.BaseRepo, pr.BaseBranch, pr.GetGitHeadRefName())
	if err != nil {
		return false, "", fmt.Errorf("GetMergeBase: %w", err)
	}

	cmd := gitcmd.NewCommand("diff", "--name-only", "-z").AddDynamicArguments(newCommitID, oldCommitID, mergeBase)

	stdoutReader, stdoutReaderClose := cmd.MakeStdoutPipe()
	defer stdoutReaderClose()
	if err := cmd.WithDir(prCtx.tmpBasePath).
		WithPipelineFunc(func(ctx gitcmd.Context) error {
			return util.IsEmptyReader(stdoutReader)
		}).
		RunWithStderr(ctx); err != nil {
		if errors.Is(err, util.ErrNotEmpty) {
			return true, mergeBase, nil
		}

		log.Error("Unable to run diff on %s %s %s in tempRepo for PR[%d]%s/%s...%s/%s: Error: %v",
			newCommitID, oldCommitID, mergeBase,
			pr.ID, pr.BaseRepo.FullName(), pr.BaseBranch, pr.HeadRepo.FullName(), pr.HeadBranch,
			err)

		return false, mergeBase, fmt.Errorf("Unable to run git diff --name-only -z %s %s %s: %w", newCommitID, oldCommitID, mergeBase, err)
	}

	return false, mergeBase, nil
}

// PushToBaseRepo pushes commits from branches of head repository to
// corresponding branches of base repository.
// FIXME: Only push branches that are actually updates?
func PushToBaseRepo(ctx context.Context, pr *issues_model.PullRequest) (err error) {
	return pushToBaseRepoHelper(ctx, pr, "")
}

func pushToBaseRepoHelper(ctx context.Context, pr *issues_model.PullRequest, prefixHeadBranch string) (err error) {
	log.Trace("PushToBaseRepo[%d]: pushing commits to base repo '%s'", pr.BaseRepoID, pr.GetGitHeadRefName())

	if err := pr.LoadHeadRepo(ctx); err != nil {
		log.Error("Unable to load head repository for PR[%d] Error: %v", pr.ID, err)
		return err
	}

	if err := pr.LoadBaseRepo(ctx); err != nil {
		log.Error("Unable to load base repository for PR[%d] Error: %v", pr.ID, err)
		return err
	}

	if err = pr.LoadIssue(ctx); err != nil {
		return fmt.Errorf("unable to load issue %d for pr %d: %w", pr.IssueID, pr.ID, err)
	}
	if err = pr.Issue.LoadPoster(ctx); err != nil {
		return fmt.Errorf("unable to load poster %d for pr %d: %w", pr.Issue.PosterID, pr.ID, err)
	}

	gitRefName := pr.GetGitHeadRefName()

	if err := gitrepo.Push(ctx, pr.HeadRepo, pr.BaseRepo, git.PushOptions{
		Branch: prefixHeadBranch + pr.HeadBranch + ":" + gitRefName,
		Force:  true,
		// Use InternalPushingEnvironment here because we know that pre-receive and post-receive do not run on a refs/pulls/...
		Env: repo_module.InternalPushingEnvironment(pr.Issue.Poster, pr.BaseRepo),
	}); err != nil {
		if git.IsErrPushOutOfDate(err) {
			// This should not happen as we're using force!
			log.Error("Unable to push PR head for %s#%d (%-v:%s) due to ErrPushOfDate: %v", pr.BaseRepo.FullName(), pr.Index, pr.BaseRepo, gitRefName, err)
			return err
		} else if git.IsErrPushRejected(err) {
			rejectErr := err.(*git.ErrPushRejected)
			log.Info("Unable to push PR head for %s#%d (%-v:%s) due to rejection:\nStdout: %s\nStderr: %s\nError: %v", pr.BaseRepo.FullName(), pr.Index, pr.BaseRepo, gitRefName, rejectErr.StdOut, rejectErr.StdErr, rejectErr.Err)
			return err
		} else if git.IsErrMoreThanOne(err) {
			if prefixHeadBranch != "" {
				log.Info("Can't push with %s%s", prefixHeadBranch, pr.HeadBranch)
				return err
			}
			log.Info("Retrying to push with %s%s", git.BranchPrefix, pr.HeadBranch)
			err = pushToBaseRepoHelper(ctx, pr, git.BranchPrefix)
			return err
		}
		log.Error("Unable to push PR head for %s#%d (%-v:%s) due to Error: %v", pr.BaseRepo.FullName(), pr.Index, pr.BaseRepo, gitRefName, err)
		return fmt.Errorf("Push: %s:%s %s:%s %w", pr.HeadRepo.FullName(), pr.HeadBranch, pr.BaseRepo.FullName(), gitRefName, err)
	}

	return nil
}

// UpdatePullsRefs update all the PRs head file pointers like /refs/pull/1/head so that it will be dependent by other operations
func UpdatePullsRefs(ctx context.Context, repo *repo_model.Repository, update *repo_module.PushUpdateOptions) {
	branch := update.RefFullName.BranchName()
	// GetUnmergedPullRequestsByHeadInfo() only return open and unmerged PR.
	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(ctx, repo.ID, branch)
	if err != nil {
		log.Error("Find pull requests [head_repo_id: %d, head_branch: %s]: %v", repo.ID, branch, err)
	} else {
		for _, pr := range prs {
			log.Trace("Updating PR[%d]: composing new test task", pr.ID)
			if pr.Flow == issues_model.PullRequestFlowGithub {
				if err := PushToBaseRepo(ctx, pr); err != nil {
					log.Error("PushToBaseRepo: %v", err)
				}
			}
		}
	}
}

// UpdateRef update refs/pull/id/head directly for agit flow pull request
func UpdateRef(ctx context.Context, pr *issues_model.PullRequest) (err error) {
	log.Trace("UpdateRef[%d]: upgate pull request ref in base repo '%s'", pr.ID, pr.GetGitHeadRefName())
	if err := pr.LoadBaseRepo(ctx); err != nil {
		log.Error("Unable to load base repository for PR[%d] Error: %v", pr.ID, err)
		return err
	}

	if err := gitrepo.UpdateRef(ctx, pr.BaseRepo, pr.GetGitHeadRefName(), pr.HeadCommitID); err != nil {
		log.Error("Unable to update ref in base repository for PR[%d] Error: %v", pr.ID, err)
	}

	return err
}

// retargetBranchPulls change target branch for all pull requests whose base branch is the branch
// Both branch and targetBranch must be in the same repo (for security reasons)
func retargetBranchPulls(ctx context.Context, doer *user_model.User, repoID int64, branch, targetBranch string) error {
	prs, err := issues_model.GetUnmergedPullRequestsByBaseInfo(ctx, repoID, branch)
	if err != nil {
		return err
	}

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

	var errs []error
	for _, pr := range prs {
		if err = pr.Issue.LoadRepo(ctx); err != nil {
			errs = append(errs, err)
		} else if err = ChangeTargetBranch(ctx, pr, doer, targetBranch); err != nil &&
			!issues_model.IsErrIssueIsClosed(err) && !IsErrPullRequestHasMerged(err) &&
			!issues_model.IsErrPullRequestAlreadyExists(err) {
			errs = append(errs, err)
		}
	}
	return errors.Join(errs...)
}

// AdjustPullsCausedByBranchDeleted close all the pull requests who's head branch is the branch
// Or Close all the plls who's base branch is the branch if setting.Repository.PullRequest.RetargetChildrenOnMerge is false.
// If it's true, Retarget all these pulls to the default branch.
func AdjustPullsCausedByBranchDeleted(ctx context.Context, doer *user_model.User, repo *repo_model.Repository, branch string) error {
	// branch as head branch
	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(ctx, repo.ID, branch)
	if err != nil {
		return err
	}

	if err := prs.LoadAttributes(ctx); err != nil {
		return err
	}
	prs.SetHeadRepo(repo)
	if err := prs.LoadRepositories(ctx); err != nil {
		return err
	}

	var errs []error
	for _, pr := range prs {
		if err = issue_service.CloseIssue(ctx, pr.Issue, doer, ""); err != nil && !issues_model.IsErrIssueIsClosed(err) && !issues_model.IsErrDependenciesLeft(err) {
			errs = append(errs, err)
		}
		if err == nil {
			if err := issues_model.AddDeletePRBranchComment(ctx, doer, pr.BaseRepo, pr.Issue.ID, pr.HeadBranch); err != nil {
				log.Error("AddDeletePRBranchComment: %v", err)
				errs = append(errs, err)
			}
		}
	}

	if setting.Repository.PullRequest.RetargetChildrenOnMerge {
		if err := retargetBranchPulls(ctx, doer, repo.ID, branch, repo.DefaultBranch); err != nil {
			log.Error("retargetBranchPulls failed: %v", err)
			errs = append(errs, err)
		}
		return errors.Join(errs...)
	}

	// branch as base branch
	prs, err = issues_model.GetUnmergedPullRequestsByBaseInfo(ctx, repo.ID, branch)
	if err != nil {
		return err
	}

	if err := prs.LoadAttributes(ctx); err != nil {
		return err
	}
	prs.SetBaseRepo(repo)
	if err := prs.LoadRepositories(ctx); err != nil {
		return err
	}

	errs = nil
	for _, pr := range prs {
		if err = issues_model.AddDeletePRBranchComment(ctx, doer, pr.BaseRepo, pr.Issue.ID, pr.BaseBranch); err != nil {
			log.Error("AddDeletePRBranchComment: %v", err)
			errs = append(errs, err)
		}
		if err == nil {
			if err = issue_service.CloseIssue(ctx, pr.Issue, doer, ""); err != nil && !issues_model.IsErrIssueIsClosed(err) && !issues_model.IsErrDependenciesLeft(err) {
				errs = append(errs, err)
			}
		}
	}
	return errors.Join(errs...)
}

// CloseRepoBranchesPulls close all pull requests which head branches are in the given repository, but only whose base repo is not in the given repository
func CloseRepoBranchesPulls(ctx context.Context, doer *user_model.User, repo *repo_model.Repository) error {
	branches, _, err := gitrepo.GetBranchesByPath(ctx, repo, 0, 0)
	if err != nil {
		return err
	}

	var errs []error
	for _, branch := range branches {
		prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(ctx, repo.ID, branch)
		if err != nil {
			return err
		}

		if err = prs.LoadAttributes(ctx); err != nil {
			return err
		}

		for _, pr := range prs {
			// If the base repository for this pr is this repository there is no need to close it
			// as it is going to be deleted anyway
			if pr.BaseRepoID == repo.ID {
				continue
			}
			if err = issue_service.CloseIssue(ctx, pr.Issue, doer, ""); err != nil && !issues_model.IsErrIssueIsClosed(err) {
				errs = append(errs, err)
			}
		}
	}

	return errors.Join(errs...)
}

// GetSquashMergeCommitMessages returns the commit messages between head and merge base (if there is one)
func GetSquashMergeCommitMessages(ctx context.Context, pr *issues_model.PullRequest) string {
	if err := pr.LoadIssue(ctx); err != nil {
		log.Error("Cannot load issue %d for PR id %d: Error: %v", pr.IssueID, pr.ID, err)
		return ""
	}

	if err := pr.Issue.LoadPoster(ctx); err != nil {
		log.Error("Cannot load poster %d for pr id %d, index %d Error: %v", pr.Issue.PosterID, pr.ID, pr.Index, err)
		return ""
	}

	if pr.HeadRepo == nil {
		var err error
		pr.HeadRepo, err = repo_model.GetRepositoryByID(ctx, pr.HeadRepoID)
		if err != nil {
			log.Error("GetRepositoryByIdCtx[%d]: %v", pr.HeadRepoID, err)
			return ""
		}
	}

	gitRepo, closer, err := gitrepo.RepositoryFromContextOrOpen(ctx, pr.HeadRepo)
	if err != nil {
		log.Error("Unable to open head repository: Error: %v", err)
		return ""
	}
	defer closer.Close()

	var headCommitRef git.RefName
	if pr.Flow == issues_model.PullRequestFlowGithub {
		headCommitRef = git.RefNameFromBranch(pr.HeadBranch)
	} else {
		pr.HeadCommitID, err = gitRepo.GetRefCommitID(pr.GetGitHeadRefName())
		if err != nil {
			log.Error("Unable to get head commit: %s Error: %v", pr.GetGitHeadRefName(), err)
			return ""
		}
		headCommitRef = git.RefNameFromCommit(pr.HeadCommitID)
	}

	mergeBaseRef := git.RefNameFromCommit(pr.MergeBase)

	limit := setting.Repository.PullRequest.DefaultMergeMessageCommitsLimit

	limitedCommits, err := gitRepo.CommitsBetween(headCommitRef, mergeBaseRef, limit)
	if err != nil {
		log.Error("Unable to get commits between: %s %s Error: %v", pr.HeadBranch, pr.MergeBase, err)
		return ""
	}

	mergeMessage := strings.TrimSpace(pr.Issue.Content) // use PR's title and description as squash commit message
	if setting.Repository.PullRequest.PopulateSquashCommentWithCommitMessages {
		mergeMessage = formatSquashMergeCommitMessages(limitedCommits) // use PR's commit messages as squash commit message
	}
	coAuthors := collectSquashMergeCommitCoAuthors(ctx, gitRepo, pr, headCommitRef, mergeBaseRef, limit, limitedCommits)
	return buildSquashMergeCommitMessages(mergeMessage, coAuthors)
}

func buildSquashMergeCommitMessages(mergeMessage string, coAuthors []string) string {
	if len(coAuthors) == 0 {
		return mergeMessage
	}

	msgContent, msgSep, msgTrailer := git.CommitMessageSplitTrailer(mergeMessage)
	if (msgSep == "" || msgSep == "\n\n") && msgTrailer == "" {
		msgContent = strings.TrimRightFunc(msgContent, unicode.IsSpace)
		msgSep = "\n\n---------\n\n"
	}
	var sb strings.Builder
	sb.WriteString(msgContent)
	sb.WriteString(msgSep)
	if msgTrailer = strings.TrimSpace(msgTrailer); msgTrailer != "" {
		sb.WriteString(msgTrailer)
		sb.WriteRune('\n')
	}
	for _, author := range coAuthors {
		sb.WriteString(git.CoAuthoredByTrailer + ": ")
		sb.WriteString(author)
		sb.WriteRune('\n')
	}
	return sb.String()
}

func collectSquashMergeCommitCoAuthors(ctx context.Context, gitRepo *git.Repository, pr *issues_model.PullRequest, headCommitRef, mergeBaseRef git.RefName, limitFirst int, limitedCommits []*git.Commit) []string {
	posterSig := pr.Issue.Poster.NewGitSig().String()
	uniqueAuthors := make(container.Set[string])
	authors := make([]string, 0, len(limitedCommits))

	for _, commit := range limitedCommits {
		authorString := commit.Author.String()
		if uniqueAuthors.Add(authorString) && authorString != posterSig {
			// Compare use account as well to avoid adding the same author multiple times
			// when email addresses are private or multiple emails are used.
			commitUser, _ := user_model.GetUserByEmail(ctx, commit.Author.Email)
			if commitUser == nil || commitUser.ID != pr.Issue.Poster.ID {
				authors = append(authors, authorString)
			}
		}
	}

	// collect the remaining authors
	if limitFirst >= 0 && setting.Repository.PullRequest.DefaultMergeMessageAllAuthors {
		skip := limitFirst
		batchLimit := 30
		for {
			commits, err := gitRepo.CommitsBetween(headCommitRef, mergeBaseRef, batchLimit, skip)
			if err != nil {
				log.Error("Unable to get commits between: %s %s Error: %v", pr.HeadBranch, pr.MergeBase, err)
				return authors
			}
			if len(commits) == 0 {
				break
			}
			for _, commit := range commits {
				authorString := commit.Author.String()
				if uniqueAuthors.Add(authorString) && authorString != posterSig {
					commitUser, _ := user_model.GetUserByEmail(ctx, commit.Author.Email)
					if commitUser == nil || commitUser.ID != pr.Issue.Poster.ID {
						authors = append(authors, authorString)
					}
				}
			}
			skip += batchLimit
		}
	}
	return authors
}

func formatSquashMergeCommitMessages(commits []*git.Commit) string {
	maxMsgSize := setting.Repository.PullRequest.DefaultMergeMessageSize
	sb := &bytes.Buffer{}
	// commits list is in reverse chronological order
	for _, commit := range slices.Backward(commits) {
		msg := strings.TrimSpace(commit.MessageUTF8())
		if msg == "" {
			continue
		}

		// This format follows GitHub's squash commit message style,
		// even if there are other "* " in the commit message body, they are written as-is.
		// Maybe, ideally, we should indent those lines too.
		_, _ = fmt.Fprintf(sb, "* %s\n\n", msg)
		if maxMsgSize > 0 && sb.Len() >= maxMsgSize {
			break
		}
	}

	buf := bytes.TrimSpace(sb.Bytes())
	if maxMsgSize > 0 && len(buf) > maxMsgSize {
		buf = buf[:maxMsgSize]
		for {
			r, sz := utf8.DecodeLastRune(buf)
			if r == utf8.RuneError && sz == 1 {
				buf = buf[:len(buf)-1]
				continue
			}
			break
		}
		buf = append(buf, '.', '.', '.')
	}
	buf = append(buf, '\n', '\n')
	return util.UnsafeBytesToString(buf)
}

// GetIssuesAllCommitStatus returns a map of issue ID to a list of all statuses for the most recent commit as well as a map of issue ID to only the commit's latest status
func GetIssuesAllCommitStatus(ctx context.Context, issues issues_model.IssueList) (map[int64][]*git_model.CommitStatus, map[int64]*git_model.CommitStatus, error) {
	if err := issues.LoadPullRequests(ctx); err != nil {
		return nil, nil, err
	}
	if _, err := issues.LoadRepositories(ctx); err != nil {
		return nil, nil, err
	}

	var (
		gitRepos = make(map[int64]*git.Repository)
		res      = make(map[int64][]*git_model.CommitStatus)
		lastRes  = make(map[int64]*git_model.CommitStatus)
		err      error
	)
	defer func() {
		for _, gitRepo := range gitRepos {
			gitRepo.Close()
		}
	}()

	for _, issue := range issues {
		if !issue.IsPull {
			continue
		}
		gitRepo, ok := gitRepos[issue.RepoID]
		if !ok {
			gitRepo, err = gitrepo.OpenRepository(ctx, issue.Repo)
			if err != nil {
				log.Error("Cannot open git repository %-v for issue #%d[%d]. Error: %v", issue.Repo, issue.Index, issue.ID, err)
				continue
			}
			gitRepos[issue.RepoID] = gitRepo
		}

		statuses, lastStatus, err := getAllCommitStatus(ctx, gitRepo, issue.PullRequest)
		if err != nil {
			log.Error("getAllCommitStatus: cant get commit statuses of pull [%d]: %v", issue.PullRequest.ID, err)
			continue
		}
		res[issue.PullRequest.ID] = statuses
		lastRes[issue.PullRequest.ID] = lastStatus
	}
	return res, lastRes, nil
}

// getAllCommitStatus get pr's commit statuses.
func getAllCommitStatus(ctx context.Context, gitRepo *git.Repository, pr *issues_model.PullRequest) (statuses []*git_model.CommitStatus, lastStatus *git_model.CommitStatus, err error) {
	sha, shaErr := gitRepo.GetRefCommitID(pr.GetGitHeadRefName())
	if shaErr != nil {
		return nil, nil, shaErr
	}

	statuses, err = git_model.GetLatestCommitStatus(ctx, pr.BaseRepo.ID, sha, db.ListOptionsAll)
	lastStatus = git_model.CalcCommitStatus(statuses)
	return statuses, lastStatus, err
}

// IsHeadEqualWithBranch returns if the commits of branchName are available in pull request head
func IsHeadEqualWithBranch(ctx context.Context, pr *issues_model.PullRequest, branchName string) (bool, error) {
	var err error
	if err = pr.LoadBaseRepo(ctx); err != nil {
		return false, err
	}
	baseGitRepo, closer, err := gitrepo.RepositoryFromContextOrOpen(ctx, pr.BaseRepo)
	if err != nil {
		return false, err
	}
	defer closer.Close()

	baseCommit, err := baseGitRepo.GetBranchCommit(branchName)
	if err != nil {
		return false, err
	}

	if err = pr.LoadHeadRepo(ctx); err != nil {
		return false, err
	}
	var headGitRepo *git.Repository
	if pr.HeadRepoID == pr.BaseRepoID {
		headGitRepo = baseGitRepo
	} else {
		var closer io.Closer

		headGitRepo, closer, err = gitrepo.RepositoryFromContextOrOpen(ctx, pr.HeadRepo)
		if err != nil {
			return false, err
		}
		defer closer.Close()
	}

	var headCommit *git.Commit
	if pr.Flow == issues_model.PullRequestFlowGithub {
		headCommit, err = headGitRepo.GetBranchCommit(pr.HeadBranch)
		if err != nil {
			return false, err
		}
	} else {
		pr.HeadCommitID, err = baseGitRepo.GetRefCommitID(pr.GetGitHeadRefName())
		if err != nil {
			return false, err
		}
		if headCommit, err = baseGitRepo.GetCommit(pr.HeadCommitID); err != nil {
			return false, err
		}
	}
	return baseCommit.HasPreviousCommit(headCommit.ID)
}

type CommitInfo struct {
	Summary               string `json:"summary"`
	CommitterOrAuthorName string `json:"committer_or_author_name"`
	ID                    string `json:"id"`
	ShortSha              string `json:"short_sha"`
	Time                  string `json:"time"`
}

// GetPullCommits returns all commits on given pull request and the last review commit sha
// Attention: The last review commit sha must be from the latest review whose commit id is not empty.
// So the type of the latest review cannot be "ReviewTypeRequest".
func GetPullCommits(ctx context.Context, baseGitRepo *git.Repository, doer *user_model.User, issue *issues_model.Issue) ([]CommitInfo, string, error) {
	pull := issue.PullRequest

	if err := pull.LoadBaseRepo(ctx); err != nil {
		return nil, "", err
	}
	baseBranch := pull.BaseBranch
	if pull.HasMerged {
		baseBranch = pull.MergeBase
	}
	compareInfo, err := git_service.GetCompareInfo(ctx, pull.BaseRepo, pull.BaseRepo, baseGitRepo, git.RefNameFromBranch(baseBranch), git.RefName(pull.GetGitHeadRefName()), false, false)
	if err != nil {
		return nil, "", err
	}

	commits := make([]CommitInfo, 0, len(compareInfo.Commits))

	for _, commit := range compareInfo.Commits {
		var committerOrAuthorName string
		var commitTime time.Time
		if commit.Author != nil {
			committerOrAuthorName = commit.Author.Name
			commitTime = commit.Author.When
		} else {
			committerOrAuthorName = commit.Committer.Name
			commitTime = commit.Committer.When
		}

		commits = append(commits, CommitInfo{
			Summary:               commit.MessageTitle(),
			CommitterOrAuthorName: committerOrAuthorName,
			ID:                    commit.ID.String(),
			ShortSha:              base.ShortSha(commit.ID.String()),
			Time:                  commitTime.Format(time.RFC3339),
		})
	}

	var lastReviewCommitID string
	if doer != nil {
		// get last review of current user and store information in context (if available)
		lastreview, err := issues_model.FindLatestReviews(ctx, issues_model.FindReviewOptions{
			IssueID:    issue.ID,
			ReviewerID: doer.ID,
			Types: []issues_model.ReviewType{
				issues_model.ReviewTypeApprove,
				issues_model.ReviewTypeComment,
				issues_model.ReviewTypeReject,
			},
		})

		if err != nil && !issues_model.IsErrReviewNotExist(err) {
			return nil, "", err
		}
		if len(lastreview) > 0 {
			lastReviewCommitID = lastreview[0].CommitID
		}
	}

	return commits, lastReviewCommitID, nil
}
