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

package files

import (
	"context"
	"fmt"
	"io"
	"path"
	"strings"
	"time"

	git_model "code.gitea.io/gitea/models/git"
	repo_model "code.gitea.io/gitea/models/repo"
	user_model "code.gitea.io/gitea/models/user"
	"code.gitea.io/gitea/modules/git"
	"code.gitea.io/gitea/modules/git/attribute"
	"code.gitea.io/gitea/modules/gitrepo"
	"code.gitea.io/gitea/modules/lfs"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/setting"
	"code.gitea.io/gitea/modules/structs"
	"code.gitea.io/gitea/modules/util"
	"code.gitea.io/gitea/routers/api/v1/utils"
	asymkey_service "code.gitea.io/gitea/services/asymkey"
	pull_service "code.gitea.io/gitea/services/pull"
)

// IdentityOptions for a person's identity like an author or committer
type IdentityOptions struct {
	GitUserName  string // to match "git config user.name"
	GitUserEmail string // to match "git config user.email"
}

// CommitDateOptions store dates for GIT_AUTHOR_DATE and GIT_COMMITTER_DATE
type CommitDateOptions struct {
	Author    time.Time
	Committer time.Time
}

type ChangeRepoFile struct {
	Operation     string
	TreePath      string
	FromTreePath  string
	ContentReader io.ReadSeeker
	SHA           string
	Options       *RepoFileOptions
}

// ChangeRepoFilesOptions holds the repository files update options
type ChangeRepoFilesOptions struct {
	LastCommitID string
	OldBranch    string
	NewBranch    string
	Message      string
	Files        []*ChangeRepoFile
	Author       *IdentityOptions
	Committer    *IdentityOptions
	Dates        *CommitDateOptions
	Signoff      bool
}

type RepoFileOptions struct {
	treePath     string
	fromTreePath string
	executable   bool
}

// ErrRepoFileDoesNotExist represents a "RepoFileDoesNotExist" kind of error.
type ErrRepoFileDoesNotExist struct {
	Path string
	Name string
}

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

func (err ErrRepoFileDoesNotExist) Error() string {
	return fmt.Sprintf("repository file does not exist [path: %s]", err.Path)
}

func (err ErrRepoFileDoesNotExist) Unwrap() error {
	return util.ErrNotExist
}

// ChangeRepoFiles adds, updates or removes multiple files in the given repository
func ChangeRepoFiles(ctx context.Context, repo *repo_model.Repository, doer *user_model.User, opts *ChangeRepoFilesOptions) (*structs.FilesResponse, error) {
	err := repo.MustNotBeArchived()
	if err != nil {
		return nil, err
	}

	// If no branch name is set, assume default branch
	if opts.OldBranch == "" {
		opts.OldBranch = repo.DefaultBranch
	}
	if opts.NewBranch == "" {
		opts.NewBranch = opts.OldBranch
	}

	gitRepo, closer, err := gitrepo.RepositoryFromContextOrOpen(ctx, repo)
	if err != nil {
		return nil, err
	}
	defer closer.Close()

	// oldBranch must exist for this operation
	if exist, err := git_model.IsBranchExist(ctx, repo.ID, opts.OldBranch); err != nil {
		return nil, err
	} else if !exist && !repo.IsEmpty {
		return nil, git_model.ErrBranchNotExist{
			RepoID:     repo.ID,
			BranchName: opts.OldBranch,
		}
	}

	var treePaths []string
	for _, file := range opts.Files {
		// If FromTreePath is not set, set it to the opts.TreePath
		if file.TreePath != "" && file.FromTreePath == "" {
			file.FromTreePath = file.TreePath
		}

		// Check that the path given in opts.treePath is valid (not a git path)
		treePath := CleanUploadFileName(file.TreePath)
		if treePath == "" {
			return nil, ErrFilenameInvalid{
				Path: file.TreePath,
			}
		}
		// If there is a fromTreePath (we are copying it), also clean it up
		fromTreePath := CleanUploadFileName(file.FromTreePath)
		if fromTreePath == "" && file.FromTreePath != "" {
			return nil, ErrFilenameInvalid{
				Path: file.FromTreePath,
			}
		}

		file.Options = &RepoFileOptions{
			treePath:     treePath,
			fromTreePath: fromTreePath,
			executable:   false,
		}
		treePaths = append(treePaths, treePath)
	}

	// A NewBranch can be specified for the file to be created/updated in a new branch.
	// Check to make sure the branch does not already exist, otherwise we can't proceed.
	// If we aren't branching to a new branch, make sure user can commit to the given branch
	if opts.NewBranch != opts.OldBranch {
		exist, err := git_model.IsBranchExist(ctx, repo.ID, opts.NewBranch)
		if err != nil {
			return nil, err
		}
		if exist {
			return nil, git_model.ErrBranchAlreadyExists{
				BranchName: opts.NewBranch,
			}
		}
	} else if err := VerifyBranchProtection(ctx, repo, doer, opts.OldBranch, treePaths); err != nil {
		return nil, err
	}

	message := strings.TrimSpace(opts.Message)

	t, err := NewTemporaryUploadRepository(repo)
	if err != nil {
		log.Error("NewTemporaryUploadRepository failed: %v", err)
	}
	defer t.Close()
	hasOldBranch := true
	if err := t.Clone(ctx, opts.OldBranch, true); err != nil {
		for _, file := range opts.Files {
			if file.Operation == "delete" {
				return nil, err
			}
		}
		if !git.IsErrBranchNotExist(err) || !repo.IsEmpty {
			return nil, err
		}
		if err := t.Init(ctx, repo.ObjectFormatName); err != nil {
			return nil, err
		}
		hasOldBranch = false
		opts.LastCommitID = ""
	}
	if hasOldBranch {
		if err := t.SetDefaultIndex(ctx); err != nil {
			return nil, err
		}
	}

	for _, file := range opts.Files {
		if file.Operation == "delete" {
			// Get the files in the index
			filesInIndex, err := t.LsFiles(ctx, file.TreePath)
			if err != nil {
				return nil, fmt.Errorf("DeleteRepoFile: %w", err)
			}

			// Find the file we want to delete in the index
			inFilelist := false
			for _, indexFile := range filesInIndex {
				if indexFile == file.TreePath {
					inFilelist = true
					break
				}
			}
			if !inFilelist {
				return nil, ErrRepoFileDoesNotExist{
					Path: file.TreePath,
				}
			}
		}
	}

	if hasOldBranch {
		// Get the commit of the original branch
		commit, err := t.GetBranchCommit(opts.OldBranch)
		if err != nil {
			return nil, err // Couldn't get a commit for the branch
		}

		// Assigned LastCommitID in "opts" if it hasn't been set
		if opts.LastCommitID == "" {
			opts.LastCommitID = commit.ID.String()
		} else {
			lastCommitID, err := t.gitRepo.ConvertToGitID(opts.LastCommitID)
			if err != nil {
				return nil, fmt.Errorf("ConvertToSHA1: Invalid last commit ID: %w", err)
			}
			opts.LastCommitID = lastCommitID.String()
		}

		for _, file := range opts.Files {
			if err = handleCheckErrors(file, commit, opts); err != nil {
				return nil, err
			}
		}
	}

	lfsContentStore := lfs.NewContentStore()
	for _, file := range opts.Files {
		switch file.Operation {
		case "create", "update", "rename":
			if err = CreateUpdateRenameFile(ctx, t, file, lfsContentStore, repo.ID, hasOldBranch); err != nil {
				return nil, err
			}
		case "delete":
			if err = t.RemoveFilesFromIndex(ctx, file.TreePath); err != nil {
				return nil, err
			}
		default:
			return nil, fmt.Errorf("invalid file operation: %s %s, supported operations are create, update, delete", file.Operation, file.Options.treePath)
		}
	}

	// Now write the tree
	treeHash, err := t.WriteTree(ctx)
	if err != nil {
		return nil, err
	}

	// Now commit the tree
	commitOpts := &CommitTreeUserOptions{
		ParentCommitID:    opts.LastCommitID,
		TreeHash:          treeHash,
		CommitMessage:     message,
		SignOff:           opts.Signoff,
		DoerUser:          doer,
		AuthorIdentity:    opts.Author,
		AuthorTime:        nil,
		CommitterIdentity: opts.Committer,
		CommitterTime:     nil,
	}
	if opts.Dates != nil {
		commitOpts.AuthorTime, commitOpts.CommitterTime = &opts.Dates.Author, &opts.Dates.Committer
	}
	commitHash, err := t.CommitTree(ctx, commitOpts)
	if err != nil {
		return nil, err
	}

	// Then push this tree to NewBranch
	if err := t.Push(ctx, doer, commitHash, opts.NewBranch); err != nil {
		log.Error("%T %v", err, err)
		return nil, err
	}

	commit, err := t.GetCommit(commitHash)
	if err != nil {
		return nil, err
	}

	// FIXME: this call seems not right, why it needs to read the file content again
	// FIXME: why it uses the NewBranch as "ref", it should use the commit ID because the response is only for this commit
	filesResponse, err := GetFilesResponseFromCommit(ctx, repo, utils.NewRefCommit(git.RefNameFromBranch(opts.NewBranch), commit), treePaths)
	if err != nil {
		return nil, err
	}

	if repo.IsEmpty {
		if isEmpty, err := gitRepo.IsEmpty(); err == nil && !isEmpty {
			_ = repo_model.UpdateRepositoryColsWithAutoTime(ctx, &repo_model.Repository{ID: repo.ID, IsEmpty: false, DefaultBranch: opts.NewBranch}, "is_empty", "default_branch")
		}
	}

	return filesResponse, nil
}

// ErrRepoFileAlreadyExists represents a "RepoFileAlreadyExist" kind of error.
type ErrRepoFileAlreadyExists struct {
	Path string
}

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

func (err ErrRepoFileAlreadyExists) Error() string {
	return fmt.Sprintf("repository file already exists [path: %s]", err.Path)
}

func (err ErrRepoFileAlreadyExists) Unwrap() error {
	return util.ErrAlreadyExist
}

// ErrFilePathInvalid represents a "FilePathInvalid" kind of error.
type ErrFilePathInvalid struct {
	Message string
	Path    string
	Name    string
	Type    git.EntryMode
}

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

func (err ErrFilePathInvalid) Error() string {
	if err.Message != "" {
		return err.Message
	}
	return fmt.Sprintf("path is invalid [path: %s]", err.Path)
}

func (err ErrFilePathInvalid) Unwrap() error {
	return util.ErrInvalidArgument
}

// ErrSHAOrCommitIDNotProvided represents a "SHAOrCommitIDNotProvided" kind of error.
type ErrSHAOrCommitIDNotProvided struct{}

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

func (err ErrSHAOrCommitIDNotProvided) Error() string {
	return "a SHA or commit ID must be proved when updating a file"
}

// handles the check for various issues for ChangeRepoFiles
func handleCheckErrors(file *ChangeRepoFile, commit *git.Commit, opts *ChangeRepoFilesOptions) error {
	if file.Operation == "update" || file.Operation == "delete" || file.Operation == "rename" {
		fromEntry, err := commit.GetTreeEntryByPath(file.Options.fromTreePath)
		if err != nil {
			return err
		}
		if file.SHA != "" {
			// If the SHA given doesn't match the SHA of the fromTreePath, throw error
			if file.SHA != fromEntry.ID.String() {
				return pull_service.ErrSHADoesNotMatch{
					Path:       file.Options.treePath,
					GivenSHA:   file.SHA,
					CurrentSHA: fromEntry.ID.String(),
				}
			}
		} else if opts.LastCommitID != "" {
			// If a lastCommitID given doesn't match the branch head's commitID throw
			// an error, but only if we aren't creating a new branch.
			if commit.ID.String() != opts.LastCommitID && opts.OldBranch == opts.NewBranch {
				if changed, err := commit.FileChangedSinceCommit(file.Options.treePath, opts.LastCommitID); err != nil {
					return err
				} else if changed {
					return ErrCommitIDDoesNotMatch{
						GivenCommitID:   opts.LastCommitID,
						CurrentCommitID: opts.LastCommitID,
					}
				}
				// The file wasn't modified, so we are good to delete it
			}
		} else {
			// When updating a file, a lastCommitID or SHA needs to be given to make sure other commits
			// haven't been made. We throw an error if one wasn't provided.
			return ErrSHAOrCommitIDNotProvided{}
		}
		// FIXME: legacy hacky approach, it shouldn't prepare the "Options" in the "check" function
		file.Options.executable = fromEntry.IsExecutable()
	}

	if file.Operation == "create" || file.Operation == "update" || file.Operation == "rename" {
		// For operation's target path, we need to make sure no parts of the path are existing files or links
		// except for the last item in the path (which is the file name).
		// And that shouldn't exist IF it is a new file OR is being moved to a new path.
		treePathParts := strings.Split(file.Options.treePath, "/")
		subTreePath := ""
		for index, part := range treePathParts {
			subTreePath = path.Join(subTreePath, part)
			entry, err := commit.GetTreeEntryByPath(subTreePath)
			if err != nil {
				if git.IsErrNotExist(err) {
					// Means there is no item with that name, so we're good
					break
				}
				return err
			}
			if index < len(treePathParts)-1 {
				if !entry.IsDir() {
					return ErrFilePathInvalid{
						Message: fmt.Sprintf("a file exists where you’re trying to create a subdirectory [path: %s]", subTreePath),
						Path:    subTreePath,
						Name:    part,
						Type:    git.EntryModeBlob,
					}
				}
			} else if entry.IsLink() {
				return ErrFilePathInvalid{
					Message: fmt.Sprintf("a symbolic link exists where you’re trying to create a subdirectory [path: %s]", subTreePath),
					Path:    subTreePath,
					Name:    part,
					Type:    git.EntryModeSymlink,
				}
			} else if entry.IsDir() {
				return ErrFilePathInvalid{
					Message: fmt.Sprintf("a directory exists where you’re trying to create a file [path: %s]", subTreePath),
					Path:    subTreePath,
					Name:    part,
					Type:    git.EntryModeTree,
				}
			} else if file.Options.fromTreePath != file.Options.treePath || file.Operation == "create" {
				// The entry shouldn't exist if we are creating the new file or moving to a new path
				return ErrRepoFileAlreadyExists{
					Path: file.Options.treePath,
				}
			}
		}
	}

	return nil
}

func CreateUpdateRenameFile(ctx context.Context, t *TemporaryUploadRepository, file *ChangeRepoFile, contentStore *lfs.ContentStore, repoID int64, hasOldBranch bool) error {
	// Get the two paths (might be the same if not moving) from the index if they exist
	filesInIndex, err := t.LsFiles(ctx, file.TreePath, file.FromTreePath)
	if err != nil {
		return fmt.Errorf("UpdateRepoFile: %w", err)
	}
	// If is a new file (not updating) then the given path shouldn't exist
	if file.Operation == "create" {
		for _, indexFile := range filesInIndex {
			if indexFile == file.TreePath {
				return ErrRepoFileAlreadyExists{
					Path: file.TreePath,
				}
			}
		}
	}

	// Remove the old path from the tree
	if file.Options.fromTreePath != file.Options.treePath && len(filesInIndex) > 0 {
		for _, indexFile := range filesInIndex {
			if indexFile == file.Options.fromTreePath {
				if err = t.RemoveFilesFromIndex(ctx, file.FromTreePath); err != nil {
					return err
				}
			}
		}
	}

	var writeObjectRet *writeRepoObjectRet
	switch file.Operation {
	case "create", "update":
		writeObjectRet, err = writeRepoObjectForCreateOrUpdate(ctx, t, file)
	case "rename":
		writeObjectRet, err = writeRepoObjectForRename(ctx, t, file)
	default:
		return util.NewInvalidArgumentErrorf("unknown file modification operation: '%s'", file.Operation)
	}
	if err != nil {
		return err
	}

	// Add the object to the index, the "file.Options.executable" is set in handleCheckErrors by the caller (legacy hacky approach)
	if err = t.AddObjectToIndex(ctx, util.Iif(file.Options.executable, "100755", "100644"), writeObjectRet.ObjectHash, file.Options.treePath); err != nil {
		return err
	}

	if writeObjectRet.LfsContent == nil {
		return nil // No LFS pointer, so nothing to do
	}
	defer writeObjectRet.LfsContent.Close()

	// Now we must store the content into an LFS object
	lfsMetaObject, err := git_model.NewLFSMetaObject(ctx, repoID, writeObjectRet.LfsPointer)
	if err != nil {
		return err
	}
	if exist, err := contentStore.Exists(lfsMetaObject.Pointer); err != nil {
		return err
	} else if exist {
		return nil
	}

	err = contentStore.Put(lfsMetaObject.Pointer, writeObjectRet.LfsContent)
	if err != nil {
		if _, errRemove := git_model.RemoveLFSMetaObjectByOid(ctx, repoID, lfsMetaObject.Oid); errRemove != nil {
			return fmt.Errorf("unable to remove failed inserted LFS object %s: %v (Prev Error: %w)", lfsMetaObject.Oid, errRemove, err)
		}
	}
	return err
}

func checkIsLfsFileInGitAttributes(ctx context.Context, t *TemporaryUploadRepository, paths []string) (ret []bool, err error) {
	attributesMap, err := attribute.CheckAttributes(ctx, t.gitRepo, "" /* use temp repo's working dir */, attribute.CheckAttributeOpts{
		Attributes: []string{attribute.Filter},
		Filenames:  paths,
	})
	if err != nil {
		return nil, err
	}
	for _, p := range paths {
		isLFSFile := attributesMap[p] != nil && attributesMap[p].Get(attribute.Filter).ToString().Value() == "lfs"
		ret = append(ret, isLFSFile)
	}
	return ret, nil
}

type writeRepoObjectRet struct {
	ObjectHash string
	LfsContent io.ReadCloser // if not nil, then the caller should store its content in LfsPointer, then close it
	LfsPointer lfs.Pointer
}

// writeRepoObjectForCreateOrUpdate hashes the git object for create or update operations
func writeRepoObjectForCreateOrUpdate(ctx context.Context, t *TemporaryUploadRepository, file *ChangeRepoFile) (ret *writeRepoObjectRet, err error) {
	ret = &writeRepoObjectRet{}
	treeObjectContentReader := file.ContentReader
	if setting.LFS.StartServer {
		checkIsLfsFiles, err := checkIsLfsFileInGitAttributes(ctx, t, []string{file.Options.treePath})
		if err != nil {
			return nil, err
		}
		if checkIsLfsFiles[0] {
			// OK, so we are supposed to LFS this data!
			ret.LfsPointer, err = lfs.GeneratePointer(file.ContentReader)
			if err != nil {
				return nil, err
			}
			if _, err = file.ContentReader.Seek(0, io.SeekStart); err != nil {
				return nil, err
			}
			ret.LfsContent = io.NopCloser(file.ContentReader)
			treeObjectContentReader = strings.NewReader(ret.LfsPointer.StringContent())
		}
	}

	ret.ObjectHash, err = t.HashObjectAndWrite(ctx, treeObjectContentReader)
	if err != nil {
		return nil, err
	}
	return ret, nil
}

// writeRepoObjectForRename the same as writeRepoObjectForCreateOrUpdate buf for "rename"
func writeRepoObjectForRename(ctx context.Context, t *TemporaryUploadRepository, file *ChangeRepoFile) (ret *writeRepoObjectRet, err error) {
	lastCommitID, err := t.GetLastCommit(ctx)
	if err != nil {
		return nil, err
	}
	commit, err := t.GetCommit(lastCommitID)
	if err != nil {
		return nil, err
	}
	oldEntry, err := commit.GetTreeEntryByPath(file.Options.fromTreePath)
	if err != nil {
		return nil, err
	}

	ret = &writeRepoObjectRet{ObjectHash: oldEntry.ID.String()}
	if !setting.LFS.StartServer {
		return ret, nil
	}

	checkIsLfsFiles, err := checkIsLfsFileInGitAttributes(ctx, t, []string{file.Options.fromTreePath, file.Options.treePath})
	if err != nil {
		return nil, err
	}
	oldIsLfs, newIsLfs := checkIsLfsFiles[0], checkIsLfsFiles[1]

	// If the old and new paths are both in lfs or both not in lfs, the object hash of the old file can be used directly
	// as the object doesn't change
	if oldIsLfs == newIsLfs {
		return ret, nil
	}

	oldEntryBlobPointerBy := func(f func(r io.Reader) (lfs.Pointer, error)) (lfsPointer lfs.Pointer, err error) {
		r, err := oldEntry.Blob().DataAsync()
		if err != nil {
			return lfsPointer, err
		}
		defer r.Close()
		return f(r)
	}

	var treeObjectContentReader io.ReadCloser
	if oldIsLfs {
		// If the old is in lfs but the new isn't, read the content from lfs and add it as a normal git object
		pointer, err := oldEntryBlobPointerBy(lfs.ReadPointer)
		if err != nil {
			return nil, err
		}
		treeObjectContentReader, err = lfs.ReadMetaObject(pointer)
		if err != nil {
			return nil, err
		}
		defer treeObjectContentReader.Close()
	} else {
		// If the new is in lfs but the old isn't, read the content from the git object and generate a lfs pointer of it
		ret.LfsPointer, err = oldEntryBlobPointerBy(lfs.GeneratePointer)
		if err != nil {
			return nil, err
		}
		ret.LfsContent, err = oldEntry.Blob().DataAsync()
		if err != nil {
			return nil, err
		}
		treeObjectContentReader = io.NopCloser(strings.NewReader(ret.LfsPointer.StringContent()))
	}
	ret.ObjectHash, err = t.HashObjectAndWrite(ctx, treeObjectContentReader)
	if err != nil {
		return nil, err
	}
	return ret, nil
}

// VerifyBranchProtection verify the branch protection for modifying the given treePath on the given branch
func VerifyBranchProtection(ctx context.Context, repo *repo_model.Repository, doer *user_model.User, branchName string, treePaths []string) error {
	protectedBranch, err := git_model.GetFirstMatchProtectedBranchRule(ctx, repo.ID, branchName)
	if err != nil {
		return err
	}
	if protectedBranch != nil {
		protectedBranch.Repo = repo
		globUnprotected := protectedBranch.GetUnprotectedFilePatterns()
		globProtected := protectedBranch.GetProtectedFilePatterns()
		canUserPush := protectedBranch.CanUserPush(ctx, doer)
		for _, treePath := range treePaths {
			isUnprotectedFile := false
			if len(globUnprotected) != 0 {
				isUnprotectedFile = protectedBranch.IsUnprotectedFile(globUnprotected, treePath)
			}
			if !canUserPush && !isUnprotectedFile {
				return ErrUserCannotCommit{
					UserName: doer.LowerName,
				}
			}
			if protectedBranch.IsProtectedFile(globProtected, treePath) {
				return pull_service.ErrFilePathProtected{
					Path: treePath,
				}
			}
		}
		if protectedBranch.RequireSignedCommits {
			_, _, _, err := asymkey_service.SignCRUDAction(ctx, repo.RepoPath(), doer, repo.RepoPath(), branchName)
			if err != nil {
				if !asymkey_service.IsErrWontSign(err) {
					return err
				}
				return ErrUserCannotCommit{
					UserName: doer.LowerName,
				}
			}
		}
	}
	return nil
}