Support migration from AWS CodeCommit (#31981)

This PR adds support for migrating repos from [AWS
CodeCommit](https://docs.aws.amazon.com/codecommit/latest/userguide/welcome.html).

The access key ID and secret access key are required to get repository
information and pull requests. And [HTTPS Git
credentials](https://docs.aws.amazon.com/codecommit/latest/userguide/setting-up-gc.html)
are required to clone the repository.

<img
src="https://github.com/user-attachments/assets/82ecb2d0-8d43-42b0-b5af-f5347a13b9d0"
width="680" />

The AWS CodeCommit icon is from [AWS Architecture
Icons](https://aws.amazon.com/architecture/icons/).

<img
src="https://github.com/user-attachments/assets/3c44d21f-d753-40f5-9eae-5d3589e0d50d"
width="320" />

services/migrations/codecommit.go

@@ -0,0 +1,269 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package migrations
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+
+	git_module "code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+	base "code.gitea.io/gitea/modules/migration"
+	"code.gitea.io/gitea/modules/structs"
+
+	"github.com/aws/aws-sdk-go-v2/credentials"
+	"github.com/aws/aws-sdk-go-v2/service/codecommit"
+	"github.com/aws/aws-sdk-go-v2/service/codecommit/types"
+	"github.com/aws/aws-sdk-go/aws"
+)
+
+var (
+	_ base.Downloader        = &CodeCommitDownloader{}
+	_ base.DownloaderFactory = &CodeCommitDownloaderFactory{}
+)
+
+func init() {
+	RegisterDownloaderFactory(&CodeCommitDownloaderFactory{})
+}
+
+// CodeCommitDownloaderFactory defines a codecommit downloader factory
+type CodeCommitDownloaderFactory struct{}
+
+// New returns a Downloader related to this factory according MigrateOptions
+func (c *CodeCommitDownloaderFactory) New(ctx context.Context, opts base.MigrateOptions) (base.Downloader, error) {
+	u, err := url.Parse(opts.CloneAddr)
+	if err != nil {
+		return nil, err
+	}
+
+	hostElems := strings.Split(u.Host, ".")
+	if len(hostElems) != 4 {
+		return nil, fmt.Errorf("cannot get the region from clone URL")
+	}
+	region := hostElems[1]
+
+	pathElems := strings.Split(u.Path, "/")
+	if len(pathElems) == 0 {
+		return nil, fmt.Errorf("cannot get the repo name from clone URL")
+	}
+	repoName := pathElems[len(pathElems)-1]
+
+	baseURL := u.Scheme + "://" + u.Host
+
+	return NewCodeCommitDownloader(ctx, repoName, baseURL, opts.AWSAccessKeyID, opts.AWSSecretAccessKey, region), nil
+}
+
+// GitServiceType returns the type of git service
+func (c *CodeCommitDownloaderFactory) GitServiceType() structs.GitServiceType {
+	return structs.CodeCommitService
+}
+
+func NewCodeCommitDownloader(ctx context.Context, repoName, baseURL, accessKeyID, secretAccessKey, region string) *CodeCommitDownloader {
+	downloader := CodeCommitDownloader{
+		ctx:      ctx,
+		repoName: repoName,
+		baseURL:  baseURL,
+		codeCommitClient: codecommit.New(codecommit.Options{
+			Credentials: credentials.NewStaticCredentialsProvider(accessKeyID, secretAccessKey, ""),
+			Region:      region,
+		}),
+	}
+
+	return &downloader
+}
+
+// CodeCommitDownloader implements a downloader for AWS CodeCommit
+type CodeCommitDownloader struct {
+	base.NullDownloader
+	ctx               context.Context
+	codeCommitClient  *codecommit.Client
+	repoName          string
+	baseURL           string
+	allPullRequestIDs []string
+}
+
+// SetContext set context
+func (c *CodeCommitDownloader) SetContext(ctx context.Context) {
+	c.ctx = ctx
+}
+
+// GetRepoInfo returns a repository information
+func (c *CodeCommitDownloader) GetRepoInfo() (*base.Repository, error) {
+	output, err := c.codeCommitClient.GetRepository(c.ctx, &codecommit.GetRepositoryInput{
+		RepositoryName: aws.String(c.repoName),
+	})
+	if err != nil {
+		return nil, err
+	}
+	repoMeta := output.RepositoryMetadata
+
+	repo := &base.Repository{
+		Name:      *repoMeta.RepositoryName,
+		Owner:     *repoMeta.AccountId,
+		IsPrivate: true, // CodeCommit repos are always private
+		CloneURL:  *repoMeta.CloneUrlHttp,
+	}
+	if repoMeta.DefaultBranch != nil {
+		repo.DefaultBranch = *repoMeta.DefaultBranch
+	}
+	if repoMeta.RepositoryDescription != nil {
+		repo.DefaultBranch = *repoMeta.RepositoryDescription
+	}
+	return repo, nil
+}
+
+// GetComments returns comments of an issue or PR
+func (c *CodeCommitDownloader) GetComments(commentable base.Commentable) ([]*base.Comment, bool, error) {
+	var (
+		nextToken *string
+		comments  []*base.Comment
+	)
+
+	for {
+		resp, err := c.codeCommitClient.GetCommentsForPullRequest(c.ctx, &codecommit.GetCommentsForPullRequestInput{
+			NextToken:     nextToken,
+			PullRequestId: aws.String(strconv.FormatInt(commentable.GetForeignIndex(), 10)),
+		})
+		if err != nil {
+			return nil, false, err
+		}
+
+		for _, prComment := range resp.CommentsForPullRequestData {
+			for _, ccComment := range prComment.Comments {
+				comment := &base.Comment{
+					IssueIndex: commentable.GetForeignIndex(),
+					PosterName: c.getUsernameFromARN(*ccComment.AuthorArn),
+					Content:    *ccComment.Content,
+					Created:    *ccComment.CreationDate,
+					Updated:    *ccComment.LastModifiedDate,
+				}
+				comments = append(comments, comment)
+			}
+		}
+
+		nextToken = resp.NextToken
+		if nextToken == nil {
+			break
+		}
+	}
+
+	return comments, true, nil
+}
+
+// GetPullRequests returns pull requests according page and perPage
+func (c *CodeCommitDownloader) GetPullRequests(page, perPage int) ([]*base.PullRequest, bool, error) {
+	allPullRequestIDs, err := c.getAllPullRequestIDs()
+	if err != nil {
+		return nil, false, err
+	}
+
+	startIndex := (page - 1) * perPage
+	endIndex := page * perPage
+	if endIndex > len(allPullRequestIDs) {
+		endIndex = len(allPullRequestIDs)
+	}
+	batch := allPullRequestIDs[startIndex:endIndex]
+
+	prs := make([]*base.PullRequest, 0, len(batch))
+	for _, id := range batch {
+		output, err := c.codeCommitClient.GetPullRequest(c.ctx, &codecommit.GetPullRequestInput{
+			PullRequestId: aws.String(id),
+		})
+		if err != nil {
+			return nil, false, err
+		}
+		orig := output.PullRequest
+		number, err := strconv.ParseInt(*orig.PullRequestId, 10, 64)
+		if err != nil {
+			log.Error("CodeCommit pull request id is not a number: %s", *orig.PullRequestId)
+			continue
+		}
+		if len(orig.PullRequestTargets) == 0 {
+			log.Error("CodeCommit pull request does not contain targets", *orig.PullRequestId)
+			continue
+		}
+		target := orig.PullRequestTargets[0]
+		pr := &base.PullRequest{
+			Number:     number,
+			Title:      *orig.Title,
+			PosterName: c.getUsernameFromARN(*orig.AuthorArn),
+			Content:    *orig.Description,
+			State:      "open",
+			Created:    *orig.CreationDate,
+			Updated:    *orig.LastActivityDate,
+			Merged:     target.MergeMetadata.IsMerged,
+			Head: base.PullRequestBranch{
+				Ref:      strings.TrimPrefix(*target.SourceReference, git_module.BranchPrefix),
+				SHA:      *target.SourceCommit,
+				RepoName: c.repoName,
+			},
+			Base: base.PullRequestBranch{
+				Ref:      strings.TrimPrefix(*target.DestinationReference, git_module.BranchPrefix),
+				SHA:      *target.DestinationCommit,
+				RepoName: c.repoName,
+			},
+			ForeignIndex: number,
+		}
+
+		if orig.PullRequestStatus == types.PullRequestStatusEnumClosed {
+			pr.State = "closed"
+			pr.Closed = orig.LastActivityDate
+		}
+
+		_ = CheckAndEnsureSafePR(pr, c.baseURL, c)
+		prs = append(prs, pr)
+	}
+
+	return prs, len(prs) < perPage, nil
+}
+
+// FormatCloneURL add authentication into remote URLs
+func (c *CodeCommitDownloader) FormatCloneURL(opts MigrateOptions, remoteAddr string) (string, error) {
+	u, err := url.Parse(remoteAddr)
+	if err != nil {
+		return "", err
+	}
+	u.User = url.UserPassword(opts.AuthUsername, opts.AuthPassword)
+	return u.String(), nil
+}
+
+func (c *CodeCommitDownloader) getAllPullRequestIDs() ([]string, error) {
+	if len(c.allPullRequestIDs) > 0 {
+		return c.allPullRequestIDs, nil
+	}
+
+	var (
+		nextToken *string
+		prIDs     []string
+	)
+
+	for {
+		output, err := c.codeCommitClient.ListPullRequests(c.ctx, &codecommit.ListPullRequestsInput{
+			RepositoryName: aws.String(c.repoName),
+			NextToken:      nextToken,
+		})
+		if err != nil {
+			return nil, err
+		}
+		prIDs = append(prIDs, output.PullRequestIds...)
+		nextToken = output.NextToken
+		if nextToken == nil {
+			break
+		}
+	}
+
+	c.allPullRequestIDs = prIDs
+	return c.allPullRequestIDs, nil
+}
+
+func (c *CodeCommitDownloader) getUsernameFromARN(arn string) string {
+	parts := strings.Split(arn, "/")
+	if len(parts) > 0 {
+		return parts[len(parts)-1]
+	}
+	return ""
+}