// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package migrations

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	user_model "code.gitea.io/gitea/models/user"
	"code.gitea.io/gitea/modules/git"
	"code.gitea.io/gitea/modules/log"
	base "code.gitea.io/gitea/modules/migration"
	"code.gitea.io/gitea/modules/repository"
	"code.gitea.io/gitea/modules/structs"

	"gopkg.in/yaml.v2"
)

var (
	_ base.Uploader = &RepositoryDumper{}
)

// RepositoryDumper implements an Uploader to the local directory
type RepositoryDumper struct {
	ctx             context.Context
	baseDir         string
	repoOwner       string
	repoName        string
	opts            base.MigrateOptions
	milestoneFile   *os.File
	labelFile       *os.File
	releaseFile     *os.File
	issueFile       *os.File
	commentFiles    map[int64]*os.File
	pullrequestFile *os.File
	reviewFiles     map[int64]*os.File

	gitRepo     *git.Repository
	prHeadCache map[string]struct{}
}

// NewRepositoryDumper creates an gitea Uploader
func NewRepositoryDumper(ctx context.Context, baseDir, repoOwner, repoName string, opts base.MigrateOptions) (*RepositoryDumper, error) {
	baseDir = filepath.Join(baseDir, repoOwner, repoName)
	if err := os.MkdirAll(baseDir, os.ModePerm); err != nil {
		return nil, err
	}
	return &RepositoryDumper{
		ctx:          ctx,
		opts:         opts,
		baseDir:      baseDir,
		repoOwner:    repoOwner,
		repoName:     repoName,
		prHeadCache:  make(map[string]struct{}),
		commentFiles: make(map[int64]*os.File),
		reviewFiles:  make(map[int64]*os.File),
	}, nil
}

// MaxBatchInsertSize returns the table's max batch insert size
func (g *RepositoryDumper) MaxBatchInsertSize(tp string) int {
	return 1000
}

func (g *RepositoryDumper) gitPath() string {
	return filepath.Join(g.baseDir, "git")
}

func (g *RepositoryDumper) wikiPath() string {
	return filepath.Join(g.baseDir, "wiki")
}

func (g *RepositoryDumper) commentDir() string {
	return filepath.Join(g.baseDir, "comments")
}

func (g *RepositoryDumper) reviewDir() string {
	return filepath.Join(g.baseDir, "reviews")
}

func (g *RepositoryDumper) setURLToken(remoteAddr string) (string, error) {
	if len(g.opts.AuthToken) > 0 || len(g.opts.AuthUsername) > 0 {
		u, err := url.Parse(remoteAddr)
		if err != nil {
			return "", err
		}
		u.User = url.UserPassword(g.opts.AuthUsername, g.opts.AuthPassword)
		if len(g.opts.AuthToken) > 0 {
			u.User = url.UserPassword("oauth2", g.opts.AuthToken)
		}
		remoteAddr = u.String()
	}

	return remoteAddr, nil
}

// CreateRepo creates a repository
func (g *RepositoryDumper) CreateRepo(repo *base.Repository, opts base.MigrateOptions) error {
	f, err := os.Create(filepath.Join(g.baseDir, "repo.yml"))
	if err != nil {
		return err
	}
	defer f.Close()

	bs, err := yaml.Marshal(map[string]interface{}{
		"name":         repo.Name,
		"owner":        repo.Owner,
		"description":  repo.Description,
		"clone_addr":   opts.CloneAddr,
		"original_url": repo.OriginalURL,
		"is_private":   opts.Private,
		"service_type": opts.GitServiceType,
		"wiki":         opts.Wiki,
		"issues":       opts.Issues,
		"milestones":   opts.Milestones,
		"labels":       opts.Labels,
		"releases":     opts.Releases,
		"comments":     opts.Comments,
		"pulls":        opts.PullRequests,
		"assets":       opts.ReleaseAssets,
	})
	if err != nil {
		return err
	}

	if _, err := f.Write(bs); err != nil {
		return err
	}

	repoPath := g.gitPath()
	if err := os.MkdirAll(repoPath, os.ModePerm); err != nil {
		return err
	}

	migrateTimeout := 2 * time.Hour

	remoteAddr, err := g.setURLToken(repo.CloneURL)
	if err != nil {
		return err
	}

	err = git.Clone(remoteAddr, repoPath, git.CloneRepoOptions{
		Mirror:  true,
		Quiet:   true,
		Timeout: migrateTimeout,
	})
	if err != nil {
		return fmt.Errorf("Clone: %v", err)
	}

	if opts.Wiki {
		wikiPath := g.wikiPath()
		wikiRemotePath := repository.WikiRemoteURL(remoteAddr)
		if len(wikiRemotePath) > 0 {
			if err := os.MkdirAll(wikiPath, os.ModePerm); err != nil {
				return fmt.Errorf("Failed to remove %s: %v", wikiPath, err)
			}

			if err := git.Clone(wikiRemotePath, wikiPath, git.CloneRepoOptions{
				Mirror:  true,
				Quiet:   true,
				Timeout: migrateTimeout,
				Branch:  "master",
			}); err != nil {
				log.Warn("Clone wiki: %v", err)
				if err := os.RemoveAll(wikiPath); err != nil {
					return fmt.Errorf("Failed to remove %s: %v", wikiPath, err)
				}
			}
		}
	}

	g.gitRepo, err = git.OpenRepository(g.gitPath())
	return err
}

// Close closes this uploader
func (g *RepositoryDumper) Close() {
	if g.gitRepo != nil {
		g.gitRepo.Close()
	}
	if g.milestoneFile != nil {
		g.milestoneFile.Close()
	}
	if g.labelFile != nil {
		g.labelFile.Close()
	}
	if g.releaseFile != nil {
		g.releaseFile.Close()
	}
	if g.issueFile != nil {
		g.issueFile.Close()
	}
	for _, f := range g.commentFiles {
		f.Close()
	}
	if g.pullrequestFile != nil {
		g.pullrequestFile.Close()
	}
	for _, f := range g.reviewFiles {
		f.Close()
	}
}

// CreateTopics creates topics
func (g *RepositoryDumper) CreateTopics(topics ...string) error {
	f, err := os.Create(filepath.Join(g.baseDir, "topic.yml"))
	if err != nil {
		return err
	}
	defer f.Close()

	bs, err := yaml.Marshal(map[string]interface{}{
		"topics": topics,
	})
	if err != nil {
		return err
	}

	if _, err := f.Write(bs); err != nil {
		return err
	}

	return nil
}

// CreateMilestones creates milestones
func (g *RepositoryDumper) CreateMilestones(milestones ...*base.Milestone) error {
	var err error
	if g.milestoneFile == nil {
		g.milestoneFile, err = os.Create(filepath.Join(g.baseDir, "milestone.yml"))
		if err != nil {
			return err
		}
	}

	bs, err := yaml.Marshal(milestones)
	if err != nil {
		return err
	}

	if _, err := g.milestoneFile.Write(bs); err != nil {
		return err
	}

	return nil
}

// CreateLabels creates labels
func (g *RepositoryDumper) CreateLabels(labels ...*base.Label) error {
	var err error
	if g.labelFile == nil {
		g.labelFile, err = os.Create(filepath.Join(g.baseDir, "label.yml"))
		if err != nil {
			return err
		}
	}

	bs, err := yaml.Marshal(labels)
	if err != nil {
		return err
	}

	if _, err := g.labelFile.Write(bs); err != nil {
		return err
	}

	return nil
}

// CreateReleases creates releases
func (g *RepositoryDumper) CreateReleases(releases ...*base.Release) error {
	if g.opts.ReleaseAssets {
		for _, release := range releases {
			attachDir := filepath.Join("release_assets", release.TagName)
			if err := os.MkdirAll(filepath.Join(g.baseDir, attachDir), os.ModePerm); err != nil {
				return err
			}
			for _, asset := range release.Assets {
				attachLocalPath := filepath.Join(attachDir, asset.Name)
				// download attachment

				err := func(attachPath string) error {
					var rc io.ReadCloser
					var err error
					if asset.DownloadURL == nil {
						rc, err = asset.DownloadFunc()
						if err != nil {
							return err
						}
					} else {
						resp, err := http.Get(*asset.DownloadURL)
						if err != nil {
							return err
						}
						rc = resp.Body
					}
					defer rc.Close()

					fw, err := os.Create(attachPath)
					if err != nil {
						return fmt.Errorf("Create: %v", err)
					}
					defer fw.Close()

					_, err = io.Copy(fw, rc)
					return err
				}(filepath.Join(g.baseDir, attachLocalPath))
				if err != nil {
					return err
				}
				asset.DownloadURL = &attachLocalPath // to save the filepath on the yml file, change the source
			}
		}
	}

	var err error
	if g.releaseFile == nil {
		g.releaseFile, err = os.Create(filepath.Join(g.baseDir, "release.yml"))
		if err != nil {
			return err
		}
	}

	bs, err := yaml.Marshal(releases)
	if err != nil {
		return err
	}

	if _, err := g.releaseFile.Write(bs); err != nil {
		return err
	}

	return nil
}

// SyncTags syncs releases with tags in the database
func (g *RepositoryDumper) SyncTags() error {
	return nil
}

// CreateIssues creates issues
func (g *RepositoryDumper) CreateIssues(issues ...*base.Issue) error {
	var err error
	if g.issueFile == nil {
		g.issueFile, err = os.Create(filepath.Join(g.baseDir, "issue.yml"))
		if err != nil {
			return err
		}
	}

	bs, err := yaml.Marshal(issues)
	if err != nil {
		return err
	}

	if _, err := g.issueFile.Write(bs); err != nil {
		return err
	}

	return nil
}

func (g *RepositoryDumper) createItems(dir string, itemFiles map[int64]*os.File, itemsMap map[int64][]interface{}) error {
	if err := os.MkdirAll(dir, os.ModePerm); err != nil {
		return err
	}

	for number, items := range itemsMap {
		var err error
		itemFile := itemFiles[number]
		if itemFile == nil {
			itemFile, err = os.Create(filepath.Join(dir, fmt.Sprintf("%d.yml", number)))
			if err != nil {
				return err
			}
			itemFiles[number] = itemFile
		}

		bs, err := yaml.Marshal(items)
		if err != nil {
			return err
		}

		if _, err := itemFile.Write(bs); err != nil {
			return err
		}
	}

	return nil
}

// CreateComments creates comments of issues
func (g *RepositoryDumper) CreateComments(comments ...*base.Comment) error {
	var commentsMap = make(map[int64][]interface{}, len(comments))
	for _, comment := range comments {
		commentsMap[comment.IssueIndex] = append(commentsMap[comment.IssueIndex], comment)
	}

	return g.createItems(g.commentDir(), g.commentFiles, commentsMap)
}

// CreatePullRequests creates pull requests
func (g *RepositoryDumper) CreatePullRequests(prs ...*base.PullRequest) error {
	for _, pr := range prs {
		// download patch file
		err := func() error {
			u, err := g.setURLToken(pr.PatchURL)
			if err != nil {
				return err
			}
			resp, err := http.Get(u)
			if err != nil {
				return err
			}
			defer resp.Body.Close()
			pullDir := filepath.Join(g.gitPath(), "pulls")
			if err = os.MkdirAll(pullDir, os.ModePerm); err != nil {
				return err
			}
			fPath := filepath.Join(pullDir, fmt.Sprintf("%d.patch", pr.Number))
			f, err := os.Create(fPath)
			if err != nil {
				return err
			}
			defer f.Close()
			if _, err = io.Copy(f, resp.Body); err != nil {
				return err
			}
			pr.PatchURL = "git/pulls/" + fmt.Sprintf("%d.patch", pr.Number)

			return nil
		}()
		if err != nil {
			return err
		}

		// set head information
		pullHead := filepath.Join(g.gitPath(), "refs", "pull", fmt.Sprintf("%d", pr.Number))
		if err := os.MkdirAll(pullHead, os.ModePerm); err != nil {
			return err
		}
		p, err := os.Create(filepath.Join(pullHead, "head"))
		if err != nil {
			return err
		}
		_, err = p.WriteString(pr.Head.SHA)
		p.Close()
		if err != nil {
			return err
		}

		if pr.IsForkPullRequest() && pr.State != "closed" {
			if pr.Head.OwnerName != "" {
				remote := pr.Head.OwnerName
				_, ok := g.prHeadCache[remote]
				if !ok {
					// git remote add
					// TODO: how to handle private CloneURL?
					err := g.gitRepo.AddRemote(remote, pr.Head.CloneURL, true)
					if err != nil {
						log.Error("AddRemote failed: %s", err)
					} else {
						g.prHeadCache[remote] = struct{}{}
						ok = true
					}
				}

				if ok {
					_, err = git.NewCommand("fetch", remote, pr.Head.Ref).RunInDir(g.gitPath())
					if err != nil {
						log.Error("Fetch branch from %s failed: %v", pr.Head.CloneURL, err)
					} else {
						// a new branch name with <original_owner_name/original_branchname> will be created to as new head branch
						ref := path.Join(pr.Head.OwnerName, pr.Head.Ref)
						headBranch := filepath.Join(g.gitPath(), "refs", "heads", ref)
						if err := os.MkdirAll(filepath.Dir(headBranch), os.ModePerm); err != nil {
							return err
						}
						b, err := os.Create(headBranch)
						if err != nil {
							return err
						}
						_, err = b.WriteString(pr.Head.SHA)
						b.Close()
						if err != nil {
							return err
						}
						pr.Head.Ref = ref
					}
				}
			}
		}
		// whatever it's a forked repo PR, we have to change head info as the same as the base info
		pr.Head.OwnerName = pr.Base.OwnerName
		pr.Head.RepoName = pr.Base.RepoName
	}

	var err error
	if g.pullrequestFile == nil {
		if err := os.MkdirAll(g.baseDir, os.ModePerm); err != nil {
			return err
		}
		g.pullrequestFile, err = os.Create(filepath.Join(g.baseDir, "pull_request.yml"))
		if err != nil {
			return err
		}
	}

	bs, err := yaml.Marshal(prs)
	if err != nil {
		return err
	}

	if _, err := g.pullrequestFile.Write(bs); err != nil {
		return err
	}

	return nil
}

// CreateReviews create pull request reviews
func (g *RepositoryDumper) CreateReviews(reviews ...*base.Review) error {
	var reviewsMap = make(map[int64][]interface{}, len(reviews))
	for _, review := range reviews {
		reviewsMap[review.IssueIndex] = append(reviewsMap[review.IssueIndex], review)
	}

	return g.createItems(g.reviewDir(), g.reviewFiles, reviewsMap)
}

// Rollback when migrating failed, this will rollback all the changes.
func (g *RepositoryDumper) Rollback() error {
	g.Close()
	return os.RemoveAll(g.baseDir)
}

// Finish when migrating succeed, this will update something.
func (g *RepositoryDumper) Finish() error {
	return nil
}

// DumpRepository dump repository according MigrateOptions to a local directory
func DumpRepository(ctx context.Context, baseDir, ownerName string, opts base.MigrateOptions) error {
	downloader, err := newDownloader(ctx, ownerName, opts)
	if err != nil {
		return err
	}
	uploader, err := NewRepositoryDumper(ctx, baseDir, ownerName, opts.RepoName, opts)
	if err != nil {
		return err
	}

	if err := migrateRepository(downloader, uploader, opts, nil); err != nil {
		if err1 := uploader.Rollback(); err1 != nil {
			log.Error("rollback failed: %v", err1)
		}
		return err
	}
	return nil
}

func updateOptionsUnits(opts *base.MigrateOptions, units []string) {
	if len(units) == 0 {
		opts.Wiki = true
		opts.Issues = true
		opts.Milestones = true
		opts.Labels = true
		opts.Releases = true
		opts.Comments = true
		opts.PullRequests = true
		opts.ReleaseAssets = true
	} else {
		for _, unit := range units {
			switch strings.ToLower(unit) {
			case "wiki":
				opts.Wiki = true
			case "issues":
				opts.Issues = true
			case "milestones":
				opts.Milestones = true
			case "labels":
				opts.Labels = true
			case "releases":
				opts.Releases = true
			case "release_assets":
				opts.ReleaseAssets = true
			case "comments":
				opts.Comments = true
			case "pull_requests":
				opts.PullRequests = true
			}
		}
	}
}

// RestoreRepository restore a repository from the disk directory
func RestoreRepository(ctx context.Context, baseDir, ownerName, repoName string, units []string) error {
	doer, err := user_model.GetAdminUser()
	if err != nil {
		return err
	}
	var uploader = NewGiteaLocalUploader(ctx, doer, ownerName, repoName)
	downloader, err := NewRepositoryRestorer(ctx, baseDir, ownerName, repoName)
	if err != nil {
		return err
	}
	opts, err := downloader.getRepoOptions()
	if err != nil {
		return err
	}
	tp, _ := strconv.Atoi(opts["service_type"])

	var migrateOpts = base.MigrateOptions{
		GitServiceType: structs.GitServiceType(tp),
	}
	updateOptionsUnits(&migrateOpts, units)

	if err = migrateRepository(downloader, uploader, migrateOpts, nil); err != nil {
		if err1 := uploader.Rollback(); err1 != nil {
			log.Error("rollback failed: %v", err1)
		}
		return err
	}
	return updateMigrationPosterIDByGitService(ctx, structs.GitServiceType(tp))
}
